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Sample records for pyramid-like v-shape groove

  1. Rayleigh-Plateau instability of slipping viscous filaments in v-shaped grooves

    Science.gov (United States)

    Brinkmann, Martin; Chan, Tak Shing; Seemann, Ralf

    2016-11-01

    Since the seminal works of Rayleigh and Plateau on the break-up of free-standing liquid jets, a large number of studies have addressed capillary instability of cylindrical interfaces in various settings. Here, we report the numerical results of a linear stability analysis of cylindrical liquid filament wetting v-shaped grooves employing a boundary element formalism. It is found that slip affects the wavelength λmax of the fastest growing mode whenever the transverse dimension W of the filaments is comparable, or smaller than the Navier slip-length B. The corresponding timescale of the decay, τmax, grows logarithmically with increasing B / W . In the opposite limit B / W > 1 are in good agreement with the numerical results only for contact angles 0 < θ - Ψ << 1 where the neutrally stable wavelength λ* <λmax is large compared to the transverse filament dimension W.

  2. Study of image processing for V-shape groove and robotic weld seam tracking based on laser vision

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Single-stripe laser was applied to acquire V-shape groove contour information. Most of arc light and splash noise was removed and stripe laser image was kept by wavelet transform. Half-threshold algorithm was used for image segmentation and stripe laser image was gotten after refining. Weld seam center position was identified and extracted by extreme curvature corner detection method. The location of torch was detected to accord the frequency of computer program with robot program and serial communication program. The tracking experiments of sidelong, reflex and curve weld line show that the system can meet the demand of the tracking precision under normal welding conditions.

  3. Differences in the thickness of mouthguards fabricated from ethylene vinyl acetate copolymer sheets with differently arranged v-shaped grooves: part 2 - effect of shape on the working model.

    Science.gov (United States)

    Takahashi, Mutsumi; Koide, Kaoru; Mizuhashi, Fumi

    2014-12-01

    The aim of this study was to evaluate the change in thickness of a working model mouthguard sheet due to different shape. Mouthguards were fabricated with ethylene vinyl acetate (EVA) sheets (4.0 mm thick) using a vacuum-forming machine. Two shapes of the sheet were compared: normal sheet or v-shaped groove 10-40 mm from the anterior end. Additionally, two shapes of the working model were compared; the basal plane was vertical to the tooth axis of the maxillary central incisor (condition A), and the occlusal plane was parallel to the basal plane (condition B). Sheets were heated until they sagged 15 mm below the clamp. Postmolding thickness was determined for the incisal portion (incisal edge and labial surface) and molar portion (cusp and buccal surface). Differences in the change in thickness due to the shape of the sheets and model were analyzed using two-way anova followed by a Bonferroni's multiple comparison tests. The thickness of the mouthguard sheet with v-shaped grooves was more than that of the normal sheet at all measuring points under condition A and condition B (P < 0.01). The thickness of condition B was less than that of condition A, there the incisal portion in the normal sheet and the incisal edge in the sheet with v-shaped grooves (P < 0.01). The present results suggested that thickness after molding was secured by the use of the sheet with v-shaped grooves. In particular, the model with the undercut on the labial surface may be clinically useful.

  4. "V"-shape rescection combined with shallow groove reconstruction to treat ingrown toenail paronychia%甲沟“V”形切除合并浅甲沟重建用于治疗嵌甲性甲沟炎的疗效观察

    Institute of Scientific and Technical Information of China (English)

    王春生; 钟怡鸣; 孙焕伟; 张洪权; 杨卫东; 高斌; 苏毅; 何明达

    2015-01-01

    目的:探讨并总结甲沟“V”形切除合并浅甲沟重建用于治疗嵌甲性甲沟炎的手术方法及临床疗效。方法2007年7月—2013年12月,对313例共计584趾嵌甲性甲沟炎实施甲沟“V”形切除合并浅甲沟重建术,分析并总结手术疗效。结果本组切口均达到一期愈合,且实现了甲沟一期成形,仅15例复发,有效率达95.1%。结论该术式简单易行,操作方便,对趾甲及软组织损伤小,对病灶切除彻底,治愈率高,病程短,值得临床广泛推广。%Objective To explore and summarize the nail groove operation procedure and clinical effect of"V" font resection combined with shallow groove reconstruction for the treatment of ingrown toenail of paronychia. Methods From July 2007-December 2013, 313 cases of total 584 ingrown toenails paronychia were treated by"V"shaped excision combined with shallow groove reconstruction. Analyze and summarize the clinical characteristics and therapeutic effect. Results All patients achieved I incision healing, and realize I phase reforming, only 15 cases of recurrence, the effective rate was 95.1%. Conclusion The technique is simple, operation is convenient, the toenail and soft tissue injury is small, complete resection of lesions, the cure rate is high, short duration, and is worth of extensive popularization.

  5. Combined Effects of Pyramid-Like Structures and Antireflection Coating on Si Solar Cell Efficiency.

    Science.gov (United States)

    Cho, Chanseob; Oh, Junghwa; Lee, Byeungleul; Kim, Bonghwan

    2015-10-01

    We developed a novel process for synthesizing Si solar cells with improved efficiencies. The process involved the formation of pyramid-like structures on the Si substrate and the deposition and subsequent thermal annealing of an antireflection coating. The process consisted of three main stages. First, pyramid-like structures were textured on the Si substrate by reactive ion etching and subsequently etched using a mixture of HF, HNO3, and deionized water for 300 s. Next, an antireflection coating was deposited on the substrate and was subsequently thermally annealed in a furnace in a N2 atmosphere. After the annealing process, the minority carrier lifetime increased by approximately 40 μs. Further, because of the increase in the minority carrier lifetime and the uniform doping of the substrate, the leakage current decreased. As a result, the efficiency of resulting solar cell increased to 17.24%, in contrast to that of the reference cell, which was only 15.89%. Thus, uniform doping and the thermal annealing of the antireflective coating improved solar cell efficiency.

  6. Sulfolobus Turreted Icosahedral Virus c92 Protein Responsible for the Formation of Pyramid-Like Cellular Lysis Structures

    DEFF Research Database (Denmark)

    Snyder, Jamie C; Brumfield, Susan K; Peng, Nan;

    2011-01-01

    Host cells infected by Sulfolobus turreted icosahedral virus (STIV) have been shown to produce unusual pyramid-like structures on the cell surface. These structures represent a virus-induced lysis mechanism that is present in Archaea and appears to be distinct from the holin/endolysin system...... described for DNA bacteriophages. This study investigated the STIV gene products required for pyramid formation in its host Sulfolobus solfataricus. Overexpression of STIV open reading frame (ORF) c92 in S. solfataricus alone is sufficient to produce the pyramid-like lysis structures in cells. Gene...... disruption of c92 within STIV demonstrates that c92 is an essential protein for virus replication. Immunolocalization of c92 shows that the protein is localized to the cellular membranes forming the pyramid-like structures....

  7. Sulfolobus turreted icosahedral virus c92 protein responsible for the formation of pyramid-like cellular lysis structures.

    Science.gov (United States)

    Snyder, Jamie C; Brumfield, Susan K; Peng, Nan; She, Qunxin; Young, Mark J

    2011-07-01

    Host cells infected by Sulfolobus turreted icosahedral virus (STIV) have been shown to produce unusual pyramid-like structures on the cell surface. These structures represent a virus-induced lysis mechanism that is present in Archaea and appears to be distinct from the holin/endolysin system described for DNA bacteriophages. This study investigated the STIV gene products required for pyramid formation in its host Sulfolobus solfataricus. Overexpression of STIV open reading frame (ORF) c92 in S. solfataricus alone is sufficient to produce the pyramid-like lysis structures in cells. Gene disruption of c92 within STIV demonstrates that c92 is an essential protein for virus replication. Immunolocalization of c92 shows that the protein is localized to the cellular membranes forming the pyramid-like structures.

  8. Bcl-2/MDM2 Dual Inhibitors Based on Universal Pyramid-Like α-Helical Mimetics.

    Science.gov (United States)

    Wang, Ziqian; Song, Ting; Feng, Yingang; Guo, Zongwei; Fan, Yudan; Xu, Wenjie; Liu, Lu; Wang, Anhui; Zhang, Zhichao

    2016-04-14

    No α-helical mimetic that exhibits Bcl-2/MDM2 dual inhibition has been rationally designed due to the different helicities of the α-helixes at their binding interfaces. Herein, we extracted a one-turn α-helix-mimicking ortho-triarene unit from o-phenylene foldamers. Linking benzamide substrates with a rotatable C-N bond, we constructed a novel semirigid pyramid-like scaffold that could support its two-turn α-helix mimicry without aromatic stacking interactions and could adopt the different dihedral angles of the key residues of p53 and BH3-only peptides. On the basis of this universal scaffold, a series of substituent groups were installed to capture the key residues of both p53TAD and BimBH3 and balance the differences of the bulks between them. Identified by FP, ITC, and NMR spectroscopy, a compound 6e (zq-1) that directly binds to Mcl-1, Bcl-2, and MDM2 with balanced submicromolar affinities was obtained. Cell-based experiments demonstrated its antitumor ability through Bcl-2/MDM2 dual inhibition simultaneously.

  9. Surface reproduction of elastomeric materials: viscosity and groove shape effects

    OpenAIRE

    Mahmood, N.; Abu Kasim, N.H.; Azuddin, M.; Kasim, N.L. Abu

    2010-01-01

    Objective: To evaluate the effect of viscosity and type of grooves on surface detail reproduction of elastomeric impression materials. Methods: Express putty/light-, Impregum medium- and heavy/light-bodied and Aquasil medium- and putty/light-bodied elastomeric impression materials were chosen for this study. Five impressions were made using a cylindrical aluminum reference block with U- and V- shaped grooves and to produce 35 master dies. Each master die was immersed in distilled water at 370...

  10. Durability test device for MR fluids with permanent magnet and V-shaped groove

    Science.gov (United States)

    Abe, Isao; Kikuchi, Takehito; Noma, Junichi

    2017-05-01

    Magnetorheological fluids (MRFs) are functional fluids whose viscosity changes when magnetic fields are applied. Therefore, these fluids are used in force and torque controllable devices. However, particle sedimentation is one of the drawbacks of conventional MRFs. To solve this problem, Kurimoto Co. Ltd developed a new fluid with sub-micron order Fe particles and a silicone-based solvent known as NanoMRF. The particle distributions of this material are stable over several months. However, its durability has not yet been fully discussed. Therefore, we developed new equipment to test endurance and examined the durability of the magnetorheological effect of the NanoMRF as well as a commercially available MRF. Our results show that the durability of the fluids was affected by the stability of the solvent. In particular, the durability is drastically improved when the solvent is supplemented by the peripheral sealing oil. The oxidation of particles is remarkably varied by the kind of solvent as well as the stability of the oxidation film on the surface of the particles. The energy of the collapse and reproduction of the particles was used not only to generate friction among the particles but also to decompose the solvent molecules.

  11. Resistance of full veneer metal crowns with different forms of axial grooves

    Science.gov (United States)

    Hidayat, A. S.; Masulili, C.; Indrasari, M.

    2017-08-01

    Dental crowns or bridges can occasionally come loose or separate from the tooth during chewing, particularly when they are situated on small, short, and conical teeth. The main cause of this separation is a lack of retention and resistance to the tooth. There are several methods available to increase the retention and resistance of the crown during both inlay and onlay preparation, including parallelism, groove preparation, crown build-up, and surface roughness. The aim of this study was to determine the differences in resistance of full veneer metal crowns with various forms of groove preparation. The study involved the compressive strength testing of a total of 24 specimens, namely six specimens without groove preparation, six specimens with box-shaped grooves, six specimens with V-shaped grooves, and six specimens with half round grooves. The mean values of the metal crowns that separated from the teeth during testing were 27.97 ± 1.08 kgF for the crowns with box-shaped grooves, 6.15 ± 0.22 kgF for those with V-shaped grooves, 1.77 ± 0.12 kgF for those with half round grooves, and 0.95 ± 0.13 kgF for those without grooves. This study found that the resistance is best in crowns with box-shaped grooves, followed by those with V-shaped grooves, half round grooves, and those without groove. When clinicians are working on short and conical molar teeth, it is therefore recommended that box-shaped grooves are used to increase the resistance of the crown.

  12. 挖掘机动臂单边V形坡口角焊缝的焊接工艺与应用%Welding Processes and Applications Excavator Boom Unilateral V-shaped Bevel Welds

    Institute of Scientific and Technical Information of China (English)

    宋秀山

    2014-01-01

    The study of the excavator boom unilateral V-shaped groove welding process to solve the lack of penetration, cracks, slag and other welding defects in the welding process unilateral V-shaped groove that appears to improve the boom overall reliability.%通过对挖掘机动臂单边V形坡口焊接工艺的研究,解决了在焊接过程中单边V形坡口出现的未焊透、裂纹、夹渣等焊接缺陷,提高了动臂的整体可靠性。

  13. Monolayer-by-monolayer stacked pyramid-like MoS2 nanodots on monolayered MoS2 flakes with enhanced photoluminescence.

    Science.gov (United States)

    Yuan, Cailei; Cao, Yingjie; Luo, Xingfang; Yu, Ting; Huang, Zhenping; Xu, Bo; Yang, Yong; Li, Qinliang; Gu, Gang; Lei, Wen

    2015-11-07

    The precise control of the morphology and crystal shape of MoS2 nanostructures is of particular importance for their application in nanoelectronic and optoelectronic devices. Here, we describe a single step route for the synthesis of monolayer-by-monolayer stacked pyramid-like MoS2 nanodots on monolayered MoS2 flakes using a chemical vapor deposition method. First-principles calculations demonstrated that the bandgap of the pyramid-like MoS2 nanodot is a direct bandgap. Enhanced local photoluminescence emission was observed in the pyramid-like MoS2 nanodot, in comparison with monolayered MoS2 flakes. The findings presented here provide new opportunities to tailor the physical properties of MoS2via morphology-controlled synthesis.

  14. V-shaped nematogens with the "magic bent angle".

    Science.gov (United States)

    Seltmann, Jens; Müller, Kathrin; Klein, Susanne; Lehmann, Matthias

    2011-06-21

    V-shaped nematogens 1a-c and 2a-b with benzodithiophene bending units have been synthesised. The derivatives 1a-c comprise a flat core with a bending angle of 109°, which is almost the tetrahedral angle proposed to be optimal in the realization of mesogens forming a biaxial nematic thermotropic mesophase.

  15. Texturing a pyramid-like structure on a silicon surface via the synergetic effect of copper and Fe(III) in hydrofluoric acid solution

    Science.gov (United States)

    Cao, Ming; Li, Shaoyuan; Deng, Jianxin; Li, Yuping; Ma, Wenhui; Zhou, Yang

    2016-05-01

    An innovative approach is proposed to texture a pyramid structure on a silicon surface via Cu-catalyzed chemical etching in the HF/FeCl3 system. The surface and cross-section morphologies of the formed pyramid structure were examined by scanning electron microscopy and atomic force microscopy. The results revealed that numerous silicon pyramid-like structures with hemlines of 0.1 ∼ 3 μm and height of 0.1 ∼ 2 μm are close together, and the top angle of the pyramid structure is 90°. Additionally, the systematic study of the effects of the etching time and the concentration of FeCl3 on the pyramid-like structures by the atom configuration model of silicon crystal faces demonstrated that the etching proceeds preferentially along the directions of silicon. A formation mechanism of the pyramid-like structure is proposed. The results imply that the synergetic effect of Cu nanoparticles and Fe(III) could conveniently generate a pyramid-like architecture on the surface of silicon in hydrofluoric acid solution.

  16. Yarkovsky V-shape identification of asteroid families

    Science.gov (United States)

    Bolin, Bryce T.; Delbo, Marco; Morbidelli, Alessandro; Walsh, Kevin J.

    2017-01-01

    There are only a few known main belt (MB) asteroid families with ages greater than 2 Gyr (Brož et al., 2013; Spoto et al., 2015). Estimates based on the family producing collision rate suggest that the lack of > 2 Gyr-old families may be due to a selection bias in current techniques used to identify families. Family fragments disperse in their orbital elements, semi-major axis, a, eccentricity, e, and inclination, i, due to secular resonances, close encounters with massive asteroids and the non-gravitational Yarkovsky force. This causes the family fragments to be indistinguishable from the background of the main belt making them more difficult to identify with the hierarchical clustering method (HCM) with increasing family age. The discovery of the Eulalia and new Polana families in the inner belt relied on new techniques because Yarkovsky spreading made them too disperse to be identified using the classical HCM. The techniques used to discover the new Polana and Eulalia families are modified here to identify asteroid families by searching for correlations between a and asteroid diameter, D, or absolute magnitude, H. A group of asteroids is identified as a collisional family if its boundary in the a vs. 1/D or a vs. H planes has a characteristic V-shape which is due to the size dependent Yarkovsky spreading. The V-shape boundary is identified with two separate techniques. The first technique identifies a border by measuring a steep drop between the number of objects inside and outside of the border. The second technique identifies the V-shape border by measuring a peak in the number density of objects in a vs. 1/D , H space. Families are identified with just one or both V-shape identifying techniques. The V-shape techniques are demonstrated on the known families of Erigone, Vesta, Koronis, and families difficult to identify by HCM such as Flora, Baptistina, new Polana, Eulalia and Karin. Future applications of the technique, such as in a large scale search for > 2

  17. V-shaped resonators for addition of broad-area laser diode arrays

    Science.gov (United States)

    Liu, Bo; Liu, Yun; Braiman, Yehuda Y.

    2012-12-25

    A system and method for addition of broad-area semiconductor laser diode arrays are described. The system can include an array of laser diodes, a V-shaped external cavity, and grating systems to provide feedback for phase-locking of the laser diode array. A V-shaped mirror used to couple the laser diode emissions along two optical paths can be a V-shaped prism mirror, a V-shaped stepped mirror or include multiple V-shaped micro-mirrors. The V-shaped external cavity can be a ring cavity. The system can include an external injection laser to further improve coherence and phase-locking.

  18. Forming mechanism of radial V-shaped microgrooves on plate using step punching method

    Directory of Open Access Journals (Sweden)

    Xiang Jian-hua

    2015-02-01

    Full Text Available The finned surface can increase the specific surface area, which could enhance the boiling efficiency of the working medium to realize the enhancement of heat transfer performance. This research adopted a step punching method to form a radial microgroove structure on the surface of a copper plate. The scanning electron microscopy analysis indicates that when the pressed metal is in the deformation range, it will flow under extrusion and is subject to the reaction force from the metal outside the deformation range, so a micro-finned structure nearby the punching tool is formed. And the deformation area of the formed microgroove is higher than the workpiece’s primitive surface. The relationships of the punching interference length Li with θc, ac, and αpt are analyzed; and the influence of forming parameters on the groove surface morphology as well as the relationships among these parameters are discussed. When the punching depth ac is 0.3 mm and the punching feeding angle θc is 2°–4°, the finned surface of the radial V-shaped microgrooves can be obtained.

  19. Yarkovsky V-shape identification of asteroid families

    Science.gov (United States)

    Bolin, Bryce T.; Delbo, Marco; Morbidelli, Alessandro; Walsh, Kevin J.

    2016-10-01

    There are only a few known main belt (MB) asteroid families with ages greater than 2 Gyrs. Estimates based on the family producing collision rate suggest that the lack of >2 Gyr-old families may be due to a selection bias in current techniques used to identify families. Family fragments disperse in their orbital elements, semi-major axis, a, eccentricity, e and inclination, i due to secular resonances, close encounters with massive asteroids and the non-gravitational Yarkovsky force. This causes the family fragments to be indistinguishable from the background of the main belt making them more difficult to identify with the hierarchical clustering method (HCM) with increasing family age. The discovery of the Eulalia and Polana families in the inner belt relied on new techniques because they were overlapping families, also, or primarily, because Yarkovsky spreading over their 2 Gyr-old lifetime made them too disperse to be identified using the classical HCM. The techniques used to discover the Polana and Eulalia are modified here to identify asteroid families by searching for correlations between a and absolute magnitude, H, the family's characteristic V-shape. In addition to demonstrating the V-shape technique on known families such as Erigone, Vesta, Flora and Polana, we will present a new investigation of the asteroid belt with this new tool looking for old, previously unidentified families.

  20. Pancreatic groove cancer

    Science.gov (United States)

    Ku, Yuan-Hao; Chen, Shih-Chin; Shyr, Bor-Uei; Lee, Rheun-Chuan; Shyr, Yi-Ming; Wang, Shin-E.

    2017-01-01

    Abstract Pancreatic groove cancer is very rare and can be indistinguishable from groove pancreatitis. This study is to clarify the characteristics, clinical features, managements, and survival outcomes of this rare tumor. Brief descriptions were made for each case of pancreatic groove cancer encountered at our institute. Individualized data of pancreatic groove cancer cases described in the literature were extracted and added to our database to expand the study sample size for a more complete analysis. A total of 33 patients with pancreatic groove cancer were included for analysis, including 4 cases from our institute. The median tumor size was 2.7 cm. The most common symptom was nausea or vomiting (89%), followed by jaundice (67%). Duodenal stenosis was noted by endoscopy in 96% of patients. The histopathological examination revealed well differentiated tumor in 43%. Perineural invasion was noted in 90%, and lymphovascular invasion and lymph node involvement in 83%. Overall 1-year survival rate was 93.3%, and 3- or 5-year survival rate was 62.2%, with a median survival of 11.0 months. Survival outcome for the well-differentiated tumors was better than those of the moderate/poorly differentiated ones. Early involvement of duodenum causing vomiting is often the initial presentation, but obstructive jaundice does not always happen until the disease progresses. Tumor differentiation is a prognostic factor for survival outcome. The possibility of pancreatic groove cancer should be carefully excluded before making the diagnosis of groove pancreatitis for any questionable case. PMID:28079795

  1. High Excitation Efficiency of Channel Plasmon Polaritons in Tailored, UV-Lithography-Defined V-Grooves

    DEFF Research Database (Denmark)

    Smith, Cameron; Thilsted, Anil Haraksingh; Garcia-Ortiz, Cesar E.

    2014-01-01

    We demonstrate >50% conversion of light to V-groove channel plasmon-polaritons (CPPs) via compact waveguide-termination mirrors. Devices are fabricated using UV-lithography and crystallographic silicon etching. The V-shape is tailored by thermal oxidation to support confined CPPs....

  2. Efficient Excitation of Channel Plasmons in Tailored, UV-Lithography-Defined V-Grooves

    DEFF Research Database (Denmark)

    Smith, Cameron L. C.; Thilsted, Anil Haraksingh; Garcia-Ortiz, Cesar E.

    2014-01-01

    silicon etching, forms the coupling mirrors innately and ensures exceptional-quality, wafer-scale device production. We tailor the V-shaped profiles by thermal silicon oxidation in order to shift initially wedge-located modes downward into the V-grooves, resulting in well-confined CPPs suitable...

  3. Self-propulsion of V-shape micro-robot

    CERN Document Server

    Vladimirov, Vladimir A

    2012-01-01

    In this paper we study the self-propulsion of a symmetric V-shape micro-robot (or V-robot) which consists of three spheres connected by two arms with an angle between them; the arms' lengths and the angle are changing periodically. Using an asymptotic procedure containing two-timing method and a distinguished limit, we obtain analytic expressions for the self-propulsion velocity and Lighthill's efficiency. The calculations show that a version of V-robot, aligned perpendicularly to the direction of self-swimming, is both the fastest one and the most efficient one. We have also shown that such $V$-robot is faster and more efficient than a linear three-sphere micro-robot. At the same time the maximal self-propulsion velocity of V-robots is significantly smaller than that of comparable microorganisms.

  4. Polymer scaffolds with preferential parallel grooves enhance nerve regeneration.

    Science.gov (United States)

    Mobasseri, Atefeh; Faroni, Alessandro; Minogue, Ben M; Downes, Sandra; Terenghi, Giorgio; Reid, Adam J

    2015-03-01

    We have modified the surface topography of poly ɛ-caprolactone (PCL) and polylactic acid (PLA) blended films to improve cell proliferation and to guide the regeneration of peripheral nerves. Films with differing shaped grooves were made using patterned silicon templates, sloped walls (SL), V-shaped (V), and square-shaped (SQ), and compared with nongrooved surfaces with micropits. The solvent cast films were tested in vitro using adult adipose-derived stem cells differentiated to Schwann cell-like cells. Cell attachment, proliferation, and cell orientation were all improved on the grooved surfaces, with SL grooves giving the best results. We present in vivo data on Sprague-Dawley rat sciatic nerve injury with a 10-mm gap, evaluating nerve regeneration at 3 weeks across a polymer nerve conduit modified with intraluminal grooves (SL, V, and SQ) and differing wall thicknesses (70, 100, 120, and 210 μm). The SL-grooved nerve conduit showed a significant improvement over the other topographical-shaped grooves, while increasing the conduit wall thickness saw no positive effect on the biological response of the regenerating nerve. Furthermore, the preferred SL-grooved conduit (C) with 70 μm wall thickness was compared with the current clinical gold standard of autologous nerve graft (Ag) in the rat 10-mm sciatic nerve gap model. At 3 weeks postsurgery, all nerve gaps across both groups were bridged with regenerated nerve fibers. At 16 weeks, features of regenerated axons were comparable between the autograft (Ag) and conduit (C) groups. End organ assessments of muscle weight, electromyography, and skin reinnervation were also similar between the groups. The comparable experimental outcome between conduit and autograft, suggests that the PCL/PLA conduit with inner lumen microstructured grooves could be used as a potential alternative treatment for peripheral nerve repair.

  5. COMBINED EFFECT OF MECHANICAL GROOVING AND STAIN-ETCHED SURFACE ON OPTICAL AND ELECTRICAL PROPERTIES OF CRYSTALLINE SILICON SUBSTRATES

    OpenAIRE

    AHMED ZARROUG; LOTFI DERBALI; RACHID OUERTANI; WISSEM DIMASSI; HATEM EZZAOUIA

    2014-01-01

    This paper investigates the combined effect of mechanical grooving and porous silicon (PS) on the front surface reflectance and the electronic properties of crystalline silicon substrates. Mechanical surface texturization leads to reduce the cell reflectance, enhance the light trapping and augment the carrier collection probability. PS was introduced as an efficient antireflective coating (ARC) onto the front surface of crystalline silicon solar cell. Micro-periodic V-shaped grooves were made...

  6. NUMERICAL SIMULATION OF A PREMIXED TURBULENT V-SHAPED FLAME

    Directory of Open Access Journals (Sweden)

    M I El Khazen

    2011-01-01

    Full Text Available In this paper we simulate a turbulent premixed V-shape flame stabilized on a hot wire. The device used is composed of a vertical combustion chamber where the methane-air mixture is convected upwards with a mean velocity of 4ms-1. The flow was simulated running Fluent 6.3, which numerically solved the stationary Favre-averaged mass balance; Navier-Stokes equations; combustion progress variable, and k-ε equations on a two-dimensional numerical mesh. We model gaseous mixture, ignoring Soret and Dufour effects and radiation heat transfer. The progress variable balance equation was closed using Eddy Break Up model. The results of our simulations allow us to analyze the influence of equivalence ratio and the turbulent intensity on the properties of the flame (velocity, fluctuation, progress variable and Thickness of flame.This work gives us an idea on the part which turbulence can play to decrease the risks of extinction and instabilities caused by the lean premixed combustion.

  7. Screw-dislocation-driven growth of two-dimensional few-layer and pyramid-like WSe₂ by sulfur-assisted chemical vapor deposition.

    Science.gov (United States)

    Chen, Liang; Liu, Bilu; Abbas, Ahmad N; Ma, Yuqiang; Fang, Xin; Liu, Yihang; Zhou, Chongwu

    2014-11-25

    Two-dimensional (2D) layered tungsten diselenides (WSe2) material has recently drawn a lot of attention due to its unique optoelectronic properties and ambipolar transport behavior. However, direct chemical vapor deposition (CVD) synthesis of 2D WSe2 is not as straightforward as other 2D materials due to the low reactivity between reactants in WSe2 synthesis. In addition, the growth mechanism of WSe2 in such CVD process remains unclear. Here we report the observation of a screw-dislocation-driven (SDD) spiral growth of 2D WSe2 flakes and pyramid-like structures using a sulfur-assisted CVD method. Few-layer and pyramid-like WSe2 flakes instead of monolayer were synthesized by introducing a small amount of sulfur as a reducer to help the selenization of WO3, which is the precursor of tungsten. Clear observations of steps, helical fringes, and herringbone contours under atomic force microscope characterization reveal the existence of screw dislocations in the as-grown WSe2. The generation and propagation mechanisms of screw dislocations during the growth of WSe2 were discussed. Back-gated field-effect transistors were made on these 2D WSe2 materials, which show on/off current ratios of 10(6) and mobility up to 44 cm(2)/(V·s).

  8. Analytical modeling and experimental validation of a V-shape piezoelectric ultrasonic transducer

    Science.gov (United States)

    Li, Xiaoniu; Yao, Zhiyuan

    2016-07-01

    In this paper, an analytical model of a V-shape piezoelectric ultrasonic transducer is presented. The V-shape piezoelectric ultrasonic transducer has been widely applied to the piezoelectric actuator (ultrasonic motor), ultrasonic aided fabrication, sensor, and energy harvesting device. The V-shape piezoelectric ultrasonic transducer consists of two Langevin-type transducers connected together through a coupling point with a certain coupling angle. Considering the longitudinal and lateral movements of a single beam, the symmetrical and asymmetrical modals of the V-shape piezoelectric ultrasonic transducer are calculated. By using Hamilton-Lagrange equations, the electromechanical coupling model of the V-shape piezoelectric ultrasonic transducer is proposed. The influence of the coupling angle and cross-section on modal characteristics and electromechanical coupling coefficient are analyzed by the analytical model. A prototype of the V-shape piezoelectric ultrasonic transducer is fabricated, and the results of the experiments are in good agreement with the analytical model.

  9. Groove / Solar energy cataloque; Groove aurinkoenergian yritysluettelo

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-06-01

    According to Tekes, renewable energy offer Finnish companies opportunities for renewal and international growth. Especially in the field of solar energy, development is fast and the market is growing rapidly. The purpose of this catalogue is to provide information about organizations active in the field of solar energy so that different players can find each other more easily. Information is provided about organizations active both on the supply side (solar energy solution and service providers) and demand side (cities, construction contractors, real estate owners) as well as research teams at universities and research centers. We hope that this catalogue will help different actors to find each other both nationally and internationally so that good development and demonstration projects in the field of solar energy can get started. Tekes participates for instance in Solar Eranet, a joint effort of several funding organizations in Europe support transnational solar projects. This catalogue is provided by Tekes program Groove - Growth from renewables. Tekes' programmes and initiatives are topical entities targeted at financial and expert service areas. Within the programmes and initiatives, businesses and public research units can develop new know-how, build networks and have an impact on the development of their field. (orig.)

  10. Propagation of Channel Plasmons at the Visible Regime in Aluminum V-Groove Waveguides

    DEFF Research Database (Denmark)

    Lotan, Oren; Smith, Cameron; Bar-David, Jonathan

    2016-01-01

    Aluminum plasmonics is emerging as a promising platform in particular for the ultraviolet-blue spectral band. We present the experimental results of propagating channel plasmon-polaritons (CPP) waves in aluminum coated V-shaped waveguides at the short visible wavelength regime. The V-grooves are ......Aluminum plasmonics is emerging as a promising platform in particular for the ultraviolet-blue spectral band. We present the experimental results of propagating channel plasmon-polaritons (CPP) waves in aluminum coated V-shaped waveguides at the short visible wavelength regime. The V......-grooves are fabricated by a process involving UV-photolithography, crystallographic silicon etching, and metal deposition. Polarization measurements of coupling demonstrate a preference to the TM-aligned mode, as predicted in simulations....

  11. Room to Groove?

    DEFF Research Database (Denmark)

    Seabrooke, Leonard

    . As long as they stay within the parameters of legitimate financial practice to signal institutional isomorphism, the `groove', creditors may well allow borrowers room for change in self-determined ways. This paper maps out the historical and conceptual terrain concerning civilizing ideas about...... the legitimacy of financial practices within global capital markets, and investigates relationships between Western `civilizers' and Emerging Market Economies during the last two periods of financial globalization, the late-nineteenth/ early-twentieth centuries and the late-twentieth century.......The use of a `standard of civilization', a preferred form of socio-political organization, in global capital markets presents both constraints and opportunities for creditors and borrowers. When imposed, civilizing standards may change how a borrower would prefer to conduct their affairs. Creditors...

  12. Impact, Spreading and Bouncing of Water Drops on Steel Surfaces with U and V Grooves

    Science.gov (United States)

    R, Kannan; S, Chandra

    2012-11-01

    The impact, spreading and bouncing of water drops (2 mm dia) was photographed as for velocities ranging from (0.26-1.1m/s) on two textured stainless steel plates, one with U-shaped and the other with V-shaped grooves running the length of the surface. Grooves were made using wire EDM, and groove volume per unit width (0.043mm3) was kept approximately the same for both surfaces and the groove depths were 236 μm and 194 μm for the U (TS1) and V grooved (TS2) surfaces, respectively. Surface wetting by gently deposited drops was different on TS1 and TS2; drops on TS1 rested on the tips of the protrusions (C-B state) while on TS2 liquid penetrated the spaces between the grooves (Wenzel state). At low We (We drops impacting on TS1 spread at the same rate in both directions, perpendicular and parallel to the channel direction. Conversely, the spreading on TS2 was anisotropic, with liquid travelling faster along compared to across the grooves. This anisotropy grew more pronounced as We increased and was observed on both TS1 and TS2 for We >10. The changes in the spreading behavior with increasing impact velocity (and therefore greater We) corresponded to a greater volume of liquid penetrating into the grooves. Photographs showed that when droplets were at their maximum spread the amount of liquid penetrating into the grooves increased sharply for We >10 on TS1. This increased S/L contact area and enhanced spreading along channels. Recoiling drops completely bounced off the surface during impact on TS1, but not on TS2. Bouncing was observed for We <35.

  13. Direct numerical simulation of Taylor-Couette flow with grooved walls: torque scaling and flow structure

    CERN Document Server

    Zhu, Xiaojue; Verzicco, Roberto; Lohse, Detlef

    2015-01-01

    We present direct numerical simulations of Taylor-Couette flow with grooved walls at a fixed radius ratio $\\eta=r_i/r_o=0.714$ with inner cylinder Reynolds number up to $Re_i=3.76\\times10^4$, corresponding to Taylor number up to $Ta=2.15\\times10^9$. The grooves are axisymmetric V-shaped obstacles attached to the wall with a tip angle of $90^\\circ$. Results are compared with the smooth wall case in order to investigate the effects of grooves on Taylor-Couette flow. We focus on the effective scaling laws for the torque, flow structures, and boundary layers. It is found that, when the groove height is smaller than the boundary layer thickness, the torque is the same as that of the smooth wall cases. With increasing $Ta$, the boundary layer thickness becomes smaller than the groove height. Plumes are ejected from tips of the grooves and a secondary circulation between the latter is formed. This is associated to a sharp increase of the torque and thus the effective scaling law for the torque vs. $Ta$ becomes much ...

  14. Investigation on the Crack Initiation of V-Shaped Notch Tip in Precision Cropping

    Directory of Open Access Journals (Sweden)

    Lijun Zhang

    2014-01-01

    Full Text Available The crack initiation of V-shaped notch tip has a very important influence on the cross-section quality and the cropping time for every segment of metal bar in course of low stress precision cropping. By the finite element method, the influence of machining precision of V-shaped notch bottom corner on the crack initiation location is analyzed and it is pointed out that the crack initiation point locates in the place at the maximal equivalent stress change rate on V-shaped notch surface. The judgment criterion of the crack initiation direction is presented and the corresponding crack initiation angle can be calculated by means of the displacement extrapolation method. The factual crack initiation angle of the metal bar has been measured by using the microscopic measurement system. The formula of the crack initiation life of V-shaped notch tip is built, which mainly includes the stress concentration factor of V-shaped notch, the tensile properties of metal material, and the cyclic loading conditions. The experimental results show that the obtained theoretical analyses about the crack initiation location, the crack initiation direction, and the crack initiation time in this paper are correct. It is also shown that the crack initiation time accounts for about 80% of the cropping time for every segment of the metal bar.

  15. RIGID-PLASTIC MECHANICAL MODEL FOR THE FORGING METHOD WITH HORIZONTAL V-SHAPED ANVIL

    Institute of Scientific and Technical Information of China (English)

    LIU Zhubai; NI Liyong; LIU Guohui; ZHANG Yongjun; ZHU Wenbo

    2006-01-01

    In order to decrease the anisotropy of mechanical properties, the rigid-plastic mechanical model for the forging method with horizontal V-shaped anvil is presented. The forging method,through the change of anvils shape, is able to control fibrous tissue direction, to improve the anisotropy of mechanical properties of axial forgings, to realize uniform forging. Therefore, the forging method can overcome the defect that conventional forging methods produce. The mechanism of the forging method with horizontal V-shaped anvil and the process of metal deformation are analyzed. The agreement of theoretical analysis with experimental study verifies the fact that the forging method with horizontal V-shaped anvil can control effectively the mechanical properties of axial forgings.

  16. Enhancement of turbulent flame speed of V-shaped flames in fractal-grid-generated turbulence

    NARCIS (Netherlands)

    Verbeek, A.A.; Willems, P.A.; Stoffels, G.G.M.; Geurts, B.J.; Meer, van der T.H.

    2016-01-01

    A variety of fractal grids is used to investigate how fractal-grid-generated turbulence affects the turbulent flame speed for premixed flames. The grids are placed inside a rectangular duct and a V-shaped flame is stabilized downstream of the duct, using a metal wire. This flame is characterized usi

  17. Discovery of Grooves on Gaspra

    Science.gov (United States)

    Veverka, J.; Thomas, P.; Simonelli, D.; Belton, M.J.S.; Carr, M.; Chapman, C.; Davies, M.E.; Greeley, R.; Greenberg, R.; Head, J.; Klaasen, K.; Johnson, T.V.; Morrison, D.; Neukum, G.

    1994-01-01

    We report the discovery of grooves in Galileo high-resolution images of Gaspra. These features, previously seen only on Mars' satellite Phobos, are most likely related to severe impacts. Grooves on Gaspra occur as linear and pitted depressions, typically 100-200 m wide, 0.8 to 2.5 km long, and 10-20 m deep. Most occur in two major groups, one of which trends approximately parallel to the asteroid's long axis, but is offset by some 15??; the other is approximately perpendicular to this trend. The first of these directions falls along a family of planes which parallel three extensive flat facets identified by Thomas et al., Icarus 107. The occurrence of grooves on Gaspra is consistent with other indications (irregular shape, cratering record) that this asteroid has evolved through a violent collisional history. The bodywide congruence of major groove directions and other structural elements suggests that present-day Gaspra is a globally coherent body. ?? 1994 Academic Press. All rights reserved.

  18. Combined Effect of Mechanical Grooving and Stain-Etched Surface on Optical and Electrical Properties of Crystalline Silicon Substrates

    Science.gov (United States)

    Zarroug, Ahmed; Derbali, Lotfi; Ouertani, Rachid; Dimassi, Wissem; Ezzaouia, Hatem

    2014-05-01

    This paper investigates the combined effect of mechanical grooving and porous silicon (PS) on the front surface reflectance and the electronic properties of crystalline silicon substrates. Mechanical surface texturization leads to reduce the cell reflectance, enhance the light trapping and augment the carrier collection probability. PS was introduced as an efficient antireflective coating (ARC) onto the front surface of crystalline silicon solar cell. Micro-periodic V-shaped grooves were made by means of a micro-groove machining process prior to junction formation. Subsequently, wafers were subjected to an isotropic potassium hydroxide (KOH) etching so that the V-shape would be turned to a U-shape. We found that the successive treatment of silicon surfaces with stain-etching, grooving then alkaline etching enhances the absorption of the textured surface, and decreases the reflectance from 35% to 7% in the 300-1200 nm wavelength range. We obtained a significant increase in the overall light path that generates the building up of the light trapping inside the substrate. We found an improvement in the illuminated I-V characteristics and an increase in the minority carrier lifetime τeff. Such a simple method was adopted to effectively reinforce the overall device performance of crystalline silicon-based solar cells.

  19. Re-entrant-Groove-Assisted VLS Growth of Boron Carbide Five-Fold Twinned Nanowires

    Institute of Scientific and Technical Information of China (English)

    FU Xin; JIANG Jun; LIU Chao; YU Zhi-Yang; Steffan LEA; YUAN Jun

    2009-01-01

    We report a preferential growth of boron carbide nanowires with a Eve-fold twinned internal structure.The nanowires are found to grow catalytically via iron boron nanoparticles,but unusually the catalytic particle is in contact with the low-energy surfaces of boron carbide with V-shaped contact lines.We propose that this catalytical growth may be caused by preferential nucleation at the re-entrant grooves due to the twinning planes,followed by rapid spreading of atomic steps.This is consistent with the observed temperature dependence of the five-fold twinned nanowire growth.

  20. Low temperature enantiotropic nematic phases from V-shaped, shape-persistent molecules.

    Science.gov (United States)

    Lehmann, Matthias; Seltmann, Jens

    2009-12-04

    A series of V-shaped, shape-persistent thiadiazole nematogens, based on an oligo(phenylene ethynylene) scaffold with ester groups connected via alkyloxy spacers, was efficiently prepared by a two-step procedure. Phase engineering results in an optimum of the mesophase range and low melting temperature when the nematogens are desymmetrised with a butoxy and a heptyloxy spacer. The mesophases are enantiotropic and over the whole temperature range nematic. For the optimised mesogen structure, optical investigations by conoscopy monitored a uniaxial nematic phase upon cooling from the isotropic phase to room temperature (ΔT = 150° C). X-ray studies on magnetic-field-aligned samples of this mesogen family revealed a general pattern, indicating the alignment of two molecular axes along individual directors in the magnetic field. These observations may be rationalised with larger assemblies of V-shaped molecules isotropically distributed around the direction of the magnetic field.

  1. Low temperature enantiotropic nematic phases from V-shaped, shape-persistent molecules

    Directory of Open Access Journals (Sweden)

    Matthias Lehmann

    2009-12-01

    Full Text Available A series of V-shaped, shape-persistent thiadiazole nematogens, based on an oligo(phenylene ethynylene scaffold with ester groups connected via alkyloxy spacers, was efficiently prepared by a two-step procedure. Phase engineering results in an optimum of the mesophase range and low melting temperature when the nematogens are desymmetrised with a butoxy and a heptyloxy spacer. The mesophases are enantiotropic and over the whole temperature range nematic. For the optimised mesogen structure, optical investigations by conoscopy monitored a uniaxial nematic phase upon cooling from the isotropic phase to room temperature (ΔT = 150 °C. X-ray studies on magnetic-field-aligned samples of this mesogen family revealed a general pattern, indicating the alignment of two molecular axes along individual directors in the magnetic field. These observations may be rationalised with larger assemblies of V-shaped molecules isotropically distributed around the direction of the magnetic field.

  2. Adaptive feature selection using v-shaped binary particle swarm optimization

    Science.gov (United States)

    Dong, Hongbin; Zhou, Xiurong

    2017-01-01

    Feature selection is an important preprocessing method in machine learning and data mining. This process can be used not only to reduce the amount of data to be analyzed but also to build models with stronger interpretability based on fewer features. Traditional feature selection methods evaluate the dependency and redundancy of features separately, which leads to a lack of measurement of their combined effect. Moreover, a greedy search considers only the optimization of the current round and thus cannot be a global search. To evaluate the combined effect of different subsets in the entire feature space, an adaptive feature selection method based on V-shaped binary particle swarm optimization is proposed. In this method, the fitness function is constructed using the correlation information entropy. Feature subsets are regarded as individuals in a population, and the feature space is searched using V-shaped binary particle swarm optimization. The above procedure overcomes the hard constraint on the number of features, enables the combined evaluation of each subset as a whole, and improves the search ability of conventional binary particle swarm optimization. The proposed algorithm is an adaptive method with respect to the number of feature subsets. The experimental results show the advantages of optimizing the feature subsets using the V-shaped transfer function and confirm the effectiveness and efficiency of the feature subsets obtained under different classifiers. PMID:28358850

  3. TEM00 mode Nd:YAG solar laser by side-pumping a grooved rod

    Science.gov (United States)

    Vistas, Cláudia R.; Liang, Dawei; Almeida, Joana; Guillot, Emmanuel

    2016-05-01

    A simple TEM00 mode solar laser system with a grooved Nd:YAG rod pumped through a heliostat-parabolic mirror system is reported here. The radiation coupling capacity of a fused silica tube lens was combined with the multipass pumping ability of a 2 V-shaped cavity to provide efficient side-pumping along a 4.0 mm diameter grooved Nd:YAG single-crystal rod. TEM00 mode solar laser power of 3.4 W was measured by adopting an asymmetric large-mode laser resonant cavity. Record TEM00 mode solar laser collection efficiency of 3.4 W/m2and slope efficiency of 1.9% was achieved, which corresponds to 1.8 and 2.4 times more than the previous TEM00 mode Nd:YAG solar laser using the PROMES-CNRS heliostat-parabolic mirror system, respectively.

  4. The minimum scale of grooving on faults

    NARCIS (Netherlands)

    Candela, T.; Brodsky, E.E.

    2016-01-01

    At the field scale, nearly all fault surfaces contain grooves generated as one side of the fault slips past the other. Grooves are so common that they are one of the key indicators of principal slip surfaces. Here, we show that at sufficiently small scales, grooves do not exist on fault surfaces. A

  5. The minimum scale of grooving on faults

    NARCIS (Netherlands)

    Candela, T.; Brodsky, E.E.

    2016-01-01

    At the field scale, nearly all fault surfaces contain grooves generated as one side of the fault slips past the other. Grooves are so common that they are one of the key indicators of principal slip surfaces. Here, we show that at sufficiently small scales, grooves do not exist on fault surfaces. A

  6. Evaporation from open microchannel grooves.

    Science.gov (United States)

    Kachel, Sibylle; Zhou, Ying; Scharfer, Philip; Vrančić, Christian; Petrich, Wolfgang; Schabel, Wilhelm

    2014-02-21

    The evaporation of water from open u-shaped microchannel grooves was investigated with particular emphasis on the roles of channel width and air flow conditions. Given the small dimensions of the microchannels, all measurements were conducted in a range where convection and diffusion are of equal importance and known correlations for the calculation of mass transfer coefficients cannot be applied. The evaporation rates were measured using a new optical method and a gravimetric method. Both measurement methods yielded mass transfer coefficients that are in agreement with each other. The observed relation between mass transfer coefficient, air velocity and channel width vastly differs from the predictions obtained from macroscopic structures. With respect to diagnostic devices we conclude that analyte concentration in an open microchannel groove strongly increases even within short times due to the evaporation process and we show that wider channels are more favourable in terms of minimizing the relative evaporation rate.

  7. Effects of Nanoscale V-Shaped Pits on GaN-Based Light Emitting Diodes.

    Science.gov (United States)

    Chen, Shuo-Wei; Li, Heng; Chang, Chia-Jui; Lu, Tien-Chang

    2017-01-28

    This paper reviews the formation of nanoscale V-shaped pits on GaN-based light emitting diodes (LEDs) grown by the metal organic chemical vapor deposition (MOCVD) system and studies the effect of V-shaped pits on quantum efficiency. Since V-pits could provide potential barriers around threading dislocations to lessen non-radiative recombinations in such a high defect environment. In our study, multiple InGaN/GaN quantum well samples with different emission wavelengths of 380, 420, 460, and 500 nm were grown, each with different nanoscale V-shaped pits of three diameters for 150, 200, and 250 nm, respectively. It was found that the multiple quantum well (MQW) sample with larger V-pits had a lower pit density, but a relatively larger total V-pits defected area. The optimum diameter of V-pits showing the highest quantum efficiency from the MQW sample depended on the emission wavelength. MQW samples with wavelengths of 380 and 500 nm exhibited the best internal quantum efficiency (IQE) performance at the smallest V-pits area; however, the best performance for MQW samples with wavelength around 420 and 460 nm occurred when large V-pit areas were presented. Photoluminescence (PL) peak shifts and Raman shifts can provide a relationship between quantum-confined Stark effect (QCSE) and IQE, as well as a comparison between strain and IQE. The results obtained in this phenomenological study shall provide a useful guide line in making high-performance GaN-based LEDs with wide emission spectra.

  8. Enhance heat transfer in the channel with V-shaped wavy lower plate using liquid nanofluids

    Directory of Open Access Journals (Sweden)

    Azher M. Abed

    2015-03-01

    Full Text Available The heat transfer and flow characteristics in corrugated with V-shape lower plate using nanofluids are numerically studied. The computations are performed on uniform heat flux over a range of Reynolds number (Re 8000–20,000. The governing equations are numerically solved in the domain by a finite volume method (FVM using the k–ε standard turbulent model. Studies are carried out for different types of nanoparticles Al2O3,CuO, SiO2 and ZnO with different volume fractions in the range of 0–4%. Three different types of base fluid (water, glycerin, ethylene glycol are also examined. Results indicated that the average Nusselt number for nanofluids is greater than that of the base liquid. The SiO2 nanofluid yields the best heat transfer enhancement among all other type of nanofluids. Heat transfer enhancement increase with increases the volumetric concentration, but it is accompanied by increasing pressure drop values. Moreover, the average Nusselt number increases with an increase in Reynolds number and volume concentration. The SiO2–glycerin nanofluid has the highest Nusselt number compared with other base fluids. The present study shows that these V-shaped wavy channels have advantages by using nanofluids and thus serve as promising candidates for incorporation into efficient heat transfer devices.

  9. V-shaped crystalline structures of di-n-alkyl esters of phosphoric acid.

    Science.gov (United States)

    Thünemann, Andreas F; Kurth, Dirk G; Beinhoff, Matthias; Bienert, Ralf; Schulz, Burkhard

    2006-06-20

    We prepared crystals of di-n-alkyl esters of phosphoric acid with chain lengths of n = 10, 12, 14, 16, and 18. These were characterized by single-crystal X-ray analysis and differential scanning calorimetry (DSC). It was found that the alkyl chains are in an extended all-trans conformation and aligned close to perpendicular, forming V-shaped molecules. This is in strong contrast to the typical arrangement of the alkyl chains of phospholipids where the two alkyl chains are arranged parallel in the same direction (e.g., tuning fork configuration in bilayers). Additionally, it was found that the arrangement of the V-shaped molecules of the di-n-alkyl esters in neighboring stacks of the lamellar crystals is antiparallel for short chain lengths (n = 10 and 12) and parallel for the longer (n = 14 and 16). DSC reveals that the melting of the crystals increases systematically with increasing chain lengths from 48 to 82 degrees C. The contribution of each methylene group to the melting enthalpy (70-133 kJ/mol) is independent of the chain length (3.9 kJ per mol CH2).

  10. Differential diagnosis of groove pancreatic carcinomas vs. groove pancreatitis: Usefulness of the portal venous phase

    Energy Technology Data Exchange (ETDEWEB)

    Ishigami, Kousei, E-mail: Ishigamikousei@aol.co [Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 (Japan); Tajima, Tsuyoshi; Nishie, Akihiro; Kakihara, Daisuke [Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 (Japan); Fujita, Nobuhiro [Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka (Japan); Asayama, Yoshiki; Ushijima, Yasuhiro; Irie, Hiroyuki [Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 (Japan); Nakamura, Masafumi; Takahata, Shunichi [Surgery and Oncology, Graduate School of Medical Sciences, Kyushu University, Fukuoka (Japan); Ito, Tetsuhide [Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka (Japan); Honda, Hiroshi [Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582 (Japan)

    2010-06-15

    Purpose: To clarify if the portal venous phase is helpful for the differential diagnosis of groove pancreatic carcinomas and groove pancreatitis. Materials and methods: MDCT and MRI of groove pancreatic carcinomas (n = 7) and groove pancreatitis (n = 15) were retrospectively reviewed by two radiologists independently. The signal intensity on T2-weighted images was subjectively assessed. The presence or absence of common bile duct (CBD) and main pancreatic duct (MPD) strictures, calcifications, and cystic lesions was evaluated. Additionally, the appearance of groove pancreatic carcinoma and that of groove pancreatitis in the portal venous phase on dynamic MDCT and MRI were compared. Results: There were no significant differences in the signal intensity on T2-weighted images and in the presence or absence of CBD and MPD strictures, calcifications, and cystic lesions between groove pancreatic carcinomas and groove pancreatitis. However, patchy focal enhancement in the portal venous phase was more commonly observed in groove pancreatitis than groove pancreatic carcinoma (Reviewers 1 and 2: 14/15 [93.3%] vs. 1/7 [14.3%], P < 0.0001). In addition, peripheral enhancement was only seen in groove pancreatic carcinomas (Reviewer 1: 4/7 [57.1%] vs. 0/15 [0%], P < 0.005, and Reviewer 2: 3/7 [42.9%] vs. 0/15 [0%], P < 0.05). Conclusion: The portal venous phase may be helpful for the differential diagnosis of groove pancreatic carcinomas and groove pancreatitis.

  11. A novel large thrust-weight ratio V-shaped linear ultrasonic motor with a flexible joint.

    Science.gov (United States)

    Li, Xiaoniu; Yao, Zhiyuan; Yang, Mojian

    2017-06-01

    A novel large thrust-weight ratio V-shaped linear ultrasonic motor with a flexible joint is proposed in this paper. The motor is comprised of a V-shaped transducer, a slider, a clamp, and a base. The V-shaped transducer consists of two piezoelectric beams connected through a flexible joint to form an appropriate coupling angle. The V-shaped motor is operated in the coupled longitudinal-bending mode. Longitudinal and bending movements are transferred by the flexible joint between the two beams. Compared with the coupled longitudinal-bending mode of the single piezoelectric beam or the symmetrical and asymmetrical modes of the previous V-shaped transducer, the coupled longitudinal-bending mode of the V-shaped transducer with a flexible joint provides higher vibration efficiency and more convenient mode conformance adjustment. A finite element model of the V-shaped transducer is created to numerically study the influence of geometrical parameters and to determine the final geometrical parameters. In this paper, three prototypes were then fabricated and experimentally investigated. The modal test results match well with the finite element analysis. The motor mechanical output characteristics of three different coupling angles θ indicate that V-90 (θ = 90°) is the optimal angle. The mechanical output experiments conducted using the V-90 prototype (Size: 59.4 mm × 30.7 mm × 4 mm) demonstrate that the maximum unloaded speed is 1.2 m/s under a voltage of 350 Vpp, and the maximum output force is 15 N under a voltage of 300 Vpp. The proposed novel V-shaped linear ultrasonic motor has a compact size and a simple structure with a large thrust-weight ratio (0.75 N/g) and high speed.

  12. Laser grooving of surface cracks on hot work tool steel

    Directory of Open Access Journals (Sweden)

    D. Klobčar

    2011-10-01

    Full Text Available The paper presents the analysis of laser grooving of 1.2343 tool steel hardened to 46 HRC. The effect of laser power and grooving speed on groove shape (i.e. depth and width, the material removal rate and the purity of produced groove as a measure of groove quality was investigated and analyzed using response surface methodology. Optimal parameters of laser grooving were found, which enables pure grooves suitable for laser welding.

  13. Influence of musical groove on postural sway.

    Science.gov (United States)

    Ross, Jessica M; Warlaumont, Anne S; Abney, Drew H; Rigoli, Lillian M; Balasubramaniam, Ramesh

    2016-03-01

    Timescales of postural fluctuation reflect underlying neuromuscular processes in balance control that are influenced by sensory information and the performance of concurrent cognitive and motor tasks. An open question is how postural fluctuations entrain to complex environmental rhythms, such as in music, which also vary on multiple timescales. Musical groove describes the property of music that encourages auditory-motor synchronization and is used to study voluntary motor entrainment to rhythmic sounds. The influence of groove on balance control mechanisms remains unexplored. We recorded fluctuations in center of pressure (CoP) of standing participants (N = 40) listening to low and high groove music and during quiet stance. We found an effect of musical groove on radial sway variability, with the least amount of variability in the high groove condition. In addition, we observed that groove influenced postural sway entrainment at various temporal scales. For example, with increasing levels of groove, we observed more entrainment to shorter, local timescale rhythmic musical occurrences. In contrast, we observed more entrainment to longer, global timescale features of the music, such as periodicity, with decreasing levels of groove. Finally, musical experience influenced the amount of postural variability and entrainment at local and global timescales. We conclude that groove in music and musical experience can influence the neural mechanisms that govern balance control, and discuss implications of our findings in terms of multiscale sensorimotor coupling. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  14. V-shape liquid crystal-based retromodulator air to ground optical communications

    CERN Document Server

    Geday, Morten A; Carrasco-Casado, Alberto; Bennis, Noureddine; Quintana, Xabier; Hernandez, Francisco Lopez; Sanchez, Jose Manuel Oton

    2015-01-01

    This paper describes the use of a 2D liquid crystal retro-modulator as a free space, wireless, optical link. The retro-modulator is made up of a retro-reflecting cornercube onto which 2 cascaded V-shape smectics liquid crystal modulators are mounted. The communication link differs with respect to more conventional optical links in not using amplitude (nor frequency) modulation, but instead state-of-polarisation (SOP) modulation known as Polarisation Shift Keying (PolSK). PolSK has the advantage over amplitude modulation, that it is less sensitive to changes in the visibility of the atmosphere, and increases inherently the bandwidth of the link. The implementation of PolSK both in liquid crystal based and in retro-modulated communication are novelties.

  15. Controllable V-Shape Multi-Scroll Butterfly Attractor: System and Circuit Implementation

    KAUST Repository

    Zidan, Mohammed A.

    2012-07-23

    In this paper, a new controllable V-shape multiscroll attractor is presented, where a variety of symmetrical and unsymmetrical attractors with a variable number of scrolls can be controlled using new staircase nonlinear function and the parameters of the system. This attractor can be used to generate random signals with a variety of symbol distribution. Digital implementation of the proposed generator is also presented using a Xilinx Virtex® 4 Field Programmable Gate Array and experimental results are provided. The digital realization easily fits into a small area (<1.5% of the total area) and expresses a high throughput (4.3 Gbit/sec per state variable). © 2012 World Scientific Publishing Company.

  16. Optimized V-shape design of GaN nanodiodes for the generation of Gunn oscillations

    Science.gov (United States)

    Millithaler, J.-F.; Iñiguez-de-la-Torre, I.; Iñiguez-de-la-Torre, A.; González, T.; Sangaré, P.; Ducournau, G.; Gaquière, C.; Mateos, J.

    2014-02-01

    In this work, recent advances in the design of GaN planar Gunn diodes with asymmetric shape, so-called self-switching diodes, are presented. A particular geometry for the nanodiode is proposed, referred as V-shape, where the width of the channel is intentionally increased as approaching the anode. This design, which reduces the effect of the surface-charges at the anode side, is the most favourable one for the onset of Gunn oscillations, which emerge at lower current levels and with lower threshold voltages as compared to the standard square geometry, thus enhancing the power efficiency of the self-switching diode as sub-millimeter wave emitters.

  17. New Methods of Determining the Mixed Mode Stress Intensity Factors for V-Shaped Notch

    Institute of Scientific and Technical Information of China (English)

    Lin Zhong-qin; Yu Haiyan; Chen Guanlong; Li Shu-hui

    2004-01-01

    In this paper, on the basis of the stress field given by D.H.Chen, three new photoelastic methods are developed for determining the stress intensity factors K1 and K2 of V-shaped notch. Some photoelastic experiments are performed on a skew -symmetric 45° notch. Measurements of the coordinates components of r,θand fringe order N are made for progressively smaller fringes and used in the proposed methods to solve K1 and K2.Plots of apparent K vs. r/l are made and extrapolated to the notch tip to yield the true values of K1 and K2.The results obtained by the three methods are very close to each other. When the notch problem is simplified as a crack problem, the corresponding equation is identical to the one proposed by D.G. Smith, which shows that the proposed methods are applicable for both notch and crack problems.

  18. Thermal Bridge Effects in Window Grooves

    DEFF Research Database (Denmark)

    Rose, Jørgen

    1997-01-01

    In this report thermal bridge effects in window grooves are analyzed. The analysis is performed using different thicknesses of the window groove insulation, to evaluate what the optimal solution is.All analysis in the report is performed using both 2- and 3-dimensional numerical analysis....

  19. Gratings in plasmonic V-groove waveguides

    DEFF Research Database (Denmark)

    Smith, Cameron; Cuesta, Irene Fernandez; Kristensen, Anders

    2011-01-01

    We introduce visible light optical gratings to surface plasmon V-groove waveguides. Gradient e-beam dosage onto silicon stamp enables structuring V-grooves of varying depth. Nanoimprint lithography maintains a Λ=265 nm corrugation for gold surface devices....

  20. Gratings in plasmonic V-groove waveguides

    DEFF Research Database (Denmark)

    Smith, Cameron; Cuesta, Irene Fernandez; Kristensen, Anders

    2011-01-01

    We introduce visible light optical gratings to surface plasmon V-groove waveguides. Gradient e-beam dosage onto silicon stamp enables structuring V-grooves of varying depth. Nanoimprint lithography maintains a Λ=265 nm corrugation for gold surface devices....

  1. Enhancing the Performance of Distributed Feedback Dye Lasers and Plasmonic V-grooves for Lab-on-a-chip Systems

    DEFF Research Database (Denmark)

    Smith, Cameron

    of the laser emission wavelength. We provide a framework for designing optimized DFB laser sensors comprising a thin TiO2 guiding layer. Regarding the second, plasmonic V-grooves offer a means to control the trade-off between e-field confinement and propagation length by varying the V-shape profile, opening......The ability to perform laboratory operations in compact systems is not only advantageous for the development of diagnostics tools and their production, but also provides unique opportunities to explore the natural world on the micro- and nanoscale. To this end, we focus on two optical schemes: 1......) polymer-based distributed feedback (DFB) dye lasers, and 2) plasmonic V-grooves. Regarding the first, DFB dye lasers are well suited to serve as compact, minimal analyte volume and highly sensitive refractive index sensors, where changes occurring in an analyte result in readily measurable shifts...

  2. New 3-D coordination polymers based on semi-rigid V-shape tetracarboxylates

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jing-Jing; Xu, Wei; Wang, Yan-Ning [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023, Jilin (China); State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Qianjin Road 2699, Changchun 130012, Jilin (China); Yu, Jie-Hui, E-mail: jhyu@jlu.edu.cn [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023, Jilin (China); State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Qianjin Road 2699, Changchun 130012, Jilin (China); Zhang, Ping, E-mail: zhangping@jlu.edu.cn [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023, Jilin (China); Xu, Ji-Qing [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023, Jilin (China); State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Qianjin Road 2699, Changchun 130012, Jilin (China)

    2015-03-15

    Under the hydrothermal conditions, the reactions of transition-metal salts, tetracarboxylic acids and N,N′-donor ligands yielded three new coordination polymers as [Cu{sub 4}(fph){sub 2}(bpe){sub 3}(H{sub 2}O){sub 2}]·2H{sub 2}O (fph=4,4′-(hexafluoroisopropylidene)diphthalate, bpe=1,2-bis(pyridyl)ethylene) 1, [Co{sub 2}(fph)(bpa){sub 2}(H{sub 2}O){sub 2}]·3H{sub 2}O (bpa=1,2-bis(pyridyl)ethylane) 2, and [Ni(H{sub 2}O)(H{sub 2}oph)(bpa)] (oph=4,4′-oxydiphthalate) 3. X-ray single-crystal diffraction analysis revealed that the title three compounds all possess the three-dimensional (3-D) network structures. For compound 1, the fph molecules first link the Cu{sup 2+} ions into a two-dimensional (2-D) wave-like layer with a (4,4) topology. The bpe molecules act as the second linkers, extending the 2-D layers into a 3-D network. For compound 2, the fph molecules still serve as the first connectors, linking the Co{sup 2+} ions into a one-dimensional (1-D) tube-like chain. Then the bpa molecules propagate the chains into a 3-D (4,4,4)-connected network. In the formation of the 3-D network of compound 3, the oph molecule does not play a role. The bpa molecules as well as the water molecules act as a mixed bridge. Only a kind of 4-connected metal node is observed in compound 3. The magnetic properties of compounds 1–3 were investigated and all exhibit the predominant antiferromegnetic magnetic behaviors. - Graphical abstract: Structures of three semi-rigid V-shape tetracarboxylate-based coordination polymers were reported, and their magnetic properties were investigated. - Highlights: • Structures of three tetracarboxylate-based coordination polymers were reported. • Role of organic bases in metal–tetracarboxylate compounds was discussed. • Characters of V-shape and semi-rigidity for tetracarboxylate play a key role in crystal growth. • Their magnetic properties were investigated.

  3. Diagnostics and Treatment of Palatal Radicular Grooves

    Institute of Scientific and Technical Information of China (English)

    James Deschner; Birgit Rath; Wang Zheng; Ding Yi

    2006-01-01

    The palatal radicular groove represents a developmental anomaly that mainly affects the maxillary incisor teeth. This anomaly is probably caused by an infolding of the enamel organ and Hertwig's epithelial root sheath during odontogenesis. The groove often originates in the central fossa or cingulum and continues towards the root apex for various distances. The anatomical defect can act as a funnel for plaque and, therefore, result in extensive bone and attachment loss. A complete lack of closure of the calcified tissues along the groove, that is a direct communication between pulp and periodontium, rarely occurs. However, accessory canals between the pulp cavity and periodontal tissues frequently exist along the groove and are main entrances of infectious material into the pulp cavity, facilitating the development of endodontic lesions. Grooves can also complicate restorative therapy or interfere with the accessibility for scaling and root planing. Patients usually present with pain and gingival inflammation in the maxillary incisor region. Bleeding on probing and increased pocket depths are strictly confined to the area of the groove in an otherwise periodontally healthy patient. Radiographs may show a parapulpal line that represents the radiographic image of the groove. Treatment of the anomaly by scaling and root planing alone or in combination with procedures such as odontoplasty, flap surgery, application of an enamel matrix derivative or guided tissue regeneration can be successful. A short case report of a patient treated successfully with an enamel matrix derivative for localized attachment loss due to this anomaly is presented.

  4. Tailorable optical scattering properties of the V-shaped plasmonic nano-antennas: a computationally efficient and fast analysis

    CERN Document Server

    Rashidi, Arash; Anagnostou, Dimitris E

    2015-01-01

    We introduce an efficient computational scheme based on Macro Basis Function (MBF) method, to analyze the scattering of a plane wave by the V-shaped plasmonic optical nano-antennas. The polarization currents and the scattered fields for symmetric and anti-symmetric excitations are investigated. We investigate how the resonant frequency of the plasmonic V-shaped nanoantenna is tailored by engineering the geometrical parameters and by changing the polarization state of the incident plane wave. The computational model presented herein is faster by orders of magnitude than commercially available finite methods and is capable to characterize also other nanoantennas comprising of junctions and bends of nanorods.

  5. Level Set Modeling of Transient Electromigration Grooving

    OpenAIRE

    Khenner, M.; Averbuch, A.; Israeli, M.; Nathan, M; Glickman, E.

    2000-01-01

    A numerical investigation of grain-boundary (GB) grooving by means of the Level Set (LS) method is carried out. GB grooving is emerging as a key element of electromigration drift in polycrystalline microelectronic interconnects, as evidenced by a number of recent studies. The purpose of the present study is to provide an efficient numerical simulation, allowing a parametric study of the effect of key physical parameters (GB and surface diffusivities, grain size, current density, etc) on the e...

  6. Effectiveness of transverse grooves in rigid pavement

    Science.gov (United States)

    Gurney, G. F.; Bryden, J. E.

    1982-10-01

    Transverse grooves were installed at 11 intersection approaches on worn rigid pavement to reduce a high rate of wet road accidents. In most cases, accident reductions were experienced only at intersections with multiple negative operational characteristics, including higher approach speeds, limited sight distances, and frequent vehicle stopping for turns or stop signs. Intersections with no more than one negative characteristic generally did not benefit from grooving.

  7. Parametric analysis of a solar still with inverted V-shaped glass condenser

    Directory of Open Access Journals (Sweden)

    Rubio Eduardo

    2015-01-01

    Full Text Available A parametric analysis of a solar still with an inverted V-shaped glass condenser is presented. Results are based on a new mathematical model obtained from a lumped-parameter analysis of the still, with an approach that makes each glass plate of the condensing system sensitive to orientation and depicts its thermal differences. Numerical computations are made to evaluate productivity and temperature differences between the condensing plates as a function of condenser orientation, extinction coefficient and thickness. From this study it was found a significant influence of incident solar radiation on the thermal performance of each condensing plate. Large extinction coefficients and thick glass plates increase absorption losses that result in an appreciable temperature difference. An extinction coefficient of 40 m-1 produces a temperature difference of 2.5°C between both condensers. A glass thickness of 10 mm may increase this temperature difference up to 3.5°C. With respect to the production, due to the still orientation, a difference of 8.7% was found for the condensing plates facing an east-west direction. The proposed model is able to reproduce the temperature and distillate production differences that arise between both condensers in good agreement with experimental data. The overall performance of the still, studied with this new approach, was also in accordance with the widely used traditional models for solar distillation. In addition, the condensing plates parameters of the still can be used to force a differential heating such that for the whole day the temperature of one condensing plate is always higher.

  8. Gap and channeled plasmons in tapered grooves: a review

    DEFF Research Database (Denmark)

    Smith, C. L. C.; Stenger, Nicolas; Kristensen, Anders

    2015-01-01

    ) that are confined laterally between the tapered groove sidewalls and propagate either along the groove axis or normal to the planar surface, and channeled plasmon polaritons (CPPs) that occupy the tapered groove profile and propagate exclusively along the groove axis. Both GSPs and CPPs exhibit an assortment...

  9. Micro Groove for Trapping of Flowing Cell

    Directory of Open Access Journals (Sweden)

    Yusuke Takahashi

    2015-06-01

    Full Text Available Micro grooves have been designed to trap a biological cell, which flows through a micro channel in vitro. Each micro groove of a rectangular shape (0.002 mm depth, 0.025 mm width and 0.2 mm length has been fabricated on the surface of the polydimethylsiloxane (PDMS disk with the photolithography technique. Variation has been made on the angle between the longitudinal direction of the groove and the flow direction: zero, 0.79, or 1.57 rad. A rectangular flow channel (0.1 mm depth x 5 mm width x 30 mm length has been constructed with a silicone film of 0.1 mm thick, which has been sandwiched by two transparent PDMS disks. Two types of biological cells were used in the test alternatively: C2C12 (mouse myoblast cell line originated with cross-striated muscle of C3H mouse, or 3T3-L1 (mouse fat precursor cells. A constant flow (2.8 x 10-11 m3/s of a suspension of cells was introduced with a syringe pump. The behavior of cells moving over the micro grooves was observed with an inverted phase contrast microscope. The results show that the cell is trapped with the micro grooves under the wall shear rate of 3 s-1 for a few seconds and that the trapped interval depends on the kind of cells.

  10. Musical groove modulates motor cortex excitability: a TMS investigation.

    Science.gov (United States)

    Stupacher, Jan; Hove, Michael J; Novembre, Giacomo; Schütz-Bosbach, Simone; Keller, Peter E

    2013-07-01

    Groove is often described as a musical quality that can induce movement in a listener. This study examines the effects of listening to groove music on corticospinal excitability. Musicians and non-musicians listened to high-groove music, low-groove music, and spectrally matched noise, while receiving single-pulse transcranial magnetic stimulation (TMS) over the primary motor cortex either on-beat or off-beat. We examined changes in the amplitude of the motor-evoked potentials (MEPs), recorded from hand and arm muscles, as an index of activity within the motor system. Musicians and non-musicians rated groove similarly. MEP results showed that high-groove music modulated corticospinal excitability, whereas no difference occurred between low-groove music and noise. More specifically, musicians' MEPs were larger with high-groove than low-groove music, and this effect was especially pronounced for on-beat compared to off-beat pulses. These results indicate that high-groove music increasingly engages the motor system, and the temporal modulation of corticospinal excitability with the beat could stem from tight auditory-motor links in musicians. Conversely, non-musicians' MEPs were smaller for high-groove than low-groove music, and there was no effect of on- versus off-beat pulses, potentially stemming from suppression of overt movement. In sum, high-groove music engages the motor system, and previous training modulates how listening to music with a strong groove activates the motor system.

  11. Xe Adsorption and Separation Properties of a Series of Microporous Metal–Organic Frameworks (MOFs) with V-Shaped Linkers

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Debasis; Elsaidi, Sameh K.; Thallapally, Praveen K.

    2017-08-28

    A series of microporous Metal-Organic Frameworks (MOFs) constructed by a V-shaped linker, 4,4’-sul-fonyldibenzoic acid were evaluated for their Xe gas adsorption properties. In particular, a cadmium based MOF exhibit noteworthy Xe adsorption and separation properties in presence of other gases under nuclear reprocessing conditions. The difference in Xe adsorption and separation properties of the materials were attributed towards their topology and pore size.

  12. Absorption Coefficient of InGaAs V-shaped Quantum Wires Integrated in Optical Waveguides by MBE Growth

    Science.gov (United States)

    1998-06-01

    Integrated in Optical Waveguides by MBE Growth DISTRIBUTION: Approved for public release, distribution unlimited Availability: Hard copy only. This...coefficient of InGaAs V-shaped quantum wires integrated in optical waveguides by MBE growth F Filipowitzt, C. Gourgont, D. Martint, Y Magnenatt, P. Giaccarit...observation The fabrication of waveguides that contains QWR consists of three process sequences: (i) MBE growth of the lower waveguide cladding and half of the

  13. Synthesis of linear and V-shaped oligo(phenylene ethynylene) derivatives:Geometric effects on photophysical properties

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A series of linear and V-shaped oligo(phenylene ethynylene) derivatives 1-3 were synthesized through sequent Sonogashira coupling and propargyl alcohol deprotection reaction in high yields.The alkoxy chains(i.e.,n-hexyloxy groups) were introduced to assure good solubility of compounds 1-3 in common solvents.The photophysical properties of 1-3 in solution depend strongly on the geometries of these compounds.

  14. Mixed convection in a baffled grooved channel

    Indian Academy of Sciences (India)

    Aayush K Sharma; Pallab S Mahapatra; Nirmal K Manna; Koushik Ghosh

    2015-05-01

    In the present numerical work, flow structure and heat transfer characteristics are investigated in a baffled grooved channel, differentially heated from the sides. The baffle is placed vertically downward from the top wall of grooved channel geometry, with the motive of diverting outside forced flow towards the inside of the square cavity. In-house CFD code based on finite volume method has been used to solve the 2D equations of continuity, momentum and energy. The effect of change in baffle position and height is investigated in the range of Richardson numbers 0.1 to 10. For the present study, external flow from both left and right of the grooved channel are considered. A remarkable enhancement of heat transfer is observed in presence of baffle. The study has also pointed out that for optimal performance, the position and height of the baffle need to be adjusted depending on the direction of external flow.

  15. Near-lossless continuous phase modulation using the analog switching mode (V-shaped switching) in ferroelectric liquid crystals.

    Science.gov (United States)

    Engström, David; Rudquist, Per; Bengtsson, Jörgen; D'havé, Koen; Galt, Sheila

    2006-07-20

    The analog switching mode in ferroelectric liquid crystals, sometimes referred to as 'V-shaped switching,' has, thanks to its submillisecond switching capability, attracted much interest for future fast electro-optic displays where it is to be used for amplitude modulation. We have studied this mode for analog phase-only modulation. As V-shaped switching is based on a conical motion of the index ellipsoid this presents a challenging problem since both the orientation of the slow and fast axes, as well as the amount of birefringence varies in the switching process. We show theoretically, partly by means of Poincaré sphere analysis, that it is in fact possible to obtain near-lossless analog phase modulation between zero and pi radians in an ideal V-shaped switching cell through careful tuning of the polarization state of the input light. Furthermore, we were able to demonstrate this experimentally in a fabricated cell. Although this cell deviated slightly from the ideal conditions, e.g., the tilt cone half-angle was 38 degrees instead of the desired 45 degrees , we still obtained a continuous phase modulation between zero and 0.78pi rad with less than 2% modulation of the amplitude; the measured values agree very well with our numerical simulations of the real device.

  16. Blast response of centrally and eccentrically loaded flat-, U-, and V-shaped armored plates: comparative study

    Science.gov (United States)

    Trajkovski, J.; Kunc, R.; Prebil, I.

    2017-07-01

    Light armored vehicles (LAVs) can be exposed to blast loading by landmines or improvised explosive devices (IEDs) during their lifetime. The bottom hull of these vehicles is usually made of a few millimeters of thin armored plate that is the vehicle's weak point in a blast-loading scenario. Therefore, blast resistance and blast load redirection are very important characteristics in providing adequate vehicle as well as occupant protection. Furthermore, the eccentric nature of loading caused by landmines was found to be omitted in the studies of simplified structures like beams and plates. For this purpose, blast wave dispersion and blast response of centrally and eccentrically loaded flat-, U-, and V-shaped plates are examined using a combined finite-element-smoothed-particle hydrodynamics (FE-SPH) model. The results showed that V-shaped plates better disperse blast waves for any type of loading and, therefore, can be successfully applied in LAVs. Based on the results of the study and the geometry of a typical LAV 6× 6, the minimum angle of V-shaped plates is also determined.

  17. Blast response of centrally and eccentrically loaded flat-, U-, and V-shaped armored plates: comparative study

    Science.gov (United States)

    Trajkovski, J.; Kunc, R.; Prebil, I.

    2016-12-01

    Light armored vehicles (LAVs) can be exposed to blast loading by landmines or improvised explosive devices (IEDs) during their lifetime. The bottom hull of these vehicles is usually made of a few millimeters of thin armored plate that is the vehicle's weak point in a blast-loading scenario. Therefore, blast resistance and blast load redirection are very important characteristics in providing adequate vehicle as well as occupant protection. Furthermore, the eccentric nature of loading caused by landmines was found to be omitted in the studies of simplified structures like beams and plates. For this purpose, blast wave dispersion and blast response of centrally and eccentrically loaded flat-, U-, and V-shaped plates are examined using a combined finite-element-smoothed-particle hydrodynamics (FE-SPH) model. The results showed that V-shaped plates better disperse blast waves for any type of loading and, therefore, can be successfully applied in LAVs. Based on the results of the study and the geometry of a typical LAV 6× 6 , the minimum angle of V-shaped plates is also determined.

  18. A Case of Right Atrioventricular Groove Paraganglioma

    Institute of Scientific and Technical Information of China (English)

    Yi ZHANG; Tie-cheng PAN

    2009-01-01

    @@ Cardiac paraganglioma is an extremely rare clinical en-tities of the heart. The usual investigations for pheochro-mocytoma are necessary, however the most useful, spe-cific to primary cardiac tumors, are coronary angiogra-phy and echocardiography. While complete surgical ex-cision is the standard treatment of mainstay. We report a case of a 55-year-old woman with cardiac paraganglioma located in fight atriaoventricular groove of the heart. As we know, this is the first case that cardiac paraganglioma located in fight atriaoventricular groove of the heart in English literature.

  19. Graphene Plasmons in Triangular Wedges and Grooves

    DEFF Research Database (Denmark)

    Gonçalves, P. A. D.; Dias, E. J. C.; Xiao, Sanshui

    2016-01-01

    and electric-field distributions. We have found that the dispersion of wedge/groove graphene plasmons follows the same functional dependence as their flat-graphene plasmon counterparts, but now scaled by a (purely) geometric factor in which all the information about the system’s geometry is contained. We...... and tunability of graphene plasmons guided along the apex of a graphene-covered dielectric wedge or groove. In particular, we present a quasi-analytic model to describe the plasmonic eigenmodes in such a system, including the complete determination of their spectrum and corresponding induced potential...

  20. Rectangular-to-circular groove waveguide junction

    Institute of Scientific and Technical Information of China (English)

    CUI; Licheng; (崔立成); YANG; Hongsheng; (杨鸿生)

    2003-01-01

    Mode matching method is used to analyze the scattering characteristics of the rectangular-to-circular groove waveguide junction. Firstly, the scattering matrix equation is obtained by matching the electromagnetic fields at the boundary of the junction. The scattering coefficients can be obtained from the equation. Secondly the scattering characteristics of the iris with rectangular window positioned in circular groove waveguide are briefly analyzed. Thirdly, the convergent problem is discussed and the numerical results are given. At last experiment is made and good agreement is found between the calculated results and the measured results.

  1. Appraisal of transverse nasal groove: A study

    Directory of Open Access Journals (Sweden)

    Belagola D Sathyanarayana

    2012-01-01

    Full Text Available Background: Transverse nasal groove is a condition of cosmetic concern which awaits due recognition and has been widely described as a shallow groove that extends transversely over the dorsum of nose. However, we observed variations in the clinical presentations of this entity, hitherto undescribed in literature. Aims: We conducted a clinicoepidemiological study of transverse nasal lesions in patients attending our outpatient department. Methods: We conducted a prospective observational study. We screened all patients attending our out-patient department for presence of transverse nasal lesions, signs of any dermatosis and associated other skin conditions. Results: One hundred patients were recruited in the study. Females (80% predominated over males. Most patients were of 15-45 years age group (70%. Majority of the transverse nasal lesions were classical transverse nasal groove (39% and others included transverse nasal line (28%, strip (28%, ridge (4% and loop (1%. Seborrhoeic diathesis was the most common condition associated with transverse nasal lesion. Conclusions: Occurrence of transverse nasal line, strip, ridge and loop, in addition to classical transverse nasal groove implies that latter is actually a subset of transverse nasal lesions. Common association of this entity with seborrheic dermatitis, seborrhea and dandruff raises a possibility of whether transverse nasal lesion is a manifestation of seborrheic diathesis.

  2. Optimization of Grooved Micromixer for Microengineering Technologies

    DEFF Research Database (Denmark)

    Sabotin, I.; Tristo, G.; Bissacco, Giuliano

    2013-01-01

    Due to the absence of turbulent flow and the slow diffusion process, mixing of solutions at micro-scale is a difficult task. This paper describes the optimization route towards the efficient design of a bottom grooved micromixer. Based on thoroughly discussed mixing mechanisms, the optimization w...

  3. Preparation and characterization of V-shaped PS-b-PEO brushes anchored on planar gold substrate through the trithiocarbonate junction group.

    Science.gov (United States)

    Wang, Zhao-Li; Xu, Jun-Ting; Du, Bin-Yang; Fan, Zhi-Qiang

    2012-10-15

    Trithiocarbonate group was introduced into the polystyrene-b-poly(ethylene oxide) (PS-b-PEO) block copolymers as the junction of the blocks through RAFT polymerization. Mixed PS and PEO brushes with a V-shape were prepared by anchoring the trithiocarbonate group on the planar gold substrate. The morphology of the V-shaped brushes was characterized by atomic force microscopy (AFM) and the surface composition responsive to solvent treatment was detected by X-ray photoelectron spectroscopy (XPS). Different morphologies were observed for the V-shaped PS-b-PEO brushes, depending on the chain structure and solvent treatment. The highly selective solvent for PEO, ethanol, can intensify or induce microphase separation of the V-shaped brushes, leading to vertical microphase separation. When the V-shaped brushes are treated with the co-solvent, THF, miscible morphology, lateral microphase separation, and vertical microphase separation are observed as the PS block length increases. After treatment with the non-selective poor solvent, cyclohexane, the V-shaped PS(106)-b-PEO(113) brush, exhibits a laterally microphase-separated morphology, but the V-shaped PS(52)-b-PEO(113) and PS(253)-b-PEO(113) brushes are vertically microphase-separated.

  4. Vacuum Infusion Molding Process (Part 2 VIMP Based on Grooves)

    Institute of Scientific and Technical Information of China (English)

    ZHU Ying-dan; DENG Jing-lan; WANG Ji-hui; TAN Hua

    2003-01-01

    The optimal parameters for flow grooves and supply grooves were determined by a series of experiments , and the influences of various molding conditions on the mold filling process were analyzed. Furthermore ,the whole VIMP procedure based on grooves was introduced in detail taking the manufacture of a sandwich panel as an example.

  5. The Richtmyer-Meshkov instability of a "V" shaped air/helium interface subjected to a weak shock

    Science.gov (United States)

    Zhai, Zhigang; Dong, Ping; Si, Ting; Luo, Xisheng

    2016-08-01

    The Richtmyer-Meshkov instability of a "V" shaped air/helium gaseous interface subjected to a weak shock wave is experimentally studied. A soap film technique is adopted to create a "V" shaped interface with accurate initial conditions. Five kinds of air/helium "V" shaped interfaces with different vertex angles (60°, 90°, 120°, 140°, and 160°), i.e., different amplitude-wavelength ratios, are formed to highlight the effects of initial conditions, especially the initial amplitude, on the flow characteristics. The interface morphologies identified by the high-speed schlieren photography show that a spike is generated from the vertex after the shock impact, and grows constantly with time accompanied by the occurrence of the phase reversal. As the vertex angle increases, vortices generated on the interface become less noticeable, and the spike develops less pronouncedly. The linear growth rate of the interface mixing width of a heavy/light interface configuration after compression phase is estimated by a linear model and a revised linear model, and the latter is proven to be more effective for the interface with high initial amplitudes. It is found for the first time in a heavy/light interface configuration that the linear growth rate of interface width is a non-monotonous function of the initial perturbation amplitude-wavelength ratio. In the nonlinear stage, it is confirmed that the width growth rate of interface with high initial amplitudes can be well predicted by a model proposed by Dimonte and Ramaprabhu ["Simulations and model of the nonlinear Richtmyer-Meshkov instability," Phys. Fluids 22, 014104 (2010)].

  6. Tunable coupling in circuit quantum electrodynamics using a superconducting charge qubit with a V-shaped energy level diagram.

    Science.gov (United States)

    Srinivasan, S J; Hoffman, A J; Gambetta, J M; Houck, A A

    2011-02-25

    We introduce a new type of superconducting charge qubit that has a V-shaped energy spectrum and uses quantum interference to provide independently tunable qubit energy and coherent coupling to a superconducting cavity. Dynamic access to the strong coupling regime is demonstrated by tuning the coupling strength from less than 200 kHz to greater than 40 MHz. This tunable coupling can be used to protect the qubit from cavity-induced relaxation and avoid unwanted qubit-qubit interactions in a multiqubit system.

  7. Solar cell with doped groove regions separated by ridges

    Energy Technology Data Exchange (ETDEWEB)

    Molesa, Steven Edward; Pass, Thomas; Kraft, Steve

    2017-01-31

    Solar cells with doped groove regions separated by ridges and methods of fabricating solar cells are described. In an example, a solar cell includes a substrate having a surface with a plurality of grooves and ridges. A first doped region of a first conductivity type is disposed in a first of the grooves. A second doped region of a second conductivity type, opposite the first conductivity type, is disposed in a second of the grooves. The first and second grooves are separated by one of the ridges.

  8. Graphene Plasmons in Triangular Wedges and Grooves

    CERN Document Server

    Gonçalves, P A D; Xiao, Sanshui; Vasilevskiy, M I; Mortensen, N Asger; Peres, N M R

    2016-01-01

    The ability to effectively guide electromagnetic radiation below the diffraction limit is of the utmost importance in the prospect of all-optical plasmonic circuitry. Here, we propose an alternative solution to conventional metal-based plasmonics by exploiting the deep subwavelength confinement and tunability of graphene plasmons guided along the apex of a graphene-covered dielectric wedge or groove. In particular, we present a quasi-analytic model to describe the plasmonic eigenmodes in such a system, including the complete determination of their spectrum and corresponding induced potential and electric field distributions. We have found that the dispersion of wedge/groove graphene plasmons follows the same functional dependence as their flat-graphene plasmons counterparts, but now scaled by a (purely) geometric factor in which all the information about the system's geometry is contained. We believe our results pave the way for the development of novel custom-tailored photonic devices for subwavelength waveg...

  9. Grooving corrosion of seam welded oil pipelines

    Directory of Open Access Journals (Sweden)

    Mohamed Hanafy El-Sayed

    2014-10-01

    Full Text Available 24” pipeline carrying oil was failed in the form of longitudinal crack at the 6 O’clock position resulting in oil spill. The failed pipe was investigated to reveal the main cause of its failure. The procedure of investigation was built on studying the intact pipe, rupture area, parent material, and intact weld. Results of chemical analysis, mechanical properties, and microstructure of the pipe material were confirmed with the specified standard. Cracks were originated from weld defected sites, initiated by grooving corrosion, propagated by inertia at the normal designed pressure condition, and stopped when stress relief is attained. It is recommended to use high quality ERW pipe, with its seam weld line positioned around the 12 O’clock during installation, to minimize and decelerate grooving corrosion. It is also important to perform regular or routine inspection, on suitable intervals, determined by past experience.

  10. T-stress estimation by the two-parameter approach for a specimen with a V-shaped notch

    Science.gov (United States)

    Bouledroua, O.; Elazzizi, A.; Hadj Meliani, M.; Pluvinage, G.; Matvienko, Y. G.

    2017-05-01

    In the present research, T-stress solutions are provided for a V-shaped notch in the case of surface defects in a pressurised pipeline. The V-shaped notch is analyzed with the use of the finite element method by the Castem2000 commercial software to determine the stress distribution ahead of the notch tip. The notch aspect ratio is varied. In contrast to a crack, it is found that the T-stress is not constant and depends on the distance from the notch tip. To estimate the T-stress in the case of a notch, a novel method is developed, inspired by the volumetric method approach proposed by Pluvinage. The method is based on averaging the T-stress over the effective distance ahead of the notch tip. The effective distance is determined by the point with the minimum stress gradient in the fracture process zone. This approach is successfully used to quantify the constraints of the notch-tip fields for various geometries and loading conditions. Moreover, the proposed T-stress estimation creates a basis for analyzing the crack path under mixed-mode loading from the viewpoint of the two-parameter fracture mechanics.

  11. Diamond grooving of rapidly solidified optical aluminium

    Science.gov (United States)

    Abou-El-Hossein, Khaled; Hsu, Wei-Yao; Ghobashy, Sameh; Cheng, Yuan-Chieh; Mkoko, Zwelinzima

    2015-10-01

    Traditional optical aluminium grades such as Al 6061 are intensively used for making optical components for applications ranging from mould insert fabrication to laser machine making. However, because of their irregular microstructure and relative inhomogeneity of material properties at micro scale, traditional optical aluminium may exhibit some difficulties when ultra-high precision diamond turned. Inhomogeneity and micro-variation in the material properties combined with uneven and coarse microstructure may cause unacceptable surface finish and accelerated tool wear, especially in grooving operation when the diamond tool edge is fully immersed in the material surface. Recently, new grades of optical aluminium that are featured by their ultra-fine microstructure and improved material properties have been developed to overcome the problem of high tool wear rates. The new aluminium grades have been developed using rapid solidification process which results in extremely small grain sizes combined with improved mechanical properties. The current study is concerned with investigating the performance of single-point diamond turning when grooving two grades of rapidly solidified aluminium (RSA) grades: RSA905 which is a high-alloyed aluminium grade and RSA443 which has a high silicon content. In this study, two series of experiments employed to create radial microgrooves on the two RSA grades. The surface roughness obtained on the groove surface is measured when different combinations of cutting parameters are used. Cutting speed is varied while feed rate and depth of cut were kept constant. The results show that groove surface roughness produced on RSA443 is higher than that obtained on RSA905. Also, the paper reports on the effect of cutting speed on surface roughness for each RSA grade.

  12. Simplification of vector ray tracing by the groove function.

    Science.gov (United States)

    Hu, Zhongwen; Liu, Zuping; Wang, Qiuping

    2005-01-01

    Tracing rays through arbitrary diffraction gratings (including holographic gratings of the second generation fabricated on a curved substrate) by the vector form is somewhat complicated. Vector ray tracing utilizes the local groove density, the calculation of which highly depends on how the grooves are generated. Characterizing a grating by its groove function, available for almost arbitrary gratings, is much simpler than doing so by its groove density, essentially being a vector. Applying the concept of Riemann geometry, we give an expression of the groove density by the groove function. The groove function description of a grating can thus be incorporated into vector ray tracing, which is beneficial especially at the design stage. A unified explicit grating ray-tracing formalism is given as well.

  13. The 2D Finite Element Microstructure Evaluation of V-Shaped Arc Welding of AISI 1045 Steel

    Directory of Open Access Journals (Sweden)

    Omer Eyercioglu

    2017-02-01

    Full Text Available In the present study, V-shaped arc welding of the AISI 1045 steel is modeled by using 2D Finite Element Model (FEM. The temperature distribution, microstructure, grain growth, and the hardness of the heat-affected zone (HAZ of the welding are simulated. The experimental work is carried out to validate the FE model. The very close agreement between the simulation and experimental results show that the FE model is very effective for predicting the microstructure, the phase transformation, the grain growth and the hardness. The effect of preheat temperature on the martensite formation is analysed, and it is shown that 225 °C preheating completely eliminates the martensite formations for the 12 mm thick plate.

  14. Comparative Numerical Analysis of Sheet Formed into a V-Shaped Die Using Conventional and Electromagnetic Forming Processes

    Directory of Open Access Journals (Sweden)

    Jeong Kim

    2014-05-01

    Full Text Available A comparative and numerical study on the formability of a sheet formed into a V-shaped die using a conventional stamping operation and an electromagnetic forming (EMF process was performed. To evaluate the damage evolution and failure prediction using a finite-element method (FEM, the Gurson-Tvergaard-Needleman plasticity material model was employed in the numerical simulation. The impact of the sheet with the die generates a complex stress state during the EMF process. Damage suppression due to the tool-sheet interaction may be one of the main factors contributing to the increased formability in the EMF process compared to the conventional forming operation. In addition, a high level of kinetic energy produces high strain-rate constitutive and inertial effects, which delay the onset of necking and may also be responsible for the increased formability using EMF.

  15. NUMERICAL ANALYSIS OF THE 3-D FLOW FIELD OF PRESSURE ATOMIZERS WITH V-SHAPED CUT AT ORIFICE

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hua

    2011-01-01

    Axisymmetric liquid jets have been studied extensively for more than one century, while non-axisymmetric jets are also very common in engineering applications but attract less concern. Based on Eulerian fluid-fluid model in Fluent software, this article analysizes the 3-D flow fields of pressure atomizers with V-shaped cut at orifice, which will result in a non-axisymmetric liquid jet.Flow rate analysis and jet structure analysis are carried out, the results show that the flow rate can be formulated by adding a correction coefficient to the formula of inviscid axisymmetric jets in atomization regime, when the Weber number is low enough to make the flow fall out of atomization regime, and the jet structure together with the flow rate formula will change. Analysis shows that the evolution of the spray and therefore the structure of the liquid jet are affected much by relative velocity and the local volume fraction of liquid phase.

  16. V-shaped double-row distal triceps tendon repair: a novel technique using unicortical button fixation.

    Science.gov (United States)

    Scheiderer, Bastian; Lacheta, Lucca; Imhoff, Andreas B; Siebenlist, Sebastian

    2017-03-14

    This report was designed to present a novel technique combining suture anchor and unicortical button fixation for distal triceps tendon repair. For anatomical reinsertion of an acute distal triceps tendon rupture, two suture anchors and one unicortical button forming a V-shaped configuration were used. The operative approach is described in detail. Excellent clinical and functional results were achieved in the early postoperative phase. The patient reached full elbow range of motion and extension muscle strength (5/5) compared to the uninjured arm 12 weeks after surgery. Complications did not occur. This is the first report using unicortical button fixation in distal triceps tendon repair with promising preliminary results. Technical description, case report, Level V.

  17. Experimental validation of a new bianisotropic parameter retrieval technique using plasmonic metasurfaces made of V-shape antennas

    Science.gov (United States)

    Liu, Jingjing; Shaltout, Amr M.; Ni, Xingjie; Shalaev, Vladimir M.; Kildishev, Alexander V.

    2013-09-01

    We report on a numerical study of a new bianisotropic parameter retrieval technique for both regular and complementary V-shape antenna metasurfaces. Each antenna element with a discrete phase shift is modeled by a homogenous bianisotropic film to represent the optical response. For the complementary design, the retrieval implies a complementary behavior of effective material properties and predicts the analogous functionalities. Further, FDFD solver is developed to integrate the bianisotropic descriptions of each antenna and describes a fully functional metasurface. The computational burden is significantly reduced, because effective material properties replace the detailed meshing of the antennas. Experimentally, large dimension arrays of nano-voids are fabricated using electron beam lithography. It is demonstrated that cross-polarized light is diffracted towards the same direction. Furthermore, the complementary design greatly increases the extinction ratio of functional fields to background fields.

  18. Subvertical grooves of interproximal facets in Neandertal posterior teeth.

    Science.gov (United States)

    Villa, G; Giacobini, G

    1995-01-01

    Subvertical grooves, located on the interproximal facets of most Neandertal posterior teeth, are less frequently noted on the teeth of other hominids, including modern humans. These grooves, 0.1-0.5 mm in width, are strictly localized within the facet area. Scanning electron microscopic (SEM) examination of grooves present on Neandertal teeth from Caverna delle Fate (Liguria, Italy) and Genay (Côte d'Or, France) demonstrated that they were produced during the life of these individuals. Characteristics of the groove surface suggest an erosion-abrasion mechanism of formation. These grooves, which developed in parts of the dentition exposed to marked stress, originated in areas characterized by changes in the orientation of enamel prism bundles (i.e., Hunter-Schreger bands). Observations carried out on modern human molars showed a subvertical disposition of these bands near interproximal ridges facilitating subvertical microfractures. Possible correlations between enamel structure, masticatory stress, and interproximal groove formation in Neandertals are discussed.

  19. Dual-phase CT findings of groove pancreatitis

    Energy Technology Data Exchange (ETDEWEB)

    Zaheer, Atif, E-mail: azaheer1@jhmi.edu [The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD 21231 (United States); Pancreatitis Center, Division of Gastroenterology, Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, MD 21231 (United States); Haider, Maera, E-mail: mhaider3@jhmi.edu [The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD 21231 (United States); Kawamoto, Satomi, E-mail: skawamo1@jhmi.edu [The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD 21231 (United States); Hruban, Ralph H., E-mail: rhruban1@jhmi.edu [Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center, the Johns Hopkins University School of Medicine, Baltimore, MD 21231 (United States); Fishman, Elliot K., E-mail: efishma1@jhmi.edu [The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD 21231 (United States)

    2014-08-15

    Purpose: Groove pancreatitis is a rare focal form of chronic pancreatitis that occurs in the pancreaticoduodenal groove between the major and minor papillae, duodenum and pancreatic head. Radiologic appearance and clinical presentation can result in suspicion of malignancy rendering pancreaticoduodenectomy inevitable. This study reports dual phase CT findings in a series of 12 patients with pathology proven groove pancreatitis. Materials and methods: Retrospective review of preoperative CT findings in 12 patients with histologically proven groove pancreatitis after pancreaticoduodenectomy. Size, location, attenuation, presence of mass or cystic components in the pancreas, groove and duodenum, calcifications, duodenal stenosis and ductal changes were recorded. Clinical data, laboratory values, endoscopic ultrasonographic and histopathological findings were collected. Results: Soft tissue thickening in the groove was seen in all patients. Pancreatic head, groove and duodenum were all involved in 75% patients. A discrete lesion in the pancreatic head was seen in half of the patients, most of which appeared hypodense on both arterial and venous phases. Cystic changes in pancreatic head were seen in 75% patients. Duodenal involvement was seen in 92% patients including wall thickening and cyst formation. The main pancreatic duct was dilated in 7 patients, with an abrupt cut off in 3 and a smooth tapering stricture in 4. Five patients had evidence of chronic pancreatitis with parenchymal calcifications. Conclusion: Presence of mass or soft tissue thickening in the groove with cystic duodenal thickening is highly suggestive of groove pancreatitis. Recognizing common radiological features may help in diagnosis and reduce suspicion of malignancy.

  20. Grooved roll for a high speed twin roll caster

    OpenAIRE

    T. Haga; HIROOKA, K.; H. Watari; S. Kumai

    2008-01-01

    Purpose: Purpose of this paper is investigation of the effect of roll-surface on the strip-surface. Improvement ofsmall cracks on the strip-surface was tried and effect of groove at the roll surface on the strip surface was shown.Design/methodology/approach: Method used in the present study was high speed twin roll caster withgrooved roll. Two kinds of grooves were used: one was parallel groove and the other was cross groove machinedby knurling and bite attached to a lathe.Findings: Findings ...

  1. Sensorimotor coupling in music and the psychology of the groove.

    Science.gov (United States)

    Janata, Petr; Tomic, Stefan T; Haberman, Jason M

    2012-02-01

    The urge to move in response to music, combined with the positive affect associated with the coupling of sensory and motor processes while engaging with music (referred to as sensorimotor coupling) in a seemingly effortless way, is commonly described as the feeling of being in the groove. Here, we systematically explore this compelling phenomenon in a population of young adults. We utilize multiple levels of analysis, comprising phenomenological, behavioral, and computational techniques. Specifically, we show (a) that the concept of the groove is widely appreciated and understood in terms of a pleasurable drive toward action, (b) that a broad range of musical excerpts can be appraised reliably for the degree of perceived groove, (c) that the degree of experienced groove is inversely related to experienced difficulty of bimanual sensorimotor coupling under tapping regimes with varying levels of expressive constraint, (d) that high-groove stimuli elicit spontaneous rhythmic movements, and (e) that quantifiable measures of the quality of sensorimotor coupling predict the degree of experienced groove. Our results complement traditional discourse regarding the groove, which has tended to take the psychological phenomenon for granted and has focused instead on the musical and especially the rhythmic qualities of particular genres of music that lead to the perception of groove. We conclude that groove can be treated as a psychological construct and model system that allows for experimental exploration of the relationship between sensorimotor coupling with music and emotion.

  2. Wetting morphologies and their transitions in grooved substrates

    Energy Technology Data Exchange (ETDEWEB)

    Seemann, Ralf; Bommer, Stefan; Herrmann, Carsten; Michler, Dominik [Experimental Physics, Saarland University, D-66123 Saarbruecken (Germany); Brinkmann, Martin; Herminghaus, Stephan; Khare, Krishnacharya; Kostourou, Konstantina; Gurevich, Evgeny [Max Planck Institute for Dynamics and Self-Organization, D-37073 Goettingen (Germany); Law, Bruce M; McBride, Sean, E-mail: r.seemann@physik.uni-saarland.de [Department of Physics, Kansas State University, Manhattan, KS 66506 (United States)

    2011-05-11

    When exposed to a partially wetting liquid, many natural and artificial surfaces equipped with complex topographies display a rich variety of liquid interfacial morphologies. In the present article, we focus on a few simple paradigmatic surface topographies and elaborate on the statics and dynamics of the resulting wetting morphologies. It is demonstrated that the spectrum of wetting morphologies increases with increasing complexity of the groove structure. On elastically deformable substrates, additional structures in the liquid morphologies can be observed, which are caused by deformations of the groove geometry in the presence of capillary forces. The emergence of certain liquid morphologies in grooves can be actively controlled by changes in wettability and geometry. For electrically conducting solid substrates, the apparent contact angle can be varied by electrowetting. This allows, depending on groove geometry, a reversible or irreversible transport of liquid along surface grooves. In the case of irreversible liquid transport in triangular grooves, the dynamics of the emerging instability is sensitive to the apparent hydrodynamic slip at the substrate. On elastic substrates, the geometry can be varied in a straightforward manner by stretching or relaxing the sample. The imbibition velocity in deformable grooves is significantly reduced compared to solid grooves, which is a result of the microscopic deformation of the elastic groove material close to the three phase contact line.

  3. Laminar streak enhancement using streamwise grooves

    Science.gov (United States)

    Martel, Carlos; Martín, Juan Ángel

    2011-11-01

    Laminar streak promotion in a flat plate boundary layer results in an increase of the stability of the Tollmien-Schlichting waves with respect to that of the 2D Blasius profile. This stabilization delays the laminar-turbulent transition, increasing the laminar phase of the flow. The stabilization effect is stronger for higher streak amplitudes, and therefore simple ways of generating high amplitude stable streaks are sought to be used as boundary layer flow control methods. In a recent experiment [Tallamelli & Franson,AIAA 2010-4291] high amplitude stable steady streaks have been produced using Miniature Vortex Generators (MGVs), where one array of MGVs is used to excite the streak and a second array is used downstream to enhance their amplitude. In this presentation we numerically explore the possibility of enhancing the streaks using a different passive mechanism: streamwise grooves carved in the plate. We will present some numerical simulations for different values of the spanwise period of the streaks and of the grooves, and we will show the combinations that provide maximum streak amplitude.

  4. Zn(II) coordination polymers with flexible V-shaped dicarboxylate ligand: Syntheses, helical structures and properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lin [School of Environment and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Liu, Chong-Bo, E-mail: cbliu@nchu.edu.cn [School of Environment and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Yang, Gao-Shan [School of Environment and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Xiong, Zhi-Qiang [Center for Analysis and Testing, Nanchang Hangkong University, Nanchang 330063 (China); Liu, Hong [School of Environment and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Wen, Hui-Liang [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047 (China)

    2015-11-15

    Hydrothermal reactions of 2,2′-[hexafluoroisopropylidenebis(p-phenyleneoxy)]diacetic acid (H{sub 2}L) and zinc ions in the presence of N-donor ancillary ligands afford four novel coordination polymers, namely, [Zn{sub 2}(μ{sub 2}-OH)(μ{sub 4}-O){sub 0.5}(L)]·0.5H{sub 2}O (1), [Zn(L)(2,2′-bipy)(H{sub 2}O)] (2), [Zn{sub 3}(L){sub 3}(phen){sub 2}]·H{sub 2}O (3) and [Zn{sub 2}(L){sub 2}(4,4′-bipy)] (4) (2,2′-bipy=2,2′-bipyridine; 4,4′-bipy=4,4′-bipyridine; phen=1,10-phenanthroline). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra, powder X-ray diffraction (PXRD), and thermogravimetric (TG) analyses. Complex 1 shows a 3-D clover framework consisting of [Zn{sub 4}(µ{sub 4}-O)(µ{sub 2}-OH){sub 2}]{sup 4+} clusters, and exhibits a novel (3,8)-connected topological net with the Schläfli symbol of {3·4·5}{sub 2}{3"4·4"4·5"2·6"6·7"1"0·8"2}, and contains double-stranded and two kinds of meso-helices. 2 displays a helical chain structure, which is further extended via hydrogen bonds into a 3-D supramolecular structure with meso-helix chains. 3 displays a 2-D {4"4·6"2} parallelogram structure, which is further extended via hydrogen bonds into a 3-D supramolecular structure with single-stranded helical chains. 4 shows a 2-D {4"4·6"2} square structure with left- and right-handed helical chains. Moreover, the luminescent properties of 1–4 have been investigated. - Graphical abstract: Four new Zn(II) coordination polymers with helical structures based on flexible V-shaped dicarboxylate ligand have been synthesized and structurally characterized. Photoluminescent properties have been investigated. - Highlights: • Four novel Zn(II) coordination polymers with V-shaped ligand were characterized. • Complexes 1–4 show diverse intriguing helical characters. • Fluorescence properties of complexes 1–4 were investigated.

  5. Research on Parts Process of V-shape Slot Carburizing Quenching%V型槽渗碳淬火零件加工工艺研究

    Institute of Scientific and Technical Information of China (English)

    陈惠娟; 黄玉方; 梁壮; 王健

    2012-01-01

    通过对V型槽渗碳淬火类零件的特性及加工难点的分析,研究V型槽渗碳淬火类零件的工艺总方案及加工工艺.主要针对2种不同结构类型的V型槽渗碳淬火类零件的加工工艺及加工过程进行分析,探讨V型槽渗碳淬火零件的特殊加工方法.通过对V型槽渗碳淬火类零件的生产加工和加工过程中的工艺改进与完善,摸索到了加工V型槽渗碳淬火零件的一些经验,供大家参考.%By analyzing the characteristics of V-shape slot carburizing quenching parts and the difficulties of processing, the paper mainly focused on the general plan and processing technology of the V-shape slot carburizing quenching parts. By analyzing parts processing technology and processing procedure of two different structures of the V-shape slot carburizing quenching, the paper discussed the specific processing method of the V-shape slot carburizing quenching parts. By making improvements and perfection of the production processing and the process technology of the V-shape slot carburizing quenching parts, we have got some experiences from the processing of the V-shape slot carburizing quenching parts for your reference.

  6. Optics of a single ultrasharp groove in metal

    DEFF Research Database (Denmark)

    Søndergaard, Thomas; Bozhevolnyi, Sergey

    2016-01-01

    Optical properties of a single ultrasharp groove of subwavelength width cut in an otherwise flat metal surface are examined theoretically. We calculate optical extinction, scattering, and absorption cross-section spectra for a wide range of groove profiles, establishing several fundamental trends...

  7. Effective slippage on superhydrophobic trapezoidal grooves

    CERN Document Server

    Zhou, Jiajia; Schmid, Friederike; Vinogradova, Olga I

    2013-01-01

    We study the effective slippage on superhydrophobic grooves with trapezoidal cross-sections of various geometries (including the limiting cases of triangles and rectangular stripes), by using two complementary approaches. First, dissipative particle dynamics (DPD) simulations of a flow past such surfaces have been performed to validate an expression [E.S.Asmolov and O.I.Vinogradova, J. Fluid Mech. \\textbf{706}, 108 (2012)] that relates the eigenvalues of the effective slip-length tensor for one-dimensional textures. Second, we propose theoretical estimates for the effective slip length and calculate it numerically by solving the Stokes equation based on a collocation method. The comparison between the two approaches shows that they are in excellent agreement. Our results demonstrate that the effective slippage depends strongly on the area-averaged slip, the amplitude of the roughness, and on the fraction of solid in contact with the liquid. To interpret these results, we analyze flow singularities near slippi...

  8. Olfactory groove meningiomas: approaches and complications.

    Science.gov (United States)

    Aguiar, Paulo Henrique Pires de; Tahara, Adriana; Almeida, Antonio Nogueira; Simm, Renata; Silva, Arnaldo Neves da; Maldaun, Marcos Vinicius Calfatt; Panagopoulos, Alexandros Theodoros; Zicarelli, Carlos Alexandre; Silva, Pedro Gabriel

    2009-09-01

    Olfactory groove meningiomas (OGM) account for 4.5% of all intracranial meningiomas. We report 21 patients with OGMs. Tumors were operated on using three surgical approaches: bifrontal (7 patients), fronto-pterional (11 patients) and fronto-orbital (3 patients). Total tumor removal (Simpson Grade 1) was achieved in 13 patients and Simpson II in 8 patients. Perioperative mortality was 4.76%. The average size of the OGM was 4.3+/-1.1cm. The overall recurrence rate was 19%. We preferred to use the pterional approach, which provides quick access to the tumor with less brain exposure. It also allows complete drainage of cisternal cerebrospinal fluid, providing a good level of brain relaxation during surgery. However, for long, thin tumors, hemostasis can be difficult using this approach.

  9. Development of a V-shape bis(tetraoxacalix[2]arene[2]triazine) stationary phase for high performance liquid chromatography.

    Science.gov (United States)

    Hu, Kai; Feng, Suxiang; Wu, Mingxia; Wang, Shuang; Zhao, Wenjie; Jiang, Qiong; Yu, Ajuan; Zhang, Shusheng

    2014-12-01

    A new stationary phase for high-performance liquid chromatography was prepared by covalently bonding a V-shape cage heteroatom-bridged calixarene onto silica gel using 3-aminopropyltriethoxysilane as coupling reagent. The structure of the new material was characterized by infrared spectroscopy, elemental analysis and thermogravimetric analysis. Linear solvation energy relationship method was successfully employed to evaluate the new phase with a set of 34 solutes. The retention characteristic of the new phase shows significant similarities with ODS, as well as distinctive features. Multiple mechanisms including hydrophobic, hydrogen bonding, π-π and n-π interaction are involved. The chromatographic behavior of the phase was illustrated by using alkylbenzenes, aromatics positional isomers and flavonoids as probes. Moreover, inorganic anions were individually separated in anion-exchange mode by using the same column. Thus, multi-interaction mechanisms and mixed-mode separation of the new phase can very likely guarantee its excellent chromatographic performance for the analysis of complex samples. The column has been successfully employed for the analysis of clenbuterol in animal urine, and it is demonstrated to be suitable and a competitive alternative analytical method for the determination of clenbuterol.

  10. Kaftas prepared with V-shaped filleting chips of the Nile tilapia (Oreochromis niloticus exposed to smoking techniques

    Directory of Open Access Journals (Sweden)

    Maria Luiza Rodrigues de Souza

    2015-05-01

    Full Text Available Kaftas with V-shaped filleting chips of the Nile tilapia (Oreochromis niloticus were developed and the effects of the smoking technique on the characteristics of chemical composition, microbiological, sensory and benzo(apyrene were investigated. The filleting chips were ground and filleting included condiments and bacon. Kaftas were molded, frozen and distributed in a completely randomized design with three treatments (T 1 = baked in a grid; T 2 = smoked by friction and T 3 = smoked by liquid smoke with 10 replications. The kaftas subjected to hot smoke had lower moisture content (13.97%, whereas the no-smoking kaftas had the highest content (20.49%. Kaftas with liquid smoke had high crude protein content (48.06% and ash (9.49%, whereas the ash content was different only from no-smoking kaftas (8.79%. There was no significant difference in sensory parameters, except for flavor; smoked kaftas with liquid smoke were more accepted by the judges and the worst kaftas were no-smoked kaftas. Microbiological analysis showed that kaftas developed were appropriate to feed human beings within the required standards. Chips filleting is an alternative for the development of kaftas and those subjected to liquid smoke were considered the best.

  11. Design, numerical simulation and experimental investigation of an SU-8 microgripper based on the cascaded V-shaped electrothermal actuators

    Science.gov (United States)

    Voicu, Rodica-Cristina

    2016-10-01

    This paper presents the numerical simulation results and the experimental investigations of a polymeric microgripper designed using the cascaded V-shaped electrothermal actuators. The microgripper was simulated using electro-thermo-mechanical finite element method (FEM) based on Coventorware 2014 software in order to check the performance of the gripper. As structural material of the microgripper, the SU-8 biocompatible polymer was used during the fabrication process. The metallic micro-heaters were encapsulated in the polymeric actuation structures of the microgrippers to reduce the undesirable out-of-plane displacement of the gripper tips, to reduce the mechanical stress and to improve the thermal efficiency. Experimental testing has been performed to determine the openings of the microgripper tips as function of electrical current. A displacement of the tips of more than 50 pm can be obtained at an electrical current of around 25-26 mA. Over 27-28 mA the heaters are still working but a softening and a damaging status in the polymer were observed.

  12. Response surface method optimization of V-shaped fin assisted latent heat thermal energy storage system during discharging process

    Directory of Open Access Journals (Sweden)

    Sina Lohrasbi

    2016-09-01

    Full Text Available Latent Heat Thermal Energy Storage Systems (LHTESS containing Phase Change Material (PCM are used to establish balance between energy supply and demand. PCMs have high latent heat but low thermal conductivity, which affects their heat transfer performance. In this paper, a novel fin array has been optimized by multi-objective Response Surface Method (RSM based on discharging process of PCM, and then this fin configuration is applied on LHTESS, and comparison between full discharging time by applying this fin array and LHTESS with other fin structures has been carried out. The employed numerical method in this paper is Standard Galerkin Finite Element Method. Adaptive grid refinement is used to solve the equations. Since the enhancement technique, which has been employed in the present study reduces the employed PCM mass, maximum energy storage capacity variations have been considered. Therefore phase change expedition and maximum energy storage capacity have been considered as the objectives of optimization and the importance of second objective is indicated which is proposed as the novelty here. Results indicate that considering maximum energy storage capacity as the objective of optimization procedure leads to efficient shape design of LHTESS. Also employing optimized V-shaped fin in LHTESS, expedites discharging process considerably in comparison with the LHTESS without fin.

  13. Multi-wavelength emitting InGan/GaN quantum well grown on V-shaped gan(1101) microfacet.

    Science.gov (United States)

    Kang, Eun-Sil; Ju, Jin-Woo; Kim, Jin Soo; Ahn, Haeng-Keun; Lee, June Key; Kim, Jin Hyeok; Shin, Dong-Chan; Lee, In-Hwan

    2007-11-01

    InGaN/GaN multiple quantum wells (MQWs) were successfully grown on the inclined GaN(1101) microfacets. Conventional photolithography and subsequent growth of GaN were employed to generate the V-shaped microfacets along (1120) direction. The well-developed microfacets observed by scanning electron microscopy and the clear transmission electron microscope interfacial images indicated that the MQW was successfully grown on the GaN microfacets. Interestingly, cathodoluminescence (CL) spectra measured on the microfacets showed a continuous change in the luminescence peak positions. The CL peaks were shifted to a longer wavelength from 420 nm to 440 nm as the probing points were changed along upward direction. This could be attributed to the nonuniform distribution of the In composition and/or the wavefunction overlapping between adjacent wells. Present works thus propose a novel route to fabricate a monolithic white light emitting diode without phosphors by growing the InGaN/GaN MQWs on (1101) facet.

  14. A series of coordination polymers based on a V-shaped multicarboxylate and bisimidazole ligands: Synthesis, characterization and luminescent properties

    Science.gov (United States)

    Guo, Huadong; Yan, Yongnian; Guo, Xianmin; Wang, Nan; Qi, Yanjuan

    2016-03-01

    Based on a V-shaped multicarboxylic acid and various bisimidazole ligands, six new coordination polymers, namely, [Zn4(otba) (1,4-bix)4]·3H2O (1), [Ni4(otba)2(1,4-bix)3(H2O)2]·2H2O (2), [Zn2(H2otba)2(bib) (H2O)2] (3), [Cd2(H2otba)2(bib)]·2H2O (4), [Zn3(otba)2(bidpe)2(H2O)2] (5), [Ni2(H2otba)2(bidpe)3(H2O)2]·H2O (6) (H4otba = 3,5,3‧,5‧-oxytetrabenzoic acid, 1,4-bix = 1,2-bis(imidazol-1-ylmethyl)benzene, bib = 1,4-bis(imidazol-1-yl)benzene and bidpe = 4,4'-bis(imidazol-1-yl)diphenyl ether) have been hydrothermally synthesized and structurally characterized. Compound 1 displays an uncommon hexanodal 3D 4-connected network. Compound 2 features a trinodal 3D (4, 4, 6)-connected framework. Compound 3 shows an interesting polythreaded 1D→3D species. Compound 4 exhibits a binodal 3D (3, 8)-connected network. Compound 5 displays a three-fold interpenetration of trinodal (3, 3, 4)-connected network. Compound 6 shows a five-fold interpenetration of five-connected bilayer network. The luminescent properties of compounds 1, 3, 4 and 5 were also measured.

  15. EGFR inhibitors erlotinib and lapatinib ameliorate epidermal blistering in pemphigus vulgaris in a non-linear, V-shaped relationship.

    Science.gov (United States)

    Sayar, Beyza S; Rüegg, Simon; Schmidt, Enno; Sibilia, Maria; Siffert, Myriam; Suter, Maja M; Galichet, Arnaud; Müller, Eliane J

    2014-01-01

    Novel insights into intra-cellular signalling involved in pemphigus vulgaris (PV), an autoimmune blistering disease of skin and mucous membranes, are now revealing new therapeutic approaches such as the chemical inhibition of PV-associated signals in conjunction with standard immunosuppressive therapy. However, extensive inhibition of signalling molecules that are required for normal tissue function and integrity may hamper this approach. Using a neonatal PV mouse model, we demonstrate that epidermal blistering can be prevented in a dose-dependent manner by clinically approved EGFR inhibitors erlotinib and lapatinib, but only up to approximately 50% of normal EGFR activity. At lower EGFR activity, blisters again aggravated and were highly exacerbated in mice with a conditional deletion of EGFR. Statistical analysis of the relation between EGFR activity and the extent of skin blistering revealed the best fit with a non-linear, V-shaped curve with a median break point at 52% EGFR activity (P = 0.0005). Moreover, lapatinib (a dual EGFR/ErbB2 inhibitor) but not erlotinib significantly reduced blistering in the oral cavity, suggesting that signalling mechanisms differ between PV predilection sites. Our results demonstrate that future clinical trials evaluating EGFR/ErbB2 inhibitors in PV patients must select treatment doses that retain a specific level of signal molecule activity. These findings may also be of relevance for cancer patients treated with EGFR inhibitors, for whom skin lesions due to extensive EGFR inhibition represent a major threat.

  16. Crystallization of Poly(3-hexylthiophene Nanofiber in a Narrow Groove

    Directory of Open Access Journals (Sweden)

    Satoshi Kushi

    2016-06-01

    Full Text Available Whisker-type poly(3-hexylthiophene-2,5-diyl (P3HT nanofibers were aligned by restricting their growth direction using an approximately 100–1000 nm wide narrow groove fabricated by thermal nanoimprinting. In grooves made of an amorphous fluoropolymer (CYTOP™ with widths of less than 1500 nm, the nanofibers oriented uniaxially perpendicular to the groove and their length was limited to the width of the groove. This result indicates that the nucleation of nanofibers tends to be selectively promoted near the interface of CYTOP™ with fluoro-groups, and nanofiber growth perpendicular to the wall is promoted because P3HT molecules are supplied more frequently from the center of the groove. Furthermore, the orientation induced anisotropic conductivity, and the conductivity parallel to the oriented nanofibers was more than an order of magnitude higher than that perpendicular to the oriented nanofibers.

  17. Forming method of axial micro grooves inside copper heat pipe

    Institute of Scientific and Technical Information of China (English)

    LI Yong; XIAO Hui; LIAN Bin; TANG Yong; ZENG Zhi-xin

    2008-01-01

    The high-speed oil-filled ball spinning and drawing process was put forward to manufacture the axially grooved heat pipe with highly efficient heat-transfer performance, and the forming mechanism of micro-grooves inside the pipe was investigated. The key factors influencing the configurations of micro-grooves were analyzed. When the spinning depth varies between 0.4 mm and 0.5 mm, drawing speed varies from 200 mm/min to 450 mm/min, rotary speed is beyond 6 000 r/min and working temperature is less than 50 ℃, the grooved tubes are formed with high quality and efficiency. The ball spinning process uses full oil-filling method to set up the steady dynamic oil-film that reduces the drawing force and improves the surface quality of grooved copper tube.

  18. Accurate analysis of arbitrarily-shaped helical groove waveguide

    Institute of Scientific and Technical Information of China (English)

    Liu Hong-Tao; Wei Yan-Yu; Gong Yu-Bin; Yue Ling-Na; Wang Wen-Xiang

    2006-01-01

    This paper presents a theory on accurately analysing the dispersion relation and the interaction impedance of electromagnetic waves propagating through a helical groove waveguide with arbitrary groove shape, in which the complex groove profile is synthesized by a series of rectangular steps. By introducing the influence of high-order evanescent modes on the connection of any two neighbouring steps by an equivalent susceptance under a modified admittance matching condition, the assumption of the neglecting discontinuity capacitance in previously published analysis is avoided, and the accurate dispersion equation is obtained by means of a combination of field-matching method and admittancematching technique. The validity of this theory is proved by comparison between the measurements and the numerical calculations for two kinds of helical groove waveguides with different groove shapes.

  19. SIMULATION AND EXPERIMENT OF BUBBLY FLOW INSIDE THROTTLING GROOVE

    Institute of Scientific and Technical Information of China (English)

    FU Xin; DU Xuewen; ZOU Jun; YANG Huayong; JI Hong

    2007-01-01

    The relationship between pressure distribution and cavitation (noise) inside throttling groove is investigated by numerical simulation and experimental method. A valve pocket with several transducers is performed to detect the pressure distributions inside the valve chamber, and the results fit quite well with the computational fluid dynamics(CFD) analysis. High-speed imaging techniques are employed to investigate the cavitation mechanisms, in particular bubble inception and cluster formation near the throttling groove. A spectrum analyzer is used to measure the sound pressure level of noise generated by the bubble flow. It is found that the pressure distributions inside the groove are sensitive to the valve port configuration and back pressure. The pressure distribution determines the bubble size and number passing through the valve grooves and the sound pressure level of noise induced by collapsing bubbles. The inlet pressure mainly affects the saturation degree of bubbly flow inside the groove and the intensity of sound pressure level accordingly.

  20. Characteristics of Multiplexed Grooved Nozzles for High Flow Rate Electrospray

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyoung Tae; Kim, Woo Jin; Kim, Sang Soo [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2007-10-15

    The electrospray operated in the cone-jet mode can generate highly charged micro droplets in an almost uniform size at flow rates. Therefore, the multiplexing system which can retain the characteristics of the cone-jet mode is inevitable for the electrospray application. This experiment reports the multiplexed grooved nozzle system with the extractor. The effects of the grooves and the extractor on the performance of the electrospray were evaluated through experiments. Using the grooved nozzle, the stable cone-jet mode can be achieved at the each groove in the grooved mode. Furthermore, the number of nozzles per unit area is increased by the extractor. The multiplexing density is 12 jets per cm{sup 2} at 30 mm distance from the nozzle tip to the ground plate. The multiplexing system for the high flow rate electrospray is realized with the extractor which can diminish the space charge effect without sacrificing characteristics of the cone-jet mode.

  1. The Effectiveness of Conflict Maps and the V-Shape Teaching Method in Science Conceptual Change among Eighth-Grade Students in Jordan

    Science.gov (United States)

    Bawaneh, Ali Khalid Ali; Zain, Ahmad Nurulazam Md; Ghazali, Munirah

    2010-01-01

    The purpose of the present study is to investigate the effectiveness of Conflict Maps and the V-Shape method as teaching methods in bringing about conceptual change in science among primary eighth-grade students in Jordan. A randomly selected sample (N = 63) from the Bani Kenana region North of Jordan was randomly assigned to the two teaching…

  2. Modeling and simulating of V-shaped piezoelectric micro-cantilevers using MCS theory considering the various surface geometries

    Science.gov (United States)

    Korayem, A. H.; Kianfar, A.; Korayem, M. H.

    2016-10-01

    Atomic force microscopy (AFM) is widely used as a tool in studying surfaces and mechanical properties of materials at nanoscale. This paper deals with mechanical and vibration analysis of AFM vibration in the non-contact and tapping modes for V-shaped piezoelectric micro-cantilever (MC) with geometric discontinuities and cross section variation in the air ambient. In the vibration analysis, Euler-Bernoulli beam theory based on modified couple stress (MCS) theory has been used. The governing equation of motion has been derived by using Hamilton's principle. By adopting finite element method (FEM), the MC differential equation has been solved. Damping matrix was considered in the modal space. Frequency response was obtained by using Laplace transform, and it has been compared with experimental results. Newmark algorithm has been used based on constant average acceleration to analyze time response of MC, and then time response results in the vibration mode, far from the sample surface have been compared with experimental data. In vicinity of sample surface, MC is influenced by various nonlinear forces between the probe tip and sample surface, including van der Waals, contact, and capillary forces. Time response was examined at different distances between MC base and sample surface, and the best distance was selected for topography. Topography results of different types of roughness showed that piezoelectric MC has been improved in the air ambient. Topography showed more accurate forms of roughness, when MC passes through sample surface at higher frequencies. The surface topography investigation for tapping and non-contact modes showed that using of these two modes are suitable for topography.

  3. Characteristic enhancement of blood pressure V-shaped waves in sinoaortic-denervated rats in a conscious and quiet state.

    Science.gov (United States)

    Chang, Huan; Gu, Hong-Xia; Gong, Min; Han, Ji-Ju; Wang, Yun; Xia, Zuo-Li; Zhao, Xiao-Min

    2016-11-08

    A hemodynamic feature of chronic sinoaortic-denervated (SAD) rats is the increase in blood pressure variability (BPV) without significant changes in the average level of blood pressure (BP). The current study was designed to investigate the changes in BP V-shaped waves (V waves) in SAD rats. Sprague-Dawley (SD) rats were divided into 2 groups: SAD rats and sham-operated rats (n=13). Hemodynamics measurements were obtained in conscious, freely moving rats, four weeks after sinoaortic denervation or sham operation. V wave indices were evaluated in rats in both conscious and quiet states. Additionally, normal and high BPV was simulated by the production of V waves with different amplitudes. The results showed that the V wave amplitude was dramatically increased, with a significantly prolonged duration and reduced frequency in SAD rats. V wave BPV in SAD rats was significantly increased, though BP remained unchanged. The twenty-four hour BPV in all rats was positively correlated with amplitude, duration time and V wave BPV and negatively correlated with frequency. The systolic BP spectral powers in the low frequency range (0.38-0.45 Hz) were significantly reduced in the V waves of SAD rats. Moreover, there was a remarkable increase in mean BPV and a normal mean BP after simulating high BPV in SAD rats. These results suggest that enhancement of V waves might be a waveform character of BP in SAD rats in both the conscious and quiet states. These types of V waves appear to be related to a depression of sympathetic regulation of BP induced by sinoaortic denervation.

  4. 0.25-μm lithography using a 50-kV shaped electron-beam vector scan system

    Science.gov (United States)

    Gesley, Mark A.; Mulera, Terry; Nurmi, C.; Radley, J.; Sagle, Allan L.; Standiford, Keith P.; Tan, Zoilo C. H.; Thomas, John R.; Veneklasen, Lee

    1995-05-01

    Performance data from a prototype 50 kV shaped electron-beam (e-beam) pattern generator is presented. This technology development is targeted towards 180-130 nm device design rules. It will be able to handle 1X NIST X-ray membranes, glass reduction reticles, and 4- to 8-inch wafers. The prototype system uses a planar stage adapted from the IBM EL-4 design. The electron optics is an 50 kV extension of the AEBLE%+TM) design. Lines and spaces of 0.12 micrometers with dynamic corrections processor (DCP). Along with its normal role of coordinate transformation and dynamic correction of deflection distortion, astigmatism, and defocus; the DCP improves accuracy by modifying deflection conditions and focus according to measured substrate height variations. It also enables yaw calibration and correction for Write-on-the FlyTM motion. The electronics incorporates JTAG components for built-in self- test (BIST), as well as syndrome checking to ensure data integrity. The design includes diagnostic capabilities from offsite as well as from the operator console. A combination of third-party software and an internal job preparation software system is used to fracture patterns. It handles tone reversal, overlap removal, sizing, and proximity correction. Processing of large files in a commercial mask shop environment is made more efficient by retaining hierarchy and using parallel processing and data compression techniques. Large GDSIITM and MEBES data files can be processed. Data includes timing benchmarks for a 1 Gbit DRAM on both proximity and reduction reticles. The paper presents 50 kV results on silicon and quartz substrates along with examples of overlay to an external grid, field butting, and critical dimension (CD) control data. Selective experiments testing system stability, calibration accuracy, and local correction software implementation on a VAX control computer are also given.

  5. A new modified forked flap and a reverse V shaped flap for secondary correction of bilateral cleft lip nasal deformities

    Institute of Scientific and Technical Information of China (English)

    YAN Wei; ZHAO Zhen-min; YIN Ning-bei; SONG Tao; LI Hai-dong; WU Di; GAO Feng; WANG Xin-gang

    2011-01-01

    Background The columella,nasal tip,lip relationship in the bilateral cleft lip nasal deformity remains a great challenge for plastic surgeon.An esthetically satisfying result is difficult to obtain.A subset of patients with bilateral cleft lip nasal deformity still require columellar lengthening and nasal correction and philtrial construction.This study aimed to provide a new method based on the forked flap to improve the final appearance of these patients.Methods A technique to correct this deformity is described.This consists of (1) a newly modified forked flap including the orbicularis oris muscle and nasalis muscle along the whole flap for columellar lengthening,(2) a reverse V shaped flap from the lower portion of the columella and the prolabium for normal size phitrum construction,(3) inserting the vermilion portion of the forked flap and advancing the nasal floor medially and anteriorly to lengthen and maintain the nasal septum side of the columella for proper tip positioning,(4) open rhinoplasty,allowing definitive repositioning of the lower lateral cartilages,(5) reconstruction of the orbicularis orismuscle as required,and (6) the flaring nostril floor advancing medially and constructing the sill.Results This technique was applied to 15 cases of secondary bilateral cleft lip nasal deformity.All the flaps took without signs of partial necrosis.In all cases,the nasal tip was projected forward with adequate columella elongation,and the height of the prolabium was added with normal size philtrial dimensions.Conclusions This method makes maximum use of the tissue containing the scar in the lip and limits tissues in the lower portion of the columella and the prolabium for adequate columella elongation and reconstruction with normal size philtrial dimensions.It is a very reasonable and useful method in correction of secondary bilateral cleft lip nasal deformities.

  6. Electrospinning of Grooved Polystyrene Fibers: Effect of Solvent Systems

    Science.gov (United States)

    Liu, Wanjun; Huang, Chen; Jin, Xiangyu

    2015-05-01

    Secondary surface texture is of great significance to morphological variety and further expands the application areas of electrospun nanofibers. This paper presents the possibility of directly electrospinning grooved polystyrene (PS) fibers using both single and binary solvent systems. Solvents were classified as low boiling point solvent (LBPS): dichloromethane (DCM), acetone (ACE), and tetrahydrofuran (THF); high boiling point solvent (HBPS): N, N-dimethylformamide (DMF) and cyclohexanone (CYCo); and non-solvent (NS): 1-butanol (BuOH). By the systematic selection and combination of these solvents at given parameters, we found that single solvent systems produced non-grooved fibers. LBPS/DMF solvent systems resulted in fibers with different grooved textures, while LBPS/CYCo led to fibers with double grooved texture. Grooved fibers can also be fabricated from LBPS/LBPS, NS/LBPS, and NS/HBPS systems under specific conditions. The results indicated that the difference of evaporation rate (DER) between the two solvents played a key role in the formation of grooved texture. The formation of this unique texture should be attributed to three separate mechanisms, namely void-based elongation, wrinkle-based elongation, and collapsed jet-based elongation. Our findings can serve as guidelines for the preparation of ultrafine fibers with grooved secondary texture.

  7. Grooved Fuel Rings for Nuclear Thermal Rocket Engines

    Science.gov (United States)

    Emrich, William

    2009-01-01

    An alternative design concept for nuclear thermal rocket engines for interplanetary spacecraft calls for the use of grooved-ring fuel elements. Beyond spacecraft rocket engines, this concept also has potential for the design of terrestrial and spacecraft nuclear electric-power plants. The grooved ring fuel design attempts to retain the best features of the particle bed fuel element while eliminating most of its design deficiencies. In the grooved ring design, the hydrogen propellant enters the fuel element in a manner similar to that of the Particle Bed Reactor (PBR) fuel element.

  8. Anterior Interhemispheric Approach for Olfactory Groove Meningioma

    Directory of Open Access Journals (Sweden)

    Imam Hidayat

    2016-09-01

    Full Text Available Objective: To evaluate the surgical technique with bifrontal interhemispheric approach for total removal of tumor in olfactory groove meningioma (OGM. Methods: This study described a case of a 38-year-old woman with bilateral blindness, anosmia, and behaviour changes. Imaging studies show a tumor mass in midfrontal base. Surgery using a bifrontal interhemispheric approach was performed and total removal was achieved and postoperative computed tomography (CT scan was performed to confirm the result. Histopathological findings established a diagnosis of meningioma. Results: A coronal skin incision behind the hairline was utilized. The scalp was elevated, taking care to reserve the vascularized pericranium medial to the linea temporalis of each side, and preserving the 2 supraorbital nerves. Eight burr holes were used, with the two initial holes made on each side of the orbitotemporal region, and the other four holes at the midline. A bifrontal craniotomy was performed. The tumor was first detached from its attachment with bipolar cautery and debulked. During this step, the main tumor feeder arteries from the anterior and posterior ethmoidal artery were interrupted, and the tumor devascularized. Total tumor removal through surgical intervention was achieved and confirmed by head CT-scan postoperatively. Conclusions: This case report supports the suitability of the bifrontal interhemispheric approach for OGM resection with additional radiation therapy.

  9. Global financial crisis making a V-shaped fluctuation in NO2 pollution over the Yangtze River Delta

    Science.gov (United States)

    Du, Yin; Xie, Zhiqing

    2017-04-01

    The Yangtze River Delta (YRD), China's main cultural and economic center, has become one of the most seriously polluted areas in the world with respect to nitrogen oxides (NOx), owing to its rapid industrialization and urbanization, as well as substantial coal consumption. On the basis of nitrogen dioxide (NO2) density data from ozone monitoring instrument (OMI) and ground-based observations, the effects of industrial fluctuations due to the financial crisis on local NO2 pollution were quantitatively assessed. The results were as follows. (1) A distinct V-shaped fluctuation of major industrial products, thermal generating capacity, electricity consumption, and tropospheric NO2 densities was associated with the global financial crisis from May 2007 to December 2009, with the largest anomalies 1.5 times more than standard deviations at the height of the crisis period from November 2008 to February 2009. (2) Among all industrial sectors, thermal power plants were mainly responsible for fluctuations in local NO2 pollution during the crisis period. Thermal generating capacity had its greatest decrease of 12.10% at the height of the crisis compared with that during November 2007-February 2008, leading to local tropospheric NO2 density decreasing by 16.97%. As the crisis appeased, thermal generating capacity increased by 29.63% from November 2009 to February 2010, and tropospheric NO2 densities correspondingly increased by 30.07%. (3) Among all industrial sectors in the YRD, the thermal power sector has the greatest coal consumption of about 65.96%. A decline in thermal power of about 10% can induce a decrease of about 30% in NOx emissions and NO2 densities, meaning that a relative small fluctuation in industrial production can lead to a large decrease in tropospheric NO2 densities over industrially developed areas like the YRD region. Since electricity is mainly obtained from local coal-burning thermal plants without NOx-processing equipment, installing NOx

  10. Fractures of the proximal humerus involving the intertubercular groove

    Energy Technology Data Exchange (ETDEWEB)

    Ahovuo, J.; Paavolainen, P.; Bjoerkenheim, J.M. (Helsinki Univ. Central Hospital (Finland). Dept. of Radiology; Helsinki Univ. Central Hospital (Finland). Div. of Traumatology and Orthopaedic Surgery)

    The purpose of this study was to analyse the involvement of the gliding surface of the biceps tendon in fractures of the proximal humerus. Fifteen patients had a fracture of the proximal humerus verified with antero-posterior and axillary radiographs. Tangential radiographs of the intertubercular groove, obtained from the shoulder joint, showed involvement of the intertubercular groove in 13 patients (87%), which could not be shown with other projections. Groove radiographs revealed in 3 patients a dislocation of the fragments of the greater tuberosity large enough to require surgical treatment, but which had not been found using conventional techniques. Therefore, a groove radiograph should be used to precise fractures of the proximal humerus. (orig.).

  11. Heat transfer and thermal stress analysis in grooved tubes

    Indian Academy of Sciences (India)

    Veysel Özceyhan; Necdet Altuntop

    2005-08-01

    Heat transfer and thermal stresses, induced by temperature differencesin the internally grooved tubes of heat transfer equipment, have been analysed numerically. The analysis has been conducted for four different kinds of internally grooved tubes and three different mean inlet water velocities. Constant temperature was applied from the external surface of the tube. Energy and governing flow equations were solved using finite difference scheme. Finite element method (FEM) was used to compute the thermal stress fields. Grooving effects on the thermal stress ratio have been discussed. As a result, maximum thermal stress occurs in the case of $p = d$ for all water inlet velocities. The maximum thermal stress ratio positions inside the tube have been indicated as MX for all investigated cases. In the light of the thermal stress values, various designs can be applied to reduce thermal stress in grooved tubes.

  12. Analysis Groove Characteristics of Friction Dishes in Wet Speeding Clutch

    Institute of Scientific and Technical Information of China (English)

    HongYue; LiuJin; JinShiliang

    2004-01-01

    The impacts of different groove shapes, numbers, and angle of friction dish on transmitting torque, speed, push pressure in wet speeding clutch are discussed in this paper. Since the wet speeed governing clutch works within hydrodynamic lubrication mixture lubrication. boundary, lubrication and contact situation, the oils combining with a-hydrocarbon or polyester are getting widely used as lubricant.The power-law fluid model with Patir-Cheng average flow model, GT asperity contact model and oil film inertia are applied for average Reynolds equation setting, In order to investigate the relationship between average push pressure within hydrodynamic lubrication and mixture lubrication, average transmitting torque and output speed, the numeral calculation and analysis are presented. According to calculation, it is found that the groove shape, groove angle and groove numbers affect the average transfer torque and push pressure with the speed rate.

  13. Interproximal grooving in the Atapuerca-SH hominid dentitions.

    Science.gov (United States)

    Bermúdez de Castro, J M; Arsuaga, J L; Pérez, P J

    1997-03-01

    The dental sample recovered from the Sima de los Huesos (SH) Middle Pleistocene cave site of the Sierra de Atapuerca (Spain) includes 296 specimens. Interproximal wear grooves have been observed in 20 maxillary and mandibular posterior teeth belonging to at least five of the 32 individuals identified so far in the SH hypodigm. Interproximal grooving affected only the adults, and at an age between 25 and 40 years. The appearance, morphology, and location pattern of the SH wear grooves are similar to those reported in other fossil hominids and in more recent human populations. Two alternative proposals, the toothpicking and the fiber or sinew processing hypotheses, compete for explaining the formation of this anomalous wear. The characteristics observed in the wear grooves of the SH teeth are compatible only with the habitual probing of interdental spaces by means of hard and inflexible objects. Dietary grit may also have contributed to the abrasion of the root walls during the motion of the dental probes.

  14. Femtosecond laser-induced blazed periodic grooves on metals.

    Science.gov (United States)

    Hwang, Taek Yong; Guo, Chunlei

    2011-07-01

    In this Letter, we generate laser-induced periodic surface structures (LIPSSs) on platinum following femtosecond laser pulse irradiation. For the first time to our knowledge, we study the morphological profile of LIPSSs over a broad incident angular range, and find that the morphological profile of LIPSSs depends significantly on the incident angle of the laser beam. We show that LIPSS grooves become more asymmetric at a larger incident angle, and the morphological profile of LIPSSs formed at an incident angle over 55° eventually resembles that of a blazed grating. Our study suggests that the formation of the blazed groove structures is attributed to the selective ablation of grooves through the asymmetric periodic surface heating following femtosecond pulse irradiation. The blazed grooves are useful for controlling the diffraction efficiency of LIPSSs.

  15. Measurement and analysis of grain boundary grooving by volume diffusion

    Science.gov (United States)

    Hardy, S. C.; Mcfadden, G. B.; Coriell, S. R.; Voorhees, P. W.; Sekerka, R. F.

    1991-01-01

    Experimental measurements of isothermal grain boundary grooving by volume diffusion are carried out for Sn bicrystals in the Sn-Pb system near the eutectic temperature. The dimensions of the groove increase with a temporal exponent of 1/3, and measurement of the associated rate constant allows the determination of the product of the liquid diffusion coefficient D and the capillarity length Gamma associated with the interfacial free energy of the crystal-melt interface. The small-slope theory of Mullins is generalized to the entire range of dihedral angles by using a boundary integral formulation of the associated free boundary problem, and excellent agreement with experimental groove shapes is obtained. By using the diffusivity measured by Jordon and Hunt, the present measured values of Gamma are found to agree to within 5 percent with the values obtained from experiments by Gunduz and Hunt on grain boundary grooving in a temperature gradient.

  16. Groove shape characteristics of echelle gratings with high diffraction efficiency

    Science.gov (United States)

    Zhang, Shanwen; Mi, Xiaotao; Zhang, Qian; Jirigalantu; Feng, Shulong; Yu, Haili; Qi, Xiangdong

    2017-03-01

    The groove shape characteristics of echelle gratings with high diffraction efficiency are investigated. Using the coordinate transformation method (C method), an r-2 aluminum echelle with 79 grooves/mm is optimized through rigorous numerical simulations and shows high diffraction efficiency of 76-81% in the high Littrow orders. A grating is found to be essentially an echelle if it contains a series of reflective facets with a specific tilt angle that are located far from the nonworking facet of the grating and have a deep groove depth; any groove shape that meets these conditions can be called an echelle grating. The underlying mechanism is analyzed phenomenologically using electromagnetic theory. The universal model proposed here, which represents a new cognitive understanding of the concept of the echelle, is ready for use in manufacturing applications and offers a new perspective for the fabrication of these gratings.

  17. Sliding and pressure evaluation on conventional and V-shaped seats of reclining wheelchairs for stroke patients with flaccid hemiplegia: a crossover trial

    Directory of Open Access Journals (Sweden)

    Chen Chi-Myn

    2011-07-01

    Full Text Available Abstract Background Reclining wheelchairs are commonly used to transport elderly stroke patients in Taiwan. However, there is concern that the patient's body in the wheelchair often slides forward when they return to a seated position, increasing the sitting pressure. Therefore, a novel reclining wheelchair with an ergonomic "V-Seat" was designed to prevent forward sliding and pressure sores. The use of these reclining chairs by stroke patients has not yet been studied. Thus, we investigated the effects of V-shaped and conventional seats in reclining wheelchairs on the extent of forward sliding and on the sitting pressure of stroke patients with flaccid hemiplegia and of able-bodied elders. Methods We recruited 13 able-bodied elders and 11 stroke patients with flaccid hemiplegia and performed 5 reclining cycles in both types of wheelchair. The amount of sliding along the backrest (BS plane and the seat (SS plane, the mean sitting pressure (MP, and the sacral peak pressure (SPP of the subjects were recorded. We used the Wilcoxon signed-rank test to compare the BS, SS, MP, and SPP in wheelchairs with conventional and V-shaped seats, and we used the Wilcoxon rank sum test to compare the differences in BS and SS between stroke patients and able-bodied elders in both types of reclining wheelchair. Results The BS, SS, and SPP of stroke patients were significantly lower in the wheelchairs with V-shaped seats than in conventional wheelchairs in most comparisons; however, the BS of able-bodied elders was higher in V-shaped seats than in conventional seats. The SS and SPP of stroke patients were significantly higher than those of able-bodied elders in both types of reclining wheelchair, and the BS of stroke patients was significantly higher than that of able-bodied elders only in conventional reclining wheelchairs. Conclusions The use of V-shaped seats in reclining wheelchairs can help reduce the forward sliding and sacral peak pressure of stroke patients

  18. Sliding and pressure evaluation on conventional and V-shaped seats of reclining wheelchairs for stroke patients with flaccid hemiplegia: a crossover trial.

    Science.gov (United States)

    Huang, Hsiu-Chen; Yeh, Cheng-Hsin; Chen, Chi-Myn; Lin, Yu-Sheng; Chung, Kao-Chi

    2011-07-16

    Reclining wheelchairs are commonly used to transport elderly stroke patients in Taiwan. However, there is concern that the patient's body in the wheelchair often slides forward when they return to a seated position, increasing the sitting pressure. Therefore, a novel reclining wheelchair with an ergonomic "V-Seat" was designed to prevent forward sliding and pressure sores. The use of these reclining chairs by stroke patients has not yet been studied. Thus, we investigated the effects of V-shaped and conventional seats in reclining wheelchairs on the extent of forward sliding and on the sitting pressure of stroke patients with flaccid hemiplegia and of able-bodied elders. We recruited 13 able-bodied elders and 11 stroke patients with flaccid hemiplegia and performed 5 reclining cycles in both types of wheelchair. The amount of sliding along the backrest (BS) plane and the seat (SS) plane, the mean sitting pressure (MP), and the sacral peak pressure (SPP) of the subjects were recorded. We used the Wilcoxon signed-rank test to compare the BS, SS, MP, and SPP in wheelchairs with conventional and V-shaped seats, and we used the Wilcoxon rank sum test to compare the differences in BS and SS between stroke patients and able-bodied elders in both types of reclining wheelchair. The BS, SS, and SPP of stroke patients were significantly lower in the wheelchairs with V-shaped seats than in conventional wheelchairs in most comparisons; however, the BS of able-bodied elders was higher in V-shaped seats than in conventional seats. The SS and SPP of stroke patients were significantly higher than those of able-bodied elders in both types of reclining wheelchair, and the BS of stroke patients was significantly higher than that of able-bodied elders only in conventional reclining wheelchairs. The use of V-shaped seats in reclining wheelchairs can help reduce the forward sliding and sacral peak pressure of stroke patients with flaccid hemiplegia. The back displacement of able

  19. [Developmental radicular groove as a cause of endodontic failure].

    Science.gov (United States)

    Fabra Campos, H; Millet Part, J

    1989-01-01

    A clinical case of apical injury on an upper lateral incisor with endodontical and surgical failures in its treatment is presented. Extraction of the incisor and its study at the stereoscopic microscope showed the existence of a developmental groove running from the cingulum to the end of the root, establishing a communication between the crevice and the apical part of the tooth. Bacterial infection through the groove could provide an explanation for treatment failure.

  20. Droplet impact on regular micro-grooved surfaces

    Institute of Scientific and Technical Information of China (English)

    Hu Hai-Bao; Huang Su-He; Chen Li-Bin

    2013-01-01

    We have investigated experimentally the process of a droplet impact on a regular micro-grooved surface.The target surfaces are patterned such that micro-scale spokes radiate from the center,concentric circles,and parallel lines on the polishing copper plate,using Quasi-LIGA molding technology.The dynamic behavior of water droplets impacting on these structured surfaces is examined using a high-speed camera,including the drop impact processes,the maximum spreading diameters,and the lengths and numbers of fingers at different values of Weber number.Experimental results validate that the spreading processes are arrested on all target surfaces at low velocity.Also,the experimental results at higher impact velocity demonstrate that the spreading process is conducted on the surface parallel to the micro-grooves,but is arrested in the direction perpendicular to the micro-grooves.Besides,the lengths of fingers increase observably,even when they are ejected out as tiny droplets along the groove direction,at the same time the drop recoil velocity is reduced by micro-grooves which are parallel to the spreading direction,but not by micro-grooves which are vertical to the spreading direction.

  1. Large-eddy simulation of turbulent flow and structures in a square duct roughened with perpendicular and V-shaped ribs

    Science.gov (United States)

    Fang, Xingjun; Yang, Zixuan; Wang, Bing-Chen; Tachie, Mark F.; Bergstrom, Donald J.

    2017-06-01

    In this paper, highly disturbed turbulent flows confined within a square duct with uniformly spaced V-shaped ribs mounted on one wall are investigated using large-eddy simulation (LES). Two V-shaped (6 0° and 4 5°) rib cases are studied in comparison with the perpendicular (9 0°) rib case. The LES results are validated against a set of water-channel measurement data newly acquired by the authors. The effects of different shaped ribs on turbulent flow are systematically studied in terms of the mean velocity field, turbulence statistics, and coherent structures. The results show that strong secondary flows in the pattern of a pair of large symmetrical streamwise-elongated vortices exist in all three rib cases. The impacts of rib geometry on turbulent coherent structures are investigated using vortex identifiers, temporal autocorrections, spatial two-point autocorrelations, and velocity spectra.

  2. Performance optimization of grooved slippers for aero hydraulic pumps

    Institute of Scientific and Technical Information of China (English)

    Chen Juan; Ma Jiming; Li Jia; Fu Yongling

    2016-01-01

    A computational fluid dynamics (CFD) simulation method based on 3-D Navier–Stokes equation and Arbitrary Lagrangian–Eulerian (ALE) method is presented to analyze the grooved slip-per performance of piston pump. The moving domain of grooved slipper is transformed into a fixed reference domain by the ALE method, which makes it convenient to take the effects of rotate speed, body force, temperature, and oil viscosity into account. A geometric model to express the complex structure, which covers the orifice of piston and slipper, vented groove and the oil film, is constructed. Corresponding to different oil film thicknesses calculated in light of hydrostatic equilibrium theory and boundary conditions, a set of simulations is conducted in COMSOL to analyze the pump characteristics and effects of geometry (groove width and radius, orifice size) on these characteristics. Furthermore, the mechanics and hydraulics analyses are employed to validate the CFD model, and there is an excellent agreement between simulation and analytical results. The simulation results show that the sealing land radius, orifice size and groove width all dramatically affect the slipper behavior, and an optimum tradeoff among these factors is conducive to optimizing the pump design.

  3. Performance optimization of grooved slippers for aero hydraulic pumps

    Directory of Open Access Journals (Sweden)

    Juan Chen

    2016-06-01

    Full Text Available A computational fluid dynamics (CFD simulation method based on 3-D Navier–Stokes equation and Arbitrary Lagrangian–Eulerian (ALE method is presented to analyze the grooved slipper performance of piston pump. The moving domain of grooved slipper is transformed into a fixed reference domain by the ALE method, which makes it convenient to take the effects of rotate speed, body force, temperature, and oil viscosity into account. A geometric model to express the complex structure, which covers the orifice of piston and slipper, vented groove and the oil film, is constructed. Corresponding to different oil film thicknesses calculated in light of hydrostatic equilibrium theory and boundary conditions, a set of simulations is conducted in COMSOL to analyze the pump characteristics and effects of geometry (groove width and radius, orifice size on these characteristics. Furthermore, the mechanics and hydraulics analyses are employed to validate the CFD model, and there is an excellent agreement between simulation and analytical results. The simulation results show that the sealing land radius, orifice size and groove width all dramatically affect the slipper behavior, and an optimum tradeoff among these factors is conducive to optimizing the pump design.

  4. Continuous blood fractionation using an array of slanted grooves

    Science.gov (United States)

    Bernate, Jorge A.; Chengxun, Liu; Lagae, Liesbet; Drazer, German

    2011-11-01

    Blood is a complex fluid having different specialized biological functions and containing a plethora of clinical information. The separation of different blood components is a crucial step in many research and clinical applications. In this work we take advantage of the flow characteristics in microfluidic devices in which the bottom surface is patterned with slanted rectangular grooves to continuously fractionate blood. We exploit the flow in the vicinity of the patterned surface when the dimensions of the grooves are much smaller than the dimensions of the main channel. In these devices, we observed that the grooves act as open channels guiding flow along them with the flow over them being in the direction of the main channel. We present experiments in which the different blood components are deflected laterally to a different extent by the flow along the grooves depending on their sedimentation velocity, which allows their continuous fractionation. In particular, the heavier red blood cells experience the largest deflection while the lighter white blood cells deflect the least, allowing their passive and minimally invasive isolation. In addition, this fluidic platform can also be used to separate magnetically labeled circulating cancer cells which can be retained in the flow along the grooves using a sufficiently strong magnetic force.

  5. Mechanisms of rectangular groove-induced multiple-microdroplet coalescences

    Science.gov (United States)

    Shen, Feng; Li, Yi; Wang, Guiren; Liu, Zhaomiao

    2017-01-01

    The mechanism of microdroplet coalescence is a fundamental issue for droplet-based microfluidics. We developed an asymmetric expansion (a rectangular groove) along one side of a microchannel to achieve multiple-microdroplet trapping, collision, and coalescence. Compared with reported symmetric expansions, this asymmetric groove could easily trap microdroplets and control two or three microdroplet coalescences precisely without a requirement for temporal and spatial synchronization. To reveal the mechanisms of multiple-droplet coalescences in a groove, we observed five different coalescence patterns under different flow conditions. Moreover, we characterized the flow behavior quantitatively by simulating the velocity vector fields in both the microdroplets and continuous phase, finding good agreement with experiments. Finally, a map of coalescence forms with different capillary numbers (0.001droplet-based microfluidic devices.

  6. The experimental and numerical investigation of a grooved vapor chamber

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Ming [Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Ministry of Education and Key Laboratory of Heat Transfer and Energy Conversion, Beijing Education Commission, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100022 (China); Liu Zhongliang [Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Ministry of Education and Key Laboratory of Heat Transfer and Energy Conversion, Beijing Education Commission, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100022 (China)], E-mail: liuzhl@bjut.edu.cn; Ma Guoyuan [Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Ministry of Education and Key Laboratory of Heat Transfer and Energy Conversion, Beijing Education Commission, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100022 (China)

    2009-02-15

    An effective thermal spreader can achieve more uniform heat flux distribution and thus enhance heat dissipation of heat sinks. Vapor chamber is one of highly effective thermal spreaders. In this paper, a novel grooved vapor chamber was designed. The grooved structure of the vapor chamber can improve its axial and radial heat transfer and also can form the capillary loop between condensation and evaporation surfaces. The effect of heat flux, filling amount and gravity to the performance of this vapor chamber is studied by experiment. From experiment, we also obtained the best filling amount of this grooved vapor chamber. By comparing the thermal resistance of a solid copper plate with that of the vapor chamber, it is suggested that the critical heat flux condition should be maintained to use vapor chamber as efficient thermal spreaders for electronics cooling. A two-dimensional heat and mass transfer model for the grooved vapor chamber is developed. The numerical simulation results show the thickness distribution of liquid film in the grooves is not uniform. The temperature and velocity field in vapor chamber are obtained. The thickness of the liquid film in groove is mainly influenced by pressure of vapor and liquid beside liquid-vapor interface. The thin liquid film in heat source region can enhance the performance of vapor chamber, but if the starting point of liquid film is backward beyond the heat source region, the vapor chamber will dry out easily. The optimal filling ratio should maintain steady thin liquid film in heat source region of vapor chamber. The vapor condenses on whole condensation surface, so that the condensation surface achieves great uniform temperature distribution. By comparing the experimental results with numerical simulation results, the reliability of the numerical model can be verified.

  7. V-groove plasmonic waveguides fabricated by nanoimprint lithography

    DEFF Research Database (Denmark)

    Fernandez-Cuesta, I.; Nielsen, R.B.; Boltasseva, Alexandra

    2007-01-01

    Propagation of channel plasmon-polariton modes in the bottom of a metal V groove has been recently demonstrated. It provides a unique way of manipulating light at nanometer length scale. In this work, we present a method based on nanoimprint lithography that allows parallel fabrication of integra......Propagation of channel plasmon-polariton modes in the bottom of a metal V groove has been recently demonstrated. It provides a unique way of manipulating light at nanometer length scale. In this work, we present a method based on nanoimprint lithography that allows parallel fabrication...

  8. Structure and thermal behavior of a nickel complex based on a V-shaped bis(4-(1 H-imidazol-1-yl)phenyl)amine ligand

    Science.gov (United States)

    Jiao, Yan; Wang, Zhe; Qiu, Yu; He, Jing-Man; Chen, Min-dong

    2015-12-01

    A new coordination polymer {[Ni(BIPA)( bpdc)(H2O)2]} n has been prepared based on a new V-shaped bis(4-(1 H-imidazol-1-yl)phenyl)amine (BIPA) ligand. Complex was characterized by elemental analysis, IR spectra, X-ray powder diffraction, thermal analysis and single crystal X-ray analysis. Complex exhibits a 1D → 3D structure. Hydrogen bonds play an important role in the formation of supramolecular network structure. Thermal analysis indicates that complex exhibits a high thermal stability.

  9. Structure and thermal behavior of a nickel complex based on a V-shaped bis(4-(1H-imidazol-1-yl)phenyl)amine ligand

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Yan, E-mail: felixjiao@163.com; Wang, Zhe; Qiu, Yu; He, Jing-Man; Chen, Min-dong [Nanjing University of Information Science & Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Innovative Research Laboratory of Energy & Environmental Catalysis, School of Environmental Science and Engineering (China)

    2015-12-15

    A new coordination polymer ([Ni(BIPA)(bpdc)(H{sub 2}O){sub 2}]){sub n} has been prepared based on a new V-shaped bis(4-(1H-imidazol-1-yl)phenyl)amine (BIPA) ligand. Complex was characterized by elemental analysis, IR spectra, X-ray powder diffraction, thermal analysis and single crystal X-ray analysis. Complex exhibits a 1D → 3D structure. Hydrogen bonds play an important role in the formation of supramolecular network structure. Thermal analysis indicates that complex exhibits a high thermal stability.

  10. Groove Pancreatitis: A Case Report and Review of Literature

    Directory of Open Access Journals (Sweden)

    Vallath Balakrishnan

    2007-09-01

    Full Text Available Context Groove pancreatitis is a rare type of segmental pancreatitis characterized by fibrous scars of the anatomic space between the dorsocranial part of the head of the pancreas, the duodenum, and the common bile duct. Case report A 40-year-old man, with a past history of chronic alcohol consumption presented with epigastric pain radiating to the back and intermittent vomiting and a weight loss of 9 kg. A CT of the abdomen revealed swelling of the pancreatic head, a hypodense mass and duodenal wall thickening with luminal narrowing. Peripancreatic fluid and dense strands were also seen. Upper gastrointestinal endoscopy revealed an edematous, shiny, reddish raised mucosa having a polypoid appearance with narrowing of the second portion of the duodenum. Histological examination of the duodenal biopsy specimens showed preservation of the crypt-villus ratio, and the submucosa showed Brunner gland hyperplasia. These findings appeared consistent with the diagnosis of groove pancreatitis. Presently, the patient is on conservative medical management with analgesics, proton pump inhibitors and a pancreatic enzyme supplement. Conclusions Groove pancreatitis often masquerades as pancreatic head carcinoma. This condition should be kept in mind when making the differential diagnosis between pancreatic masses and duodenal stenosis. In all cases of focal pancreatitis involving the head or uncinate process of the pancreas with involvement of the adjacent duodenum, the possibility of groove pancreatitis should be considered.

  11. Computational analysis of frictional drag over transverse grooved ...

    African Journals Online (AJOL)

    user

    ... gaining interest as it plays important role in aircraft and submarine fuel efficiencies and noise ..... for the flow to relax, the flow reaches the last groove with less energy caused by the ... freestream velocity of air, mm ... wall shear stress, N/m2 ...

  12. Tailoring channeled plasmon polaritons in metallic V-grooves

    DEFF Research Database (Denmark)

    Smith, Cameron; Thilsted, Anil Haraksingh; Marie, Rodolphe

    2013-01-01

    of propagating plasmons to optimize the trade-off between lateral confinement and loss [2]. Accordingly, the traits of CPPs in metallic V-grooves suggest their widespread implementation, with applications ranging from ultracompact photonic circuitry [3] to lab-on-a-chip sensing. Current CPP research focuses...

  13. Syncopation, body-movement and pleasure in groove music.

    Science.gov (United States)

    Witek, Maria A G; Clarke, Eric F; Wallentin, Mikkel; Kringelbach, Morten L; Vuust, Peter

    2014-01-01

    Moving to music is an essential human pleasure particularly related to musical groove. Structurally, music associated with groove is often characterised by rhythmic complexity in the form of syncopation, frequently observed in musical styles such as funk, hip-hop and electronic dance music. Structural complexity has been related to positive affect in music more broadly, but the function of syncopation in eliciting pleasure and body-movement in groove is unknown. Here we report results from a web-based survey which investigated the relationship between syncopation and ratings of wanting to move and experienced pleasure. Participants heard funk drum-breaks with varying degrees of syncopation and audio entropy, and rated the extent to which the drum-breaks made them want to move and how much pleasure they experienced. While entropy was found to be a poor predictor of wanting to move and pleasure, the results showed that medium degrees of syncopation elicited the most desire to move and the most pleasure, particularly for participants who enjoy dancing to music. Hence, there is an inverted U-shaped relationship between syncopation, body-movement and pleasure, and syncopation seems to be an important structural factor in embodied and affective responses to groove.

  14. Steady progression of osteoarthritic features in the canine groove model

    NARCIS (Netherlands)

    Marijnissen, A.C.A.; Roermund, P.M. van; Verzijl, N.; Tekoppele, J.M.; Bijlsma, J.W.J.; Lafeber, F.P.J.G.

    2002-01-01

    Objective: Recently we described a canine model of osteoarthritis (OA), the groove model with features of OA at 10 weeks after induction, identical to those seen in the canine anterior cruciate ligament transection (ACLT) model. This new model depends on cartilage damage accompanied by transient int

  15. Syncopation, body-movement and pleasure in groove music.

    Directory of Open Access Journals (Sweden)

    Maria A G Witek

    Full Text Available Moving to music is an essential human pleasure particularly related to musical groove. Structurally, music associated with groove is often characterised by rhythmic complexity in the form of syncopation, frequently observed in musical styles such as funk, hip-hop and electronic dance music. Structural complexity has been related to positive affect in music more broadly, but the function of syncopation in eliciting pleasure and body-movement in groove is unknown. Here we report results from a web-based survey which investigated the relationship between syncopation and ratings of wanting to move and experienced pleasure. Participants heard funk drum-breaks with varying degrees of syncopation and audio entropy, and rated the extent to which the drum-breaks made them want to move and how much pleasure they experienced. While entropy was found to be a poor predictor of wanting to move and pleasure, the results showed that medium degrees of syncopation elicited the most desire to move and the most pleasure, particularly for participants who enjoy dancing to music. Hence, there is an inverted U-shaped relationship between syncopation, body-movement and pleasure, and syncopation seems to be an important structural factor in embodied and affective responses to groove.

  16. Novel scaffold design with multi-grooved PLA fibers

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Sangwon; King, Martin W [Fiber and Polymer Science, North Carolina State University, Raleigh, NC (United States); Gamcsik, Mike P, E-mail: martin_king@ncsu.edu [Joint Department of Biomedical Engineering, North Carolina State University and University of North Carolina Chapel Hill, NC (United States)

    2011-08-15

    A novel prototype nonwoven textile structure containing polylactide (PLA) multigrooved fibers has been proposed as a possible scaffold material for superior cell attachment and proliferation. Grooved cross-sectional fibers with larger surface area were obtained by a bi-component spinning system and the complete removal of the sacrificial component was confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and x-ray photon spectroscopy (XPS) analysis. These PLA nonwoven scaffolds containing the grooved fibers exhibited enhanced wettability, greater flexibility and tensile properties, and a larger surface area compared to a traditional PLA nonwoven fabric containing round fibers. To evaluate cellular attachment on the two types of PLA nonwoven scaffolds, NIH 3T3 fibroblasts were cultured for up to 12 days. It was evident that the initial cellular attachment was superior on the scaffold with grooved fibers, which was confirmed by MTT viability assay (p < 0.01) and SEM analysis. In the future, by modulating the size of the grooves on the fibers, such a scaffold material with a large surface area could serve as an alternative matrix for culturing different types of cells.

  17. Steady progression of osteoarthritic features in the canine groove model

    NARCIS (Netherlands)

    Marijnissen, A.C.A.; Roermund, P.M. van; Verzijl, N.; Tekoppele, J.M.; Bijlsma, J.W.J.; Lafeber, F.P.J.G.

    2002-01-01

    Objective: Recently we described a canine model of osteoarthritis (OA), the groove model with features of OA at 10 weeks after induction, identical to those seen in the canine anterior cruciate ligament transection (ACLT) model. This new model depends on cartilage damage accompanied by transient int

  18. Photocarrier dynamics near V-shaped pits in In{sub x}Ga{sub 1−x}N/GaN multiple quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Taeho; Li, Xiang-Shu; Ko, Dong-Su; Won, Jung-Yeon; Kim, Seong-Heon [Analytical Science Group, Samsung Advanced Institute of Technology, Suwon, Gyeonggi-do 443-803 (Korea, Republic of); Kim, Jaekyun; Kim, Joosung; Tak, Youngjo; Kim, Jun-Youn [GaN Device Group, Samsung Advanced Institute of Technology, Suwon, Gyeonggi-do 443-803 (Korea, Republic of); Park, Gyeong-Su [Analytical Science Group, Samsung Advanced Institute of Technology, Suwon, Gyeonggi-do 443-803 (Korea, Republic of); Lee, Eunha, E-mail: eunhayo.lee@samsung.com [Analytical Science Group, Samsung Advanced Institute of Technology, Suwon, Gyeonggi-do 443-803 (Korea, Republic of)

    2014-06-03

    Highlights: • Correlations between carrier dynamics and structural defects of InGaN MQWs exist. • PL intensity is much weaker in the V-shaped pits than in the regular c-plane. • Blue-shifted photoluminescence spectrum is not observed at the V-pits. • A kinetic model including carriers recombination and diffusion is presented. • The model estimates the nonradiative recombination time as 10 ps at the V-pits. - Abstract: Space- and time-resolved photoluminescence (PL) has been employed to investigate correlations between the carrier dynamics and structural defects known as V-shaped pits in InGaN/GaN multiple quantum wells (MQWs). The pits exhibit much lower PL intensity compared to MQWs of the normal c-plane indicating a high density of nonradiative recombination centers in the pits. However, the PL peak wavelength, which is expected to experience a blueshift at the pits due to the stronger confinement effect and reduced quantum-confined Stark effect, do not show any spatial dependence that is correlated with the defects. This is ascribed to dominant ultrafast (<10 ps) nonradiative recombination at the pits and additional diffusion into the c-plane leading to radiative recombination. By contrast, weak but clear correlations between the pits and PL decay time were observed on nanosecond timescales. This can be explained by a kinetic model that includes the nonradiative recombination and diffusion of carriers at the pits.

  19. Groove pancreatitis: A rare form of chronic pancreatitis

    Directory of Open Access Journals (Sweden)

    Bharivi Jani

    2015-01-01

    Full Text Available Context: Groove pancreatitis is a rare form of chronic pancreatitis affecting the "groove" of the pancreas among the pancreatic head, duodenum, and common bile duct. The exact cause is unknown, although there are associations with long-term alcohol abuse, smoking, peptic ulcer disease, heterotopic pancreas, gastric resection, biliary disease, and anatomical or functional obstruction of the minor papilla. The diagnosis can be challenging. Endoscopic ultrasound (EUS and magnetic resonance cholangiopancreatography are the preferred imaging modalities. The treatment of choice is conservative although surgical intervention can sometimes be required. Case Report: A 57-year-old male with a history of human immunodeficiency virus and hepatitis B presented with 4 days of epigastric pain. Abdominal exam revealed absent bowel sounds and epigastric tenderness. He had a creatinine of 1.72 mg/dL, potassium of 2.9 mmol/L, and a normal lipase level of 86 U/L. Liver enzymes and total bilirubin were normal. Computed tomography abdomen showed high-grade obstruction of the second portion of the duodenum without any obvious mass. An esophagogastroduodenoscopy showed a mass at the duodenal bulb causing luminal narrowing, with biopsies negative for malignancy. Magnetic resonance imaging revealed a mass in the region of the pancreatic head and descending duodenum. EUS revealed a 3 cm mass in the region of pancreatic head with irregular borders and no vascular invasion. Fine needle aspiration (FNA was nondiagnostic. The patient then underwent a Whipple′s procedure. Pathology of these specimens was negative for malignancy but was consistent with para-duodenal or groove pancreatitis. Conclusion: The low incidence of groove pancreatitis is partly due to lack of familiarity with the disease. Groove pancreatitis should be considered in the differential for patients presenting with pancreatic head lesions and no cholestatic jaundice, especially when a duodenal obstruction

  20. Realization and characterization of high precision micro grooves on green ceramic

    DEFF Research Database (Denmark)

    Bissacco, Giuliano; Andrijasevic, Daniela; Hansen, Hans Nørgaard

    2006-01-01

    rectangular feature underneath. For manufacturing of the grooves a grooving process was chosen and a tool was manufactured by micro electro discharge milling. The accuracy of the tool was evaluated by means of a SEM. Grooves were measured using a stylus profilometer. The results showed that the required...

  1. Variations of structures and solid-state conductivity of isomeric silver(I) coordination polymers having linear and V-shaped thiophene-centered ditriazole ligands

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Bin [State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); School of Environmental and Chemical Engineering, Nanchang Hangkong University, Nanchang, 330063 (China); Geng, Jiao; Zhang, Lie [State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Huang, Wei, E-mail: whuang@nju.edu.cn [State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)

    2014-07-01

    A pair of new linear and V-shaped acceptor–donor–acceptor (A−D−A) thiophene-centered ditriazole structural isomers, i.e., 2,5-di(1H-1,2,4-triazol-1-yl)thiophene (L{sup 1}) and 3,4-di(1H-1,2,4-triazol-1-yl)thiophene (L{sup 2}), has been synthesized and characterized. They are used as μ{sub 2}-bridging ligands to prepare a pair of silver(I) coordination polymers formulated as [Ag(L{sup 1})(NO{sub 3})]{sub n} (1) and [Ag(L{sup 2})(NO{sub 3})]{sub n} (2), which are also structural isomers at the supramolecular level. X-ray single-crystal diffraction analyses for 1 and 2 reveal that they exhibit the same one-dimensional (1D) coordination polymers but different structural architectures because of the distinguishable shape and configuration of isomeric ligands (L{sup 1} and L{sup 2}) and the alterations of the coordination numbers. More interestingly, compared with the free ligands, 1D silver(I) polymeric isomers 1 and 2 show significant enhancement of solid-state conductivity to different extents (1.42×10{sup 4} and 2.17×10{sup 3} times), where 6.96 times' enhancement of solid-state conductivity from 1 to 2 has been observed. The formation of Ag–N coordinative bonds and the configurational discrepancy of L{sup 1} and L{sup 2} are believed to play important roles in facilitating the electron transport between molecules, which can also be supported by Density Function Theory calculations of their band gaps. - Graphical abstract: A pair of linear and V-shaped isomeric thiophene-centered ditriazole ligands (L{sup 1}) and L{sup 2} are used to prepare a pair of silver(I) polymeric isomers (1 and 2), where significant enhancement of solid-state conductivity to different extents are observed originating from the distinguishable shape and configuration of isomeric ligands. - Highlights: • A pair of linear and V-shaped thiophene-centered ditriazole structural isomers is prepared. • They are used as µ{sub 2}-bridging ligands to prepare a pair of silver

  2. Hole injection from the sidewall of V-shaped pits into c-plane multiple quantum wells in InGaN light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Xiaoming; Liu, Junlin, E-mail: liujunlin@ncu.edu.cn; Jiang, Fengyi [National Engineering Technology Research Center for LED on Si Substrate, Nanchang University, Nanchang 330047 (China)

    2015-10-28

    The role which the V-shaped pits (V-pits) play in InGaN/GaN multiple quantum well (MQW) light emitting diodes (LEDs) has been proposed to enable the formation of sidewall MQWs, whose higher bandgap than that of the c-plane MQWs is considered to act as an energy barrier to prevent carriers from reaching the dislocations. Here, with increasing proportion of current flowing via the V-pits, the emission of the c-plane MQWs broadens across the short-wavelength band and shows a blueshift successively. This phenomenon is attributed to hole injection from the sidewall of V-pits into the c-plane MQWs, which is a new discovery in the injection mechanism of InGaN/GaN MQW LEDs.

  3. Super-V-shaped structure on 3C-SiC grown on the C-face of 4H-SiC

    Science.gov (United States)

    Xin, Bin; Jia, Ren-Xu; Hu, Ji-Chao; Zhang, Yu-Ming

    2016-08-01

    We investigate a unique super-V-shaped structure (SVSS) on the C-face of 3C/4H-SiC heteroepitaxial films. Atomic force microscopy (AFM) and optical images reveal that two low protruding straight lines of an SVSS join at a common higher protruding point. Transmission electron microscopy images determine that the protruding point is induced by polycrystalline nucleation, and straight lines are found to be 3C crystals without any specific defects. High-resolution AFM reveals that the directions of the SVSSs are strongly related to step-flow. It is believed that the straight lines are caused by redundant adatoms gathering and crystallizing when they meet and deviate around the protruding point defect on their original migration path. The effects of step-flow and anti-step-flow in the formation of SVSSs are discussed.

  4. 5.5 W continuous-wave TEM00-mode Nd:YAG solar laser by a light-guide/2V-shaped pump cavity

    Science.gov (United States)

    Almeida, J.; Liang, D.; Vistas, C. R.; Bouadjemine, R.; Guillot, E.

    2015-12-01

    A significant progress in TEM00-mode solar laser power and efficiency with heliostat-parabolic mirror system is reported here. A double-stage light-guide/2V-shaped pump cavity is used to efficiently couple and redistribute the concentrated pump light from a 2-m-diameter parabolic mirror to a 4-mm-diameter, 30-mm-length, 1.1 at.% Nd:YAG single-crystal rod. The light guide with large rectangular cross section enables a stable uniform pumping profile along the laser rod, resulting also in an enhanced tracking error compensation capacity. 5.5 W cw TEM00-mode solar laser power was measured at the output of a thermally near unstable asymmetric resonator. 150 and 157 % improvement in TEM00-mode solar laser collection efficiency and slope efficiency were obtained, respectively.

  5. Dance, Music, Meter and Groove: A Forgotten Partnership.

    Science.gov (United States)

    Fitch, W Tecumseh

    2016-01-01

    I argue that core aspects of musical rhythm, especially "groove" and syncopation, can only be fully understood in the context of their origins in the participatory social experience of dance. Musical meter is first considered in the context of bodily movement. I then offer an interpretation of the pervasive but somewhat puzzling phenomenon of syncopation in terms of acoustic emphasis on certain offbeat components of the accompanying dance style. The reasons for the historical tendency of many musical styles to divorce themselves from their dance-based roots are also briefly considered. To the extent that musical rhythms only make sense in the context of bodily movement, researchers interested in ecologically valid approaches to music cognition should make a more concerted effort to extend their analyses to dance, particularly if we hope to understand the cognitive constraints underlying rhythmic aspects of music like meter and groove.

  6. Dance, Music, Meter and Groove: A Forgotten Partnership

    Directory of Open Access Journals (Sweden)

    W Tecumseh eFitch

    2016-03-01

    Full Text Available I argue that core aspects of musical rhythm, especially groove and syncopation, can only be fully understood in the context of their origins in the participatory social experience of dance. Musical meter is first considered in the context of bodily movement. I then offer an interpretation of the pervasive but somewhat puzzling phenomenon of syncopation in terms of acoustic emphasis on certain offbeat components of the accompanying dance style. The reasons for the historical tendency of many musical styles to divorce themselves from their dance-based roots are also briefly considered. To the extent that musical rhythms only make sense in the context of bodily movement, researchers interested in ecologically valid approaches to music cognition should make a more concerted effort to extend their analyses to dance, particularly if we hope to understand the cognitive constraints underlying rhythmic aspects of music like meter and groove.

  7. Scattering by a groove in an impedance plane

    Science.gov (United States)

    Bindiganavale, Sunil; Volakis, John L.

    1993-09-01

    An analysis of two-dimensional scattering from a narrow groove in an impedance plane is presented. The groove is represented by a impedance surface and the problem reduces to that of scattering from an impedance strip in an otherwise uniform impedance plane. On the basis of this model, appropriate integral equations are constructed using a form of the impedance plane Green's functions involving rapidly convergent integrals. The integral equations are solved by introducing a single basis representation of the equivalent current on the narrow impedance insert. Both transverse electric (TE) and transverse magnetic (TM) polarizations are treated. The resulting solution is validated by comparison with results from the standard boundary integral method (BIM) and a high frequency solution. It is found that the presented solution for narrow impedance inserts can be used in conjunction with the high frequency solution for the characterization of impedance inserts of any given width.

  8. Dynamic multileaf collimation without `tongue-and-groove' underdosage effects

    Science.gov (United States)

    van Santvoort, J. P. C.; Heijmen, B. J. M.

    1996-10-01

    In all commercially available multileaf collimators, a `tongue-and-groove' - or similar - construction is used for reduction of leakage radiation between adjacent leaves. These constructions can cause serious underdosages in intensity-modulated photon beams. A method for leaf trajectory calculation for dynamic multileaf collimation, which fully avoids these underdosage effects, is presented. The method is based on pairwise synchronizations of trajectories of adjacent leaf pairs, such that the delivered beam intensity in each `tongue-and-groove' region is always equal to the smallest of the two prescribed intensities for the two corresponding leaf pairs. The effectiveness of the method has been proven for a large number of intensity-modulated fields, using the dynamic multileaf collimation mode of our MM50 Racetrack Microtron. Compared to dynamic multileaf collimation without synchronization, beam-on times are always equal or longer. For the cases that we studied, the beam-on time was typically increased by 5 to 15%.

  9. Dynamic multileaf collimation without 'tongue-and-groove' underdosage effects.

    Science.gov (United States)

    van Santvoort, J P; Heijmen, B J

    1996-10-01

    In all commercially available multileaf collimators, a 'tongue-and-groove'--or similar--construction is used for reduction of leakage radiation between adjacent leaves. These constructions can cause serious underdosages in intensity-modulated photon beams. A method for leaf trajectory calculation for dynamic multileaf collimation, which fully avoids these underdosage effects, is presented. The method is based on pairwise synchronizations of trajectories of adjacent leaf pairs, such that the delivered beam intensity in each 'tongue-and-groove' region is always equal to the smallest of the two prescribed intensities for the two corresponding leaf pairs. The effectiveness of the method has been proven for a large number of intensity-modulated fields, using the dynamic multileaf collimation mode of our MM50 Racetrack Microtron. Compared to dynamic multileaf collimation without synchronization, beam-on times are always equal or longer. For the cases that we studied, the beam-on time was typically increased by 5 to 15%.

  10. Competitive coordination aggregation for V-shaped [Co3] and disc-like [Co7] complexes: synthesis, magnetic properties and catechol oxidase activity.

    Science.gov (United States)

    Singha Mahapatra, Tufan; Basak, Dipmalya; Chand, Santanu; Lengyel, Jeff; Shatruk, Michael; Bertolasi, Valerio; Ray, Debashis

    2016-09-14

    Unique dependence on the nature of metal salt and reaction conditions for coordination assembly reactions of varying architecture and nuclearity have been identified in V-shaped [Co3L4] and planar disc-like [Co7L6] compounds: [CoL2(μ-L)2(μ-OH2)2(CF3CO2)2] (1) and [Co(μ-L)6(μ-OMe)6]Cl2 (2) (HL = 2-{(3-ethoxypropylimino)methyl}-6-methoxyphenol). At room temperature varying reaction conditions, cobalt-ligand ratios and use of different bases allowed unique types of coordination self-assembly. The synthetic marvel lies in the nature of aggregation with respect to the two unrelated cores in 1 and 2. Complex 1 assumes a V-shaped arrangement bound to L(-), water and a trifluoroacetate anion, while 2 grows around a central Co(II) ion surrounded by a {Co} hexagon bound to methoxide and L(-). Magnetic measurements revealed that the intermetallic interactions are antiferromagnetic in nature in the case of complex 1 and ferromagnetic in the case of 2 involving high spin cobalt(ii) ions with stabilization of the high-spin ground state in the latter case. In MeCN solutions complexes 1 and 2 showed catalytic oxidation of 3,5-di-tert-butylcatechol (3,5-DTBCH2) to 3,5-di-tert-butylbenzoquinone (3,5-DTBQ) in air. The kinetic study in MeCN revealed that with respect to the catalytic turnover number (kcat) 2 is more effective than 1 for oxidation of 3,5-DTBCH2.

  11. Design of a Vertically Comb-Driven Micromirror with V-Shaped Beams%一种垂直梳齿驱动V型梁微镜设计

    Institute of Scientific and Technical Information of China (English)

    李晓莹; 孙瑞康; 燕斌; 乔大勇

    2011-01-01

    A scanning micromirror suspended by a pair of V-shaped beams, driven by vertically electrostatic comb actuators, was designed and modeled. The static and dynamic analysis was carried out by both theory calculation and FEM simulation. The static characteristic shows that a torsion angle of 0.7° can be achieved at 100V DC voltage,which is sufficient for the startup of the mirror scanning operation. Moreover, modal analysis of three types of torsion beams were performed with ANSYS, and the comparison of results reveals that the mirror with V-shaped beams has the most stable torsional mode. The torsional stress are also investigated.%设计了一种垂直梳齿驱动的V型扭转梁支撑的微镜器件.采用有限元仿真和解析方法对该器件进行了静态和动态分析.在100V直流电压下,镜面转角可达0.7°,能够满足镜而扫描所需要的起始角.同时对比了不同支撑梁结构下的前五阶模态频率以及前两阶频率比,并分析了不同梁间距以及V型梁夹角下各个参数的变化趋势,得出了使微扭转镜工作在最稳定振型的V型梁倾斜角度,确定了所设计结构的优化尺寸.最后对V型梁的扭转应力进行了分析.

  12. Channel plasmon polariton propagation in nanoimprinted V-groove waveguides

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Bundgaard; Fernandez-Cuesta, I.; Boltasseva, Alexandra;

    2008-01-01

    We present the results of optical characterization of metal V-groove waveguides using scanning near-field microscopy, showing broadband transmission with subwavelength confinement and propagation lengths exceeding 100 mu m. An updated fabrication method using a combination of UV and nanoimprint l...... lithography is presented. The developed approach is mass-production compatible, adaptable to different designs, and offers wafer-scale parallel fabrication of plasmonic components based on profiled metal surfaces....

  13. Experimental investigations on an axial grooved cryogenic heat pipe

    Directory of Open Access Journals (Sweden)

    Senthil Kumar Muniappan

    2012-01-01

    Full Text Available This paper deals with development and studies of a trapezoidal axial grooved nitrogen heat pipe. A special liquid nitrogen cryostat has been designed and developed for evaluating the performance of heat pipe where the condenser portion is connected to the cold sink externally. Experiments have been performed on the heat pipe as well as on an equivalent diameter copper rod at different heat loads. The steady state performance of the heat pipe is compared with that of copper rod.

  14. V-groove gratings on silicon for infrared beam splitting.

    Science.gov (United States)

    Rajkumar, N; McMullin, J N

    1995-05-10

    Infrared beam-splitting transmission gratings that utilize anisotropically etched v-grooves on silicon wafers are proposed. With scalar diffraction theory to find the amplitudes of the different diffraction orders, a numerical search is used to find optimum designs for 1:3, 1:5, and 1:7 splitters with efficiencies greater than 70% with a standard deviation in intensity of no more than 7%.

  15. Grooved organogel surfaces towards anisotropic sliding of water droplets.

    Science.gov (United States)

    Zhang, Pengchao; Liu, Hongliang; Meng, Jingxin; Yang, Gao; Liu, Xueli; Wang, Shutao; Jiang, Lei

    2014-05-21

    Periodic micro-grooved organogel surfaces can easily realize the anisotropic sliding of water droplets attributing to the formed slippery water/oil/solid interface. Different from the existing anisotropic surfaces, this novel surface provides a versatile candidate for the anisotropic sliding of water droplets and might present a promising way for the easy manipulation of liquid droplets for water collection, liquid-directional transportation, and microfluidics.

  16. Groove model of tibia-femoral osteoarthritis in the rat.

    Science.gov (United States)

    de Visser, Huub M; Weinans, Harrie; Coeleveld, Katja; van Rijen, Mattie H P; Lafeber, Floris P J G; Mastbergen, Simon C

    2017-03-01

    Several experimental models of osteoarthritis in rats are used to study the pathophysiology of osteoarthritis. Many mechanically induced models have the limitation that permanent joint instability is induced by, for example, ligament transection or meniscal damage. This permanent instability will counteract the potential beneficial effects of therapy. The groove model of osteoarthritis uses a one-time trigger, surgically induced cartilage damage on the femoral condyles, and has been validated for the canine tibia-femoral compartment. The present study evaluates this model for the rat knee joint. The articular cartilage of the weight bearing surface of both femoral condyles and trochlea were damaged (grooved) without damaging the underlying subchondral bone. Severity of joint degeneration was histologically assessed, in addition to patella cartilage damage, and subchondral bone characteristics by means of (contrast-enhanced) micro-CT. Mild histological degeneration of the surgically untouched tibial plateau cartilage was observed in addition to damage of the femoral condyles, without clear synovial tissue inflammation. Contrast enhanced micro-CT demonstrated proteoglycan loss of the surgically untouched patella cartilage. Besides, a more sclerotic structure of the subchondral bone was observed. The tibia-femoral groove model in a rat results in mild knee joint degeneration, without permanent joint instability and joint inflammation. This makes the rat groove model a useful model to study the onset and progression of post-traumatic non-inflammatory osteoarthritis, creating a relatively sensitive model to study disease modifying osteoarthritic drugs. © 2016 The Authors. Journal of Orthopaedic Research published by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society. J Orthop Res 35:496-505, 2017.

  17. CHARACTERISTCS OF FLUID FILM IN OPTIMIZED SPIRAL GROOVE MECHANICAL SEAL

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relationship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.

  18. Thermal Characteristics of Grooved Heat pipe with Hybrid Nanofluids

    Directory of Open Access Journals (Sweden)

    W S Han

    2011-01-01

    Full Text Available In the present study, the specially designed grooved heat pipe charged with nanofluids was investigated in terms of various parameters such as heat transfer rate(50∼300W with 50 W interval, volume concentration(0.005%, 0.05%, 0.1%, and hybrid combinations, inclination(5°, 45°, 90°, cooling water temperature (1℃, 10℃, and 20℃, surface state, transient state and so on. Hybrid nanofluids with different volume concentration ratios with Ag-H2O and Al2O3-H2O were used as working fluids on a grooved heat pipe(GHP. Comparing with the pure water system, nanofluidic and hybrid nanofluidic system shows greater overall thermal resistance with increasing nano-particle concentration. Also hybrid nanofluids make the system deteriorate in terms of thermal resistance. The post nanofluid experimental data regarding GHP show that the heat transfer performance is similar to the results of nanofluid system. The thermal performance of a grooved heat pipe with nanofluids and hybrid nanofluids were varied with driving parameters but they led to worse system performance.

  19. Repair welding process of friction stir welding groove defect

    Institute of Scientific and Technical Information of China (English)

    LIU Hui-jie; ZHANG Hui-jie

    2009-01-01

    The groove defect formed in the friction stir welding dramatically deteriorates weld appearances and mechanical properties of the joints owing to its larger size and penetration. Therefore, the friction stir repair welding was utilized to remove such a groove defect, and the focus was placed on the mechanical properties and microstructural characteristics of the repair joints so as to obtain an optimum repair welding process. The experimental results indicate that the groove defect can be removed by friction stir repair welding, and the offset repair welding process is superior to the symmetrical repair welding process. In the symmetrical repair welding process, a large number of fine cavity defects and an obvious aggregation of hard-brittle phase Al2Cu occur, accordingly the mechanical properties of the repair joint are weakened, and the fracture feature of repair joint is partially brittle and partially plastic. A good-quality repair joint can be obtained by the offset repair welding process, and the repair joint is fractured near the interface between the weld nugget zone and thermal-mechanically affected zone.

  20. The flow past a cactus-inspired grooved cylinder

    Science.gov (United States)

    El-Makdah, Adnan M.; Oweis, Ghanem F.

    2013-02-01

    The star-shaped cross section of giant cylindrical cactus plants is thought to be aerodynamically favorable for protection against toppling by strong winds. Particle image velocimetry is used to investigate the flow details within the surface grooves and in the immediate wake of a cactus-inspired model cylinder with eight longitudinal grooves, at biologically relevant Reynolds numbers between 50 × 103 and 170 × 103. The wake flow is analyzed and compared to a similarly sized circular cylinder. At the lowest Re tested, the wakes from the two geometries are similar. At higher Re, the cactus wake exhibits superior behavior as seen from the mean and turbulent velocities, suggesting that the flow mechanisms are Re dependent. The flow within the surface grooves reveals counter rotating rollers, while the geometrical ridges act as vortex generators known to help with the surface flow attachment. Lastly, a simplistic analysis is described to recover, qualitatively, certain time-dependent flow features from the randomly acquired PIV realizations.

  1. Parasitic capacitance characteristics of deep submicrometre grooved gate MOSFETs

    Science.gov (United States)

    Sreelal, S.; Lau, C. K.; Samudra, G. S.

    2002-03-01

    Grooved gate metal-oxide-semiconductor field-effect transistors (MOSFETs) are known to alleviate many of the short channel and hot carrier effects that arise when MOSFET devices are scaled down to very short channel lengths. However, they exhibit much higher parasitic capacitance with stronger bias dependence when compared to conventional planar devices. In this paper, we present a model for gate-to-drain and gate-to-source capacitance characteristics of a deep submicrometre grooved gate MOSFET. Both the intrinsic and extrinsic parts of the capacitance are modelled separately. In particular, the model presents a novel but simple way to account for the accumulation layer formation in the source/drain region of MOSFETs due to the application of the gate voltage. The results are compared with those obtained from a two-dimensional device simulator. The close match between the modelled and simulated data establishes the validity of the model. The model is then used to account for the superiority of capacitance characteristics of planar device structures and to arrive at optimization guidelines for grooved gate devices to match these characteristics.

  2. Study On the Performance of Solar Air Collectors with Cross V-Shaped Absorbing Plate and V-Shaped Bottom Plate%交叉V形吸热板V形底板空气集热器性能特性研究

    Institute of Scientific and Technical Information of China (English)

    闫崇强; 李明; 季旭; 罗熙

    2013-01-01

    以两种不同的交叉V形吸热板V形底板空气集热器(垂直型集热器:V形吸热板的方向与流道方向垂直,V形底板的方向与流道方向平行;平行型集热器:V形吸热板的方向与流道方向平行,V形底板的方向与流道方向垂直)为研究对象,对不同倾角、不同空气流速下两种空气集热器的性能进行了比较实验研究,同时对正向和反向通气时垂直型空气集热器的性能进行了测试分析.结果表明:垂直型空气集热器的性能优于平行型空气集热器,45°倾角时两台集热器的温升最高;垂直型和平行型空气集热器的最大效率分别为71%,68%;垂直型空气集热器反向流动时比正向流动时性能更好.%Two different types of solar air collectors with cross V-shaped absorbing plate and V-shaped bottom plate (for the vertical type collector,the direction of the V-shaped bottom plate is parallel to the flow direction while the direction of the V-shaped absorbing plate is perpendicular to it; for the parallel type collector,the direction of the V-shaped absorbing plate is parallel to the flow direction while the direction of the V-shaped bottom plate is perpendicular to it) are used as the research object in this paper,and their performances are studied and compared under different dip angle and different air flow velocity; meanwhile,the performance of the vertical type air collector is tested and analysed under forward and reverse entilation.The results show that the performance of the vertical type air collector is better than that of the parallel type air collector,and the rise of temperature of both collectors is the highest with an angle of 45°.The maximum efficiency of the vertical and the parallel type is 71% and 68%,respectively.With a reverse flow,the performance of the vertical type air collector is better than with a forward flow.

  3. Tailoring the grooved texture of electrospun polystyrene nanofibers by controlling the solvent system and relative humidity

    Science.gov (United States)

    2014-01-01

    In this study, we have successfully fabricated electrospun polystyrene (PS) nanofibers having a diameter of 326 ± 50 nm with a parallel grooved texture using a mixed solvent of tetrahydrofuran (THF) and N,N-dimethylformamide (DMF). We discovered that solvent system, solution concentration, and relative humidity were the three key factors to the formation of grooved texture and the diameter of nanofibers. We demonstrated that grooved nanofibers with desired properties (e.g., different numbers of grooves, widths between two adjacent grooves, and depths of grooves) could be electrospun under certain conditions. When THF/DMF ratio was higher than 2:1, the formation mechanism of single grooved texture should be attributed to the formation of voids on the jet surface at the early stage of electrospinning and subsequent elongation and solidification of the voids into a line surface structure. When THF/DMF ratio was 1:1, the formation mechanism of grooved texture should be ascribed to the formation of wrinkled surface on the jet surface at the early stage of electrospinning and subsequent elongation into a grooved texture. Such findings can serve as guidelines for the preparation of grooved nanofibers with desired secondary morphology. PMID:25114643

  4. Arthroscopically assisted stabilization of acute high-grade acromioclavicular joint separations in a coracoclavicular Double-TightRope technique: V-shaped versus parallel drill hole orientation.

    Science.gov (United States)

    Kraus, Natascha; Haas, Norbert P; Scheibel, Markus; Gerhardt, Christian

    2013-10-01

    The arthroscopically assisted Double-TightRope technique has recently been reported to yield good to excellent clinical results in the treatment of acute, high-grade acromioclavicular dislocation. However, the orientation of the transclavicular-transcoracoidal drill holes remains a matter of debate. A V-shaped drill hole orientation leads to better clinical and radiologic results and provides a higher vertical and horizontal stability compared to parallel drill hole placement. This was a cohort study; level of evidence, 2b. Two groups of patients with acute high-grade acromioclavicular joint instability (Rockwood type V) were included in this prospective, non-randomized cohort study. 15 patients (1 female/14 male) with a mean age of 37.7 (18-66) years were treated with a Double-TightRope technique using a V-shaped orientation of the drill holes (group 1). 13 patients (1 female/12 male) with a mean age of 40.9 (21-59) years were treated with a Double-TightRope technique with a parallel drill hole placement (group 2). After 2 years, the final evaluation consisted of a complete physical examination of both shoulders, evaluation of the Subjective Shoulder Value (SSV), Constant Score (CS), Taft Score (TF) and Acromioclavicular Joint Instability Score (ACJI) as well as a radiologic examination including bilateral anteroposterior stress views and bilateral Alexander views. After a mean follow-up of 2 years, all patients were free of shoulder pain at rest and during daily activities. Range of motion did not differ significantly between both groups (p > 0.05). Patients in group 1 reached on average 92.4 points in the CS, 96.2 % in the SSV, 10.5 points in the TF and 75.9 points in the ACJI. Patients in group 2 scored 90.5 points in the CS, 93.9 % in the SSV, 10.5 points in the TF and 84.5 points in the ACJI (p > 0.05). Radiographically, the coracoclavicular distance was found to be 13.9 mm (group 1) and 13.4 mm (group 2) on the affected side and 9.3 mm (group 1

  5. 倒V形钢支撑加固RC框架的PUSHOVER分析%PUSHOVER analysis on inverted V-shape steelbrace strengthening RC frame structure

    Institute of Scientific and Technical Information of China (English)

    吴永河; 习会峰; 穆建春

    2013-01-01

    为揭示倒V形钢支撑加固RC框架在罕遇地震作用下的性能,建立了4层RC框架结构及在RC框架结构上后加钢支撑的结构模型,并对模型进行了PUSHOVER分析.从基底剪力-顶点位移曲线、楼层位移曲线及出铰顺序等方面对结构在罕遇地震作用下的抗震性能进行了评估.结果表明,在罕遇地震作用下,后加倒V形钢支撑的RC框架结构达到性能点时的基底剪力较原RC框架结构大,顶点位移较原RC框架结构小;钢支撑作为第一道抗震防线能吸收大部分的地震能量,对梁、柱构件能起有效的保护作用;此外,钢支撑对抗连接倒塌也有较大的现实意义.%In order to reveal the performance of RC frame structure with inverted V-shape steel brace under function of rare earthquake, 4-layer RC frame structure and the RC structure with inverted V-shape steel brace as well as PUSHOVER on model is performed. The evaluation on anti-seismic performance is performed under function of rare earthquake for structure from such aspects as base shear- top displacement curve, floor displacement curve and hinged out mechanism. The results show that under function of rare occurrence earthquake, the base shear while RC frame structure with inverted V-steel brace reaching the performance point is greater than the one of original RC frame structure, and the top displacement is less than the one of original RC frame structure. As the first anti-seismic defensive line, the steel brace can absorb most earthquake energy to play the effective protection for beam and column elements. Additionally, the steel brace is provided with greater practical significance for resisting the progressive collapse.

  6. Subpixel accuracy for extracting groove center based on corner detection

    Institute of Scientific and Technical Information of China (English)

    Liu Suyi; Wang Guorong; Shi Yonghua

    2006-01-01

    Subpixel accuracy for V-groove center in robot welding is researched and a software measure to increase the accuracy of seam tracking by laser is presented.LOG( Laplacian of Gaussian ) operator is adopted to detect image edge.Vgroove center is extracted by corner detection of extremum curvature.Subpixel position is obtained by Lagarange polynomial interpolation algorithm.Experiment results show that the method is brief and applied, and is sufficient for the real time of robot welding by laser sensors.

  7. Coronary sinus and atrioventricular groove avulsion after motor vehicle crash

    Directory of Open Access Journals (Sweden)

    Bradley M Dennis

    2014-01-01

    Full Text Available Simultaneous cardiac and pericardial rupture from blunt chest trauma is a highly lethal combination with rarely reported survival. We report of a case of young patient with a right atrioventricular groove injury, pericardial rupture and a unique description of a coronary sinus avulsion following blunt chest trauma. Rapid recognition of this injury is crucial to patient survival, but traditional diagnostic adjuncts such as ultrasound, echocardiography and computed tomography are often unhelpful. Successful repair of these injuries requires high suspicion of injury, early cardiac surgery involvement of and possible even placement of the patient on cardiopulmonary bypass.

  8. Revamping Grooving Process for Sustainability using Fuzzy Expert System

    Directory of Open Access Journals (Sweden)

    Iqba Asif

    2016-01-01

    Full Text Available The article presents an application of a fuzzy expert system for renovating a metal cutting process to cope with the sustainability requirements. The work seeks a sustainable balance between energy consumption, productivity and tool damage. Cylindrical grooving experiments were performed to generate data related to quantification of the effects of material hardness, cutting speed, width of cut and feed rate on the aforementioned sustainability measures. A fuzzy knowledge-base was developed that suggests the most suitable adjustments of the controlled variables that would lead to achievement of various combinations of the objectives.

  9. Ligands recognizing the minor groove of DNA: development and applications.

    Science.gov (United States)

    Wemmer, D E

    Polyamide ligands comprised of pyrrole, imidazole and hydroxypyrrole rings have been developed over the past decade which can be used to target many different, predetermined DNA sequences through recognition of functional groups in the minor groove. The design principles for these ligands are described with a description of the characterization of their binding. Variations containing linked recognition modules have been described which allow high affinity and specificity recognition of DNA sequences of over 15 base pairs. Recent applications of these ligands in affecting biological response through competition with proteins for DNA binding sites are reviewed. Copyright 2001 John Wiley & Sons, Inc.

  10. Syncopation affects free body-movement in musical groove

    DEFF Research Database (Denmark)

    Witek, Maria A. G.; Popescu, Tudor; Clarke, Eric F

    2016-01-01

    One of the most immediate and overt ways in which people respond to music is by moving their bodies to the beat. However, the extent to which the rhythmic complexity of groove-specifically its syncopation-contributes to how people spontaneously move to music is largely unexplored. Here, we measured...... on the body-part. We demonstrate that while people do not move or synchronise much to rhythms with high syncopation when dancing spontaneously to music, the relationship between rhythmic complexity and synchronisation is less linear than in simple finger-tapping studies....

  11. Deep-groove nickel gratings for solar thermal absorbers

    Science.gov (United States)

    Ahmad, N.; Núñez-Sánchez, S.; Pugh, J. R.; Cryan, M. J.

    2016-10-01

    This paper presents measured and modelled optical absorptance and reflectance for deep-groove nickel nano-gratings in the 450-950 nm wavelength range. The structures have been fabricated using focused ion beam etching and characterised using Fourier spectroscopy and the field distributions on the gratings have been studied using finite difference time domain modelling. Realistic grating structures have been modelled based on focused ion beam cross sections and these results are in good agreement between measured and modelled results. The roles of surface plasmon polaritons and slot modes are highlighted in the strong broadband absorbance that can be achieved with these structures.

  12. Optimization design of main parameters for double spiral grooves face seal

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The optimization design of the parameters, such as the groove depth, groove number, ratio of the groove width to the land width, and spiral angle of a new kind of double spiral grooves face seal, which works under the condition of high velocity, high sealing pressure and ultra-low temperature, is presented under the assump-tion of fixed closure force by finite element analysis method. The results show that the stiffness of the maximum film can be obtained when the ratio of the groove width to the land width is 0.5 and the spiral angle is about 75 degrees, when the influence of the groove number on the sealing performance is not obvious.

  13. Optimization design of main parameters for double spiral grooves face seal

    Institute of Scientific and Technical Information of China (English)

    LIU Zhong; LIU Ying; LIU XiangFeng

    2007-01-01

    The optimization design of the parameters, such as the groove depth, groove number, ratio of the groove width to the land width, and spiral angle of a new kind of double spiral grooves face seal, which works under the condition of high velocity, high sealing pressure and ultra-low temperature, is presented under the assumption of fixed closure force by finite element analysis method. The results show that the stiffness of the maximum film can be obtained when the ratio of the groove width to the land width is 0.5 and the spiral angle is about 75 degrees, when the influence of the groove number on the sealing performance is not obvious.

  14. A review of interproximal wear grooves on fossil hominin teeth with new evidence from Olduvai Gorge.

    Science.gov (United States)

    Ungar, P S; Grine, F E; Teaford, M F; Pérez-Pérez, A

    2001-04-01

    Interproximal (approximal) grooves at the cementum-enamel junction of premolar and molar teeth have been observed in a broad range of human ancestors and related extinct species from 1.84 million years ago to the present. Many hypotheses have been presented to explain the aetiology of these grooves, though their form and positioning are most consistent with tooth-picking behaviours. This paper reviews occurrences of interproximal grooves in the cheek teeth of modern and fossil humans, evaluates hypotheses on their cause, and reports on a previously undescribed groove found in OH 60, a molar tooth from Olduvai Gorge. This specimen is among the earliest to show such grooving, and is most likely attributable to Homo erectus. It is concluded that, because interproximal grooves have been observed only on Homo teeth, they probably reflect a behaviour or behaviours unique to that genus.

  15. Generation of visible wavelength by the phase-matching four-wave mixing in an Yb-doped V-shape photonic crystal fiber

    Science.gov (United States)

    Li, Lixiao; Yuan, Jinhui; Sang, Xinzhu; Yan, Binbin; Wang, Kuiru; Yu, Chongxiu; Han, Ying; Xia, Changming; Zhou, Guiyao; Wei, Shuai; Wang, Chao; Yang, Jianju; Wang, Shuang; Cheng, Xu; Hou, Lantian

    2015-07-01

    In this paper, an Ytterbium-doped V-shape photonic crystal fiber (Yb-VPCF) with low dispersion and high nonlinearity is designed and fabricated in our laboratory. Through coupling femtosecond pulses into the fundamental mode of Yb-VPCF, the tunable anti-Stokes signals at the visible wavelength are efficiently generated based on the phase-matching four-wave mixing. When the pump wavelength is changed from 810, to 820, and to 830 nm and the input average power is increased from 0.4, to 0.5, and to 0.6 W, respectively, the anti-Stokes signals are generated within the wavelength range of 562-477 nm. The wavelength-tunable range is over 100 nm, and the maximum power ratio of anti-Stokes signal at 477 nm and the residual pump at 830 nm can be up to 23.9:1. The anti-Stokes signals generated can be used as the ultrashort pulse sources for ultrafast optoelectronics and spectroscopy.

  16. An investigation of heat transfer augmentation and friction characteristics in solar air heater duct with V-shaped wire as artificial roughness on absorber plate

    Directory of Open Access Journals (Sweden)

    Madhukeshwara N., E. S. Prakash

    2013-01-01

    Full Text Available An experimental investigation of heat transfer augmentation and friction characteristics of fully developed turbulent flow in a rectangular duct of solar air heater with absorber plate having V-shaped wire ribs as artificial roughness on its underside is carried out. The investigation covers wide range of different parameters of wire ribbed roughness: relative roughness pitch (p/e from 10 to 40, relative roughness height (e/Dh from 0.01 to 0.04 and angle of attack of flow from 20° to 90°. Duct aspect ratio (W/B is kept 5 and Reynolds number (Re is varied from 2,500 to 8,500. The heat transfer and friction factor values obtained are compared with those of smooth duct under similar flow conditions. Expressions are developed for Nusselt number and friction factor for the roughness geometry. Enhancement of Nusselt number and friction factor for roughened duct are 1.5 and 2.7 times of smooth duct respectively.

  17. An investigation of heat transfer augmentation and friction characteristics in solar air heater duct with V-shaped wire as artificial roughness on absorber plate

    Energy Technology Data Exchange (ETDEWEB)

    Madhukeshwara, N. [Department of Mechanical Engineering, B.I.E.T, Davanagere, Karnataka (India); Prakash, E.S. [Department of Studies in Mechanical Engineering, U.B.D.T.C.E, Davanagere, Karnataka (India)

    2013-07-01

    An experimental investigation of heat transfer augmentation and friction characteristics of fully developed turbulent flow in a rectangular duct of solar air heater with absorber plate having V-shaped wire ribs as artificial roughness on its underside is carried out. The investigation covers wide range of different parameters of wire ribbed roughness: relative roughness pitch (p/e) from 10 to 40, relative roughness height (e/Dh) from 0.01 to 0.04 and angle of attack of flow from 20° to 90°. Duct aspect ratio (W/B) is kept 5 and Reynolds number (Re) is varied from 2,500 to 8,500. The heat transfer and friction factor values obtained are compared with those of smooth duct under similar flow conditions. Expressions are developed for Nusselt number and friction factor for the roughness geometry. Enhancement of Nusselt number and friction factor for roughened duct are 1.5 and 2.7 times of smooth duct respectively.

  18. Kinetics of thermal grooving during low temperature recrystallization of pure aluminum

    DEFF Research Database (Denmark)

    Zhang, Yubin; Godfrey, Andy; Juul Jensen, Dorte

    2013-01-01

    The migration of a recrystallization boundary in pure aluminum was followed during in situ annealing in a scanning electron microscope. The microstructure was characterized using the electron channeling contrast technique, and a typical stop-go grain boundary motion was observed during annealing...... time. The kinetics of thermal grooving are determined. Effects of the surface oxidation layer on the formation of thermal grooving as well as the overall influence of grooves on boundary migration are discussed. © (2013) Trans Tech Publications, Switzerland....

  19. HEAT TRANSFER ENHANCEMENT AND PRESSURE DROP OF GROOVED ANNULUS OF DOUBLE PIPE HEAT EXCHANGER

    Directory of Open Access Journals (Sweden)

    Putu Wijaya Sunu

    2017-05-01

    Full Text Available This investigation was performed to experimentally investigate the enhancement of heat transfer and the friction of an annulus in a double pipe heat exchanger system with rectangular grooves in the turbulent flow regime. The shell is made of acrylic and its diameter is 28 mm. The tube is made of aluminium and its diameter is 20 mm. Grooves were incised in the annulus room with a circumferential pattern, with a groove space of 2 mm, a distance between the grooves of 8mm and a groove height of 0.3 mm. The experiments consist of temperature and pressure measurement and a flow visualization. Throughout the investigation, the cold fluid flowed in the annulus room. The Reynold number of cold fluid varied from about 31981 to 43601 in a counter flow condition. The volume flow rate of hot fluid remains constant with Reynold number about 30904. Result showed the effect of grooves, which are applied in the annulus room. The grooves induce the pressure drop, the pressure drop in the grooved annulus was greater by about 15.88% to 16.72% than the one in the smooth annulus. The total heat transfer enhancement is of 1.09–1.11. Moreover, the use of grooves in the annulus of the heat exchanger not only increase the heat transfer process, but also increase the pressure drop, which is related to the friction factor.

  20. Space qualification of high capacity grooved heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, M.; Mullender, B.; Druart, J. [SABCA, Societe Anomyme Belgel de Construction Aeronautique (Belgium); Supper, W.; Beddows, A. [ESTEC-The (Netherlands)

    1996-12-31

    Based on the thermal requirements of the future telecommunication satellites, the development of a High Capacity Grooved Heat Pipe (HPG), was contracted by ESA to SABCA leading to an aluminium extruded heat pipe (outer diameter of 25 mm) based on a multi re-entrant grooves design. After an intensive acceptance test campaign whose results showed a good confidence in the design and the fulfillment of the required specifications of heat transport and on tilt capability (experimental maximum heat transport capability of 1500 Watt metres for a vapour temperature of 20 deg C), similar heat pipes have been developed with various outer diameters (11 mm, 15 mm and 20 mm) and with various shapes (circular outer shapes, integrated saddles). Several of these heat pipes were tested during two parabolic flight campaigns, by varying the heat loads during the micro-gravity periods. This HGP heat pipe family is now being submitted to a space qualification program according to ESA standards (ESA PSS-49), both in straight and bent configuration. Within this qualification, the heat pipes are submitted to an extended test campaign including environmental (random/sinus vibration, constant acceleration) and thermal tests (thermal performance, thermal cycle, thermal soak, ageing). (authors) 9 refs.

  1. Capillary Contact Angle in a Completely Wet Groove

    Science.gov (United States)

    Parry, A. O.; Malijevský, A.; Rascón, C.

    2014-10-01

    We consider the phase equilibria of a fluid confined in a deep capillary groove of width L with identical side walls and a bottom made of a different material. All walls are completely wet by the liquid. Using density functional theory and interfacial models, we show that the meniscus separating liquid and gas phases at two phase capillary coexistence meets the bottom capped end of the groove at a capillary contact angle θcap(L) which depends on the difference between the Hamaker constants. If the bottom wall has a weaker wall-fluid attraction than the side walls, then θcap>0 even though all the isolated walls are themselves completely wet. This alters the capillary condensation transition which is now first order; this would be continuous in a capped capillary made wholly of either type of material. We show that the capillary contact angle θcap(L) vanishes in two limits, corresponding to different capillary wetting transitions. These occur as the width (i) becomes macroscopically large, and (ii) is reduced to a microscopic value determined by the difference in Hamaker constants. This second wetting transition is characterized by large scale fluctuations and essential critical singularities arising from marginal interfacial interactions.

  2. Prevalence of palate-gingival groove in patients of Dhulikhel Hospital

    Directory of Open Access Journals (Sweden)

    D Shreshta

    2015-06-01

    Full Text Available Background: Palato-gingival groove is a rare developmental anomaly leading to pulpal and periodontal diseases. Radicular extensions of these grooves are areas for plaque accumulation which are difficult to clean. Its clinical and radiographic findings mimic endo-perio lesions leading to diagnostic dilemma, ineffective treatment attempts and treatment failures. Objectives: To investigate the prevalence of coronal and radicular palato-gingival groove in dental patients visiting Dhulikhel Hospital and its association with gingival disease. Methods: Patients (N=231 visiting dental out-patient department of Dhulikhel Hospital, were examined for the presence or absence of palato-gingival groove in maxillary anteriors. Loe and Silness Gingival index was also recorded for all the patients using University of North Caroline-15 periodontal probe. Chisquare test was used to test the association of the presence of palato-gingival groove and gingival disease. P value of <0.05 was considered to be significant. Results: A total of 1362 maxillary anterior teeth were included in the study. The prevalence of coronal palatogingival groove among 1362 teeth was 6.6%. Coronal palato-gingival grooves were more common in females (56.6% than in male (43.3% patients. Prevalence of radicular groove was only 0.88% for lateral incisors and 0.2% for canines. There was no significant association between palate-gingival groove and gingival disease (P=0.91. Conclusion: The prevalence of palato-gingival groove is common in dental patients visiting Dhulikhel Hospital. Gingival disease is not significantly associated with palate-gingival groove. DOI: http://dx.doi.org/10.3126/jcmsn.v10i1.12765 Journal of College of Medical Sciences-Nepal, 2014, Vol.10(1; 32-36

  3. Optimally oriented grooves on dental implants improve bone quality around implants under repetitive mechanical loading.

    Science.gov (United States)

    Kuroshima, Shinichiro; Nakano, Takayoshi; Ishimoto, Takuya; Sasaki, Muneteru; Inoue, Maaya; Yasutake, Munenori; Sawase, Takashi

    2017-01-15

    The aim was to investigate the effect of groove designs on bone quality under controlled-repetitive load conditions for optimizing dental implant design. Anodized Ti-6Al-4V alloy implants with -60° and +60° grooves around the neck were placed in the proximal tibial metaphysis of rabbits. The application of a repetitive mechanical load was initiated via the implants (50N, 3Hz, 1800 cycles, 2days/week) at 12weeks after surgery for 8weeks. Bone quality, defined as osteocyte density and degree of biological apatite (BAp) c-axis/collagen fibers, was then evaluated. Groove designs did not affect bone quality without mechanical loading; however, repetitive mechanical loading significantly increased bone-to-implant contact, bone mass, and bone mineral density (BMD). In +60° grooves, the BAp c-axis/collagen fibers preferentially aligned along the groove direction with mechanical loading. Moreover, osteocyte density was significantly higher both inside and in the adjacent region of the +60° grooves, but not -60° grooves. These results suggest that the +60° grooves successfully transmitted the load to the bone tissues surrounding implants through the grooves. An optimally oriented groove structure on the implant surface was shown to be a promising way for achieving bone tissue with appropriate bone quality. This is the first report to propose the optimal design of grooves on the necks of dental implants for improving bone quality parameters as well as BMD. The findings suggest that not only BMD, but also bone quality, could be a useful clinical parameter in implant dentistry.

  4. Measurement Accuracy Analysis of Double-V Shaped Six-light-screen Array%双V型六光幕阵列测试精度分析

    Institute of Scientific and Technical Information of China (English)

    陈瑞; 倪晋平; 胡旭

    2016-01-01

    光幕阵列测试射击密集度已在靶场得到应用,阵列的结构参数直接影响测试精度。本文针对双V型六光幕阵列,理论分析了结构参数、弹丸入射角度及弹丸入射位置对弹丸速度测试精度和坐标测试精度的影响,并建立测试误差传播公式,通过 MATLAB 仿真得到了各因素影响弹丸速度和坐标测试精度的规律和关系曲线。文中的结果为提高六光幕阵列测试精度和工程设计优化提供了参考。%Light screen array is applied to measure firing dispersion in range, and the structure parameters of the array influences the measuring result directly. Based on double-V shaped six-light-screen array, the influence of the structure parameter, the angles of incidence and the impact location to the measurement accuracy of velocity and coordinates are analyzed, and then the error transfer formulas are deduced. The relations between the measurement accuracy of velocity and coordinates to each influence factors are simulated and plotted in MATLAB. The conclusion provided a reference for improving the measuring accuracy and optimizing the engineering design.

  5. The effect of combined hypergravity and micro-grooved surface topography on the behaviour of fibroblasts.

    NARCIS (Netherlands)

    Loesberg, W.A.; Walboomers, X.F.; Loon, J.J. van; Jansen, J.A.

    2006-01-01

    This study evaluated in vitro the differences in morphological behaviour between fibroblast cultured on smooth and micro-grooved substrata (groove depth: 1 mum, width: 1, 2, 5, 10 microm), which undergo artificial hypergravity by centrifugation (10, 24 and 50 g; or 1 g control). The aim of the study

  6. Beaming light from a subwavelength slit surrounded by an array of grooves with different depth

    Science.gov (United States)

    Luo, Xiangang; Wang, Changtao; Du, Chunlei; Shi, Haofei; Gao, Hongtao; Ma, Junxian; Fu, Yongqi; Li, Haiying

    2005-08-01

    In this paper, we discussed the beam focusing of light emerged from a subwavlength metallic slit surrounded by a set of grooves with constant space and width but variant depth at the exit side surface. Based on the numerical model presented by L. Martin-Moreno, F. J. Garcia-Vidal etc. (published in PRL 167401), we attempted to optimize grooves depth to obtain general beam manipulation, such as beam focusing. This attempt did not prove successful for many cases with variant focal length in our optimization practice, although some specific results display agreeable beam focusing with elongated focal depth. Further numerical computation shows that the excited electromagnetic field intensity around groove openings has a strong dependence on the groove depth, but the phase only vary with a maximum change value of π by tuning the groove depth. This property restricts greatly the modulation of electromagnetic field by just changing each groove depth. More geometrical parameters, including groove space and width, are recommended for optimization in the design of nano metallic groove and slit structures for specific beam manipulation.

  7. Current Teaching of Proximal Retention Grooves for Class II Amalgam Preparations.

    Science.gov (United States)

    Moore, David L.

    1992-01-01

    A survey gathered information on methods of class II amalgam preparation taught in 59 dental schools. Focus was on the teaching and testing of proximal retention groove use, stated rationale for placing retention grooves, and the relationship of the instruction to board criteria for cavity preparation. (MSE)

  8. Study of the cavitating instability on a grooved Venturi profile

    CERN Document Server

    Danlos, Amélie; Ravelet, Florent; Coutier-Delgosha, Olivier; Bakir, Farid

    2012-01-01

    Cavitation is a limiting phenomenon in many domains of fluid mechanics. Instabilities of a partial cavity developed on an hydrofoil, a converging-diverging step or in an inter-blade channel in turbomachinery, have already been investigated and described in many previous works. The aim of this study is to evaluate a passive control method of the sheet cavity. According to operating conditions, cavitation can be described by two different regimes: an unstable regime with a cloud cavitation shedding and a stable regime with only a pulsating sheet cavity. Avoiding cloud cavitation can limit structure damages since a pulsating sheet cavity is less agressive. The surface condition of a converging-diverging step, like a Venturi-type obstacle, is here studied as a solution for a passive control of the cavitation. This study discusses the effect of an organized roughness, in the shape of longitudinal grooves, on the developed sheet cavity. Analyzes conducted with Laser Doppler Velocimetry, visualisations and pressure ...

  9. Study of surface plasmon chirality induced by Archimedes' spiral grooves.

    Science.gov (United States)

    Ohno, Tomoki; Miyanishi, Shintaro

    2006-06-26

    A chirality of surface plasmons excited on a silver film with Archimedes' spiral grooves during incidence of a circularly polarized light is analytically and numerically studied by using the finite-difference time-domain (FDTD) modeling method. We found that the surface of a plasmon has selective chirality, which is given by the sum of the chiralities of the incident light and the spiral structure. The surface plasmons with the chirality lead to zero-order, first-order, and high-order evanescent Bessel beams with electric charge distributions on the film. This selectivity could be widely applied for chiral detection of the incident light and chiral excitation of several optical modes in nanophotonics.

  10. Design of ANSYS-based Cathode with Complex Groove

    Institute of Scientific and Technical Information of China (English)

    范植坚; 赵刚刚; 张丽娟

    2012-01-01

    The profile of cathode with complex groove needs to be modified time after time during design of electrochemical machining (ECM) cathode.A design scheme using finite element method (FEM) for cathode with complex profile is put forward to shorten the period of cathode design.Based on Laplace equation,the potential distribution on parameter-transformation model was calculated by using ANSYS,which is compared to the potential distribution calculated by substituting conductivity and current efficiency into Laplace equation.According to the difference between the results calculated and simulated by ANSYS,the cathode profile was modified by adjusting the cathode boundary.The experiments show that the dimensions and shape of workpiece machined by numerically simulated cathode conform well with the blueprint.

  11. Dance, Music, Meter and Groove: A Forgotten Partnership

    Science.gov (United States)

    Fitch, W. Tecumseh

    2016-01-01

    I argue that core aspects of musical rhythm, especially “groove” and syncopation, can only be fully understood in the context of their origins in the participatory social experience of dance. Musical meter is first considered in the context of bodily movement. I then offer an interpretation of the pervasive but somewhat puzzling phenomenon of syncopation in terms of acoustic emphasis on certain offbeat components of the accompanying dance style. The reasons for the historical tendency of many musical styles to divorce themselves from their dance-based roots are also briefly considered. To the extent that musical rhythms only make sense in the context of bodily movement, researchers interested in ecologically valid approaches to music cognition should make a more concerted effort to extend their analyses to dance, particularly if we hope to understand the cognitive constraints underlying rhythmic aspects of music like meter and groove. PMID:26973489

  12. Finite Element Analysis of 6300 Deep Groove Ball Bearing

    Institute of Scientific and Technical Information of China (English)

    DENG Chi; YANG Guang-hui

    2013-01-01

    Rolling bearing is widely used in mechanical support, its general components are the inner ring, outer ring, the ball, retainer etc.. Now many companies in developed countries and university in the rolling bearing as the research object, and has made great progress in design theory, the experiment method and production technology etc. We will use the finite element ANSYS to establish the model of deep groove ball bearing. Through the contact analysis, we can get the contact stress between the rings and balls, strain, contact state, penetration, sliding distance and the friction stress distribution. These values are compared to the theoretical values with Hertz theory, and they have better consistency, provide the good theoretical basis for the optimization design of rolling bearings.

  13. New phacoemulsification tip with a grooved, threaded-tip construction.

    Science.gov (United States)

    Watanabe, Akinari

    2011-07-01

    To visually compare ultrasonic tip vibrations between a phaco tip with internal grooves (threaded tip) and a standard phaco tip during continuous-mode ultrasound (US) using ultra-high-speed digital video imaging. Watanabe Eye Clinic, Hyogo, Japan. Experimental study. The threaded tip was constructed by creating grooves inside a standard phaco tip using a screw. An ultra-high-speed digital video camera was used to record the image during continuous-mode US. Samples used in the test chamber during phacoemulsification included a piece of chestnut as a representative human lens sample and actual human lens fragments. Ultra-high-speed digital images showed that the threaded tip created a larger amount of cavitation than the standard phaco tip during US oscillation. Phacoemulsification of the sample using the standard phaco tip produced a chattering motion, making it difficult to maintain a steady tip position. The threaded tip produced little chattering motion, making it relatively easy to maintain a steady tip position. Once a piece of sample was gripped by the threaded tip, it was shaved and aspirated into the threaded tip without chattering motion. The mean effective phacoemulsification time (EPT) of the threaded tip was significantly shorter than that of the normal phaco tip (6.0 seconds ± 1.9 [SD] versus 15.4 ± 1.3 seconds; P=.002). The threaded tip created larger amounts of cavitation and had strong destructive and holding power. This threaded construction is simple to produce and appears to be very effective for phacoemulsification. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  14. Dielectric effect on the rf characteristics of a helical groove travelling wave tube

    Institute of Scientific and Technical Information of China (English)

    Wei Yan-Yu(魏彦玉); Wang Wen-Xiang(王文祥); Sun Jia-Hong(孙嘉鸿); Liu Sheng-Gang(刘盛纲); Baofu Jia; Gun-Sik Park

    2002-01-01

    A new type of partial-dielectric-loaded helical groove slow-wave structure (SWS) for millimetre wave travellingwave tube (TWT) is presented in this paper. The radio-frequency characteristics including the dispersion properties,the longitudinal electric field distribution and the beam-wave coupling impedance of this structure are analysed. Theresults show that the dispersion of the helical groove circuit is weakened, the phase velocity is reduced and the positionof the maximum Ez is moved from the mouth to the inside of the groove after partially filling the dielectric materialsin the helical groove SWS. Therefore, the dielectric-loaded helical groove SWS is suitable for a multi-beam TWT withbroad band and high gain.

  15. Source-model technique analysis of electromagnetic scattering by surface grooves and slits.

    Science.gov (United States)

    Trotskovsky, Konstantin; Leviatan, Yehuda

    2011-04-01

    A computational tool, based on the source-model technique (SMT), for analysis of electromagnetic wave scattering by surface grooves and slits is presented. The idea is to use a superposition of the solution of the unperturbed problem and local corrections in the groove/slit region (the grooves and slits are treated as perturbations). In this manner, the solution is obtained in a much faster way than solving the original problem. The proposed solution is applied to problems of grooves and slits in otherwise planar or periodic surfaces. Grooves and slits of various shapes, both smooth ones as well as ones with edges, empty or filled with dielectric material, are considered. The obtained results are verified against previously published data.

  16. Some effects of grooved runway configurations on aircraft tire braking traction under flooded runway conditions

    Science.gov (United States)

    Byrdsong, T. A.

    1973-01-01

    An experimental investigation was conducted to study the effect of grooved runway configurations on aircraft tire braking traction on flooded runway surfaces. The investigation was performed, utilizing size 49 x 17, type VII, aircraft tires with an inflation pressure of 170 lb per square inch at ground speeds up to approximately 120 knots. The results of this investigation indicate that when the runway is flooded, grooved surfaces provide better braking traction than an ungrooved surface and, in general, the level of braking traction was found to improve as the tire bearing pressure was increased because of an increase in the groove area of either the surface or the tire tread. Rounding the groove edges tended to degrade the tire braking capability from that developed on the same groove configuration with sharp edges. Results also indicate that braking friction coefficients for the test tires and runway surfaces decreased as ground speed was increased because of the hydroplaning effects.

  17. Dispersion characteristics of planar grating with arbitrary grooves for terahertz Smith-Purcell radiation

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Miaomiao, E-mail: mona486@yeah.net; Li, Ke, E-mail: like3714@163.com [Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Liu, Wenxin, E-mail: lwenxin@mail.ie.ac.cn; Wang, Yong, E-mail: wangyong3845@sina.com [Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-03-15

    In this paper, a novel method of getting the dispersion relations in planar grating with arbitrary grooves for terahertz Smith-Purcell radiation is investigated analytically. The continuous profile of the groove is approximately replaced by a series of rectangular steps. By making use of field matches method and the continuity of transverse admittance, the universal dispersion equation for grating with arbitrarily shaped grooves is derived. By solving the dispersion equation in presence of electron beam, the growth rate is obtained directly and the dependence on beam parameters is analyzed. Comparisons of the dispersion characteristics among some special groove shapes have been made by numerical calculation. The results show that the rectangular-step approximation method provides a novel approach to obtain the universal dispersion relation for grating with arbitrary grooves for Smith-Purcell radiation.

  18. Dielectric effect on the rf characteristics of a helical groove travelling wave tube

    Science.gov (United States)

    Wei, Yan-Yu; Wang, Wen-Xiang; Sun, Jia-Hong; Liu, Sheng-Gang; Baofu, Jia; Gun-Sik, Park

    2002-03-01

    A new type of partial-dielectric-loaded helical groove slow-wave structure (SWS) for millimetre wave travelling wave tube (TWT) is presented in this paper. The radio-frequency characteristics including the dispersion properties, the longitudinal electric field distribution and the beam-wave coupling impedance of this structure are analysed. The results show that the dispersion of the helical groove circuit is weakened, the phase velocity is reduced and the position of the maximum Ez is moved from the mouth to the inside of the groove after partially filling the dielectric materials in the helical groove SWS. Therefore, the dielectric-loaded helical groove SWS is suitable for a multi-beam TWT with broad band and high gain.

  19. Experimental Study of Turbulent Boundary Layers on Groove/Smooth Flat Surfaces

    Institute of Scientific and Technical Information of China (English)

    Hongwei MA; Qiao TIAN; Hui WU

    2005-01-01

    This paper presents an experimental investigation of the turbulent boundary layers on both groove and smooth flat surfaces. The flow structures were shown in a water tunnel using the hydrogen-bubble flow visualization technique. The measurement results indicate that: (1) the grooves can effectively reduce accumulation of low-speed fluids, decrease the number of the low-speed streaks and depress oscillation of the streaks in the sublayer; (2) the grooves can restrain forming of the horseshoe vortices in the buffer region; (3) the grooves bate oscillation and kinking of the quasi-streamwise vortices and restrain production of the hairpin vortices and the ring vortices, reducing both frequency and intensity of the turbulence bursting; (4) the grooves directly affect the flow structures in the sublayer of the boundary layer and then modulate the flow field up to the buffer region and the logarithmic region by restraining development and interaction of the vortices.

  20. Treatment of a Developmental Groove and Supernumerary Root Using Guided Tissue Regeneration Technique

    Directory of Open Access Journals (Sweden)

    Zahra Alizadeh Tabari

    2016-01-01

    Full Text Available Introduction. The radicular groove is a developmental groove which is usually found on the palatal or lateral aspects of the maxillary incisor teeth. The present case is a maxillary lateral incisor with a small second root and a deep radicular groove. The developmental groove caused a combined periodontal-endodontic lesion. Methods. Case was managed using a combined treatment procedure involving nonsurgical root canal therapy and surgical periodontal treatment. After completion of root canal treatment, guided tissue regeneration (GTR was carried out using decalcified freeze dried bone allograft (DFDBA and a bioabsorbable collagenous membrane. Tooth also was splinted for two months. Results. After 12 months the tooth was asymptomatic. The periapical radiolucency disappeared and probing depth did not exceed 3 mm. Conclusion. Combined treatment procedure involving nonsurgical root canal therapy and surgical periodontal regenerative treatment can be a predictable technique in treating combined endodontic-periodontal lesions caused by radicular groove.

  1. A simple method for fabrication of high-aspect-ratio all-silicon grooves

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Yuncan; Pan, An; Si, Jinhai, E-mail: jinhaisi@mail.xjtu.edu.cn; Chen, Tao; Chen, Feng; Hou, Xun

    2013-11-01

    A simple method using 800-nm femtosecond laser irradiation and chemical selective etching has been proposed for fabrication of high-aspect-ratio all-silicon grooves. Grooves with the maximum aspect ratio of 44 were produced. A scanning electronic microscopy equipped with an energy dispersive X-ray spectroscopy was employed to characterize the morphology and chemical composition of the grooves respectively. The formation mechanism of the grooves was attributed to the chemical reaction of the laser induced refractive index change microstructures and hydrofluoric acid solution. The dependences of the aspect ratio of the grooves on the laser irradiation parameters, such as: the numerical aperture of the microscope objective lens, the laser average power and the laser scanning velocity, are discussed.

  2. Treatment of a Developmental Groove and Supernumerary Root Using Guided Tissue Regeneration Technique.

    Science.gov (United States)

    Alizadeh Tabari, Zahra; Homayouni, Hamed; Pourseyediyan, Tahere; Arvin, Armita; Eiland, Derrick; Moradi Majd, Nima

    2016-01-01

    Introduction. The radicular groove is a developmental groove which is usually found on the palatal or lateral aspects of the maxillary incisor teeth. The present case is a maxillary lateral incisor with a small second root and a deep radicular groove. The developmental groove caused a combined periodontal-endodontic lesion. Methods. Case was managed using a combined treatment procedure involving nonsurgical root canal therapy and surgical periodontal treatment. After completion of root canal treatment, guided tissue regeneration (GTR) was carried out using decalcified freeze dried bone allograft (DFDBA) and a bioabsorbable collagenous membrane. Tooth also was splinted for two months. Results. After 12 months the tooth was asymptomatic. The periapical radiolucency disappeared and probing depth did not exceed 3 mm. Conclusion. Combined treatment procedure involving nonsurgical root canal therapy and surgical periodontal regenerative treatment can be a predictable technique in treating combined endodontic-periodontal lesions caused by radicular groove.

  3. Thermal performance of heat pipe with different micro-groove structures

    Institute of Scientific and Technical Information of China (English)

    白鹏飞; 汤勇; 唐彪; 陆龙生

    2008-01-01

    Four kinds of micro heat pipe of trapezoidal groove wick structure with different numbers of grooves or aspect ratios were studied and compared about thermal transfer performances in order to optimize the manufacture of micro heat pipe with groove wick structure. The results show that these micro heat pipes have excellent performance in heat transfer; the equivalent thermal conductivity coefficient is two orders of magnitude compared with that of copper; the number and aspect ratio of grooves have a prominent effect on the performance of such thermal transfer. The optimum number of grooves is lower than 60 and the best aspect ratio is near to 1.5. The temperature and thermal transport rate are almost directly proportional relationship, but this relationship will be broken up suddenly when the critical heat flux is reached.

  4. An Optimum Method for a Grooved 2D Planar Ion Trap Design

    Institute of Scientific and Technical Information of China (English)

    JI Wei-Bang; WAN Jin-Yin; CHENG Hua-Dong; LIU Liang

    2011-01-01

    We investigate an effective grooved 2D ion chip design and optimize the ratio between the size of the rf electrodes and the groove.We calculate the optimal size of the groove using the analyticai model,which was introduced by House,and the optimum result is obtained. We aiso obtain the simulated scattering points with the finite element analysis method.The analytical curve and simulated scattering points are coincident with each other.It is shown that this analytical model also fits for the grooved planar ion chip.Thus the optimum grooved 2D planar ion chip design could be obtained.It is effective for scalable quantum information processing.

  5. Treatment of a Developmental Groove and Supernumerary Root Using Guided Tissue Regeneration Technique

    Science.gov (United States)

    Alizadeh Tabari, Zahra; Pourseyediyan, Tahere; Eiland, Derrick

    2016-01-01

    Introduction. The radicular groove is a developmental groove which is usually found on the palatal or lateral aspects of the maxillary incisor teeth. The present case is a maxillary lateral incisor with a small second root and a deep radicular groove. The developmental groove caused a combined periodontal-endodontic lesion. Methods. Case was managed using a combined treatment procedure involving nonsurgical root canal therapy and surgical periodontal treatment. After completion of root canal treatment, guided tissue regeneration (GTR) was carried out using decalcified freeze dried bone allograft (DFDBA) and a bioabsorbable collagenous membrane. Tooth also was splinted for two months. Results. After 12 months the tooth was asymptomatic. The periapical radiolucency disappeared and probing depth did not exceed 3 mm. Conclusion. Combined treatment procedure involving nonsurgical root canal therapy and surgical periodontal regenerative treatment can be a predictable technique in treating combined endodontic-periodontal lesions caused by radicular groove. PMID:27965900

  6. Individual differences in beat perception affect gait responses to low- and high-groove music.

    Directory of Open Access Journals (Sweden)

    Li-Ann eLeow

    2014-10-01

    Full Text Available Slowed gait in Parkinson’s disease (PD patients can be improved when patients synchronize footsteps to isochronous metronome cues, but limited retention of such improvements suggest that permanent cueing regimes are needed for long-term improvements. If so, music might make permanent cueing regimes more pleasant, improving adherence; however, music cueing requires patients to synchronize movements to the beat, which might be difficult for PD patients who tend to show weak beat perception. One solution may be to use high groove music, which has high beat salience that may facilitate synchronization, and affective properties which may improve motivation to move. As a first step in understanding how beat perception affects gait in complex neurological disorders, we examined how beat perception ability affected gait in neurotypical adults. Synchronization performance and gait parameters were assessed as healthy young adults with strong or weak beat perception synchronized to low groove music, high groove music, and metronome cues. High groove music was predicted to elicit better synchronization than low groove music, due to its higher beat salience. Two musical tempi, or rates, were used: (1 preferred tempo: beat rate matched to preferred step rate and (2 faster tempo: beat rate adjusted to 22.5% faster than preferred step rate. For both strong and weak beat-perceivers, synchronization performance was best with metronome cues, followed by high groove music, and worst with low groove music. In addition, high groove music elicited longer and faster steps than low groove music, both at preferred tempo and at faster tempo. Low groove music was particularly detrimental to gait in weak beat-perceivers, who showed slower and shorter steps compared to uncued walking. The findings show that individual differences in beat perception affect gait when synchronizing footsteps to music, and have implications for using music in gait rehabilitation.

  7. Individual differences in beat perception affect gait responses to low- and high-groove music.

    Science.gov (United States)

    Leow, Li-Ann; Parrott, Taylor; Grahn, Jessica A

    2014-01-01

    Slowed gait in patients with Parkinson's disease (PD) can be improved when patients synchronize footsteps to isochronous metronome cues, but limited retention of such improvements suggest that permanent cueing regimes are needed for long-term improvements. If so, music might make permanent cueing regimes more pleasant, improving adherence; however, music cueing requires patients to synchronize movements to the "beat," which might be difficult for patients with PD who tend to show weak beat perception. One solution may be to use high-groove music, which has high beat salience that may facilitate synchronization, and affective properties, which may improve motivation to move. As a first step to understanding how beat perception affects gait in complex neurological disorders, we examined how beat perception ability affected gait in neurotypical adults. Synchronization performance and gait parameters were assessed as healthy young adults with strong or weak beat perception synchronized to low-groove music, high-groove music, and metronome cues. High-groove music was predicted to elicit better synchronization than low-groove music, due to its higher beat salience. Two musical tempi, or rates, were used: (1) preferred tempo: beat rate matched to preferred step rate and (2) faster tempo: beat rate adjusted to 22.5% faster than preferred step rate. For both strong and weak beat-perceivers, synchronization performance was best with metronome cues, followed by high-groove music, and worst with low-groove music. In addition, high-groove music elicited longer and faster steps than low-groove music, both at preferred tempo and at faster tempo. Low-groove music was particularly detrimental to gait in weak beat-perceivers, who showed slower and shorter steps compared to uncued walking. The findings show that individual differences in beat perception affect gait when synchronizing footsteps to music, and have implications for using music in gait rehabilitation.

  8. Experimental studies on heat transfer and friction factor characteristics of a turbulent flow for internally grooved tubes

    Directory of Open Access Journals (Sweden)

    Ponnusamy Selvaraj

    2016-01-01

    Full Text Available This paper reports experimental studies on friction factor, Nusselt number, and thermal hydraulic performance of a tube equipped with the classic three modified internally grooved tubes. Heat transfer and friction factor characteristics and pres- sure drop results have been obtained experimentally for a fully developed water flow in a grooved tube is also reported. Tests were performed for Reynolds number ranges from 5000-13500 for different geometric grooved tubes (circular, square, and rapezium. The ratio of length-to-diameter is 38.69 D. Among the grooved tubes, heat transfer enhancement obtained up to 47% for circular grooved tube, 31% for square grooved tube, and 52% for trapezoidal grooved tube in comparison with the smooth tube. It has been observed that the friction factor high in the case of square grooved tube than those of other tubes.

  9. Characteristics of Arbitrarily-Shaped Helical Groove Slow-Wave Structure Loaded with a Concentric Dielectric-Rod

    Science.gov (United States)

    Gong, Yu-Bin; Wei, Yan-Yu; Liu, Hong-Tao

    2010-12-01

    The dielectric-rod is loaded on the central axis of the arbitrarily-shaped helical groove slow-wave structure. Meanwhile, the profile of the groove is replaced by a series of continuous rectangular steps. The unified dispersion equation of the arbitrarily-shaped helical groove waveguide loaded with a concentric dielectric-rod is obtained by means of a combination of filed-matching method and admittance-matching technique. Then, the effect of the change of groove shape and the dielectric-rod parameters on the dispersion and coupling impedance is approached by theory calculation. The results show that: loaded with dielectric-rod, the bandwidth of the helical groove traveling wave tube (TWT) is effectively broadened, but the coupling impedance is reduced. Among the five different groove shapes, the triangle-type groove has the widest bandwidth but the smallest coupling impedance, and the swallow-tailed-type groove has the narrowest bandwidth but the largest coupling impedance.

  10. Determination of Tongue and Groove parameters for multileaf collimators; Determinaco de parametros de Tongue and Groove de colimadores de multilaminas

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Aluisio; Almeida, Carlos E. de, E-mail: alu_neto@hotmail.com [Universidade Estadual do Rio de Janeiro (UERJ), RJ (Brazil). Laboratorio de Ciencias Radiologicas; Nguyen, Bihn [Prowess Inc., Concord, CA (United States)

    2012-08-15

    The Tongue and Groove effect (TandG) is characterized by an additional attenuation between adjacent and opposing leaves on multileaf collimators (MLCs) in adjacent or complementary fields. This is a typical situation in of intensity-modulated radiotherapy treatments. The aim of this study was to measure the width and transmission of TandG effect for two commercial MLCs: Varian Millennium 120 (6 MV and 16 MV beams) and BrainLab m3 (only for 6 MV). The methodology used was based on the creation of MLC shapes that emphasizes TandG effect, the irradiation of these fields on radiochromic film and the sensitometric evaluation of the films in order to determine the TandG width and transmission. The results for TandG width for studied MLCs were 2.5, 1.8 and 2 mm, respectively, whit transmission TandG values of 87, 90 and 85%. (author)

  11. Rational assembly of Pb(II)/Cd(II)/Mn(II) coordination polymers based on flexible V-shaped dicarboxylate ligand: Syntheses, helical structures and properties

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Gao-Shan [School of Environment and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Liu, Chong-Bo, E-mail: cbliu@nchu.edu.cn [School of Environment and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China); School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Liu, Hong [School of Environment and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Robbins, Julianne; Zhang, Z. John [School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Yin, Hong-Shan [School of Environment and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Wen, Hui-Liang [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047 (China); Wang, Yu-Hua [School of Environment and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China)

    2015-05-15

    Six new coordination polymers, namely, [Pb(L)(H{sub 2}O)] (1), [Pb(L)(phen)] (2), [Pb{sub 2}(L){sub 2}(4,4′-bipy){sub 0.5}] (3), [Cd(L)(phen)] (4), [Cd(L)(4,4′-bipy)]·H{sub 2}O (5) and [Mn(L)(4,4′-bipy)]·H{sub 2}O (6) have been synthesized by the hydrothermal reaction of 2,2′-[hexafluoroisopropylidenebis(p-phenyleneoxy)]diacetic acid (H{sub 2}L) with Pb(II)/Cd(II)/Mn(II) in the presence of ancillary ligands 4,4′-bipyridine (4,4′-bipy) or 1,10-phenanthroline (phen). Complexes 1 and 4–6 exhibit 2-D structures, and complexes 2–3 display 3-D frameworks, of which L{sup 2−} ligands join metal ions to single-stranded helical chains of 1, 3–6 and double-stranded helical chains of 2. Complexes 2 and 3 also contain double-stranded Metal–O helices. Topology analysis reveals that complexes 1 and 4 both represent 4-connected sql net, 2 represents 6-connected pcu net, 3 exhibits a novel (3,12)-connected net, while 5 and 6 display (3,5)-connected gek1 net. The six complexes exhibit two kinds of inorganic–organic connectivities: I{sup 0}O{sup 2} for 1, 4–6, and I{sup 1}O{sup 2} for 2–3. The photoluminescent properties of 4–5 and the magnetic properties of 6 have been investigated. - Graphical abstract: Six new Pb(II)/Cd(II)/Mn(II) coordination polymers with helical structures based on flexible V-shaped dicarboxylate ligand have been synthesized and structurally characterized. Photoluminescent and magnetic properties have been investigated. - Highlights: • Six novel M(II) coordination polymers with 2,2′-[hexafluoroisopropylidenebis(p-phenyleneoxy)]diacetic acid and N-donor ligands. • Complexes 1–6 show diverse intriguing helical characters. • The luminescent properties of complexes 1–5 were investigated. • Complex 6 shows antiferromagnetic coupling.

  12. Syntheses, crystal structures, and optical properties of five metal complexes constructed from a V-shaped thiophene-containing ligand and different dicarboxylate ligands.

    Science.gov (United States)

    Shi, Zhi-Qiang; Guo, Zi-Jian; Zheng, He-Gen

    2014-09-21

    Five new metal complexes, {[Ni(DIDP)(m-bdc)(H2O)]·5H2O}n (1), {[Zn(DIDP)(hfipbb)]·2DMA}n (2), {[Zn(DIDP)(4,4'-sdb)]·H2O}n (3), {[Co(DIDP)(p-bdc)]}n (4), and {[Co2(DIDP)(hfipbb)2]·H2O}n (5), have been synthesized by reactions of the corresponding metal ions with a V-shaped ligand 2,8-di(1H-imidazol-1-yl)dibenzothiophene (DIDP) and different aromatic dicarboxylic acids, namely isophthalic acid (m-H2bdc), terephthalic acid (p-H2bdc), 4,4'-(hexafluoroisopropylidene)bis(benzoic acid) (H2hfipbb), and 4,4'-sulfonyldicarboxylic acid (4,4'-H2sdb), respectively. The structures of the complexes were determined by X-ray single-crystal diffraction. Complex 1 is a 1D chain structure containing a one-dimensional channel along the a direction and is further extended via O-H···S hydrogen bonds and C-H···π stacking interactions into a 3D framework. Complex 2 exhibits a quasi 2D + 2D → 2D with parallel polycatenation of 2D (4, 4) nets. Complex 3 displays an unusual 2D + 2D → 3D parallel polycatenated framework based on a 2D 6(3)-hcb network. Complex 4 shows a 2D 4-connected {4(4)·6(2)}-sql network containing a one-dimensional channel along the b direction. The adjacent 2D networks are further extended via C-H···O hydrogen bonds into a 3D supramolecular framework. Complex 5 features a 2-fold interpenetrating 3D framework with a 6-connected {4(12)·6(3)} pcu topology. Furthermore, the thermal stability for 1-5 and luminescence properties of 2 and 3 have been studied. Moreover, the solid-state UV-visible spectroscopy experiments show that complexes 1-5 are all optical semiconductors with band gaps of 3.06, 3.18, 3.23, 2.98, and 3.17 eV, respectively.

  13. Structural diversity and photocatalytic properties of Cd(II) coordination polymers constructed by a flexible V-shaped bipyridyl benzene ligand and dicarboxylate derivatives.

    Science.gov (United States)

    Liu, Lei-Lei; Yu, Cai-Xia; Ma, Feng-Ji; Li, Ya-Ru; Han, Jing-Jing; Lin, Lu; Ma, Lu-Fang

    2015-01-28

    Hydrothermal reactions of Cd(OAc)2·2H2O with a flexible V-shaped bipyridyl benzene ligand and five benzenedicarboxylic acid derivatives gave rise to five new coordination polymers i.e., [Cd(1,4-BDC)(bpmb)(H2O)]n (1), {[Cd(1,3-BDC)(bpmb)]·0.125H2O}n (2), [Cd2(5-Me-1,3-BDC)2(bpmb)2]n (3), [Cd(5-NO2-1,3-BDC)(bpmb)(H2O)]n (4) and [Cd(5-OH-1,3-BDC)(bpmb)(H2O)]n (5) (bpmb = 1,3-bis(pyridine-3-ylmethoxy)benzene, 1,4-H2BDC = 1,4-benzenedicarboxylic acid, 1,3-H2BDC = 1,3-benzenedicarboxylic acid, 5-Me-1,3-H2BDC = 5-methyl-1,3-benzenedicarboxylic acid, 5-NO2-1,3-H2BDC = 5-nitro-1,3-benzenedicarboxylic acid, 5-OH-1,3-H2BDC = 5-hydroxy-1,3-benzenedicarboxylic acid). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Compound 1 is a two-fold interpenetrating network showing the coexistence of polyrotaxane and polycatenane characters. Compounds 2 and 3 exhibit similar 2D (3,5)-connected (4(2)·6(7)·8)(4(2)·6) nets in which the bpmb ligands work as lockers in interlocking 1D [Cd(1,3-BDC/5-Me-1,3-BDC)]n chains. Compound 4 shows a 2D 4-connected (6(6)) sandwich-like structure with differently oriented [Cd(5-NO2-1,3-BDC)]n chains. Compound 5 is a 3D supramolecular pcu net based on a 1D ladder-shaped chain. These results suggest that the substituted positions of carboxylate groups and changes in substituted R groups in the 5-position of BDC ligands have significant effect on the final structures. These compounds exhibited relatively good photocatalytic activity towards the degradation of methylene blue (MB) in aqueous solution under UV irradiation. Moreover, solid-state photoluminescence properties of 1-5 were also investigated.

  14. Effect of groove on socket welds under the condition of vibration fatigue

    Science.gov (United States)

    Xiu, Junjie; Jing, Hongyang; Han, Yongdian; Zhao, Lei; Xu, Lianyong

    2013-02-01

    Root failures of socket welds in small bore piping caused by vibration mainly occur at nuclear power plants (NPPs). It was observed that at higher stress level failures tended to originate at the toe while for the case of lower stress failures tended to occur at the root. The groove can increase the penetration depth (PD) of root, which is beneficial to the fatigue life. The effect of groove was also investigated by finite element method (FEM). The simulation results show that groove can decline the stress distribution, stress triaxiality and maximum principal plastic strain in the weld root, and the 5 mm groove suffering σmax (the highest stress of root failure) is almost same as no groove subjecting to σf (fatigue limit). The test results show that the socket weld with groove can increase the natural frequency and damping of specimen, which make the system more difficult to vibrate. Moreover, the groove can also improve the fatigue property of specimen which do not exist the root failure even under high cycle fatigue (HCF).

  15. Phase-Field Modeling of Grain-Boundary Grooving Under Electromigration

    Science.gov (United States)

    Mukherjee, Arnab; Ankit, Kumar; Mukherjee, Rajdip; Nestler, Britta

    2016-12-01

    In the present work, we study the phenomenon of grain-boundary grooving under electromigration using a phase-field method. The specific focus of the work is to explore the role of grain boundaries as potential electromigration pathways. We consider the evolution of grooves under the combined influence of capillary and electromigration-mediated surface diffusion and electromigration-induced grain-boundary diffusion. Mechanisms of grooving are elucidated using flux density maps that indicate various regimes depending upon the direction of net material transport. When grain-boundary atomic mobility is lower than the surface mobility, the groove depth is found to be lower than that evolving solely under surface diffusion (no electromigration). At comparable or larger values of grain-boundary atomic mobility, grooving is initially expedited but shows groove replenishment at later stages. A detailed investigation using the phase-field method reveals the influence of an incumbent healing mechanism on grain-boundary grooving which is electrically induced. The drift characteristics such as edge and root displacement and velocity are examined in light of this assuaging effect.

  16. Effective slip for flow through a channel bounded by lubricant-impregnated grooved surfaces

    Science.gov (United States)

    Sun, Rui; Ng, Chiu-On

    2017-04-01

    This study aims to investigate effective slip arising from pressure-driven flow through a slit channel bounded by lubricant-impregnated grooved surfaces. The problem for flow over longitudinal grooves is solved analytically using the methods of domain decomposition and eigenfunction expansion, while that for flow over transverse grooves is solved numerically using the front tracking method. It is found that the effective slip length and the lubricant flow rate can depend strongly on the geometry of the microstructure, the direction of flow, and the lubricant viscosity. In particular, the effective slip can be effectively enhanced by increasing the thickness of a lubricating film atop the ribs. Under the same conditions, a flow that is parallel to the lubricant-impregnated grooves will have a larger effective slip, but also a larger lubricant flow rate, when compared with the case of flow normal to the grooves. It is also shown that, in the case of transverse grooves, because of the downward displacement of the interface between the working/lubricating fluids, the effective slip length and lubricant flow rate may vary non-monotonically with the groove depth.

  17. Microcirculation within grooved substrates regulates cell positioning and cell docking inside microfluidic channels.

    Science.gov (United States)

    Manbachi, Amir; Shrivastava, Shamit; Cioffi, Margherita; Chung, Bong Geun; Moretti, Matteo; Demirci, Utkan; Yliperttula, Marjo; Khademhosseini, Ali

    2008-05-01

    Immobilization of cells inside microfluidic devices is a promising approach for enabling studies related to drug screening and cell biology. Despite extensive studies in using grooved substrates for immobilizing cells inside channels, a systematic study of the effects of various parameters that influence cell docking and retention within grooved substrates has not been performed. We demonstrate using computational simulations that the fluid dynamic environment within microgrooves significantly varies with groove width, generating microcirculation areas in smaller microgrooves. Wall shear stress simulation predicted that shear stresses were in the opposite direction in smaller grooves (25 and 50 microm wide) in comparison to those in wider grooves (75 and 100 microm wide). To validate the simulations, cells were seeded within microfluidic devices, where microgrooves of different widths were aligned perpendicularly to the direction of the flow. Experimental results showed that, as predicted, the inversion of the local direction of shear stress within the smaller grooves resulted in alignment of cells on two opposite sides of the grooves under the same flow conditions. Also, the amplitude of shear stress within microgrooved channels significantly influenced cell retainment in the channels. Therefore, our studies suggest that microscale shear stresses greatly influence cellular docking, immobilization, and retention in fluidic systems and should be considered for the design of cell-based microdevices.

  18. The Effect of Expert Performance Microtiming on Listeners' Experience of Groove in Swing or Funk Music

    Science.gov (United States)

    Senn, Olivier; Kilchenmann, Lorenz; von Georgi, Richard; Bullerjahn, Claudia

    2016-01-01

    This study tested the influence of expert performance microtiming on listeners' experience of groove. Two professional rhythm section performances (bass/drums) in swing and funk style were recorded, and the performances' original microtemporal deviations from a regular metronomic grid were scaled to several levels of magnitude. Music expert (n = 79) and non-expert (n = 81) listeners rated the groove qualities of stimuli using a newly developed questionnaire that measures three dimensions of the groove experience (Entrainment, Enjoyment, and the absence of Irritation). Findings show that music expert listeners were more sensitive to microtiming manipulations than non-experts. Across both expertise groups and for both styles, groove ratings were high for microtiming magnitudes equal or smaller than those originally performed and decreased for exaggerated microtiming magnitudes. In particular, both the fully quantized music and the music with the originally performed microtiming pattern were rated equally high on groove. This means that neither the claims of PD theory (that microtiming deviations are necessary for groove) nor the opposing exactitude hypothesis (that microtiming deviations are detrimental to groove) were supported by the data. PMID:27761117

  19. The Effect of Expert Performance Microtiming on Listeners' Experience of Groove in Swing or Funk Music.

    Science.gov (United States)

    Senn, Olivier; Kilchenmann, Lorenz; von Georgi, Richard; Bullerjahn, Claudia

    2016-01-01

    This study tested the influence of expert performance microtiming on listeners' experience of groove. Two professional rhythm section performances (bass/drums) in swing and funk style were recorded, and the performances' original microtemporal deviations from a regular metronomic grid were scaled to several levels of magnitude. Music expert (n = 79) and non-expert (n = 81) listeners rated the groove qualities of stimuli using a newly developed questionnaire that measures three dimensions of the groove experience (Entrainment, Enjoyment, and the absence of Irritation). Findings show that music expert listeners were more sensitive to microtiming manipulations than non-experts. Across both expertise groups and for both styles, groove ratings were high for microtiming magnitudes equal or smaller than those originally performed and decreased for exaggerated microtiming magnitudes. In particular, both the fully quantized music and the music with the originally performed microtiming pattern were rated equally high on groove. This means that neither the claims of PD theory (that microtiming deviations are necessary for groove) nor the opposing exactitude hypothesis (that microtiming deviations are detrimental to groove) were supported by the data.

  20. The effect of expert performance microtiming on listeners’ experience of groove in swing or funk music

    Directory of Open Access Journals (Sweden)

    Olivier Senn

    2016-10-01

    Full Text Available This study tested the influence of expert performance microtiming on listeners' groove experience. Two professional rhythm section (bass/drums performances in swing and funk style were recorded, and the performances' original microtemporal deviations from a regular metronomic grid were scaled to several magnitude levels. Music expert (n=79 and non-expert (n=81 listeners rated the groove qualities of stimuli using a newly developed questionnaire that measures three dimensions of the groove experience (Entrainment, Enjoyment, and the absence of Irritation. Findings show that music expert listeners were more sensitive to microtiming manipulations than non-experts. Across both expertise groups and for both styles, groove ratings were high for microtiming magnitudes equal or smaller than those originally performed and decreased for exaggerated microtiming magnitudes. In particular, both the fully quantized music and the music with the originally performed microtiming pattern were rated equally high on groove. This means that neither the claims of PD theory (that microtiming deviations are necessary for groove nor the opposing exactitude hypothesis (that microtiming deviations are detrimental to groove were supported by the data.

  1. Electrowetting actuated microfluidic transport in surface grooves with triangular cross section.

    Science.gov (United States)

    Barman, Jitesh; Swain, Digendranath; Law, Bruce M; Seemann, Ralf; Herminghaus, Stephan; Khare, Krishnacharya

    2015-01-27

    Liquids show different static wetting morphologies in open triangular grooves depending upon the wedge angle (ψ) of the groove and the liquid contact angle (θ) with the substrate. Switching between different morphologies can be achieved either by varying the contact angle of the liquid or by changing the wedge angle of the groove. In the present work we manipulate the apparent contact angle of a liquid by electrowetting to switch between liquid morphologies, from droplet to filament, to achieve microfluidic transport of the liquid into open triangular grooves. The static length of liquid filaments in grooves is analyzed as a function of applied voltage for different applied ac frequencies. The dynamic advancement of the filament lengths in grooves is analyzed as a function of time for different applied voltages for two different liquids: first with contact angle greater than the wedge angle and second with contact angle smaller than the wedge angle. Later an exact electrical model is derived to explain the liquid transport in triangular grooves actuated by electrowetting which includes the precise geometry of the liquid morphology.

  2. Recent developments in sequence selective minor groove DNA effectors.

    Science.gov (United States)

    Reddy, B S; Sharma, S K; Lown, J W

    2001-04-01

    DNA is a well characterized intracellular target but its large size and sequential nature make it an elusive target for selective drug action. Binding of low molecular weight ligands to DNA causes a wide variety of potential biological responses. In this respect the main consideration is given to recent developments in DNA sequence selective binding agents bearing conjugated effectors because of their potential application in diagnosis and treatment of cancers as well as in molecular biology. Recent progress in the development of cross linked lexitropsin oligopeptides and hairpins, which bind selectively to the minor groove of duplex DNA, is discussed. Bis-distamycins and related lexitropsins show inhibitory activity against HIV-1 and HIV-2 integrases at low nanomolar concentrations. Benzoyl nitrogen mustard analogs of lexitropsins are active against a variety of tumor models. Certain of the bis-benzimidazoles show altered DNA sequence preference and bind to DNA at 5'CG and TG sequences rather than at the preferred AT sites of the parent drug. A comparison of bifunctional bizelesin with monoalkylating adozelesin shows that it appears to have an increased sequence selectivity such that monoalkylating compounds react at more than one site but bizelesin reacts only at sites where there are two suitably positioned alkylation sites. Adozelesin, bizelesin and carzelesin are far more potent as cytotoxic agents than cisplatin or doxorubicin. A new class of 1,2,9,9a-tetrahydrocyclo-propa[c]benz[e]indole-4-one (CBI) analogs i.e., CBI-lexitropsin conjugates arising from the latter leads are also discussed.A number of cyclopropylpyrroloindole (CPI) and CBI-lexitropsin conjugates related to CC-1065 alkylate at the N3 position of adenine in the minor groove of DNA in a sequence specific manner, and also show cytotoxicities in the femtomolar range. The cross linking efficiency of PBD dimers is much greater than that of other cross linkers including cisplatin, and melphalan. A new

  3. 高硫矿床崩落法采场V形堑沟底部结构的改进%Improvement of V - shaped Trench Structure of Stope Bottom for Sublevel Caving Method in High -sulfur Deposit

    Institute of Scientific and Technical Information of China (English)

    肖广哲; 饶运章; 黄苏锦

    2012-01-01

    对某矿两起硫化矿尘爆炸机理进行了研究,发现高硫矿床分段崩落采矿法开采过程中矿尘爆炸的点火源是采场V形堑沟底部结构内三角矿堆的氧化自燃。提出用不合硫的废石混凝土在采场底部V形堑沟内构筑三角堆,替换V形堑沟底部结构内的桃柱体,使出矿口处不聚热,消去点火源。结果表明,出矿口处矿石温度明显降低,由最高时的48℃降至31℃,同时V形堑沟内不存留三角堆矿石,使矿石损失率由39%降到38%。%The mechanism of sulfide ore dust explosion mechanism occurred in a mine was analyzed, and it was found that the spontaneous oxidation and combustion of triangle ore pile in V - shaped trench structure of stope bottom was the ignition source of ore dust explosion in the process of sublevel stoping. It was advanced to construct triangle pile in the V - shaped trench of stope bottom with waste rock concrete to replace the triangle ore in the V -shaped trench, so as to make no heat accumulation at ore -drawing mouth, and eliminate the ignition source. The results showed that the temperature of ore at ore - drawing mouth significantly reduced from 48 ℃ fo 31 ℃ , meanwhile, as no triangle ore pile in the V - shaped trench, the ore loss was reduced from 39% to 38%.

  4. The Study on Lift Lateral Force Characteristics of the V Shaped Winglet for Water Test Aircraft%喷水试验机桁杆系统V形控制小翼升侧力特性研究

    Institute of Scientific and Technical Information of China (English)

    张锋; 王磊; 郝琳召

    2015-01-01

    V shaped winglet of water test aircraft with fewer components achieves the control of the longitudinal and lateral movement of the truss rod system. It's lift and side force characteristics determines the longitudinal and lateral moment of the truss rod system. By solving the N-S equation' method with numerical calculation, the paper studys the relationship between the lift and side force of the V shaped winglet and the angle of attack, sideslip and winglet, and establish the control equation of the V shaped winglet. The result can provide reference for the aerodynamic layout design of the truss rod system and the control of the V shaped winglet for water test aircraft.%喷水试验机桁杆系统V形控制小翼以较少的部件实现了纵向和侧向操纵桁杆系统的作用,其升力和侧力特性决定着整个桁杆系统的纵侧向力矩.基于某喷水试验机所采用的V形控制小翼,通过求解N-S方程数值计算方法,研究其升力和侧力随迎角、侧滑角和翼面偏转的关系,建立V形控制小翼的力学控制方程,为喷水试验机桁杆系统的气动布局设计及V翼控制设计提供参考.

  5. Computational Study of the Supersonic Ejector Flows with a V-shape Nozzle%V形喷嘴的超声速引射器的数值模拟

    Institute of Scientific and Technical Information of China (English)

    孔凡实; 崔宝玲; 金英子; 金羲东

    2013-01-01

    To improve the performance of supersonic ejector,this paper redesigns a new V-shape nozzle based on the experimental result of the original convergent nozzle; makes it introduce more vortexes,thus improving the drainage flow by changing the number of lobes of V-shape nozzle,and obtains a geometric model of V-shape nozzle with a good performance; simulates the complex flow in supersonic ejector with FLUENT software and conducts contrastive analysis on the performance of various nozzles in numerical calculation.The result of numerical calculation shows that V-shape nozzle has certain influence on the distribution of flow field and impact wave at the supersonic nozzle and can effectively improve the performance of eiector and make the ejector reach a higher compression ratio and pressure recovery.%为了提高超音速引射器的性能,基于原有收敛形喷嘴的实验结果,重新设计了新型的V形喷嘴.通过改变V形喷嘴的波瓣数,使其引入更多涡流来提高引流流量,得到性能较好的V形喷嘴几何模型.采用FLUENT软件模拟超声速引射器中的复杂流动,对比分析了数值计算的各种喷嘴的性能.数值模拟结果显示:V形喷嘴对超音速喷嘴处的流场分布以及激波分布有一定的影响,可以有效提高引射器的性能,使引射器达到更大的压缩比和压力恢复.

  6. An Improvement on the Method for Calculating the Capillary Limit of Axial—Grooved Heat Piper

    Institute of Scientific and Technical Information of China (English)

    ChenHanzhuo; MaTongze

    1993-01-01

    A new model has been developed to predict the capillary limit of axial-grooved heat pipe.In the model the concepts of liquid saturation or liquid fraction of the cross-sectional area of groove,the modified relative permeability,absolute permeability of groove and Leverrt's function are used.The Leverrt's function is well represented by the functionf(s)=1(1/√5)(1/2-)0.175.In the model the effects of gravitational force,capillary force and viscous force are considered.The calcuated results are in good agreement with existing experimental data reported in the literature.

  7. Mathematical modeling of photovoltaic thermal PV/T system with v-groove collector

    Science.gov (United States)

    Zohri, M.; Fudholi, A.; Ruslan, M. H.; Sopian, K.

    2017-07-01

    The use of v-groove in solar collector has a higher thermal efficiency in references. Dropping the working heat of photovoltaic panel was able to raise the electrical efficiency performance. Electrical and thermal efficiency were produced by photovoltaic thermal (PV/T) system concurrently. Mathematical modeling based on steady-state thermal analysis of PV/T system with v-groove was conducted. With matrix inversion method, the energy balance equations are explained by means of the investigative method. The comparison results show that in the PV/T system with the V-groove collector is higher temperature, thermal and electrical efficiency than other collectors.

  8. Antineoplastic DNA-binding compounds: intercalating and minor groove binding drugs.

    Science.gov (United States)

    Mišković, Katarina; Bujak, Maro; Baus Lončar, Mirela; Glavaš-Obrovac, Ljubica

    2013-12-01

    DNA intercalating and minor groove binding compounds are new weapons in the battle against malignant diseases. These antineoplastic agents target the DNA molecule and interfere with the cell cycle leading to rapidly proliferating cell death. They are mainly derivates of a naturally occurring organic compound derived from a microorganism or plant. Intercalators usually act as topoisomerase I and/or II poisons, while the mechanisms of DNA minor groove binders are a combination of several steps including topoisomerase poisoning. This paper gives an overview of some of the developed DNA intercalating and minor groove binding compounds, as well as an explanation of their chemical structures, origins, and application in chemotherapy.

  9. Characterisation of a grooved heat pipe with an anodised surface

    Science.gov (United States)

    Solomon, A. Brusly; Ram Kumar, A. M.; Ramachandran, K.; Pillai, B. C.; Senthil Kumar, C.; Sharifpur, Mohsen; Meyer, Josua P.

    2017-03-01

    A grooved heat pipe (GHP) is an important device for managing heat in space applications such as satellites and space stations, as it works efficiently in the absence of gravity. Apart from the above application, axial GHPs are used in many applications, such as electronic cooling units for temperature control and permafrost cooling. Improving the performance of GHPs is essential for better cooling and thermal management. In the present study, the effect of anodization on the heat transfer characteristics of a GHP is studied with R600a as a working fluid. In addition, the effects of fill ratio, inclination angle and heat inputs on the heat transfer performance of a GHP are studied. Furthermore, the effect of heat flux on dimensional numbers, such as the Webber, Bond, Kutateladze and condensation numbers, are studied. The inclination angle, heat input and fill ratio of GHPs are varied in the range of 0°-90°, 25-250 W and 10-70 % respectively. It is found that the above parameters have a significant effect on the performance of a GHP. Due to the anodisation, the maximum enhancement in heat transfer coefficient at the evaporator is 39 % for a 90° inclination at a heat flux of 11 kW/m2. The reported performance enhancement of a GHP may be due to the large numbers of nucleation sites created by the anodisation process and enhancement in the capillary force due to the coating.

  10. Characterisation of a grooved heat pipe with an anodised surface

    Science.gov (United States)

    Solomon, A. Brusly; Ram Kumar, A. M.; Ramachandran, K.; Pillai, B. C.; Senthil Kumar, C.; Sharifpur, Mohsen; Meyer, Josua P.

    2016-06-01

    A grooved heat pipe (GHP) is an important device for managing heat in space applications such as satellites and space stations, as it works efficiently in the absence of gravity. Apart from the above application, axial GHPs are used in many applications, such as electronic cooling units for temperature control and permafrost cooling. Improving the performance of GHPs is essential for better cooling and thermal management. In the present study, the effect of anodization on the heat transfer characteristics of a GHP is studied with R600a as a working fluid. In addition, the effects of fill ratio, inclination angle and heat inputs on the heat transfer performance of a GHP are studied. Furthermore, the effect of heat flux on dimensional numbers, such as the Webber, Bond, Kutateladze and condensation numbers, are studied. The inclination angle, heat input and fill ratio of GHPs are varied in the range of 0°-90°, 25-250 W and 10-70 % respectively. It is found that the above parameters have a significant effect on the performance of a GHP. Due to the anodisation, the maximum enhancement in heat transfer coefficient at the evaporator is 39 % for a 90° inclination at a heat flux of 11 kW/m2. The reported performance enhancement of a GHP may be due to the large numbers of nucleation sites created by the anodisation process and enhancement in the capillary force due to the coating.

  11. Minor groove binder distamycin remodels chromatin but inhibits transcription.

    Directory of Open Access Journals (Sweden)

    Parijat Majumder

    Full Text Available The condensed structure of chromatin limits access of cellular machinery towards template DNA. This in turn represses essential processes like transcription, replication, repair and recombination. The repression is alleviated by a variety of energy dependent processes, collectively known as "chromatin remodeling". In a eukaryotic cell, a fine balance between condensed and de-condensed states of chromatin helps to maintain an optimum level of gene expression. DNA binding small molecules have the potential to perturb such equilibrium. We present herein the study of an oligopeptide antibiotic distamycin, which binds to the minor groove of B-DNA. Chromatin mobility assays and circular dichroism spectroscopy have been employed to study the effect of distamycin on chromatosomes, isolated from the liver of Sprague-Dawley rats. Our results show that distamycin is capable of remodeling both chromatosomes and reconstituted nucleosomes, and the remodeling takes place in an ATP-independent manner. Binding of distamycin to the linker and nucleosomal DNA culminates in eviction of the linker histone and the formation of a population of off-centered nucleosomes. This hints at a possible corkscrew type motion of the DNA with respect to the histone octamer. Our results indicate that distamycin in spite of remodeling chromatin, inhibits transcription from both DNA and chromatin templates. Therefore, the DNA that is made accessible due to remodeling is either structurally incompetent for transcription, or bound distamycin poses a roadblock for the transcription machinery to advance.

  12. Investigation of four classical groove patterns with three typical tool types for use in the rigid tool smoothing process

    Science.gov (United States)

    Wu, Hsing-Yu; Meng, Kai

    2016-07-01

    When a surface experiencing robotic processing to improve its optical performance (such as removing mid-spatial frequencies, localized grinding errors, and regional surface scratches), spindle speed, tool travel speed, pressure, slurry density as well as groove patterns are main factors to influence surface finishes. Based on the desired material removal rate, the Preston equation can provide optimized pressures and velocities between the tool and processed surface. Various groove patterns, however, can hardly predict by the equation because different patterns can cause unique tool deformation and pressure distribution, leading to determine unique smoothing result. In this paper, four typical groove patterns are studied: non-groove, grid grove, annular groove and radial groove with three typical tool types are evaluated by Finite Element Method (FEM) and statistics. Characteristics of these tools and groove patterns are presented in the end of this paper.

  13. The resistance of high frequency inductive welded pipe to grooving corrosion in salt water

    Energy Technology Data Exchange (ETDEWEB)

    Duran, C.; Triess, E.; Herbsleb, G.

    1986-09-01

    When exposed to neutral, salt-containing waters, electric resistant welded pipe in carbon and low alloy steels with increased sulfur contents may suffer preferential corrosion attack in the weld area. Because of its appearance, this type of corrosion is called grooving corrosion. The susceptibility to grooving corrosion may be determined and quantitatively described by means of an accelerated potentiostatic exposure test. The importance of type, concentration, and temperature of the electrolytic solution; potential; test duration; and the sulfur content of the steel in the accelerated corrosion test and the susceptibility of steels to grooving corrosion are described. Line pipe in high frequency inductive (HFI) welded carbon and low alloy steels are resistant to grooving corrosion particularly because of their low sulfur content.

  14. Groove Pancreatitis with Several Cystic Lesions around the Pancreatic Head Treated Conservatively: Report of a Case

    Directory of Open Access Journals (Sweden)

    Ryusuke Ito

    2008-11-01

    Full Text Available A 61-year-old man was admitted to our hospital with epigastric pain and vomiting. Enhanced abdominal computed tomography revealed inflammatory change of the pancreatic groove and focal wall thickening of the second portion of the duodenum with several cystic lesions around the head of the pancreas. We diagnosed atypical type of groove pancreatitis. The patient made a satisfactory recovery by conservative medication treatment for acute on chronic pancreatitis and cystic lesions disappeared in parallel with pancreatitis. Groove pancreatitis is a rare form of chronic pancreatitis, and to the best of our knowledge, our patient is the first case in the English literature of groove pancreatitis with cystic lesions around the head of the pancreas, which disappeared after conservative treatment for pancreatitis.

  15. Investigation of mechanism: spoof SPPs on periodically textured metal surface with pyramidal grooves

    Science.gov (United States)

    Tian, Lili; Liu, Jianlong; Zhou, Keya; Gao, Yang; Liu, Shutian

    2016-08-01

    In microwave and terahertz frequency band, a textured metal surface can support spoof surface plasmon polaritons (SSPPs). In this paper, we explore a SSPPs waveguide composed of a metal block with pyramidal grooves. Under the deep subwavelength condition, theoretical formulas for calculation of dispersion relations are derived based on the modal expansion method (MEM). Using the obtained formulas, a general analysis is given about the properties of the SSPPs in the waveguides with upright and downward pyramidal grooves. It is demonstrated that the SSPPs waveguides with upright pyramidal grooves give better field-confinement. Numerical simulations are used to check the theoretical analysis and show good agreement with the analytical results. In addition, the group velocity of the SSPPs propagating along the waveguide is explored and two structures are designed to show how to trap the SSPPs on the metal surface. The calculation methodology provided in this paper can also be used to deal with the SSPPs waveguides with irregular grooves.

  16. Theory of groove-envelope phase effects in self-diffraction

    CERN Document Server

    Reislöhner, Jan; Pfeiffer, Adrian N

    2016-01-01

    If two laser beams cross in a medium under shallow angle, the laser-induced grating consists of only a few grooves. In this situation, the phase between the grooves of the grating and its envelope is a decisive parameter for nonlinear effects. Here, models are established for reproducing the groove-envelope phase effects that have been observed in the interference pattern of self-diffraction. Four-wave mixing leads to interferences that are dominant in the spatial region between the orders of diffraction and with tilted interference fringes in the diagram of transverse coordinate vs. pulse delay. The vertical interference fringes that are dominant directly on the diffraction orders, experimentally observed at high intensity close to the damage threshold, require a model beyond four-wave mixing. A model is suggested that is based on optical transmission changes with confinement to regions in the medium that are smaller than the groove spacing.

  17. The potential impact of groove modes on Type II planetary migration

    CERN Document Server

    Meschiari, Stefano

    2008-01-01

    In this letter, we briefly describe the evolution of a variety of self-gravitating protoplanetary disk models that contain annular grooves (e.g. gaps) in their surface density. These grooves are inspired by the density gaps that are presumed to open in response to the formation of a giant planet. Our work provides an extension of the previously studied groove modes that are known in the context of stellar disks. The emergence of spiral gravitational instabilities (GI) is predicted via a generalized eigenvalue code that performs a linear analysis, and confirmed with hydrodynamical simulations. We find the presence of a groove drives a fast-growing two-armed mode in moderately massive disks, and extends the importance of self-gravitating instabilities down to lower disk masses than for which they would otherwise occur. We discuss the potential importance of this instability in the context of planet formation, e.g. the modification of the torques driving Type II migration.

  18. Palatal radicular groove: Clinical implications of early diagnosis and surgical sealing

    Directory of Open Access Journals (Sweden)

    P Corrêa-Faria

    2011-01-01

    Full Text Available Palatal radicular groove is a discreet alteration in tooth morphology, characterized by an invagination that begins near the cingulum of the tooth and moves in an apical direction. Clinically, palatal radicular groove may be associated with periodontal and/or endodontic problems. This paper describes a clinical case of a young patient with palatal radicular groove with no signs of periodontal disease or endodontic impairment. An early diagnosis was made and treatment consisted of surgical sealing of the defect. After a 2-year period, reexaminations demonstrated adequate hygiene, maintenance of tooth vitality and periodontal health. The early diagnosis and sealing of the groove observed surgically made the root surface smooth, avoiding subgingival bacterial plaque buildup, and preventing possible periodontal and/or pulp impairment stemming from the defect.

  19. Buckling Analysis of Supporting Legs and Steel Groove in Uranium Liquor Critical Facility

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The main structure of the uranium liquor critical facility is sit on the long steel tubal supporting legs, and the main vessel is connected with the supporting legs by steel groove, it is possible for the supporting

  20. Large eddy simulation of the subcritical flow over a V grooved circular cylinder

    Energy Technology Data Exchange (ETDEWEB)

    Alonzo-García, A. [Instituto Politécnico Nacional, SEPI-ESIME Zacatenco, U.P. Adolfo López Mateos Edif. 5, 3er. Piso, LABINTHAP, Av. Instituto Politénicno Nacional s/n, Col. Lindavista, C.P. 07738, México D.F., México (Mexico); Gutiérrez-Torres, C. del C., E-mail: cgutierrezt@ipn.mx [Instituto Politécnico Nacional, SEPI-ESIME Zacatenco, U.P. Adolfo López Mateos Edif. 5, 3er. Piso, LABINTHAP, Av. Instituto Politénicno Nacional s/n, Col. Lindavista, C.P. 07738, México D.F., México (Mexico); Jiménez-Bernal, J.A. [Instituto Politécnico Nacional, SEPI-ESIME Zacatenco, U.P. Adolfo López Mateos Edif. 5, 3er. Piso, LABINTHAP, Av. Instituto Politénicno Nacional s/n, Col. Lindavista, C.P. 07738, México D.F., México (Mexico); and others

    2015-09-15

    Highlights: • We compared numerically the turbulent flow over a smooth circular cylinder and a V grooved cylinder in the subcritical regime. • Turbulence intensities in both streamwise and normal direction suffered attenuations. • The swirls structures on grooves peaks seemed to have a cyclic behavior. • The evolution of the flow inside grooves showed that swirls structures located in peaks suffered elongations in the normal direction. • The secondary vortex structures formed in the grooved cylinder near wake were smaller in comparison of the smooth cylinder flow. - Abstract: In this paper, a comparative numerical study of the subcritical flow over a smooth cylinder and a cylinder with V grooves (Re = 140,000) is presented. The implemented technique was the Large Eddy Simulation (LES), which according to Kolmogorov's theory, resolves directly the most energetic largest eddies and models the smallest and considered universal high frequency ones. The Navier-Stokes (N-S) equations were solved using the commercial software ANSYS FLUENT V.12.1, which applied the finite volume method (FVM) to discretize these equations in their unsteady and incompressible forms. The grid densities were 2.6 million cells and 13.5 million cells for the smooth and V grooved cylinder, respectively. Both meshes were composed of structured hexahedral cells and close to the wall of the cylinders, additional refinements were employed in order to obtain y{sup +<5} values. All cases were simulated during at least 15 vortex shedding cycles with the aim of obtaining significant statistical data. Results: showed that for both cases (smooth and V grooved cylinder flow), the numerical code was capable of reproducing the most important physical quantities of the subcritical regime. Velocity distribution and turbulence intensity in the flow direction suffered a slight attenuation along the wake, as a consequence of grooves perturbation, which also caused an increase in the pressure

  1. A Novel Design of Grooved Fibers for Fiber-Optic Localized Plasmon Resonance Biosensors

    Directory of Open Access Journals (Sweden)

    Lai-Kwan Chau

    2009-08-01

    Full Text Available Bio-molecular recognition is detected by the unique optical properties of self-assembled gold nanoparticles on the unclad portions of an optical fiber whose surfaces have been modified with a receptor. To enhance the performance of the sensing platform, the sensing element is integrated with a microfluidic chip to reduce sample and reagent volume, to shorten response time and analysis time, as well as to increase sensitivity. The main purpose of the present study is to design grooves on the optical fiber for the FO-LPR microfluidic chip and investigate the effect of the groove geometry on the biochemical binding kinetics through simulations. The optical fiber is designed and termed as U-type or D-type based on the shape of the grooves. The numerical results indicate that the design of the D-type fiber exhibits efficient performance on biochemical binding. The grooves designed on the optical fiber also induce chaotic advection to enhance the mixing in the microchannel. The mixing patterns indicate that D-type grooves enhance the mixing more effectively than U-type grooves. D-type fiber with six grooves is the optimum design according to the numerical results. The experimental results show that the D-type fiber could sustain larger elongation than the U-type fiber. Furthermore, this study successfully demonstrates the feasibility of fabricating the grooved optical fibers by the femtosecond laser, and making a transmission-based FO-LPR probe for chemical sensing. The sensor resolution of the sensor implementing the D-type fiber modified by gold nanoparticles was 4.1 × 10-7 RIU, which is much more sensitive than that of U-type optical fiber (1.8 × 10-3 RIU.

  2. V-groove gratings on silicon for infrared beam splitting: comment.

    Science.gov (United States)

    Turunen, J; Noponen, E

    1996-02-10

    In a recent paper [Appl. Opt. 34, 2556 (1995)] beam-splitter gratings with one or more v-shaped features within the period were designed by the complex-amplitude transmittance method. We argue that this approach leads to incorrect results in the geometries considered and provide the evidence of its failure by numerical calculations based on rigorous electromagnetic diffraction theory.

  3. NMR studies of DNA oligomers and their interactions with minor groove binding ligands

    Energy Technology Data Exchange (ETDEWEB)

    Fagan, Patricia A. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

    1996-05-01

    The cationic peptide ligands distamycin and netropsin bind noncovalently to the minor groove of DNA. The binding site, orientation, stoichiometry, and qualitative affinity of distamycin binding to several short DNA oligomers were investigated by NMR spectroscopy. The oligomers studied contain A,T-rich or I,C-rich binding sites, where I = 2-desaminodeoxyguanosine. I•C base pairs are functional analogs of A•T base pairs in the minor groove. The different behaviors exhibited by distamycin and netropsin binding to various DNA sequences suggested that these ligands are sensitive probes of DNA structure. For sites of five or more base pairs, distamycin can form 1:1 or 2:1 ligand:DNA complexes. Cooperativity in distamycin binding is low in sites such as AAAAA which has narrow minor grooves, and is higher in sites with wider minor grooves such as ATATAT. The distamycin binding and base pair opening lifetimes of I,C-containing DNA oligomers suggest that the I,C minor groove is structurally different from the A,T minor groove. Molecules which direct chemistry to a specific DNA sequence could be used as antiviral compounds, diagnostic probes, or molecular biology tools. The author studied two ligands in which reactive groups were tethered to a distamycin to increase the sequence specificity of the reactive agent.

  4. Structure of a pheromone receptor-associated MHC molecule with an open and empty groove.

    Directory of Open Access Journals (Sweden)

    2005-08-01

    Full Text Available Neurons in the murine vomeronasal organ (VNO express a family of class Ib major histocompatibility complex (MHC proteins (M10s that interact with the V2R class of VNO receptors. This interaction may play a direct role in the detection of pheromonal cues that initiate reproductive and territorial behaviors. The crystal structure of M10.5, an M10 family member, is similar to that of classical MHC molecules. However, the M10.5 counterpart of the MHC peptide-binding groove is open and unoccupied, revealing the first structure of an empty class I MHC molecule. Similar to empty MHC molecules, but unlike peptide-filled MHC proteins and non-peptide-binding MHC homologs, M10.5 is thermally unstable, suggesting that its groove is normally occupied. However, M10.5 does not bind endogenous peptides when expressed in mammalian cells or when offered a mixture of class I-binding peptides. The F pocket side of the M10.5 groove is open, suggesting that ligands larger than 8-10-mer class I-binding peptides could fit by extending out of the groove. Moreover, variable residues point up from the groove helices, rather than toward the groove as in classical MHC structures. These data suggest that M10s are unlikely to provide specific recognition of class I MHC-binding peptides, but are consistent with binding to other ligands, including proteins such as the V2Rs.

  5. Structure of a Pheromone Receptor-Associated Mhc Molecule With An Open And Empty Groove

    Energy Technology Data Exchange (ETDEWEB)

    Olson, R.; Huey-Tubman, K.E.; Dulac, C.; Bjorkman, P.J.; /Caltech /Harvard U.

    2006-10-06

    Neurons in the murine vomeronasal organ (VNO) express a family of class Ib major histocompatibility complex (MHC) proteins (M10s) that interact with the V2R class of VNO receptors. This interaction may play a direct role in the detection of pheromonal cues that initiate reproductive and territorial behaviors. The crystal structure of M10.5, an M10 family member, is similar to that of classical MHC molecules. However, the M10.5 counterpart of the MHC peptide-binding groove is open and unoccupied, revealing the first structure of an empty class I MHC molecule. Similar to empty MHC molecules, but unlike peptide-filled MHC proteins and non-peptide-binding MHC homologs, M10.5 is thermally unstable, suggesting that its groove is normally occupied. However, M10.5 does not bind endogenous peptides when expressed in mammalian cells or when offered a mixture of class I-binding peptides. The F pocket side of the M10.5 groove is open, suggesting that ligands larger than 8-10-mer class I-binding peptides could fit by extending out of the groove. Moreover, variable residues point up from the groove helices, rather than toward the groove as in classical MHC structures. These data suggest that M10s are unlikely to provide specific recognition of class I MHC-binding peptides, but are consistent with binding to other ligands, including proteins such as the V2Rs.

  6. Grooved surface topography alters matrix-metalloproteinase production by human fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Brydone, Alistair S; Dominic Meek, R M [Department of Orthopaedics, Southern General Hospital, 1345 Govan Road, Glasgow G51 4TF (United Kingdom); Dalby, Matthew J; Berry, Catherine C; McNamara, Laura E, E-mail: alibrydone@gmail.com [Centre for Cell Engineering, Joseph Black Building, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

    2011-06-15

    Extracellular matrix (ECM) remodelling is an essential physiological process in which matrix-metalloproteinases (MMPs) have a key role. Manipulating the manner in which cells produce MMPs and ECMs may enable the creation of a desired tissue type, i.e. effect repair, or the prevention of tissue invasion (e.g. metastasis). The aim of this project was to determine if culturing fibroblasts on grooved topography altered collagen deposition or MMP production. Human fibroblasts were seeded on planar or grooved polycaprolactone substrates (grooves were 12.5 {mu}m wide with varying depths of 240 nm, 540 nm or 2300 nm). Cell behaviour and collagen production were studied using fluorescence microscopy and the spent culture medium was assessed using gel zymography to detect MMPs. Total collagen deposition was high on the 240 nm deep grooves, but decreased as the groove depth increased, i.e. as cell contact guidance decreased. There was an increase in gelatinase on the 2300 nm deep grooved topography and there was a difference in the temporal expression of MMP-3 observed on the planar surface compared to the 540 nm and 2300 nm topographies. These results show that topography can alter collagen and MMP production. A fuller understanding of these processes may permit the design of surfaces tailored to tissue regeneration e.g. tendon repair.

  7. Large Eddy Simulation of the Subcritical Flow over a U-Grooved Circular Cylinder

    Directory of Open Access Journals (Sweden)

    A. Alonzo-García

    2014-07-01

    Full Text Available With the aim of numerically replicating a drag reduction phenomenon induced by grooves presence, this paper presents a comparative large eddy simulation study of the flow over a smooth circular cylinder, and the flow over a U-grooved cylinder, at Re = 140,000, which is near transition between the subcritical and critical flow regimes. The grid densities were 2.6 million cells and 20.7 million cells for the smooth and the U-grooved cylinder, respectively. Both meshes were composed of hexahedral cells disposed in a structured form with additional refinements in near-wall regions, in order to obtain y+< 5 values. The cases were simulated during 25 vortex shedding cycles with the purpose of obtaining significant statistic data through the commercial software FLUENT V.12.1, which solved the Navier-Stokes equations in their unsteady and incompressible forms. Regarding the U-grooved cylinder flow, parameters such as the drag coefficient, lengths of recirculation, the transition from subcritical to critical flow, and the formation of a wake formed by secondary vortices of smaller sizes were predicted satisfactorily by the LES technique. From the manner in which the flow separates at different angles for both valleys and peaks of the U-grooves, a distinctive transitional mechanism induced by grooves presence is conjectured.

  8. Numerical Simulation of the Flow Field in Circumferential Grooved Liquid Seals

    Directory of Open Access Journals (Sweden)

    Meng Zhang

    2013-01-01

    Full Text Available Circumferential grooved liquid seals are utilized inside turbomachinery to provide noncontacting control of internal incompressible fluid leakage. Accurate prediction of the flow field is fundamental in producing robust and efficient designs. To validate the capabilities of the computational fluid dynamics FLUENT for incompressible fluid seal flow, comparisons of velocity parameters are made to the published experimental results and other CFD code for a circumferential grooved liquid seal. This work employs a pressure-based CFD code FLUENT to calculate the flow field in the seal, using four different turbulence models respectively. The velocity contours are compared with experimental values. It shows good overall agreement of the axial, radial, and azimuthal velocities in the through-flow jet, shear layer, and recirculation zone. Quantitative comparisons of velocity profiles at the center of the groove are made to experiment. This study verifies the prediction accuracy of three turbulence models. Various structures were considered to obtain a better understanding of the circumferential grooved liquid flow characteristics. The best groove structure to control leakage was also found within the limited designed seal. This study will provide a useful reference for designing the circumferential grooved liquid seal.

  9. Temperature Approach Optimization in the Double Pipe Heat Exchanger with Groove

    Directory of Open Access Journals (Sweden)

    Sunu Putu Wijaya

    2016-01-01

    Full Text Available Heat transfer in double pipe heat exchanger with circumference-rectangular grooves has been investigated experimentally. The volume flowrate of cold and hot water were varied to determine its influence on the approach temperature of the outlet terminals. In this experimental design, the grooves were incised in annular room that is placed on the outside surface of the inner pipe. The shell diameter is 38.1 mm and tube diameter 19.4 mm with 1 m length, which is made of aluminum. The flow pattern of the two fluids in the heat exchanger is a parallel flow. The working fluid is water with volume flow rate of 27.1, 23.8 and 19.8 l/minute. The temperature of water on the inlet terminals are 50±1°C for hot stream and 30±1°C for cold stream. Temperature measurements conducted on each terminal of the inlet and outlet heat exchanger. The results showed that the grooves induced the approach temperature. The change of the approach temperature from the grooves compared to that of without grooves decreased by 37.9%. This phenomenon indicates an increase in heat transfer process and performance of the heat exchanger. Groove improves the heat surface area of the inner pipe, increasing the momentum transfer and in the other hand, reducing the weight of heat exchangers itself.

  10. Relationship Between Measured Friction Coefficients and Two Tread Groove Design Parameters for Footwear Pads

    Institute of Scientific and Technical Information of China (English)

    LI Kai Way; CHEN Chin Jung; LIN Ching-Hua; HSU Yao Wen

    2006-01-01

    The shoe sole geometrical design parameters are believed to be important factors affecting the coefficient of friction (COF) between the shoe/floor interface. This study is concerned with the relationship between the measured COF and the tread groove orientation and width on the footwear pad. Friction measurements using the Brungraber Mark Ⅱ slipmeter were conducted. Six tread groove width/orientations designs on the footwear pads under 27 footwear material/floor/contamination conditions were tested. The results show that tread orientation and width affect the measured COF significantly. Wider grooved footwear pads result in higher COF values and footwear pads with tread grooves perpendicular to the friction measurement direction have higher COF values. A regression model using measured COF as the dependent variable and tread groove width, groove orientation, footwear material, floor, and contamination conditions as independent variables was established. The models are significant at p<0.0001 with R2 of 0.97, which may be used in predicting the COF at the shoe-floor interface.

  11. Numerical modeling and verification of gas flow through a network of crossed narrow v-grooves

    Science.gov (United States)

    Bejhed, Johan; Nguyen, Hugo; Åstrand, Peter; Eriksson, Anders; Köhler, Johan

    2006-10-01

    The gas flow through a network of crossing thin micro-machined channels has been successfully modeled and simulated. The crossings are formed by two sets of v-grooves that intersect as two silicon wafers are bonded together. The gas is distributed from inlets via a manifold of channels to the narrow v-grooves. The narrow v-grooves could work as a particle filter. The fluidic model is derived from the Navier-Stokes equation and assumes laminar isothermal flow and incorporates small Knudsen number corrections and Poiseuille number calculations. The simulations use the finite element method. Several elements of the full crossing network model are treated separately before lumping them together: the straight v-grooves, a single crossing in an infinite set and a set of exactly four crossings along the flow path. The introduction of a crossing effectively corresponds to a virtual reduction of the length of the flow path, thereby defining a new effective length. The first and last crossings of each flow path together contribute to a pressure drop equal to that from three ordinary crossings. The derived full network model has been compared to previous experimental results on several differently shaped crossed v-groove networks. Within the experimental errors, the model corresponds to the mass flow and pressure drop measurements. The main error source is the uncertainty in v-groove width which has a profound impact on the fluidic behavior.

  12. Effect of DNA groove binder distamycin A upon chromatin structure.

    Directory of Open Access Journals (Sweden)

    Parijat Majumder

    Full Text Available BACKGROUND: Distamycin A is a prototype minor groove binder, which binds to B-form DNA, preferentially at A/T rich sites. Extensive work in the past few decades has characterized the binding at the level of double stranded DNA. However, effect of the same on physiological DNA, i.e. DNA complexed in chromatin, has not been well studied. Here we elucidate from a structural perspective, the interaction of distamycin with soluble chromatin, isolated from Sprague-Dawley rat. METHODOLOGY/PRINCIPAL FINDINGS: Chromatin is a hierarchical assemblage of DNA and protein. Therefore, in order to characterize the interaction of the same with distamycin, we have classified the system into various levels, according to the requirements of the method adopted, and the information to be obtained. Isothermal titration calorimetry has been employed to characterize the binding at the levels of chromatin, chromatosome and chromosomal DNA. Thermodynamic parameters obtained thereof, identify enthalpy as the driving force for the association, with comparable binding affinity and free energy for chromatin and chromosomal DNA. Reaction enthalpies at different temperatures were utilized to evaluate the change in specific heat capacity (ΔCp, which, in turn, indicated a possible binding associated structural change. Ligand induced structural alterations have been monitored by two complementary methods--dynamic light scattering, and transmission electron microscopy. They indicate compaction of chromatin. Using transmission electron microscopy, we have visualized the effect of distamycin upon chromatin architecture at di- and trinucleosome levels. Our results elucidate the simultaneous involvement of linker bending and internucleosomal angle contraction in compaction process induced by distamycin. CONCLUSIONS/SIGNIFICANCE: We summarize here, for the first time, the thermodynamic parameters for the interaction of distamycin with soluble chromatin, and elucidate its effect on

  13. Clinical, radiological, surgical, and pathological determinants of olfactory groove schwannoma

    Directory of Open Access Journals (Sweden)

    Andi Sadayandi Ramesh

    2014-01-01

    Full Text Available Background: Olfactory groove schwannomas (OGS are rare anterior cranial fossa base tumors with only 41 cases reported in literature. Olfactory ensheathing cell schwannoma (OECS has similar clinico-radiological features as OGS, but a different cell of origin. In recent years, there is growing interest in OECS as more cases are being reported. Aims: The objective was to study the clinico-radiological features of OGS and define the histological differentiation from OECS. Materials and Methods: We retrospectively analyzed clinical, radiological, surgical and histopathological picture of all cases of OGS managed in our institute. Immuno histochemical studies were performed in these tumors for differentiating from OECS. A comprehensive review of articles published until date describing the operative treatment was done. Results: All three cases had presented with seizures, two had anosmia and papilledema. Gross-total resection was achieved in all our patients. One patient expired in the postoperative period due to septicemia. Positive expression to newer immuno histochemical biomarker CD57 (Leu7, with negative staining to smooth muscle α-actin (SMA was helpful in confirming the diagnosis of OGS and differentiating it from OECS in all our cases. Conclusions: OECS, though rare has to be differentiated from OGS using immuno histochemistry. Gross-total resection of OGS with preservation of olfactory function is often possible and curative. Although these tumors are commonly treated with microsurgical skull base approaches, an endoscopic endonasal approach can be considered in some cases, with repair using mucoperiosteal pedicled flap to prevent cerebrospinal fluid leak.

  14. Experimental study of partially flattened axial grooved heat pipes

    Institute of Scientific and Technical Information of China (English)

    TAO HanZhong; ZHANG Hong; ZHUANG Jun; Jerry W. BOWMANS

    2008-01-01

    This article made experimental study on mini-axial grooved heat pipes (AGHP) with 11 flattening forms. It analyzed how the flattening form, flattening thickness and working temperature affect axial tem-perature distribution, thermal resistance, heat transfer limit and the phase-change heat transfer coeffi-cients in evaporator and condenser sections. The result indicates that all forms of AGHPs can maintain good isothermal performance under normal operating condition. The geometric shape of AGHP has obvious impact on heat transfer limit. With respect to an AGHP with 2 mm-thick evaporator section, when the thickness of its condenser section increases from 2 to 3 mm, its heat transfer limit increases by 81%; with respect to an AGHP with 3 mm-thick evaporator section, when the thickness of its con-denser section increases from 2 to 3 mm, its heat transfer limit increases by 134%; with respect to an AGHP with 4 mm-thick condenser section, when the thickness of its evaporator section increases from 2 to 3 mm, its heat transfer limit increases by 26%. When the thickness of the evaporator section in-creases by 1 mm, the heat transfer limit will increase by 9%-26%, while when the thickness of the condenser section increases by 1 mm, the heat transfer limit will increase by 20%-86%. The thickness of the condenser section has greater impact on heat transfer performance of an AGHP than the thick-ness of the evaporator section does. The study content of this article will help understand the heat transfer performance of AGHP, and electronic thermal design process.

  15. Engineered SOI slot waveguide ring resonator V-shape resonance combs for refraction index sensing up to 1300nm/RIU (Conference Presentation)

    Science.gov (United States)

    Zhang, Weiwei; Serna, Samuel; Le Roux, Xavier; Vivien, Laurent; Cassan, Eric

    2016-05-01

    breakthrough of the performance of slot ring resonator sensing ability. Different from the normal sensing regime by monitoring one specific resonance (λres) peak shift, the proposed approach stems from the sensitivity of the RR critical coupling. The critical coupling peak is auto-selected out by matching the following condition: the ring resonator's round trip attenuation coefficient a(λ) being equal to the coupler self-coupling coefficient k(λ), thus resulting in the deepest extinction ratio (ER) among the spectrum RR comb. The obtained sensing comb, based on a V-shape spectrum envelop, is engineered by controlling a(λ) and k(λ) with opposite monotonicities. Both a(λ)and k(λ) are tuned to have a large dispersion along the wavelength, which means that |a(λ)-k(λ)| keeps rapidly increasing as λres is far away from λc, eliminating the resonance ER quickly down to 0. Experimentally, slot waveguide ring resonators with a radius of 50µm have been fabricated on a standard silicon platform with a Si thickness of 220nm, loaded by racetrack couplers with a straight coupling length of 20µm. Sensing experiments have been carried out by changing the top cladding material from a series of Cargille optical liquids with refraction index values ranging from 1.3 to 1.5. The Q factors of critical coupling resonances was monitored from 2,000 to 6,000, and measured wavelength shifts of this peak are from 1.41µm to 1.56µm. The maximum sensitivity of 1300nm/RIU is observed in the cladding index range 1.30-1.35. To conclude, a new sensing regime by tracking the critical coupling resonance λc of slot waveguide ring resonators is demonstrated. The reported sensitivity is up 1300nm/RIU around the water RI of 1.33, and the monitored sensing FOM is about 2300, which is very close to the FOM values achieved from nanobeam cavities. This work can thus contribute to future integrated optical sensing schemes based on slot RRs.

  16. Effects of Collector Temperature on the Performance of Grooved Electrode Thermionic Converters

    Science.gov (United States)

    Momozaki, Yoichi; El-Genk, Mohamed S.

    2003-01-01

    Experiments are conducted to compare the performance of the smooth electrodes, grooved emitter, and grooved collector converters at the same emitter and collector temperatures. The focus of the experiments is to investigate the effects of collector temperature on the performance of grooved electrode converters. The converters with various electrode configurations and a 0.5 mm gap are tested at emitter temperatures, TE = 1473 - 1673 K, collector temperatures, TC = 773 - 1023 K, and cesium pressures, PCs = 10 - 500 Pa. All electrodes are planar and fabricated with polycrystalline Molybdenum. The grooved electrodes have concentric macro-grooves 0.5 mm wide, 0.5 mm deep, and 1.0 mm apart. The output electrical power density and the conversion efficiency are calculated from the measured I-V curves and the maximum power density and conversion efficiency are determined from the calculated PD-V and ɛ-V envelopes. At TE = 1473 K, the electrical power density for the smooth electrodes converter at the optimum collector temperature (873 K) is 2.25 W/cm2 at ɛ = 13.8 %, decreasing to 1.46 W/cm2 at ɛ = 12.4 % as TC increases by only 75 K to 948 K. However, the corresponding decrease in the electrical power density for the grooved collector converter is only 0.04 W/cm2 (from 1.24 W/cm2 at ɛ = 11.4 % and TC = 873 K to 1.20 W/cm2 at ɛ =10.7 % and TC = 948 K) and that for the grooved emitter converter is 0.12 W/cm2 (from 0.82 W/cm2 at ɛ = 8.1 % and TC = 873 K to 0.70 W/cm2 at ɛ = 6.8 % and TC = 948 K). At the higher emitter temperatures of 1573 K and 1673 K, similar results are obtained. In all experimental conditions, however, the grooved emitter converter shows the lowest power density and conversion efficiency, followed by the grooved collector converter, and the smooth electrodes converter, except for TF = 1673 K and TC = 1023 K at which the converter with a grooved collector operates at the highest power density (2.38 W/cm2) and conversion efficiency (14.0 %).

  17. Instantaneous slip length in superhydrophobic microchannels having grooves with curved or dissimilar walls

    Science.gov (United States)

    Hemeda, A. A.; Vahedi Tafreshi, H.

    2015-10-01

    Superhydrophobic (SHP) surfaces can be used to reduce the skin-friction drag in a microchannel. This is due to the peculiar ability of these surfaces to entrap air in their pores and thereby reduce the contact area between water and the solid surface. The favorable drag-reduction effect, however, can quickly deteriorate if the surface geometry is not designed properly. The deterioration can be sudden, caused by exposure to excessive pressures, or gradual, due to the dissolution of the entrapped air into the ambient water. The formulations presented here provide a means for studying the time-dependent drag-reduction in a microchannel enhanced with transverse or longitudinal SHP grooves of varying wall profiles or wettabilities. Moreover, different mathematical approaches are developed to distinguish the performance of a sharp-edged groove from that of a groove with round entrance. The work starts by deriving an equation for the balance of forces on the air-water interface (AWI) inside a groove and solving this differential equation, along with Henry's law, for the rate of dissolution of the entrapped air into water over time. It was shown that the performance of a SHP groove depends mostly on the interplay between the effects of the apparent contact angle of the AWI and the initial volume of the groove. The instantaneous slip length is then calculated by solving the Navier-Stokes equations for flow in microchannels with SHP grooves. Our results are compared with the studies in the literature whenever available, and good agreement has been observed.

  18. Grooved Terrain on Ganymede: First Results from Galileo High-Resolution Imaging

    Science.gov (United States)

    Pappalardo, R.T.; Head, J.W.; Collins, G.C.; Kirk, R.L.; Neukum, G.; Oberst, J.; Giese, B.; Greeley, R.; Chapman, C.R.; Helfenstein, P.; Moore, Johnnie N.; McEwen, A.; Tufts, B.R.; Senske, D.A.; Herbert, Breneman H.; Klaasen, K.

    1998-01-01

    High-resolution Galileo imaging has provided important insight into the origin and evolution of grooved terrain on Ganymede. The Uruk Sulcus target site was the first imaged at high resolution, and considerations of resolution, viewing geometry, low image compression, and complementary stereo imaging make this region extremely informative. Contrast variations in these low-incidence angle images are extreme and give the visual impression of topographic shading. However, photometric analysis shows that the scene must owe its character to albedo variations. A close correlation of albedo variations to topography is demonstrated by limited stereo coverage, allowing extrapolation of the observed brightness and topographic relationships to the rest of the imaged area. Distinct geological units are apparent across the region, and ridges and grooves are ubiquitous within these units. The stratigraphically lowest and most heavily cratered units ("lineated grooved terrain") generally show morphologies indicative of horst-and-graben-style normal faulting. The stratigraphically highest groove lanes ("parallel ridged terrain") exhibit ridges of roughly triangular cross section, suggesting that tilt-block-style normal faulting has shaped them. These extensional-tectonic models are supported by crosscutting relationships at the margins of groove lanes. Thus, a change in tectonic style with time is suggested in the Uruk Sulcus region, varying from horst and graben faulting for the oldest grooved terrain units to tilt block normal faulting for the latest units. The morphologies and geometries of some stratigraphically high units indicate that a strike-slip component of deformation has played an important role in shaping this region of grooved terrain. The most recent tectonic episode is interpreted as right-lateral transtension, with its tectonic pattern of two contemporaneous structural orientations superimposed on older units of grooved terrain. There is little direct evidence for

  19. The colonic groove or furrow: a comparative morphological study of six species of African mole-rats (Rodentia, Bathyergidae).

    Science.gov (United States)

    Kotzé, S H; van der Merwe, E L; Ndou, R; O'Riain, M J; Bennett, N C

    2009-08-01

    Herbivorous mammals such as nutrias, guinea pigs, chinchillas, and mole-rats have a longitudinal mucosal colonic groove (furrow) in their ascending colon, which is thought to play a role in the colonic separation mechanism (CSM). It is not known whether this groove is structurally modified to adapt to this function in mole-rat species. The morphology of this groove was studied in 32 mol-rats, four species, one of which consisted of three subspecies, endemic to southern Africa and two species found in eastern Africa. The macroscopic morphology of the groove was documented, and samples for histological examination were taken. The groove was wide at its origin at the cecocolic junction and was lined on either side by a row of papillae with the opposing papillae slightly offset in arrangement. The papillated groove gradually decreased in size toward the distal part of the ascending colon where it disappeared. This pattern was similar in all species except in Heterocephalus glaber, where the papillae were absent and the groove was lined by two longitudinal ridges. A histological examination of cross sections revealed that the mucosa covering the inner and outer walls of the groove was rich in mucous-secreting goblet cells. The walls of the groove contained smooth muscle extending from the inner circular smooth muscle layer at the base to the tips of the papillae in all species examined as well as arteries, lymphatic vessels, and prominent sinusoid-like veins. The groove could be demonstrated both macroscopically and histologically in three Bathyergus suillus fetuses of varying sizes. The sinusoid-like veins present in all grooves, regardless of macroscopic shape, suggest that they have a role in the functioning of the groove. (c) 2009 Wiley-Liss, Inc.

  20. What musicians do to induce the sensation of groove in simple and complex melodies, and how listeners perceive it

    Directory of Open Access Journals (Sweden)

    Guy eMadison

    2014-08-01

    Full Text Available Groove is the experience of wanting to move when hearing music, such as snapping fingers or tapping feet. This is a central aspect of much music, in particular of music intended for dancing. While previous research has found considerable consistency in ratings of groove across individuals, it remains unclear how groove is induced, that is, what are the physical properties of the acoustic signal that differ between more and less groove-inducing versions. Here, we examined this issue with a performance experiment, in which 4 musicians performed 6 simple and 6 complex melodies in two conditions with the intention of minimizing and maximizing groove. Analyses of rhythmical and temporal properties from the performances demonstrated some general effects. For example, more groove was associated with more notes on faster metrical levels and syncopation, and less groove was associated with deadpan timing and destruction of the regular pulse. We did not observe that deviations from the metrical grid (i.e. micro-timing were a predictor of groove. A listener experiment confirmed that the musicians’ manipulations had the intended effects on the experience of groove. A Brunswikian lens model was applied, which estimates the performer-perceiver communication across the two experiments. It showed that the communication achievement for simple melodies was 0.62, and that the matching of performers’ and listeners’ use of 9 rhythmical cues was 0.83. For complex melodies with an already high level of groove, the corresponding values were 0.39 and 0.34, showing that it was much more difficult to take out groove from musical structures designed to induce groove.

  1. STUDY ON RECTANGULAR WAVEGUIDE GRATING SLOW-WAVE STRUCTURE WITH COSINE-SHAPED GROOVES

    Institute of Scientific and Technical Information of China (English)

    Lu Zhigang; Wei Yanyu; Gong Yubin; Wu Zhoumiao; Wang Wenxiang

    2007-01-01

    This paper focuses on a new rectangular waveguide grating Slow-Wave Structure(SWS)with cosine-shaped grooves and studies the propagation characteristics of the wave in the SWS.By using the approximate field-matching conditions,the dispersion equation and the coupling impedance of this circuit are obtained.The dispersion curves and coupling impedances of the fundamental wave are calculated and the influences of the various geometrical dimensions are discussed.The results show that the bandwidth of the cosine-shaped groove SWS is much wider than that of rectangular-shaped groove one.And reducing the groove width can broaden the frequency-band and decrease the phase-velocity,while increment of the groove-depth can also decrease phase-velocity.For above cases,the coupling impedance is more than 16Ω.The present analysis will be helpful on further study and design of the RF systems used in millimeter wave Traveling Wave Tube(TWT).

  2. Measuring phacoemulsification groove depth using probe tip dimensions and biometry lens thickness readings

    Directory of Open Access Journals (Sweden)

    Dunne K

    2016-08-01

    Full Text Available Kevin Dunne, Alex J Buller Department of Ophthalmology, Hawkes Bay District Health Board, Hastings, New Zealand Aim: To describe a useful technique utilizing lens thickness from biometric data as well as phacoemulsification (phaco probe tip dimensions, in order to more accurately determine safe groove depth during divide and conquer techniques for cataract surgery. Methods: Single center, selection of patients for cataract surgery deemed low risk and suitable for surgical teaching cases. Individual lens thickness measurements from biometry were calculated with known phaco tip dimensions to give an individualized safe number of phaco tip depths for grooving during divide and conquer. This technique was then applied during cataract surgery. Results: Utilization of this technique allows calculation and determination of an appropriate number of phaco tip depths of grooving for each individual patient. This technique was applied as a teaching tool for surgical trainees, with subsequent successful safe cataract surgeries completed. No posterior capsule ruptures were noted for these cases. Conclusion: By combining the biometric measurements of an individual patient’s lens thickness together with known phaco tip dimensions, individualized safe groove depths can be theoretically determined and applied during divide and conquer cataract surgery. Keywords: cataract, divide and conquer, groove depth, lens thickness, probe tip

  3. Wide polytef (Gore-Tex) implants in lip augmentation and nasolabial groove correction.

    Science.gov (United States)

    Conrad, K; MacDonald, M R

    1996-06-01

    To describe a new technique of polytef (Gore-Tex) implantation into the upper and lower lips and nasolabial grooves by using large implants as a method that achieves effective cosmetic improvement. A private cosmetic surgery center. Thirty-three (female) patients who desired fuller lips and 62 patients (52 female and 10 male) who requested less prominent cheek lip grooves. Significant patient satisfaction after 12 to 54 months. Conspicuous aesthetic effect that related to both lip and nasolabial groove correction was documented. All patients but 4 (2 in each group) were pleased with the final outcome of the treatment. In the opinion of the authors, the threading technique of polytef implantation creates inconspicuous improvement-both in lip augmentation and nasolabial groove correction. Large polytef implants that were inserted through a tunneling technique produced consistently good results. Implants (lip augmentation: width, < or = 10 mm, and thickness, 4 mm; nasolabial groove correction: width, 8 mm, and thickness, < or = 8 mm) were found to be safe, simple, and effective.

  4. Multiphysics Modeling of a Single Channel in a Nuclear Thermal Propulsion Grooved Ring Fuel Element

    Science.gov (United States)

    Kim, Tony; Emrich, William J., Jr.; Barkett, Laura A.; Mathias, Adam D.; Cassibry, Jason T.

    2013-01-01

    In the past, fuel rods have been used in nuclear propulsion applications. A new fuel element concept that reduces weight and increases efficiency uses a stack of grooved discs. Each fuel element is a flat disc with a hole on the interior and grooves across the top. Many grooved ring fuel elements for use in nuclear thermal propulsion systems have been modeled, and a single flow channel for each design has been analyzed. For increased efficiency, a fuel element with a higher surface-area-to-volume ratio is ideal. When grooves are shallower, i.e., they have a lower surface area, the results show that the exit temperature is higher. By coupling the physics of turbulence with those of heat transfer, the effects on the cooler gas flowing through the grooves of the thermally excited solid can be predicted. Parametric studies were done to show how a pressure drop across the axial length of the channels will affect the exit temperatures of the gas. Geometric optimization was done to show the behaviors that result from the manipulation of various parameters. Temperature profiles of the solid and gas showed that more structural optimization is needed to produce the desired results. Keywords: Nuclear Thermal Propulsion, Fuel Element, Heat Transfer, Computational Fluid Dynamics, Coupled Physics Computations, Finite Element Analysis

  5. CFD and Experimental Analysis of a Falling Film outside Smooth and Helically Grooved Tubes

    Directory of Open Access Journals (Sweden)

    Cenk Onan

    2014-08-01

    Full Text Available Simultaneous heat and mass transfer are investigated in a falling film outside grooved and smooth tubes. A numerical analysis of the helically trapezoidal-grooved and reference smooth tube was performed in the computational fluid dynamics program “Ansys Fluent 14.” The three-dimensional model drawings in the x, y, and z coordinates are used, and the effects of the falling film outside the helically grooved tube on the surface temperature and surface heat transfer coefficient are determined. The average surface temperature, heat transfer coefficient, and Nu values are determined experimentally for a constant heat flux. An uncertainty analysis and Nu correlation for the grooved tube are also provided in this study. The Reynolds number varied between 50 and 350 for the falling film and between 1500 and 3500 for air. Using a computational fluid dynamics (CFD analysis for the reference smooth tube, the experimental results are validated within 2–12% difference. The experimental results are also within 6–13% of the grooved tubes.

  6. A novel design of spiral groove bearing in a hydrodynamically levitated centrifugal rotary blood pump.

    Science.gov (United States)

    Han, Qing; Zou, Jun; Ruan, Xiaodong; Fu, Xin; Yang, Huayong

    2012-08-01

    Good washout is very important in spiral groove bearing (SGB) designs when applied to blood pumps due to the micrometer scales of lubrication films and groove depths. To improve washout, flow rate or leakage through SGBs should be as large as possible. However, this special goal violates conventional SGB designs in which no leakage is desired as the leakage would decrease load-carrying capacity significantly. So, a design concept is formed fulfilling the two goals of high load-carrying capacity and large flow rate: let groove width decrease along flow path and the mating surface of the rotor rotate with a direction facilitating the flow through the grooves. Under this concept, a novel SGB is designed, contrary to conventional ones, with groove width decreasing with increasing spiral radius. This SGB is mounted on the motionless upper plate of our designed centrifugal blood pump, with the mating surface of rotor rotating with a direction facilitating the outward flow. To assess SGB designs, a characteristic plane is originally presented relating to pressure-normalized load-carrying capacity and flow rate. Comparisons between various kinds of SGB designs are made, and computational fluid dynamics (CFD) results are plotted in this characteristic plane from which load/flow performances can be directly read out. CFD and comparison results show that the new designs have superior load/flow characteristics. However, the impact of SGB designs upon hemolysis/thrombus formation is still to be verified according to the concept presented.

  7. The study of microstructure and mechanical properties of twin-roll cast AZ31 magnesium alloy after constrained groove pressing

    Science.gov (United States)

    Zimina, M.; Bohlen, J.; Letzig, D.; Kurz, G.; Cieslar, M.; Zník, J.

    2014-08-01

    Microstructure investigation and microhardness mapping were done on the material with ultra-fine grained structure prepared by constrained groove pressing of twin-roll cast AZ31 magnesium strips. The microstructure observations showed significant drop of the grain size from 200 gm to 20 gm after constrained groove pressing. Moreover, the heterogeneities in the microhardness along the cross-section observed in the as-cast strip were replaced by the bands of different microhardness in the constrained groove pressed material. It is shown that the constrained groove pressing technique is a good tool for the grain refinement of magnesium alloys.

  8. 径向精密锻造机V字锥形锤砧锻造分析及数值模拟%Deformation Analysis and Numerical Simulation of V-shaped Cone Anvil Forging in the Fine Forging Machine

    Institute of Scientific and Technical Information of China (English)

    王连东; 高全德; 梁晨; 刘助柏; 张健; 刘唯唯

    2011-01-01

    A new type V-shaped cone anvil is developed to improve the transverse mechanical property of axial forgings in fine forging machine. Two V-shaped cone whose opening opposite is welded by piling up on the main working inclined planes which being located both sides of the fixed diameter area of the anvil. The mobility of the metal under the V-shaped cone and the deformation on the meridian plane and the transverse section is analysed, the numerical simulation is done for common anvil forging and V-shaped cone anvil forging with the DEFORM soft, and the results is compared for the stress and strain at the typical points on the chosen five transverse sections. It is revealed that when V-shaped cone anvil is used, the transverse mobility of metal is enhanced, the equivalent stress and equivalent strain increased, the deformation diversity decreased by 30%, the stress state in the zone around the axis improved, and the axial tension stress at the central point cut down by 50%. It is revealed by the production of the mandrel forgings that the mechanical property is raised effectively.%为改善精密锻造机锻造轴类件横向性能,设计一种新型锤砧——V字锥形锤砧,即在普通锤砧定径区两侧的主工作斜面上堆焊开口相反的两个V字锥形突起.对V字锥形下端的金属流动情况及坯料子午面与横截面上的变形进行分析,运用DEFORM软件对普通锤砧锻造与V字锥形锤砧锻造进行数值模拟,比较选定的5个横截面上典型点的应力应变,结果表明:使用V字锥形锤砧锻造,增加了金属的横向流动性,变形区的等效应变等效应力增大;减小了变形差异程度,横截面上各点的变形差异程度减小30%以上;改善了轴线心部的应力状态,中心点的轴向拉应力减小50%.生产实践表明,使用V字锥形锤砧替代普通锤砧锻造芯轴,有效提高了锻件的力学性能.

  9. Ancient schwannoma at the olfactory groove mimicking meningioma: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Young Jin; Jeong, Hae Woong [Dept. of Radiology, Busan Paik Hospital, Inje University College of Medicine, Busan (Korea, Republic of)

    2015-12-15

    Schwannomas are benign slow-growing nerve sheath tumors, which can develop in any peripheral or central nerve that contains Schwann cells. Schwannomas located near the olfactory groove are extremely rare and radiological diagnosis can be difficult. Moreover, ancient schwannoma is an uncommon variant, and radiologic findings are rarely reported. Herein, we reported a surgically confirmed case of ancient schwannoma at the olfactory groove in a 44-year-old woman presenting with headache and visual disturbance. Brain magnetic resonance imaging (MRI) showed a solid and cystic extra-axial mass located in the subfrontal area mimicking an olfactory groove meningioma. Histopathologic diagnosis of ancient schwannoma was confirmed by immunohistochemical staining for S100, CD56, vimentin, and other markers. Furthermore, we described the clinical manifestations, MRI characteristics, and histopathologic findings of the case, and presented a review of related literature.

  10. V-groove-based compact FBG package for thermal tuning and mechanical stability

    Science.gov (United States)

    Zhang, Li; Fang, Wei; Wang, Di; Chen, Di-Jun; Cai, Hai-Wen; Qu, Rong-Hui

    2016-04-01

    We demonstrated a V-groove-based fiber Bragg grating (FBG) package that has been glue-filled and cured to make it a bulky component with much improved mechanical stability. The V-groove can be executed with many types of materials including plastics, ceramics, semiconductors, and metals, providing an easy method for redesigning the thermal tuning performance of FBGs by selecting among a wide variety of materials and processes. We achieved more than 10-nm thermal wavelength tuning and thermal sensitivity ranging from 15 to 160 pm/K. The original FBG spectrum can be maintained without any degradation because the fiber is buried in the V-groove. The compact package does not increase the original grating length and turns the FBG into a planar waveguide grating, improving FBG applications in telecommunications, external cavity lasers, and sensing areas.

  11. Mode Ⅱ fracture mechanism of direct shearing specimen with guiding grooves of rock

    Institute of Scientific and Technical Information of China (English)

    饶秋华; 孙宗颀; 王桂尧; 徐纪成; 张静宜

    2001-01-01

    Fracture mechanism of direct shear specimen with guiding grooves of rock was investigated experimentally and numerically in order to explore a favorable stress condition for creating Mode Ⅱ fracture and guide design of specimen configuration for determining Mode Ⅱ fracture toughness of rock, KⅡC. The experimental and numerical results demonstrate that Mode Ⅱ fracture can be successfully achieved in the direct shearing specimen with guiding groove because the guiding grooves added in the notch plane can generate a favorable stress condition for Mode Ⅱ fracture, i.e. tensile stress at the notch tip is completely depressed and shear stress at the notch tip is very high in the notch plane. The optimum design of the specimen configuration for KⅡC testing should aim to reduce tensile stress to be compressive stress or be lower than tensile strength and greatly increase shear stress at crack tip.

  12. Tunable graphene based plasmonic absorber with grooved metal film in near infrared region

    Science.gov (United States)

    Zare, Mohammad Sadegh; Nozhat, Najmeh; Rashiditabar, Reza

    2017-09-01

    In this paper, we have proposed a graphene based absorber with two absorption peaks at near infrared wavelengths. The metal-graphene nanostructure is composed of a single layer of graphene on a metal film with L-shaped grooves. The results show that by utilizing only one graphene layer the absorption of the structure is increased to more than 0.9 due to the localized surface plasmon resonance (LSPR) in the grooves that amplifies the interaction of light and graphene. We have shown that the full width at half maximum (FWHM) of the absorber is enhanced by decreasing the perpendicular L-shaped grooves length. Also, the absorption spectrum of the proposed structure can be tuned by changing the geometric parameters and chemical potential of graphene.

  13. Palatogingival Groove: Recognizing and Managing the Hidden Tract in a Maxillary Incisor: A Case Report

    Science.gov (United States)

    Sharma, Sarang; Deepak, Passi; Vivek, Sharma; Ranjan Dutta, Shubha

    2015-01-01

    Palatogingival grooves are developmental malformations quite notorious for precipitating endodontic - periodontal lesions. Owing to their inconspicuous occurrence, funnel-shaped morphology and variable extent on tooth root, they promote adherence of plaque and bacteria to levels significant for the development of pathology. Several treatment approaches have been recognized in literature for the management of this anomaly. Here in this report, a 25-year-old patient reported with the complaint of pain and swelling in maxillary right lateral incisor. Clinical examination confirmed an endodontic - periodontal lesion in relation to palatogingival groove. Endodontic treatment was instituted, followed by odontoplasty of the groove and restoration with newer calcium silicate cement, Biodentine. Combined endodontic - periodontal approach was successful in resolving the pathology with complete healing seen both clinically and radiographically. Timely diagnosis, prevention and management are highly recommended to prevent tooth loss due to complications arising secondary to their presence. PMID:26124612

  14. Nexus between directionality of THz waves and structural parameters in groove-patterned InAs

    CERN Document Server

    Yim, Jong-Hyuk; Jeong, Hoonil; Song, Jin-Dong; Jho, Young-Dahl

    2012-01-01

    We have performed terahertz (THz)-time domain spectroscopy in various geometries, for characterizing the directivity of THz waves emitted from groove-patterned InAs structures. First, we have distinguished the THz emission mechanisms as a function of epilayer thickness. The carrier drift was predominant in thin sample group (10-70 nm) which the electronic diffusion motion was overriding the oppositely aligned drifting dipoles in thick sample group (370-900 nm) as revealed via amplitude and phase variations. By combined use of the electron-beam lithography and the inductively coupled plasma etching in 1 {\\mu}m-thick InAs epilayers, we have further fabricated either asymmetric V-groove patterns or symmetric parabolic patterns. The THz amplitude was enhanced, particularly along line-of-sight transmissive direction when the groove patterns act as microscale reflective mirrors periodically separated by a scale of diffusion length.

  15. "Fluid bearing" effect of enclosed liquids in grooves on drag reduction in microchannels

    Science.gov (United States)

    Chen, Haosheng; Gao, Yang; Stone, Howard A.; Li, Jiang

    2016-12-01

    We report details of the fluid motion formed within and above grooves when a laminar continuous phase fluid flows over a second immiscible fluid enclosed in a grooved microchannel. Vortical structures within the transverse grooves were caused by a slip velocity at the fluid-fluid interface and act as "fluid bearings" on the boundary to lubricate the flow of the continuous phase. We investigated the drag reduction in the laminar flow in the microchannel by measuring slip at the boundaries and calculating an effective slip length, taking into account the influence of the effect of the viscosity ratio of the two fluids on the effective slip length. The "fluid bearing" effect can be used to transport high viscosity fluids using low viscosity fluids trapped in cavities to reduce drag.

  16. Profile Control of a Borosilicate-Glass Groove Formed by Deep Reactive Ion Etching

    CERN Document Server

    Akashi, T

    2008-01-01

    Deep reactive ion etching (DRIE) of borosilicate glass and profile control of an etched groove are reported. DRIE was carried out using an anodically bonded silicon wafer as an etching mask. We controlled the groove profile, namely improving its sidewall angle, by removing excessively thick polymer film produced by carbonfluoride etching gases during DRIE. Two fabrication processes were experimentally compared for effective removal of the film : DRIE with the addition of argon to the etching gases and a novel combined process in which DRIE and subsequent ultrasonic cleaning in DI water were alternately carried out. Both processes improved the sidewall angle, and it reached 85o independent of the mask-opening width. The results showed the processes can remove excessive polymer film on sidewalls. Accordingly, the processes are an effective way to control the groove profile of borosilicate glass.

  17. Combined treatment of a lateral incisor with palato-radicular groove: 1 year follow-up

    Directory of Open Access Journals (Sweden)

    Gülen Kamak

    2014-01-01

    Full Text Available Periodontic - endodontic lesion with a palato-radicular groove as a contributing factor for periodontitis is the most important diagnostic and therapeutic challenges faced by periodontists and the maxillary lateral incisors are the most frequently affected teeth. These developmental grooves promotes the accumulation of plaque and calculus, which destroys the sulcular epithelium and later deeper parts of the periodontium, finally resulting in the formation of a severe localized periodontal lesion since proper cleaning of that site is difficult, if not impossible, for the patient. There are different types of treatment such as scaling and root planning, odontoplasty, amalgam restoration, and extraction of the tooth to treat palatogingival groove and associated periodontal bone defects. In this case, a successful management of an endodontic-periodontal combined lesion by combined treatment and guided tissue regeneration was presented.

  18. Comparative evaluation of three heat transfer enhancement strategies in a grooved channel

    Energy Technology Data Exchange (ETDEWEB)

    Herman, C.; Kang, E. [Dept. of Mechanical Engineering, Johns Hopkins Univ., Baltimore, MD (United States)

    2001-09-01

    Results of a comparative evaluation of three heat transfer enhancement strategies for forced convection cooling of a parallel plate channel populated with heated blocks, representing electronic components mounted on printed circuit boards, are reported. Heat transfer in the reference geometry, the asymmetrically heated parallel plate channel, is compared with that for the basic grooved channel, and the same geometry enhanced by cylinders and vanes placed above the downstream edge of each heated block. In addition to conventional heat transfer and pressure drop measurements, holographic interferometry combined with high-speed cinematography was used to visualize the unsteady temperature fields in the self-sustained oscillatory flow. The locations of increased heat transfer within one channel periodicity depend on the enhancement technique applied, and were identified by analyzing the unsteady temperature distributions visualized by holographic interferometry. This approach allowed gaining insight into the mechanisms responsible for heat transfer enhancement. Experiments were conducted at moderate flow velocities in the laminar, transitional and turbulent flow regimes. Reynolds numbers were varied in the range Re = 200-6500, corresponding to flow velocities from 0.076 to 2.36 m/s. Flow oscillations were first observed between Re = 1050 and 1320 for the basic grooved channel, and around Re = 350 and 450 for the grooved channels equipped with cylinders and vanes, respectively. At Reynolds numbers above the onset of oscillations and in the transitional flow regime, heat transfer rates in the investigated grooved channels exceeded the performance of the reference geometry, the asymmetrically heated parallel plate channel. Heat transfer in the grooved channels enhanced with cylinders and vanes showed an increase by a factor of 1.2-1.8 and 1.5-3.5, respectively, when compared to data obtained for the basic grooved channel; however, the accompanying pressure drop penalties

  19. PIV measurements of near wake behind a U-grooved cylinder

    Science.gov (United States)

    Lim, H.-C.; Lee, S.-J.

    2003-08-01

    The flow structure around a circular cylinder with U-grooved surfaces has been investigated experimentally. The results were compared with that of a smooth cylinder having the same diameter. Drag force and turbulence statistics of wake behind each cylinder were measured for Reynolds numbers based on the cylinder diameter (/D=60mm) in the range ReD=8×103-1.4×105. At ReD=1.4×105, the U-type grooves reduce the drag coefficient acting on the cylinder by 18.6%, compared with that of smooth cylinder. The flow characteristics of wake behind the U-grooved cylinder have been analyzed using two kinds of particle image velocimetry (PIV) velocity measurement techniques, cinematic PIV and high-resolution PIV. Consecutive instantaneous velocity fields were measured using the cinematic PIV technique at time interval of 5ms, corresponding to about 1% of the vortex shedding frequency of the wake. The instantaneous velocity fields measured with the high-resolution PIV technique were ensemble-averaged to get the spatial distributions of turbulent statistics including turbulent intensities and turbulent kinetic energy. For the case of smooth cylinder, large-scale vortices formed behind the cylinder maintain round shape and do not spread out noticeably in the near wake. However, for the case of U-grooved cylinder, the vortices are largely distorted and spread out significantly as they go downstream. The longitudinal grooves seem to shift the location of spanwise vortices toward the cylinder, reducing the vortex formation region, compared with the smooth cylinder. The sharp peaks of longitudinal U-shaped grooves also suppress the formation of large-scale secondary streamwise vortices. The secondary vortices are broken into smaller eddies, reducing turbulent kinetic energy in the near-wake region.

  20. Dynamical transition of water in the grooves of DNA duplex at low temperature.

    Science.gov (United States)

    Biswal, Debasmita; Jana, Biman; Pal, Subrata; Bagchi, Biman

    2009-04-02

    At low temperature (below its freezing/melting temperature), liquid water under confinement is known to exhibit anomalous dynamical features. Here we study structure and dynamics of water in the grooves of a long DNA duplex using molecular dynamics simulations with TIP5P potential at low temperature. We find signatures of a dynamical transition in both translational and orientational dynamics of water molecules in both the major and the minor grooves of a DNA duplex. The transition occurs at a slightly higher temperature (T(GL) approximately 255 K) than the temperature at which the bulk water is found to undergo a dynamical transition, which for the TIP5P potential is at 247 K. Groove water, however, exhibits markedly different temperature dependence of its properties from the bulk. Entropy calculations reveal that the minor groove water is ordered even at room temperature, and the transition at T approximately 255 K can be characterized as a strong-to-strong dynamical transition. Confinement of water in the grooves of DNA favors the formation of a low density four-coordinated state (as a consequence of enthalpy-entropy balance) that makes the liquid-liquid transition stronger. The low temperature water is characterized by pronounced tetrahedral order, as manifested in the sharp rise near 109 degrees in the O-O-O angle distribution. We find that the Adams-Gibbs relation between configurational entropy and translational diffusion holds quite well when the two quantities are plotted together in a master plot for different region of aqueous DNA duplex (bulk, major, and minor grooves) at different temperatures. The activation energy for the transfer of water molecules between different regions of DNA is found to be weakly dependent on temperature.

  1. Transition from Cassie to impaled state during drop impact on groove-textured solid surfaces.

    Science.gov (United States)

    Vaikuntanathan, V; Sivakumar, D

    2014-05-07

    Liquid drops impacted on textured surfaces undergo a transition from the Cassie state characterized by the presence of air pockets inside the roughness valleys below the drop to an impaled state with at least one of the roughness valleys filled with drop liquid. This occurs when the drop impact velocity exceeds a particular value referred to as the critical impact velocity. The present study investigates such a transition process during water drop impact on surfaces textured with unidirectional parallel grooves referred to as groove-textured surfaces. The process of liquid impalement into a groove in the vicinity of drop impact through de-pinning of the three-phase contact line (TPCL) beneath the drop as well as the critical impact velocity were identified experimentally from high speed video recordings of water drop impact on six different groove-textured surfaces made from intrinsically hydrophilic (stainless steel) as well as intrinsically hydrophobic (PDMS and rough aluminum) materials. The surface energy of various 2-D configurations of liquid-vapor interface beneath the drop near the drop impact point was theoretically investigated to identify the locally stable configurations and establish a pathway for the liquid impalement process. A force balance analysis performed on the liquid-vapor interface configuration just prior to TPCL de-pinning provided an expression for the critical drop impact velocity, Uo,cr, beyond which the drop state transitions from the Cassie to an impaled state. The theoretical model predicts that Uo,cr increases with the increase in pillar side angle, α, and intrinsic hydrophobicity whereas it decreases with the increase in groove top width, w, of the groove-textured surface. The quantitative predictions of the theoretical model were found to show good agreement with the experimental measurements of Uo,cr plotted against the surface texture geometry factor in our model, {tan(α/2)/w}(0.5).

  2. Comparative evaluation of three heat transfer enhancement strategies in a grooved channel

    Science.gov (United States)

    Herman, C.; Kang, E.

    Results of a comparative evaluation of three heat transfer enhancement strategies for forced convection cooling of a parallel plate channel populated with heated blocks, representing electronic components mounted on printed circuit boards, are reported. Heat transfer in the reference geometry, the asymmetrically heated parallel plate channel, is compared with that for the basic grooved channel, and the same geometry enhanced by cylinders and vanes placed above the downstream edge of each heated block. In addition to conventional heat transfer and pressure drop measurements, holographic interferometry combined with high-speed cinematography was used to visualize the unsteady temperature fields in the self-sustained oscillatory flow. The locations of increased heat transfer within one channel periodicity depend on the enhancement technique applied, and were identified by analyzing the unsteady temperature distributions visualized by holographic interferometry. This approach allowed gaining insight into the mechanisms responsible for heat transfer enhancement. Experiments were conducted at moderate flow velocities in the laminar, transitional and turbulent flow regimes. Reynolds numbers were varied in the range Re=200-6500, corresponding to flow velocities from 0.076 to 2.36m/s. Flow oscillations were first observed between Re=1050 and 1320 for the basic grooved channel, and around Re=350 and 450 for the grooved channels equipped with cylinders and vanes, respectively. At Reynolds numbers above the onset of oscillations and in the transitional flow regime, heat transfer rates in the investigated grooved channels exceeded the performance of the reference geometry, the asymmetrically heated parallel plate channel. Heat transfer in the grooved channels enhanced with cylinders and vanes showed an increase by a factor of 1.2-1.8 and 1.5-3.5, respectively, when compared to data obtained for the basic grooved channel; however, the accompanying pressure drop penalties also

  3. Tip clearance flow interaction with circumferential groove casing treatment in a transonic axial compressor

    Science.gov (United States)

    Ross, Mark Hamilton

    Experimental and computational studies were conducted to study the role of the tip leakage flow in axial compressor stall and the relationship between the tip clearance flow flow field and surge margin extension from circumferential groove casing treatment. The CFD results were used to identify the existence of an interface between the approach ow and the tip-leakage flow. The experiments used a surface streaking visualization method to identify the time-averaged location of this interface as a line of zero axial shear stress at the casing. The axial position of this line, denoted xzs, moved upstream with decreasing ow coefficient in both the experiments and computations. The line was consistently located at the rotor leading edge plane at the stalling flow coefficient, regardless of in flow boundary condition. These results were successfully modeled using a control volume approach that balanced the reverse axial momentum ux of the tip-leakage flow with the momentum flux of the approach fluid. Non-uniform tip clearance measurements demonstrated that movement of the interface upstream of the rotor leading edge plane leads to the generation of short length scale rotating disturbances. Therefore, stall was interpreted as a critical point in the momentum flux balance of the approach ow and the reverse axial momentum flux of the tip-leakage flow. Experimental measurements of surge margin extension from seven CGCT configurations with a fixed groove geometry demonstrated that the contribution of individual grooves in a multi-groove casing to surge margin extension is an (a) additive and (b) linear function of the smooth wall tip clearance axial momentum ux at the location of a each groove. Extending the axial momentum model to include the in uence of a CGCT showed that circumferential grooves reduce the tip leakage flow axial momentum through radial transport. The equivalent force due to a circumferential groove was demonstrated to be related to the smooth wall tip

  4. Presentation of computer code SPIRALI for incompressible, turbulent, plane and spiral grooved cylindrical and face seals

    Science.gov (United States)

    Walowit, Jed A.

    1994-01-01

    A viewgraph presentation is made showing the capabilities of the computer code SPIRALI. Overall capabilities of SPIRALI include: computes rotor dynamic coefficients, flow, and power loss for cylindrical and face seals; treats turbulent, laminar, Couette, and Poiseuille dominated flows; fluid inertia effects are included; rotor dynamic coefficients in three (face) or four (cylindrical) degrees of freedom; includes effects of spiral grooves; user definable transverse film geometry including circular steps and grooves; independent user definable friction factor models for rotor and stator; and user definable loss coefficients for sudden expansions and contractions.

  5. Endoscopic Endonasal Approach for Olfactory Groove Meningiomas: Operative Technique and Nuances.

    Science.gov (United States)

    Liu, James K; Hattar, Ellina; Eloy, Jean Anderson

    2015-07-01

    Olfactory groove meningiomas represent approximately 10% of all intracranial meningiomas. Because these tumors originate at the ventral skull base, the endonasal route provides direct access to the tumor blood supply for early devascularization and removal of the underlying hyperostotic bone at the cranial base. In carefully selected patients, these tumors can be totally removed without additional brain retraction or manipulation. In this report, we describe the surgical technique and operative nuances for removal of olfactory groove meningiomas using the endoscopic endonasal approach, and also discuss the indications, limitations, complication avoidance and management, and postoperative care.

  6. Plasmonic V-groove waveguides with Bragg grating filters via nanoimprint lithography

    DEFF Research Database (Denmark)

    Smith, Cameron L. C.; Desiatov, Boris; Goykmann, Ilya

    2012-01-01

    We demonstrate spectral filtering with state-of-the-art Bragg gratings in plasmonic V-groove waveguides fabricated by wafer scale processing based on nanoimprint lithography. Transmission spectra of the devices having 16 grating periods exhibit spectral rejection of the channel plasmon polaritons...... with 8.2 dB extinction ratio and -3 dB bandwidth of Δλ = 39.9 nm near telecommunications wavelengths. Near-field scanning optical microscopy measurements verify spectral reflection from the grating structures, and the oscillations of propagating modes along grating-less V- grooves correspond well...

  7. An explanation of a groove found on the nasal process of the equine incisive bone.

    Science.gov (United States)

    Pérez, W; Martin, E

    2001-12-01

    Thirteen fresh equine heads were dissected in an attempt to determine the cause of a groove frequently found on the dorsal border and medial side of the nasal process of the incisive bone. This groove appeared on both sides in 40 out of 44 equine skulls. The sulcus seems to be caused by the combined action of the lateralis nasi muscle and the medial accessory cartilage of the nose (cartilago nasalis accessoria medialis). Other sulci found on the nasal process of the bone may be explained as impressions caused by nerves.

  8. An analysis of the Circumferential Grooves Casing Treatment for transonic compressor flow

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The stall mechanism of the NASA Rotor 37 is investigated through the analysis of the critical flow structures near the stall under the transonic condition. The performance of the rotor with Circumferential Grooves Casing Treatment (CGCT) is also studied based on the Reynolds-Averaging Navier-Stokes approach. The study finds that stall margin improvement can be achieved without significant penalty on the efficiency for the two CGCT configurations applied. The effects of circumferential grooves on the critical flow structures are studied through the analysis of the tip leakage mass and momentum transport that further re-veal the CGCT mechanism.

  9. Analysis and Control of Axial Thrust in Centrifugal Pump by Use of J-Groove

    OpenAIRE

    Abe, Heishiro; Matsumoto, Kazunari; Kurokawa, Junichi; Matsui, Jun; Choi, Young-Do

    2006-01-01

    In order to control and balance axial thrust of turbo machine, many types of balancing devices are used but most of them are complicated and sometimes cause troubles. In this study, a very simple device of using shallow grooves mounted on a casing wall, known as "J-Groove", is proposed and studied experimentally and theoretically. The result shows that 70% of axial thrust in an industry, 4-stage centrifugal pump can be reduced at the best efficiency point. Moreover, the analytical method of "...

  10. Numerical analysis of loaded stress and central displacement of deep groove ball bearing

    Institute of Scientific and Technical Information of China (English)

    杨磊; 邓松; 李红星

    2016-01-01

    The aim of this work is to develop a three-dimensional model of deep groove ball bearing to investigate the loaded stresses and central displacements of bearing rings. The equivalent stresses and central displacements of bearing rings are obtained based on the simulated analysis. Moreover, several parameters, such as load magnitude, raceway groove curvature radius (RGCR), thicknesses of outer and inner rings, are varied to investigate their effects on the equivalent stresses and central displacements of bearing rings. Research results provide useful guidelines for determining the design parameters.

  11. Plasmonic black gold by adiabatic nanofocusing and absorption of light in ultra-sharp convex grooves

    DEFF Research Database (Denmark)

    Søndergaard, Thomas; Novikov, Sergey M.; Stær, Tobias Holmgaard

    2012-01-01

    Excitation of localized and delocalized surface plasmon resonances can be used for turning excellent reflectors of visible light, such as gold and silver, into efficient absorbers, whose wavelength, polarization or angular bandwidths are however necessarily limited owing to the resonant nature......-defined geometry by using ultra-sharp convex metal grooves via adiabatic nanofocusing of gap surface plasmon modes excited by scattering off subwavelength-sized wedges. We demonstrate experimentally that two-dimensional arrays of sharp convex grooves in gold ensure efficient (>87%) broadband (450-850 nm...

  12. Use of modified Brisson's operation(V-shaped incision) in treating buried penis%“V”形切口改良Brisson手术治疗小儿隐匿阴茎

    Institute of Scientific and Technical Information of China (English)

    周维; 徐延波; 黄国显; 陈海琛; 胡杨

    2011-01-01

    目的 介绍使用“V”形切口改良Brisson手术治疗隐匿性阴茎34例的方法和效果.方法 手术通过用阴茎腹侧“V”形切口改良Brisson术来完成,松解阴茎伸展外露后,修剪包皮系带伸直阴茎头,对合缝合包皮,从阴茎腹侧V形切口,去除发育不良的筋膜组织,在阴茎腹侧根部将皮下筋膜层与尿道前筋膜缝合固定.结果 手术时间约40~60 min,随访6~12个月,阴茎发育及外观效果满意,1例较肥胖的患儿术后显露效果不佳.3例水肿患儿术后2周内均基本消退.结论 本术式相对简单损伤小,外观良好,我们认为是治疗隐匿性阴茎比较理想的手术方式之一.%Objective To determine the effectiveness of modified Brisson method (V-shaped incision) as a new surgical treatment method for the buried penis.Methods From February 2009 to December 2010,34 patients with buried penis underwent the modified Brissors operation.At first,the penis was stretched by incising the stricture ring and degloved.And then,the frenulum was trimmed and sutured.Lastly,a V-shape incision was made at ventral side of penis,the dysplastic fibrotic tissue was excised and the fascia at the ventaral side of penis fixed.Results The operative time ranged from 40 min to 60 min.The follow-up period was for between 6~9 months.The appearance of penis was satisfactory in 30 patients.1 patient had sub-optimal result because of underlying obesity.Conclusions Modified Brisson's operation(V-shaped icision) has the advantages of less trauma and satisfactory appearance.It should be recommended as an ideal operation to treat buried penis in children.

  13. Modeling and simulation of stamp deflections in nanoimprint lithography: Exploiting backside grooves to enhance residual layer thickness uniformity

    DEFF Research Database (Denmark)

    Taylor, Hayden; Smistrup, Kristian; Boning, Duane

    2011-01-01

    We describe a model for the compliance of a nanoimprint stamp etched with a grid of backside grooves. We integrate the model with a fast simulation technique that we have previously demonstrated, to show how etched grooves help reduce the systematic residual layer thickness (RLT) variations that ...

  14. Observations on the effects of grooved surfaces on the interfacial torque in highly loaded rolling and sliding tests

    DEFF Research Database (Denmark)

    Janakiraman, Shravan; Klit, Peder; Jensen, Niels Steenfeldt;

    2014-01-01

    Some efforts have been undertaken to study the effects of grooved surfaces on the interfacial film thickness and torque between two contacting non-conformal surfaces under heavy loads. Transverse grooves of micrometer scale depth were engraved on polished, flat ring surfaces using established...... industrial methods like laser engraving and wire cutting. The grooved surfaces were then run against a polished flat surface at loads corresponding to high normal Hertzian pressures. Experiments were conducted to study the effects of the following parameters on the interfacial torque-groove depth, groove...... wavelength, load, inlet speed and slide-roll ratio. Experimental results were then justified, in certain cases, based on a multigrid model predicting the interfacial pressure and film thickness....

  15. Analytical and experimental investigations into the controlled energy absorption characteristics of thick-walled tubes with circumferential grooves

    Energy Technology Data Exchange (ETDEWEB)

    Darvizeh, Abolfazl [Islamic Azad University, Bandar-e Anzali (Iran, Islamic Republic of); Darvizeh, Mansour; Ansari, Reza; Meshkinzar, Ata [University of Guilan, Rasht (Iran, Islamic Republic of)

    2014-10-15

    In this paper, the energy absorption characteristics of grooved circular tubes are investigated under quasi-static loading condition. For experiments, thick-walled tubes with circumferential grooves are prepared. The grooves divide the thick-walled tube into several shorter thin-walled portions. Specimens are subjected to axial crushing load to observe the effect of distribution of circular grooves on the deformation mechanism and energy absorption capacity. Geometrical parameters of the specimens are designed utilizing the Taguchi method to cover a reasonably wide range of groove length-to-wall thickness ratios. An analytical approach based on the concept of energy dissipation through the plastic hinges is applied. Taking the effect of strain hardening into account, the obtained analytical results are in good agreement with the experimental ones. The agreement between analytical and experimental results may indicate the validity of the proposed analytical approach. Desirable mechanism of deformation observed justifies the pre-forming method for obtaining favorable energy absorption characteristics.

  16. Binding to the DNA Minor Groove by Heterocyclic Dications: From AT Specific Monomers to GC Recognition with Dimers

    Science.gov (United States)

    Nanjunda, Rupesh; Wilson, W. David

    2012-01-01

    Compounds that bind in the DNA minor groove have provided critical information on DNA molecular recognition, they have found extensive uses in biotechnology and they are providing clinically useful drugs against diseases as diverse as cancer and sleeping sickness. This review focuses on the development of clinically useful heterocyclic diamidine minor groove binders. These compounds have shown us that the classical model for minor groove binding in AT DNA sequences must be expanded in several ways: compounds with nonstandard shapes can bind strongly to the groove, water can be directly incorporated into the minor groove complex in an interfacial interaction, and the compounds can form cooperative stacked dimers to recognize GC and mixed AT/GC base pair sequences. PMID:23255206

  17. Effect of sessile drop volume on the wetting anisotropy observed on grooved surfaces.

    Science.gov (United States)

    Yang, Jing; Rose, Felicity R A J; Gadegaard, Nikolaj; Alexander, Morgan R

    2009-03-03

    This study reports experimental measurements of the water contact angle (WCA) measured on surfaces with grooves of different widths using drop volumes ranging from 400 pL to 4.5 microL. These measurements were carried out on both relatively hydrophobic and hydrophilic surface chemistry formed using a conformal plasma polymer coating of topographically embossed poly(methyl methacrylate) (PMMA). Anisotropic wetting of the grooved surfaces was found to be more marked for larger drops on both the hydrophilic and hydrophobic surfaces. Above a certain drop base diameter to groove width ratio, topography had no effect on the measured WCA; this ratio was found to be dependent on the water drop volume. The WCA measured from the direction perpendicular to the grooves using submicroliter water drops is found to be a good indicator of the WCA on the flat surface with equivalent wettabilities. To the best of our knowledge, this is the first study on the phenomenon of anisotropic wetting using picoliter water drops.

  18. Enhancement heat transfer characteristics in the channel with Trapezoidal rib–groove using nanofluids

    Directory of Open Access Journals (Sweden)

    Ali Najah Al-Shamani

    2015-03-01

    Full Text Available Numerical study of heat transfer due to turbulent flow of nanofluids through rib–groove channel have been investigated. The continuity, momentum and energy equations are solved by the finite volume method (FVM. Four different rib–groove shapes have been examined. Four different types of nanoparticles, Al2O3, CuO, SiO2, and ZnO with different volumes fractions in the range of 1–4% and different nanoparticle diameter in the range of 25–70 nm, have been also studied. The computations are performed under constant temperature over a range of Reynolds number (Re 10,000–40,000. Results indicate that the Trapezoidal with increasing height in the flow direction rib–trapezoidal groove has the best heat transfer rate and high Nusselt number. It is also found that the SiO2 – nanofluid has the highest value of Nusselt number in comparison with the other type of nanofluids. The Nusselt number increases as the volume fraction increases and it decreases as the nanoparticle diameter increases. The present study shows that these Trapezoidal rib–groove using nanofluids have the potential to dramatically increase heat transfer characteristics and thus can be good candidates for the development of efficient heat exchanger device.

  19. Polarization-resolved two-photon luminescence microscopy of V-groove arrays

    DEFF Research Database (Denmark)

    Beermann, J.; Novikov, S. M.; Holmgaard, T.

    2012-01-01

    Using two-photon luminescence (TPL) microscopy and local reflection spectroscopy we investigate electromagnetic field enhancement effects from a mu m-sized composition of 450-nm-deep V-grooves milled by focused ion beam in a thick gold film and assembled to feature, within the same structure...

  20. Concerted intercalation and minor groove recognition of DNA by a homodimeric thiazole orange dye

    DEFF Research Database (Denmark)

    Bunkenborg, Jakob; Gadjev, N I; Deligeorgiev, T

    2000-01-01

    The thiazole orange dye TOTO binds to double-stranded DNA (dsDNA) by a sequence selective bis-intercalation. Each chromophore is sandwiched between two base pairs in a (5'-CpT-3'):(5'-ApG-3') site, and the linker spans two base pairs in the minor groove. We have used one- and two-dimensional NMR...

  1. Numerical Modeling and Analysis of Grooved Surface Applied to Film Cooling

    Institute of Scientific and Technical Information of China (English)

    L. Guo; Z. C. Liu; Y.Y.Yan; Z.W.Han

    2011-01-01

    In order to improve the efficiency of film cooling,numerical investigation was carried out to study the effects of different film-cooled plates on surface heat transfer.Both grooved and non-grooved surfaces were concerned.The modeling was performed using Fluent software with the adoption of Shear-Stress Transport (SST) k-co model as the turbulence closure.The coolant was supplied by a single film cooling hole with an inclination angle of 30°.The Mach numbers for the coolant flow and the mainstream flow were fixed at 0 and 0.6,respectively.At three blowing ratios of 0.5,1.0 and 1.5,the aerodynamic behaviour of the mixing process as well as the heat transfer performance of the film cooling were presented.The numerical results were validated using experimental data extracted from a benchmark test.Good agreements between numerical results and the experimental data were observed.For the film cooling efficiency,it shows that both local and laterally averaged cooling effectiveness can be improved by the non-smooth surface at different blowing ratios.Using the grooved surface,the turbulence intensity upon the plate can be reduced notably,and the mixing between the two flows is weakened due to the reduced turbulence level.The results indicate that the cooling effectiveness of film cooling can be enhanced by applying the grooved surface.

  2. Measuring phacoemulsification groove depth using probe tip dimensions and biometry lens thickness readings.

    Science.gov (United States)

    Dunne, Kevin; Buller, Alex J

    2016-01-01

    To describe a useful technique utilizing lens thickness from biometric data as well as phacoemulsification (phaco) probe tip dimensions, in order to more accurately determine safe groove depth during divide and conquer techniques for cataract surgery. Single center, selection of patients for cataract surgery deemed low risk and suitable for surgical teaching cases. Individual lens thickness measurements from biometry were calculated with known phaco tip dimensions to give an individualized safe number of phaco tip depths for grooving during divide and conquer. This technique was then applied during cataract surgery. Utilization of this technique allows calculation and determination of an appropriate number of phaco tip depths of grooving for each individual patient. This technique was applied as a teaching tool for surgical trainees, with subsequent successful safe cataract surgeries completed. No posterior capsule ruptures were noted for these cases. By combining the biometric measurements of an individual patient's lens thickness together with known phaco tip dimensions, individualized safe groove depths can be theoretically determined and applied during divide and conquer cataract surgery.

  3. Micro-Grooving and Micro-Threading Tools for Fabricating Curvilinear Features

    Energy Technology Data Exchange (ETDEWEB)

    ADAMS,DAVID P.; VASILE,MICHAEL J.; KRISHNAN,A.S.M.

    2000-07-24

    This paper presents techniques for fabricating microscopic, curvilinear features in a variety of workpiece materials. Micro-grooving and micro-threading tools having cutting widths as small as 13 {micro}m are made by focused ion beam sputtering and used for ultra-precision machining. Tool fabrication involves directing a 20 keV gallium beam at polished cylindrical punches made of cobalt M42 high-speed steel or C2 tungsten carbide to create a number of critically aligned facets. Sputtering produces rake facets of desired angle and cutting edges having radii of curvature equal to 0.4 {micro}m. Clearance for minimizing frictional drag of a tool results from a particular ion beam/target geometry that accounts for the sputter yield dependence on incidence angle. It is believed that geometrically specific cutting tools of this dimension have not been made previously. Numerically controlled, ultra-precision machining with micro-grooving tools results in a close match between tool width and feature size. Microtools are used to machine 13 {micro}m wide, 4 {micro}m deep, helical grooves in polymethyl methacrylate and 6061 Al cylindrical workplaces. Micro-grooving tools are also used to fabricate sinusoidal cross-section features in planar metal samples.

  4. Role of minor groove width and hydration pattern on amsacrine interaction with DNA.

    Directory of Open Access Journals (Sweden)

    Deepak K Jangir

    Full Text Available Amsacrine is an anilinoacridine derivative anticancer drug, used to treat a wide variety of malignancies. In cells, amsacrine poisons topoisomerase 2 by stabilizing DNA-drug-enzyme ternary complex. Presence of amsacrine increases the steady-state concentration of these ternary complexes which in turn hampers DNA replication and results in subsequent cell death. Due to reversible binding and rapid slip-out of amsacrine from DNA duplex, structural data is not available on amsacrine-DNA complexes. In the present work, we designed five oligonucleotide duplexes, differing in their minor groove widths and hydration pattern, and examined their binding with amsacrine using attenuated total reflection Fourier transform infrared (ATR-FTIR spectroscopy. Complexes of amsacrine with calf thymus DNA were also evaluated for a comparison. Our results demonstrate for the first time that amsacrine is not a simple intercalator; rather mixed type of DNA binding (intercalation and minor groove takes place between amsacrine and DNA. Further, this binding is highly sensitive towards the geometries and hydration patterns of different minor grooves present in the DNA. This study shows that ligand binding to DNA could be very sensitive to DNA base composition and DNA groove structures. Results demonstrated here could have implication for understanding cytotoxic mechanism of aminoacridine based anticancer drugs and provide directions to modify these drugs for better efficacy and few side-effects.

  5. Different thermodynamic signatures for DNA minor groove binding with changes in salt concentration and temperature.

    Science.gov (United States)

    Wang, Shuo; Kumar, Arvind; Aston, Karl; Nguyen, Binh; Bashkin, James K; Boykin, David W; Wilson, W David

    2013-10-04

    The effects of salt concentration and temperature on the thermodynamics of DNA minor groove binding have quite different signatures: binding enthalpy is salt concentration independent but temperature dependent. Conversely, binding free energy is salt dependent but essentially temperature independent through enthalpy-entropy compensation.

  6. Different Thermodynamic Signatures for DNA Minor Groove Binding with Changes in Salt Concentration and Temperature

    OpenAIRE

    2013-01-01

    The effects of salt concentration and temperature on the thermodynamics of DNA minor groove binding have quite different signatures: binding enthalpy is salt concentration independent but temperature dependent. Conversely, binding free energy is salt dependent but essentially temperature independent through enthalpy-entropy compensation.

  7. Erosion of a grooved surface caused by impact of particle-laden flow

    Science.gov (United States)

    Jung, Sohyun; Yang, Eunjin; Kim, Ho-Young

    2016-11-01

    Solid erosion can be a life-limiting process for mechanical elements in erosive environments, thus it is of practical importance in many industries such as construction, mining, and coal conversion. Erosion caused by particle-laden flow occurs through diverse mechanisms, such as cutting, plastic deformation, brittle fracture, fatigue and melting, depending on particle velocity, total particle mass and impingement angle. Among a variety of attempts to lessen erosion, here we investigate the effectiveness of millimeter-sized grooves on the surface. By experimentally measuring the erosion rates of smooth and triangular-grooved surfaces under various impingement angles, we find that erosion can be significantly reduced within a finite range of impingement angles. We show that such erosion resistance is attributed to the swirls of air within grooves and the differences in erosive strength of normal and slanted impact. In particular, erosion is mitigated when we increase the effective area under normal impact causing plastic deformation and fracture while decreasing the area under slanted impact that cuts the surface to a large degree. Our quantitative model for the erosion rate of grooved surfaces considering the foregoing effects agrees with the measurement results.

  8. Saying Hello World with GROOVE - A Solution to the TTC 2011 Instructive Case

    NARCIS (Netherlands)

    Ghamarian, Amir Hossein; Mol, de Maarten; Rensink, Arend; Zambon, Eduardo; Gorp, van Pieter; Mazanek, Steffen; Rose, Louis

    2011-01-01

    This report presents a solution to the Hello World case study using GROOVE. We provide and explain the grammar that we used to solve the case study. Every requested question of the case study was solved by a single rule application.

  9. Saying Hello World with GROOVE - A Solution to the TTC 2011 Instructive Case

    Directory of Open Access Journals (Sweden)

    Amir Hossein Ghamarian

    2011-11-01

    Full Text Available This report presents a solution to the Hello World case study of TTC 2011 using GROOVE. We provide and explain the grammar that we used to solve the case study. Every requested question of the case study was solved by a single rule application.

  10. A grooved glass surface-plate for making a flat polished surface

    Science.gov (United States)

    Miyagi, Isoji

    2017-01-01

    To obtain a flat polished surface for microchemical analyses such as EPMA, SIMS, and ATR micro-FTIR, a glass plate with a grooved surface was developed for hand polishing with an abrasive film. It eases the polishing process by minimizing slipping or sticking, and results in negligible relief in the sample surface.

  11. Measurement repeatability of tibial tuberosity-trochlear groove offset distance in red fox (Vulpes vulpes) cadavers

    NARCIS (Netherlands)

    Miles, J.E.; Jensen, B.R.; Kirpensteijn, J.; Svalastoga, E.L.; Eriksen, T.

    2013-01-01

    Abstract OBJECTIVE: To describe CT image reconstruction criteria for measurement of the tibial tuberosity-trochlear groove (TT-TG) offset distance, evaluate intra- and inter-reconstruction repeatability, and identify key sources of error in the measurement technique, as determined in vulpine hind li

  12. Excitation of fluorescent nanoparticles by channel plasmon polaritons propagating in V-grooves

    DEFF Research Database (Denmark)

    Cuesta, Irene Fernandez; Nielsen, Rasmus Bundgaard; Boltasseva, Alexandra;

    2009-01-01

    Recently, it has been proven that light can be squeezed into metallic channels with subwavelength lateral dimensions. Here, we present the study of the propagation of channel plasmon polaritons confined in gold V-grooves, filled with fluorescent particles. In this way, channel plasmon polaritons ...

  13. Does loading influence the severity of cartilage degeneration in the canine groove-model of OA?

    NARCIS (Netherlands)

    Vos, P.; Intema, F.; El, B. van; Groot, J. de; Bijlsma, J.W.J.; Lafeber, F.; Mastbergen, S.

    2009-01-01

    Many animal models are used to study osteoarthritis (OA). In these models the role of joint loading in the development of OA is not fully understood. We studied the effect of loading on the development of OA in the canine Groove-model. In ten female beagle dogs OA was induced in one knee according t

  14. Does Loading Influence the Severity of Cartilage Degeneration in the Canine Groove-Model of OA?

    NARCIS (Netherlands)

    Vos, Petra; Intema, Femke; van El, Benno; DeGroot, Jeroen; Bijlsma, J. W. J.; Lafeber, Floris; Mastbergen, Simon

    2009-01-01

    Many animal models are used to study osteoarthritis (OA). In these models the role of joint loading in the development of CA is not fully understood. We studied the effect of loading on the development of CIA in the canine Groove-model. In ten female beagle dogs OA was induced in one knee according

  15. Saying Hello World with GROOVE - A Solution to the TTC 2011 Instructive Case

    NARCIS (Netherlands)

    Ghamarian, A.H.; de Mol, M.J.; Rensink, Arend; Zambon, Eduardo; van Gorp, Pieter; Mazanek, Steffen; Rose, Louis

    This report presents a solution to the Hello World case study using GROOVE. We provide and explain the grammar that we used to solve the case study. Every requested question of the case study was solved by a single rule application.

  16. Multi-scale and angular analysis of ray-optical light trapping schemes in thin-film solar cells: micro lens array, V-shaped configuration, and double parabolic trapper.

    Science.gov (United States)

    Cho, Changsoon; Lee, Jung-Yong

    2013-03-11

    An efficient light trapping scheme is a key to enhancing the power conversion efficiency (PCE) of thin-film photovoltaic (PV) cells by compensating for the insufficient light absorption. To handle optical components from nano-scale to micro-scale seamlessly, a multi-scale optical simulation is carefully designed in this study and is used to qualitatively analyze the light trapping performances of a micro lens array (MLA), a V-shaped configuration, and the newly proposed scheme, which is termed a double parabolic trapper (DPT) according to both daily and annual movement of the sun. DPT has the potential to enhance the PCE significantly, from 5.9% to 8.9%, for PCDTBT:PC(70)BM-based polymer solar cells by perfectly trapping the incident light between two parabolic PV cells.

  17. Full-mouth composite rehabilitation of a mixed erosion and attrition patient: a case report with v-shaped veneers and ultra-thin CAD/CAM composite overlays.

    Science.gov (United States)

    Bahillo, Jose; Jané, Luis; Bortolotto, Tissiana; Krejci, Ivo; Roig, Miguel

    2014-10-01

    Loss of tooth substance has become a common pathology in modern society. It is of multifactorial origin, may be induced by a chemical process or by excessive attrition, and frequently has a combined etiology. Particular care should be taken when diagnosing the cause of dental tissue loss, in order to minimize its impact. Several publications have proposed the use of minimally invasive procedures to treat such patients in preference to traditional full-crown rehabilitation. The use of composite resins, in combination with improvements in dental adhesion, allows a more conservative approach. In this paper, we describe the step-by-step procedure of full-mouth composite rehabilitation with v-shaped veneers and ultra-thin computer-aided design/computer-assisted manufacture (CAD/CAM)- generated composite overlays in a young patient with a combination of erosion and attrition disorder.

  18. TR-PIV measurement of the wake behind a grooved cylinder at low Reynolds number

    Science.gov (United States)

    Liu, Ying Zheng; Shi, Liu Liu; Yu, Jun

    2011-04-01

    A comparative study of the wakes behind cylinders with grooved and smooth surfaces was performed with a view to understand the wake characteristics associated with the adult Saguaro cacti. A low-speed recirculation water channel was established for the experiment; the Reynolds number, based on the free-stream velocity and cylinder diameter (D), was kept at ReD=1500. State-of-the-art time-resolved particle image velocimetry (TR-PIV) was employed to measure a total of 20 480 realizations of the wake field at a frame rate of 250 Hz, enabling a comprehensive view of the time- and phase-averaged wake pattern. In comparison to the wake behind the smooth cylinder, the length of the recirculation zone behind the grooved cylinder was extended by nearly 18.2%, yet the longitudinal velocity fluctuation intensity was considerably weakened. A global view of the peaked spectrum of the longitudinal velocity component revealed that the intermediate region for the grooved cylinder, which approximately corresponds to the transition region where the shear layer vortices interact, merge and shed before the formation of the Karman-like vortex street, was much wider than that for the smooth one. The unsteady events near St=0.3-0.4 were detected in the intermediate region behind the grooved cylinder, but no such events were found in the smooth cylinder system. Although the formation of the Karman-like vortex street was delayed by about 0.6D downstream for the grooved cylinder, no prominent difference in the vortex street region was found in the far wake for both cylinders. The Proper Orthogonal Decomposition (POD) method was used extensively to decompose the vector and swirling strength fields, which gave a close-up view of the vortices in the near wake. The first two POD modes of the swirling strength clarified the spatio-temporal characteristics of the shear layer vortices behind the grooved cylinder. The small-scale vortices superimposed on the shear layers behind the grooved cylinder

  19. Design and Analysis of V-shaped Combination Seal Used in Downhole Tools%井下工具用V形组合密封的设计分析

    Institute of Scientific and Technical Information of China (English)

    李奎为; 贾长贵; 卫然

    2011-01-01

    The traditional single seal component can' t suit the downhole complex harsh environment. The combination seal is composed of several sealing components, it can meet the downhole complex environment based on the complementary advantages of single seal component. The work principle and design method of V-shaped combination seal used in downhoule tools were introduced. The feasibility that V-shaped combination seal can choose several seal rings of different materials to meet the downhole complex environment. The design methods of nonstandard dimension V-ring was proposed from the angle of practical application. The formula of ensuring the coherence of section dimension was given.%传统的单一密封件在应用于复杂井下环境时具有一定的局限性,而组合密封通过几种密封件的优势互补可适应井下复杂环境.介绍井下工具用V形组合密封的工作原理及其设计方法,指出同一组合密封可同时选用不同材料的圈组合使用,通过优势互补来适应井下复杂环境.介绍了非标准尺寸V形密封圈设计方法,分析如何通过尺寸计算来保证密封组合各部件的截面尺寸的一致性.

  20. Flow dynamics of a spiral-groove dry-gas seal

    Science.gov (United States)

    Wang, Bing; Zhang, Huiqiang; Cao, Hongjun

    2013-01-01

    The dry-gas seal has been widely used in different industries. With increased spin speed of the rotator shaft, turbulence occurs in the gas film between the stator and rotor seal faces. For the micro-scale flow in the gas film and grooves, turbulence can change the pressure distribution of the gas film. Hence, the seal performance is influenced. However, turbulence effects and methods for their evaluation are not considered in the existing industrial designs of dry-gas seal. The present paper numerically obtains the turbulent flow fields of a spiral-groove dry-gas seal to analyze turbulence effects on seal performance. The direct numerical simulation (DNS) and Reynolds-averaged Navier-Stokes (RANS) methods are utilized to predict the velocity field properties in the grooves and gas film. The key performance parameter, open force, is obtained by integrating the pressure distribution, and the obtained result is in good agreement with the experimental data of other researchers. Very large velocity gradients are found in the sealing gas film because of the geometrical effects of the grooves. Considering turbulence effects, the calculation results show that both the gas film pressure and open force decrease. The RANS method underestimates the performance, compared with the DNS. The solution of the conventional Reynolds lubrication equation without turbulence effects suffers from significant calculation errors and a small application scope. The present study helps elucidate the physical mechanism of the hydrodynamic effects of grooves for improving and optimizing the industrial design or seal face pattern of a dry-gas seal.

  1. A morphometric assessment and classification of coral reef spur and groove morphology

    Science.gov (United States)

    Duce, S.; Vila-Concejo, A.; Hamylton, S. M.; Webster, J. M.; Bruce, E.; Beaman, R. J.

    2016-07-01

    Spurs and grooves (SaGs) are a common and important feature of coral reef fore slopes worldwide. However, they are difficult to access and hence their morphodynamics and formation are poorly understood. We use remote sensing, with extensive ground truthing, to measure SaG morphometrics and environmental factors at 11,430 grooves across 17 reefs in the southern Great Barrier Reef, Australia. We revealed strong positive correlations between groove length, orientation and wave exposure with longer, more closely-spaced grooves oriented easterly reflecting the dominant swell regime. Wave exposure was found to be the most important factor controlling SaG distribution and morphology. Gradient of the upper reef slope was also an important limiting factor, with SaGs less likely to develop in steeply sloping (> 5°) areas. We used a subset of the morphometric data (11 reefs) to statistically define four classes of SaG. This classification scheme was tested on the remaining six reefs. SaGs in the four classes differ in morphology, groove substrate and coral cover. These differences provide insights into SaG formation mechanisms with implications to reef platform growth and evolution. We hypothesize SaG formation is dominated by coral growth processes at two classes and erosion processes at one class. A fourth class may represent relic features formed earlier in the Holocene transgression. The classes are comparable with SaGs elsewhere, suggesting the classification could be applied globally with the addition of new classes if necessary. While further research is required, we show remotely sensed SaG morphometrics can provide useful insights into reef platform evolution.

  2. Effectiveness of various irrigation protocols for the removal of calcium hydroxide from artificial standardized grooves.

    Science.gov (United States)

    Gokturk, Hakan; Ozkocak, Ismail; Buyukgebiz, Feyzi; Demir, Osman

    2017-01-01

    The aim of this study was to investigate the ability of laser-activated irrigation (LAI), XP-endo Finisher, CanalBrush, Vibringe, passive ultrasonic irrigation (PUI), and conventional syringe irrigation systems on the removal of calcium hydroxide (CH) from simulated root canal irregularities. The root canals of one hundred and five extracted single-rooted teeth were instrumented using Reciproc rotary files up to size R40. The teeth were split longitudinally. Two of the three standard grooves were created in the coronal and apical section of one segment, and another in the middle part of the second segment. The standardized grooves were filled with CH and the root halves were reassembled. After 14 days, the specimens were randomly divided into 7 experimental groups (n=15/group). CH was removed as follows: Group 1: beveled needle irrigation; Group 2: double side-vented needle irrigation; Group 3: CanalBrush; Group 4: XP-endo Finisher; Group 5: Vibringe; Group 6: PUI; Group 7: LAI. The amount of remaining CH in the grooves was scored under a stereomicroscope at 20× magnification. Statistical evaluation was performed using Kruskal-Wallis and Bonferroni-Correction Mann-Whitney U tests. Groups 1 and 2 were the least efficient in eliminating CH from the grooves. Groups 6 and 7 eliminated more CH than the other protocols; however, no significant differences were found between these two groups (P>.05). Nevertheless, none of the investigated protocols were able to completely remove all CH from all three root regions. LAI and PUI showed less residual CH than the other protocols from artificial grooves.

  3. A highly sensitive Pb(Zr,Ti)O3 thin film ultrasonic micro-sensor with a grooved diaphragm.

    Science.gov (United States)

    Matsushima, Tomoaki; Xiong, Sibei; Kawada, Hiroshi; Yamanaka, Hiroshi; Muralt, Paul

    2007-12-01

    A highly sensitive piezoelectric ultrasonic micro-sensor with a grooved multilayer membrane was developed by a Si-based MEMS technique. The groove was located at one-quarter of the distance away from the edge of the membrane and opened into piezoelectric layer. The piezoelectric layer Pb(Zr,Ti)O(3) (PZT) was 2.2 microm thick and was prepared by a sol-gel method. The prepared PZT film was pure perovskite and showed a highly (100) textured structure. The sensitivity of the fabricated piezoelectric ultrasonic sensor without the groove structure was 100 microV/Pa. In comparison, the sensitivity of the ultrasonic sensor with the groove structure was about 500 microV/Pa, which is 5 times that without the groove structure. The diaphragm having grooves showed a corrugate-like structure that was formed by residual stress. The high sensitivity of the membrane with the grooved diaphragm is considered to relate to the corrugate-like structure.

  4. Computational fluid dynamics analysis on heat transfer and friction factor characteristics of a turbulent flow for internally grooved tubes

    Directory of Open Access Journals (Sweden)

    Selvaraj P.

    2013-01-01

    Full Text Available The article presents computational fluid dynamics studies on heat transfer, pressure drop, friction factor, Nusselt number and thermal hydraulic performance of a plain tube and tube equipped with the three types of internal grooves (circular, square and trapezoidal.Water was used as the working fluid. Tests were performed for Reynolds number ranges from 5000 to 13500 for plain tube and different geometry inside grooved tubes. The maximum increase of pressure drop was obtained from numerical modeling 74% for circular, 38% for square and 78% for trapezoidal grooved tubes were compared with plain tube. Based on computational fluid dynamics analysis the average Nusselt number was increased up to 37%, 26% and 42% for circular, square and trapezoidal grooved tubes respectively while compared with the plain tube. The thermal hydraulic performance was obtained from computational fluid dynamics analysis up to 38% for circular grooved tube, 27% for square grooved tube and 40% for trapezoidal grooved tube while compared with the plain tube.

  5. Origin of Shore-Normal Grooves (gutters) on a Steep Sandstone Beach-Face Subject to Wave Action

    Science.gov (United States)

    Carling, P. A.; Williams, J.; Leyland, J.; Esteves, L.

    2016-12-01

    Shore-normal grooves (gutters) cut into the seabed have been reported widely from the marine geological record. Often grooves are spaced regularly across plane, consolidated surfaces in the littoral and sub-littoral zones and may be deeply incised. Despite their common occurrence in the rock record, there are few detailed descriptions of examples from modern environments. The reported examples have been ascribed to erosion by wave-induced currents, especially storm-driven near-shore flows. In particular, examples from beach-faces have been related to either wave swash or back-swash. However, no conceptual model exists to explain the presence of grooves, their morphology or their spacing alongshore. Herein, quasi-regularly spaced grooves on a soft sandstone beach-face are described that it is argued formed due to wave breaking and swash zone processes consequent upon exceptional storms at sea. The groove morphologies are quantified using terrestrial laser scanning. Numerical modelling of the translation from offshore waves to nearshore breaking waves provides estimates of the swash zone parameters. A consideration of swash zone processes provides an explanation for formation of the grooves. In particular, the swash zone shear stress distribution and consequent bed erosion is a dome-shaped function of distance across the beach-face, which function controls the cross-shore variability in groove depths. High-speed sheet flows, such as swash and back-swash, develop periodic, shore-normal high and low speed streaks alongshore. Consequent streaky erosion controls the quasi-regular alongshore groove spacings. However, on any given beach-face the specific spacing of grooves is likely a property, not only of the local sheet flow attributes, but also of larger-scale morphological forcing. This outcome suggest that spacing is an emergent property of the coupled sheet flow and larger-scale forcing and specific spacings on any beach-face remain unpredictable.

  6. Instability of a Biaxial Nematic Liquid Crystal Formed by Homeotropic Anchoring on Surface Grooves

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-Dong; XUAN Li

    2011-01-01

    A method used to treat the elastic distortion of a uniaxial nematic liquid crystal induced by homogeneous anchoring on the surface grooves is generalized to biaxial nematic liquid crystals under the homeotropic anchoring condition.Employing some approximations for the elastic constants,we obtain an additional term in the elastic energy per unit area which depends on the angle between the minor director at infinity and the direction of the grooves,with a period of π/2.This leads to instability on the surface grooves so that two states with crossed minor directors are energetically indistinguishable.Our theoretical study explains why the homeotropic alignment method developed for uniaxial liquid crystals loses efficacy for biaxial nematics.In most liquid crystal devices,the liquid crystals are sandwiched between two substrates coated with alignment layers.In the absence of externally applied fields,the orientation of the liquid crystal in the cell is determined by the anchoring condition of the alignment layer.[1-3] One usually distinguishes three main types of liquid crystalline director alignment near solid walls:homeotropic,homogeneous (or planar) and tilted orientations.Here we study the first of these and consider the biaxial nematic phase,which was observed in lyotropic systems as early as 1980[4] and has been confirmed by deuterium NMR spectroscopy.%A method used to treat the elastic distortion of a uniaxial nematic liquid crystal induced by homogeneous anchoring on the surface grooves is generalized to biaxial nematic liquid crystals under the homeotropic anchoring condition. Employing some approximations for the elastic constants, we obtain an additional term in the elastic energy per unit area which depends on the angle between the minor director at infinity and the direction of the grooves, with a period of π/2. This leads to instability on the surface grooves so that two states with crossed minor directors are energetically indistinguishable. Our

  7. Finite Element Method Analysis of the Stress for Line Pipe with Corrode Groove During Outdoor Storage

    Institute of Scientific and Technical Information of China (English)

    Zhuanzhao YANG; Daoxin LIU; Xiaohua ZHANG

    2013-01-01

    The basic principle of corrode groove on outside of steel pipe during storage was analyzed in this paper,namely the water film on the contacted surface of steel pipe,which gathered from humidity in the air,rain or gel,and the suspended particles in air,and the corrosive composition,such as SO2,CO2,O2 and NaCl,in addition to the inhomogeneity of the organization and composition,which lead to the corrosion cell reaction,so that cause the corrosion initial from the contact surface of the between steel pipes,so as to form the corrosion groove.At the same time,the corrosion groove with depth of 0.125t (t pipe wall thickness) on the pipe of φ 1016 mm×21 mm X70 API SPEC 5L was simulated using the FEM (finite element method),and the stress and strain distribution of the defect area near corrosion groove were solved at the inner pressure of 12 MPa,10 MPa,8 MPa,6 MPa,4 MPa and 2 MPa,respectively,which showed that no matter the pressure values were,the maximum stress and strain were lied at the bottom of corrosion defects groove and were in good linear relationship with the internal pressure increasing from 2 MPa to 6 MPa.When the internal pressures were greater than 6 MPa,they felled into the nonlinear model and to be yielded or even to be destroyed.In addition,the residual strength and the limit operation pressure of the corrode pipe with the defects groove of 0.125t were calculated or simulated according to the theoretical calculation,the finite element method based on the stress,the finite element method based on strain,DNV-RP-F101,ASME B31G and experimental methods respectively.The results showed that the residual strength and the limit operation pressure of the defective parts solved by the finite element method based on stress were 424 MPa,and 15.34 MPa,respectively,which was very close to that of experimental method,the residual strength was 410 MPa and the limit operation pressure 14.78 MPa.Besides,the results also showed that it was feasible and effective to

  8. V 形喉硅胶膜在声门型喉癌中的应用研究%Application Study on V-shaped Laryngeal Silica Membrane in Glottic Laryngeal Cancer

    Institute of Scientific and Technical Information of China (English)

    漫一凡; 张超; 周延辉; 李怡楠

    2015-01-01

    目的:分析 T 形与 V 形喉硅胶膜在早期声门型喉癌喉裂开术后的应用价值。方法收集2012年7月至2015年3月我院收治的早期声门型喉癌(T1~T2期)行喉裂开病变切除术共60例,34例术后放置 T 形硅胶膜,26例放置 V 形喉硅胶膜。对比两组患者术后的疼痛程度、呼吸功能、发音功能、吞咽功能及黏膜的恢复等情况。结果两组患者术后疼痛程度(NRS)评分比较,差异有统计学意义(P <0.05)。两组在胃管拔除时间上 T 形膜组时间长于 V 形膜组(P <0.05)。T 形膜组发音质量(VHI)与 V 形组相比差异有统计学意义(21.13±6.10 Vs 18.36±7.28,P <0.05),嗓音总嘶哑度评估中,两组大部分为轻中度异常,差异有统计学意义(82.35% Vs 96.15%,P <0.05)。结论本研究显示喉硅胶膜置入能有效避免声门型喉癌喉裂开术后瘢痕形成而引起喉狭窄,V 形硅胶膜则是从声门正常的结构考虑能更有效恢复患者的嗓音学状态,术后痛苦小、恢复快、并发症少,术后喉功能保全良好,提高了患者的生存质量。%Objective To investigate the applicational value and curative effect between T-shaped silicone membrane and V-shaped silicone membrane in early glottic laryngeal cancer after laryngofissure cardectomy. Methods 60 patients with early glottic laryngeal cancer on T1 ~T2 stage from July 2012 to March 2015 treated in our hospital were included.All the patients accepted the laryngofissure cordectomy,in which 34 patients were placed T-shaped silicone membrane and 26 patients were placed V-shaped silicone membrane.After operation we analysed the differences on pain degree,respiratory function,phonation, swallowing function and mucosa recovery between the two groups of patients. Results Comparing postoperative pain degree via using numeric rating scales (NRS),the differences between the two groups had

  9. Recognition and management of palatogingival groove for tooth survival: a literature review.

    Science.gov (United States)

    Kim, Hee-Jin; Choi, Yoorina; Yu, Mi-Kyung; Lee, Kwang-Won; Min, Kyung-San

    2017-05-01

    Palatogingival groove (PGG) is an anomaly in the maxillary anterior teeth, often accompanied by the area of bony destruction adjacent to the teeth with no carious or traumatic history. The hidden trap in the tooth can harbor plaque and bacteria, resulting in periodontal destruction with or without pulpal pathologic change. Related diseases can involve periodontal destruction, combined endodontic-periodontal lesions, or separate endodontic and periodontal lesions. Disease severity and prognosis related to PGG depend on several factors, including location, range, depth, and type of the groove. Several materials have been used and recommended for cases of extensive periodontal destruction from PGG to remove and block the inflammatory source and recover the health of surrounding periodontal tissues. Even in cases of severe periodontal destruction, several studies have reported favorable treatment outcomes with proper management. With new options in diagnosis and treatment, clinicians need a detailed understanding of the characteristics, treatment, and prognosis of PGG to successfully manage the condition.

  10. V-groove all-fiber core-cladding intermodal interferometer for high-temperature sensing.

    Science.gov (United States)

    Yin, Zhen; Geng, Youfu; Li, Xuejin; Tan, Xiaoling; Gao, Rong

    2015-01-10

    Novel V-groove all-fiber core-cladding intermodal interferometers fabricated by CO2 laser irradiation on a standard single-mode fiber are described. The high-order cladding modes are excited due to the special V-groove structure. The interferometers are classified as Mach-Zehnder and Michelson type based on the way they are structured. Benefiting from the large difference of thermal coefficients of the core and high-order cladding modes, both types receive high temperature sensitivity by monitoring the wavelength shift of the interference spectrum, and their responses to temperature are similar. Compared with the Mach-Zehnder interferometer, the Michelson interferometer is more compact and more flexible in application.

  11. Studies on a Novel Minor-groove Targeting Artificial Nuclease: Synthesis and DNA Binding Behavior

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Nucleases play an important role in molecular biology, for example, in DNA sequencing. Synthetic polyamide conjugates can be considered as a novel tool for the selective inhibition of gene expressions and also as potential drugs in anticancer or antiviral chemotherapy. In this article, the synthesis of a novel minor-groove targeting artificial nuclease, an oligopyrrol-containing compound, has been reported. It was found that this novel compound can bind DNA in AT-rich minor groove with high affinity and site specificity. DNA binding behavior was determined by using UV-Vis and CD. It is indicated that compound 6 can enhance the Tm of DNA from 80. 4 C to 84. 4 ℃ and that it possesses a high binding constant value(Kb = 3.05×104 L/mol).

  12. Biological Glue Application in Repair of Atrioventricular Groove Rupture: A Case Report

    Directory of Open Access Journals (Sweden)

    Ahmet Baris-Durukan

    2015-10-01

    Full Text Available Atrioventricular groove rupture is a rare, albeit mortal, complication following mitral valve surgery. Avoidance is the best strategy but it cannot fully prevent the occurrence of this complication. Several repair techniques have been described with varying success rates; however, the rarity of the complication precludes consensus about the safest technique.Here we report two cases of posterior atrioventricular groove rupture. Both cases were diagnosed immediately after the cessation of cardiopulmonary bypass. Repair was performed successfully with a technique involving the use of biological glue. The postoperative course was uneventful for both of them. Both cases are well with normally functioning mitral prostheses; one with a follow-up time of 5.5 years and the other 10 months. We believe that the glue provides additional hemostasis and support to the repaired area.

  13. Studies of interaction between a new synthesized minor-groove targeting artificial nuclease and DNA

    Science.gov (United States)

    Yin, Qiang; Zhang, Zhen; Zhao, Yu-Fen

    2007-04-01

    Nuclease plays an important role in molecular biology, such as DNA sequencing. Synthetic polyamide conjugates can be considered as new tool in the selective inhibition of gene expression and as potential drugs in anticancer or antiviral chemotherapy. In this paper, a new synthesized minor-groove targeting artificial nuclease, oligopyrrol-containing peptide, was reported. It was found that this new compound can bind DNA in AT-riched minor groove with high affinity and site specificity. DNA binding behavior was determined by UV-vis and circular dichroism (CD) methods. It was indicated that compound 6 can enhance the Tm of oligomer DNA from 51.8 to 63.5 °C and possesses large binding constant ( Kb = 8.83 × 10 4 L/mol).

  14. Regenerated collagen fibers with grooved surface texture: Physicochemical characterization and cytocompatibility.

    Science.gov (United States)

    Wang, Xiang; Wu, Tong; Wang, Wei; Huang, Chen; Jin, Xiangyu

    2016-01-01

    A novel type of protein fibers, regenerated collagen fibers (RC) from cattle skin, was prepared through wet-spinning. Due to the combined effect of solvent exchange and subsequent drawing process, the fibers were found to have a grooved surface texture. The grooves provided not only ordered topographical cues, but also increased surface area. Protein content of the RC fibers was confirmed by Fourier Transform infrared spectroscopy (FTIR) and ninhydrin color reaction. The fibers could be readily fabricated into nonwovens or other textiles, owning to their comparable physical properties to other commercialized fibers. Cell growth behavior on RC nonwovens suggested both early adhesion and prompt proliferation. The high moisture regain, good processability, along with the excellent cytocompatibility indicated that the RC fibers and nonwovens developed in this study might offer a good candidate for biomedical and healthcare applications.

  15. Self-assembling morphologies of symmetrical PS-b-PMMA in different sized confining grooves

    DEFF Research Database (Denmark)

    Chen, Wenhui; Luo, Jun; Shi, Peixiong

    2014-01-01

    and pattern registration. In this work, self-assembling morphologies of the lamellar diblock copolymer poly(styrene-b-methyl methacrylate) were investigated to gain a better understanding of the DSA process and to offer some reference for the pattern transfer process. A quantized number of lines was obtained......Directed self-assembly (DSA), an emerging lithographic technique, has attracted increasing attention as a result of its advantages of low cost, high throughput and convenient processing. However, DSA still presents some challenges, such as the control of defects, the fabrication of complex patterns...... in the directing grooves, although warps and dislocations appeared when the number of lines jumped from n to (n + 1). Gradational variations in line width were observed near the edge of the confining grooves, which shows the lack of uniformity in the patterns. A novel structure model is proposed to interpret...

  16. Palato-gingival groove: An innocuous culprit for endo-perio lesion

    Directory of Open Access Journals (Sweden)

    Rafeza Sultana

    2016-09-01

    Full Text Available This case report represents the clinical management of tooth with palato-gingival groove in a right maxillary lateral incisor with endo-perio lesion leading to dento-alveolar abscess and sinus tract. The right maxillary lateral incisor was examined clinico-radiographically. On clinical examination, the offending tooth revealed localized swelling and an intraoral draining sinus pointing on the labial gingiva without any evidence of caries, discoloration and trauma. The palatal surface of lateral incisor showed a groove with mild calculus embedded in it. The radiographic examination revealed periapical radiolucency. This case provides an evidence of morphological defect of tooth. Complete clinical and radiological examination and adequate knowledge of such morphological/ developmental defects of teeth are necessary for recognition and identification especially because of their diagnostic complexity and further consequences. 

  17. Simulation of inside-grooved mould improving heat transfer of original shell of casting slab

    Institute of Scientific and Technical Information of China (English)

    Kexin Zhao; Minggang Shen; Xueda Wang

    2005-01-01

    The dipping experiment was carried out by putting the water-cooled copper plate into the stannum-lead alloy to simulate the process of initial solidification of steel, and the result that the heat transfer of original shell improved by grooving on the surface of the water-cooled copper plate was investigated. A mathematical model of heat transfer was set up and the temperature field of casting slab 1000 mm×200mm was calculated. The experimentation and simulation results indicate that the inside-grooved mould could improve the heat transfer of original shell, decrease the non-uniformity of original shell thickness and reduce the longitudinal surface cracks of casting slab.

  18. Minor groove RNA triplex in the crystal structure of a ribosomal frameshifting viral pseudoknot

    Science.gov (United States)

    Su, L.; Chen, L.; Egli, M.; Berger, J. M.; Rich, A.

    1999-01-01

    Many viruses regulate translation of polycistronic mRNA using a -1 ribosomal frameshift induced by an RNA pseudoknot. A pseudoknot has two stems that form a quasi-continuous helix and two connecting loops. A 1.6 A crystal structure of the beet western yellow virus (BWYV) pseudoknot reveals rotation and a bend at the junction of the two stems. A loop base is inserted in the major groove of one stem with quadruple-base interactions. The second loop forms a new minor-groove triplex motif with the other stem, involving 2'-OH and triple-base interactions, as well as sodium ion coordination. Overall, the number of hydrogen bonds stabilizing the tertiary interactions exceeds the number involved in Watson-Crick base pairs. This structure will aid mechanistic analyses of ribosomal frameshifting.

  19. A grooved planar ion trap design for scalable quantum information processing

    Institute of Scientific and Technical Information of China (English)

    Ji Wei-Bang; Wan Jin-Yin; Cheng Hua-Dong; Liu Liang

    2012-01-01

    We describe a new electrode design for a grooved surface-electrode ion trap,which is fabricated in printed-circuitboard technology with segmented electrodes.This design allows a laser beam to get through the central groove to avoid optical access blocking and laser scattering from the ion trap surface.The confining potentials are modeled both analytically and numerically.We optimize the radio frequency (rf) electrodes and dc electrodes to achieve the maximum trap depth for a given ion height above the trap electrodes.We also compare our design with the reality ion chip MI I for practical considerations.Comparison results show that our design is superior to MI I.This ion trap design may form the basis for large scale quantum computers or parallel quadrupole mass spectrometers.

  20. Steady State Thermo-Hydrodynamic Analysis of Two-Axial groove and Multilobe Hydrodynamic Bearings

    Directory of Open Access Journals (Sweden)

    C. Bhagat

    2014-12-01

    Full Text Available Steady state thermo-hydrodynamic analysis of two axial groove and multi lobe oil journal bearings is performed in this paper. To study the steady state thermo-hydrodynamic characteristics Reynolds equation is solved simultaneously along with the energy equation and heat conduction equation in bush and shaft. The effect of groove geometry, cavitation in the fluid film, the recirculation of lubricant, shaft speed has also been taken into account. Film temperature in case of three-lobe bearing is found to be high as compared to other studied bearing configurations. The data obtained from this analysis can be used conveniently in the design of such bearings, which are presented in dimensionless form.

  1. Non-spectroscopic refractometric nanosensor based on a tilted slit-groove plasmonic interferometer.

    Science.gov (United States)

    Li, Xiaowei; Tan, Qiaofeng; Bai, Benfeng; Jin, Guofan

    2011-10-10

    Plasmonic nanosensors are promising for chip-based refractometric detections, most of which are based on spectroscopic monitoring of surface plasmon resonance. Here, we propose a simple non-spectroscopic refractometric sensing scheme based on a plasmonic interferometer integrating a metallic groove array and a tilted nanoslit. Owing to the interference of the directly transmitted light from the nanoslit and that mediated by the surface plasmon polaritons launched from the groove array, high-contrast intensity fringe can be detected under the illumination of monochromatic light. By inspecting the spatial shift of the interference fringe, the refractive index change of the cover analyte can be derived. In our experiment, the interferometer shows a sensitivity up to 5 × 10³ μm/RIU and a figure of merit as high as 250. This sensor shows great potential for low-cost, portable, and high-throughput sensing applications due to its simple, robust, and non-spectroscopic scheme.

  2. Risk Analysis of V-shaped Pier in Construction Process by Means of RBF Artificial Neural Network%基于RBF神经网络的V撑施工过程风险分析

    Institute of Scientific and Technical Information of China (English)

    王立峰; 肖子旺; 王子强

    2011-01-01

    By taking finite element analysis results as sample data, an invisible mapping relationship between basic variables and structural response is established and a risk quantitative analysis method of high-risk location identification during V-shaped pier construction, by using RBF (Radial Basis Function) artificial neuron network is presented. Through a numerical simulation based on the principle of Monte Carlo, structural failure probability of each checking section of Vshaped pier during construction is calculated. It is proved by engineering project and concluded that, the method of construction risk analyzing based on radial basis function neural network can be used as an efficient reliability analysis method. It is reasonable and applicable, which can provide a theoretical basis for risk-decision during V-shaped pier construction.%运用RBF神经网络(Radial Basis Function Neural Network)理论,分析了大夹角V撑施工期间最大风险因素可能发生的部位,并对V撑的结构失效风险性进行了定量分析.将有限元分析结果作为神经网络训练样本数据,利用径向基神经网络建立了基本变量和结构响应之间的隐性映射关系,根据蒙特卡洛原理进行模拟计算,最终得出V撑施工过程中各个危险截面出现结构失效的概率预估值.通过工程实例验证表明,基于径向基神经网络所建立的施工过程风险分析方法计算效率高,具有可行性和有效性,同时为V撑施工风险决策提供了理论依据.

  3. Development and Application of V-shape Inclined Plate Enhanced Contact Flocculation Settler%V形斜板强化接触絮凝沉淀设备的研发与应用

    Institute of Scientific and Technical Information of China (English)

    刘希邈; 沈本贤; 范志伟; 徐峰; 李楠; 徐立群

    2009-01-01

    V-shape inclined plate settling technology can improve the performance of settling process thanks to its unique structure and cross-section difference, which will induce the velocity differ-ence of the water at the vertical direction and result in a dynamic floe blocking-layer in the inclined plate unit. And a vertical settling accessory unit is introduced to enhance the contact flocculation and sedimentation. The pilot results show that the optimal performance of the settler can be achieved when the inclined plate length is 850 mm, the plate distance is 25 mm, and the vertical plate length is 150 mm, and the settler can operate well when the treatment capacity exceeds 20% of the design value. In the reconstruction project of water treatment plant, the turbidity of the effluent is below 0.4 NTU when using the V-shape inclined plate, which is much lower than 1.63 NTU of the former settler. Moreover, 49% coagulant is also saved.%V形斜板强化接触絮凝沉淀技术利用设备的流体上升流道截面差造成水流沿重力方向的速度差,使斜板沉淀单元内部形成一定厚度的具有自我更新能力的絮体动态悬浮层,同时通过增设的垂直板来增加絮体悬浮层厚度,实现强化接触絮凝、提高絮体沉淀分离性能的目的.中试结果表明,当斜板长为850 mm、斜板间距为25 mm、直板长为150 mm时,沉淀设备达到最佳性能;在处理水量超过设计负荷的20%时,设备仍运行效果良好.在水厂改造项目中,V形斜板沉淀设备的出水浊度稳定在0.4 NTU以下,低于原设备的出水浊度(1.63 NTU),同时节省了49%的投药量.

  4. The Effect of Desizing and Scouring with Enzyme on Grooved Polyester/Cotton Denim

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zeng-qiang; ZHU Jiang-bo

    2009-01-01

    The denim woven by cotton and grooved polyester fiber (Coolconl) is desized by amylase and scouring enzyme. The technological parameters are discussed, such as concentrations of amylase and compound enzyme HK, time, temperature, and pH value. The technical conditions are optimized through experimental analysis. This eco-finishing process is very helpful to improve the denim production and the performance of moisture absorption and sweat transmission function.

  5. Direct numerical simulation of Taylor–Couette flow with grooved walls: torque scaling and flow structure

    NARCIS (Netherlands)

    Zhu, X.; Ostilla-Monico, Rodolfo; Verzicco, R.; Lohse, D.

    2016-01-01

    We present direct numerical simulations of Taylor–Couette flow with grooved walls at a fixed radius ratio ${\\it\\eta}=r_{i}/r_{o}=0.714$η=ri/ro=0.714 with inner cylinder Reynolds number up to $Re_{i}=3.76\\times 10^{4}$Rei=3.76×104, corresponding to Taylor number up to $Ta=2.15\\times 10^{9}$Ta=2.15×10

  6. Self-consistent treatment of v-groove quantum wire band structure in no parabolic approximation

    Directory of Open Access Journals (Sweden)

    Crnjanski Jasna V.

    2004-01-01

    Full Text Available The self-consistent no parabolic calculation of a V-groove-quantum-wire (VQWR band structure is presented. A comparison with the parabolic flat-band model of VQWR shows that both, the self-consistency and the nonparabolicity shift sub band edges, in some cases even in the opposite directions. These shifts indicate that for an accurate description of inter sub band absorption, both effects have to be taken into the account.

  7. Palatogingival groove - a silent killer: Treatment of an osseous defect due to it

    Directory of Open Access Journals (Sweden)

    Krishna Kumar Gupta

    2011-01-01

    Full Text Available A male patient of 21 years of age reported to the Department of Periodontology and Implantology with a chief complain of pus discharge in both right and left upper lateral incisors. On clinical examination a deep pocket of about 10-14 mm was noticed in both lateral incisors. Radiographic interpretation shows a teardrop-shaped radiolucency in both the laterals giving suspicion of palatogingival groove, which was later discovered and treated surgically.

  8. Deflection Reduction of GaN Wafer Bowing by Coating or Cutting Grooves in the Substrates

    Institute of Scientific and Technical Information of China (English)

    SUN Tao; WANG Ming-Qing; SUN Yong-Jian; WANG Bo-Ping; ZHANG Guo-Yi; TONG Yu-Zhen; DUAN Hui-Ling

    2011-01-01

    @@ GaN films on sapphire substrates are obtained using the metal-organic chemical vapor deposition growth technique.We present two methods to reduce the GaN wafer bowing caused by the mismatch of the thermal expansion coefficients(TECs)between the film and the substrate.The first method is to use coating materials on the back side of the substrate whose TECs are smaller than that of the GaN films.The second is to cut grooves on the back side of the sapphire substrate and filling the grooves with appropriate materials(e.g., tungsten, silicon nitride).For each method, we minimize wafer bowing and even reduce it to zero.Moreover, the two methods can reduce stress concentration and suppress the propagation of cracks in the GaN/sapphire structure.%GaN films on sapphire substrates are obtained using the metal-organic chemical vapor deposition growth technique. We present two methods to reduce the GaN wafer bowing caused by the mismatch of the thermal expansion coefficients (TECs) between the film and the substrate. The first method is to use coating materials on the back side of the substrate whose TECs are smaller than that of the GaN films. The second is to cut grooves on the back side of the sapphire substrate and filling the grooves with appropriate materials (e.g., tungsten, silicon nitride).For each method, we minimize wafer bowing and even reduce it to zero. Moreover, the two methods can reduce stress concentration and suppress the propagation of cracks in the GaN/sapphire structure.

  9. Apical groove type and molecular phylogeny suggests reclassification of Cochlodinium geminatum as Polykrikos geminatum.

    Directory of Open Access Journals (Sweden)

    Dajun Qiu

    Full Text Available Traditionally Cocholodinium and Gymnodinium sensu lato clade are distinguished based on the cingulum turn number, which has been increasingly recognized to be inadequate for Gymnodiniales genus classification. This has been improved by the combination of the apical groove characteristics and molecular phylogeny, which has led to the erection of several new genera (Takayama, Akashiwo, Karenia, and Karlodinium. Taking the apical groove characteristics and molecular phylogeny combined approach, we reexamined the historically taxonomically uncertain species Cochlodinium geminatum that formed massive blooms in Pearl River Estuary, China, in recent years. Samples were collected from a bloom in 2011 for morphological, characteristic pigment, and molecular analyses. We found that the cingulum in this species wraps around the cell body about 1.2 turns on average but can appear under the light microscopy to be >1.5 turns after the cells have been preserved. The shape of its apical groove, however, was stably an open-ended anticlockwise loop of kidney bean shape, similar to that of Polykrikos. Furthermore, the molecular phylogenetic analysis using 18S rRNA-ITS-28S rRNA gene cistron we obtained in this study also consistently placed this species closest to Polykrikos within the Gymnodinium sensu stricto clade and set it far separated from the clade of Cochlodinium. These results suggest that this species should be transferred to Polykrikos as Polykrikos geminatum. Our results reiterate the need to use the combination of apical groove morphology and molecular phylogeny for the classification of species within the genus of Cochlodinium and other Gymnodiniales lineages.

  10. Svengi ja groove rytmimusiikissa : Rytmiikkaan ja hienorytmiikkaan keskittyvÀ vertaileva musiikkianalyysi

    OpenAIRE

    Pesonen, Matti

    2010-01-01

    KÀsitteillÀ svengi ja groove viitataan useimmiten kappaleen tietyn tulkinnan eli esityksen pÀÀasiallisesti rytmisten ominaisuuksien laatuun. Tutkimuksen tavoitteena on kehittÀÀ musiikin rytmiikkaan ja hienorytmiikkaan keskittyviÀ musiikkikognitiivisia analyysimetodeja, joita soveltamalla nÀmÀ ominaisuudet voitaisiin tavoittaa. KÀsitteiden monitulkintaisuus, joka tuodaan esiin tutkimuksen alussa aiheuttaa tÀlle monenlaisia haasteita. -- Tutkimuksen rytmiikkaan keskittyviÀ analyysim...

  11. Computer simulation of viscous fingering in a lifting Hele-Shaw cell with grooved plates

    Indian Academy of Sciences (India)

    Sujata Tarafdar; Soma Nag; Tapati Dutta; Suparna Sinha

    2009-10-01

    We simulate viscous fingering generated by separating two plates with a constant force, in a lifting Hele-Shaw cell. Variation in the patterns for different fluid viscosity and lifting force is studied. Viscous fingering is strongly affected by anisotropy. We report a computer simulation study of fingering patterns, where circular or square grooves are etched on to the lower plate. Results are compared with experiments.

  12. Minor Groove Binding between Norfloxacin and DNA Duplexes in Solution: A Molecular Dynamics Study

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Molecular dynamics were used to investigate the interaction between norfloxacin and DNA duplex. The results showed that norfloxacin was situated in the minor groove of DNA,binding to the TCGA region of d [ATATCGATAT] 2. Specific hydrogen bonds were formed between norfloxacin and guanine base of DNA during the 2 ns MD, which may be the reason for the preferentiality of quinolone antibacterial towards the guanine base of DNA duplex.

  13. Internet-Based Optimization and Choice of Insert Grooves for Face-Milling

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Manufacture is facing more furiously competition in the new century. It tends to be globalized. Rapid response and technology innovation have become the key factor to the success of manufacture enterprise. At present, internet-based manufacturing develops rapidly. With the development of engineering material and machining techniques, better cutting properties of metal cutting tools are required. The world is paying more attention to the study of indexable carbide inserts with three-dimensional complex groov...

  14. Polarization-resolved two-photon luminescence microscopy of V-groove arrays

    DEFF Research Database (Denmark)

    Beermann, J.; Novikov, S. M.; Holmgaard, T.;

    2012-01-01

    Using two-photon luminescence (TPL) microscopy and local reflection spectroscopy we investigate electromagnetic field enhancement effects from a mu m-sized composition of 450-nm-deep V-grooves milled by focused ion beam in a thick gold film and assembled to feature, within the same structure...... obtained to evaluation of local field enhancements using TPL microscopy, especially when investigating extended structures exhibiting different radiation channels, are discussed. (C)2011 Optical Society of America...

  15. Performance comparison and parametric study on spiral groove gas film face seals

    Institute of Scientific and Technical Information of China (English)

    LIU Yuchuan; SHEN Xinmin; XU Wanfu; WANG Zhili

    2004-01-01

    Several spiral groove gas film face seals (SGFS) with different layouts are compared quantitatively to analyze their merits and faults and application behaviors. In addition, a parametric study on downstream mode SGFS is conducted to determine its optimal parameters under certain working conditions. In the computation of gas film pressure on the face, finite element method (FEM) is applied to adapt to complicated geometrical boundary.

  16. MULTIPARAMETER MEASUREMENT FOR RACEWAY GROOVE OF BEARING BASED ON 3D RECONSTRUCTION WITH DIGITAL STRUCTURED LIGHT

    Institute of Scientific and Technical Information of China (English)

    He Tao; Zhong Ming; Li Wei; Zhong Yuning; Shi Tielin

    2005-01-01

    A fast 3D reconstruction method based on structured light to measure various parameters of the raceway groove is presented. Digital parallel grating stripes distributed with sine density are projected onto the raceway groove by a DLP projector, and distorting of stripes is happened on the raceway. Simultaneously, aided by three-step phase-shifting approach, three images covered by different stripes are obtained by a high-resolution CCD camera at the same location, thus a more accuracy local topography can be obtained. And then the bearing is rotated on a high precision computer controlled rotational stage. Three images are also obtained as the former step at next planned location triggered by the motor. After one cycle, all images information is combined through the mosaics. As a result, the 3D information of raceway groove can be gained. Not only geometric properties but also surface flaws can be extracted by software. A preliminary hardware system has been built, with which some geometric parameters have been extracted from reconstructed local topography.

  17. Dynamic Characteristics of the Herringbone Groove Gas Journal Bearings: Numerical Simulations

    Directory of Open Access Journals (Sweden)

    Bin Wang

    2016-01-01

    Full Text Available Dynamic characteristics of the herringbone grooved gas journal bearings (HGGJB under fluid-structure interactions are systematically investigated using the finite element method. Stability and bearing capacity of the HGGJB are estimated and compared with those of the plain gas journal bearings (PGJB. Influences of the structural parameters, including the spiral angle, the groove number, the groove depth, the pressure relief hole diameter, the bearing radial clearance, the length to diameter ratio, and the rotating speed, on dynamic characteristics of HGGJB are analyzed. To verify the numerical simulation results, pressure nephograms and cross-section pressure curves of the same rotor model, calculated by the numerical simulation and the theoretical method, respectively, are compared. Similar results are obtained. Compared to the common constrained boundary conditions in the previous numerical simulations, boundary conditions adopted in this paper are complete self-absorption and the change of the gas inlet and outlet depends on the rotating state of the rotor, which are more accordant with the real dynamic characteristics of the HGGJB. In all, the results presented in this paper provide a deeper and better understanding of the dynamic characteristics of the HGGJB under fluid-structure interactions.

  18. Design and experimental study of a micro-groove grinding wheel with spray cooling effect

    Directory of Open Access Journals (Sweden)

    Shi Chaofeng

    2014-04-01

    Full Text Available The effectiveness of grinding fluid supply has a crucial impact on grinding quality and efficiency in high speed grinding. In order to improve the cooling and lubrication, through in-depth research of self-inhaling internal cooling method and intermittent grinding mechanism, a new spray cooling method used in high speed grinding is proposed. By referring to the structure of bowl-shaped dispersion disk, the grinding wheel matrix with atomization ability is designed; through studying heat transfer of droplet collision and the influence of micro-groove on the boiling heat transfer, grinding segment with micro-groove is designed to enhance the heat flux of coolant and achieve maximum heat transfer between droplets and grinding contact zone. High-speed grinding experiments on GH4169 with the developed grinding wheel are carried out. The results show that with the micro-groove grinding wheel just 5.4% of pump outlet flow rate and 0.5% of spindle energy is needed to reduce the grinding temperature to 200 °C, which means the developed grinding wheel makes cooling high efficient and low energy consuming.

  19. Debris removal from artificial grooves using different endodontic irrigation activation techniques: ex vivo

    Directory of Open Access Journals (Sweden)

    Mügem Aslı Ekici

    2016-12-01

    Full Text Available Objective: The aim of this study was to compare the debris removal efficiency of different irrigation activation techniques from artificially formed endodontic grooves. Materials and Method: Crowns of twenty maxillary incisor teeth were removed and the root canals were prepared. Specimens were embedded in acrylic resin and placed into teflon molds. Acrylic resin blocks were removed from the molds and split longitudinally into equal two halves. A standardized artificial groove (4 mm x 0.2 mm x 0.5 mm was prepared at 2 mm distance from the apex and filled with dentinal debris. Acrylic resin blocks were placed into the teflon mold again and compressed. Four different irrigation activation techniques; Manual Dynamic Irrigation (MDI, Passive Ultrasonic Irrigation (PUI, Sonic Irrigation (SI and Apical Negative Pressure Irrigation (ANPI were used for debris removal. Conventional Irrigation (CI was applied as control. For standardization, each specimen was cleaned and reused (n=20. Before and after irrigation, images of the grooves were taken by using an operating microscope at x30 magnification. Amount of remaining debris was evaluated by using a scoring system. Data were analyzed by using Kruskall-Wallis and Mann-Whitney U tests (α=0.05. Results: There were statistically significant differences between the experimental groups (p0.05. Conclusion: PUI yielded the lowest debris scores. A simple and low-cost technique, MDI, yielded similar results with PUI.

  20. Forming method of micro heat pipe with compound structure of sintered wick on grooved substrate

    Science.gov (United States)

    Li, Xibing; Li, Mingjian; Li, Ming; Wu, Ruchen; Wan, Yingsi; Cheng, Tian

    2016-03-01

    Micro heat pipes (MHPs) with excellent heat transfer performance have been the ideal radiating components to meet increasingly higher requirements posed by high heat-flux products. Based on MHPs' working principle, this study deduced capillary limit of a novel MHP with compound structure of sintered wick on grooved substrate, and probed into its forming mechanism: first, high-speed oil-filled spinning was applied to fabricating micro grooves, with optimal spinning and drawing speeds determined; then a mini-type vibration machine was used to help fill copper powders fast and uniformly, with appropriate sintering temperature and time fixed; the manufacturing method that integrates vacuum-pumping-cold-welding with secondary-degassing-cold-welding to increase vacuumizing efficiency. The results of experiments on its heat transfer performance show that the MHPs with sintered-wick-on-grooved-substrate structure fabricated through the proposed forming method can not only acquire much better heat transfer performance, but have advantages such as higher productivity and lower cost.

  1. Insight into mechanics of AFM tip-based nanomachining: bending of cantilevers and machined grooves

    Science.gov (United States)

    Al-Musawi, R. S. J.; Brousseau, E. B.; Geng, Y.; Borodich, F. M.

    2016-09-01

    Atomic force microscope (AFM) tip-based nanomachining is currently the object of intense research investigations. Values of the load applied to the tip at the free end of the AFM cantilever probe used for nanomachining are always large enough to induce plastic deformation on the specimen surface contrary to the small load values used for the conventional contact mode AFM imaging. This study describes an important phenomenon specific for AFM nanomachining in the forward direction: under certain processing conditions, the deformed shape of the cantilever probe may change from a convex to a concave orientation. The phenomenon can principally change the depth and width of grooves machined, e.g. the grooves machined on a single crystal copper specimen may increase by 50% on average following such a change in the deformed shape of the cantilever. It is argued that this phenomenon can take place even when the AFM-based tool is operated in the so-called force-controlled mode. The study involves the refined theoretical analysis of cantilever probe bending, the analysis of experimental signals monitored during the backward and forward AFM tip-based machining and the inspection of the topography of produced grooves.

  2. Minor-Groove Binding Drugs: Where Is the Second Hoechst 33258 Molecule?

    KAUST Repository

    Fornander, Louise H.

    2013-05-16

    Hoechst 33258 binds with high affinity into the minor groove of AT-rich sequences of double-helical DNA. Despite extensive studies of this and analogous DNA binding molecules, there still remains uncertainty concerning the interactions when multiple ligand molecules are accommodated within close distance. Albeit not of direct concern for most biomedical applications, which are at low drug concentrations, interaction studies for higher drug binding are important as they can give fundamental insight into binding mechanisms and specificity, including drug self-stacking interactions that can provide base-sequence specificity. Using circular dichroism (CD), isothermal titration calorimetry (ITC), and proton nuclear magnetic resonance (1H NMR), we examine the binding of Hoechst 33258 to three oligonucleotide duplexes containing AT regions of different lengths: [d(CGCGAATTCGCG)]2 (A2T2), [d(CGCAAATTTGCG)]2 (A3T 3), and [d(CGAAAATTTTCG)]2 (A4T4). We find similar binding geometries in the minor groove for all oligonucleotides when the ligand-to-duplex ratio is less than 1:1. At higher ratios, a second ligand can be accommodated in the minor groove of A4T4 but not A2T2 or A3T3. We conclude that the binding of the second Hoechst to A4T4 is not cooperative and that the molecules are sitting with a small separation apart, one after the other, and not in a sandwich structure as previously proposed. © 2013 American Chemical Society.

  3. Acute radial nerve entrapment at the spiral groove: detection by DTI-based neurography.

    Science.gov (United States)

    Jengojan, Suren; Kovar, Florian; Breitenseher, Julia; Weber, Michael; Prayer, Daniela; Kasprian, Gregor

    2015-06-01

    This study evaluated the potential of three-tesla diffusion tensor imaging (DTI) and tractography to detect changes of the radial (RN) and median (MN) nerves during transient upper arm compression by a silicon ring tourniquet. Axial T2-weighted and DTI sequences (b = 700 s/mm(2), 16 gradient encoding directions) of 13 healthy volunteers were obtained. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of the MN and RN were measured at the spiral groove and further visualized in 3D by deterministic tractography (thresholds: FA = .15, angle change = 27°). Local/lesional RN FA values increased (p = 0.001) and ADC values decreased (p = 0.02) during a 20-min upper arm compression, whereas no significant FA (p = 0.49) or ADC (p = 0.73) changes of the MN were detected. There were no T2-w nerve signal changes or alterations of nerve trajectories in 3D. Acute nerve compression of the RN leads to changes of its three-tesla DTI metrics. Peripheral nerve DTI provides non-invasive insights into the "selective" vulnerability of the RN at the spiral groove. • DTI-based neurography detects nerve changes during acute nerve compression. • Compression leads to a transient increase in local radial nerve FA values. • DTI provides insights into radial nerve vulnerability at the spiral groove.

  4. Insight into mechanics of AFM tip-based nanomachining: bending of cantilevers and machined grooves.

    Science.gov (United States)

    Al-Musawi, R S J; Brousseau, E B; Geng, Y; Borodich, F M

    2016-09-23

    Atomic force microscope (AFM) tip-based nanomachining is currently the object of intense research investigations. Values of the load applied to the tip at the free end of the AFM cantilever probe used for nanomachining are always large enough to induce plastic deformation on the specimen surface contrary to the small load values used for the conventional contact mode AFM imaging. This study describes an important phenomenon specific for AFM nanomachining in the forward direction: under certain processing conditions, the deformed shape of the cantilever probe may change from a convex to a concave orientation. The phenomenon can principally change the depth and width of grooves machined, e.g. the grooves machined on a single crystal copper specimen may increase by 50% on average following such a change in the deformed shape of the cantilever. It is argued that this phenomenon can take place even when the AFM-based tool is operated in the so-called force-controlled mode. The study involves the refined theoretical analysis of cantilever probe bending, the analysis of experimental signals monitored during the backward and forward AFM tip-based machining and the inspection of the topography of produced grooves.

  5. Azimuthal anchoring of a nematic liquid crystal on a grooved interface with anisotropic polar anchoring

    Institute of Scientific and Technical Information of China (English)

    Zhou Xuan; Zhang Zhi-Dong; Ye Wen-Jiang; Xuan Li

    2012-01-01

    Zhang Y Jet al.[Zhang Y J,Zhang Z D,Zhu L Z and Xuan L 2011 Liquid Cryst.38 355] investigated the effects of finite polar anchoring on the azimuthal anchoring energy at a grooved interface,in which polar anchoring was isotropic in the local tangent plane of the surface.In this paper,we investigate the effects of both isotropic and anisotropic polar anchoring on the surface anchoring energy in the frame of Fukuda et al.'s theory.The results show that anisotropic polar anchoring strengthens the azimuthal anchoring of grooved surfaces.In the one-elastic-constant approximation (K11 =K22 =K33 =K),the surface-groove-induced azimuthal anchoring energy is entirely consistent with the result of Faetti,and it reduces to the original result of Berreman with an increase in polar anchoring.Moreover,the contribution of the surface-like elastic term to the Rapini-Papoular anchoring energy is zero.

  6. Phase development and critical current density of Bi-2223 tapes fabricated by groove rolling

    Science.gov (United States)

    Iyer, A. N.; Salib, S.; Vipulanandan, C.; Salama, K.; Balachandran, U.

    1999-07-01

    The powder-in-tube technique is the most widely used method for fabricating silver-clad Bi-2223 wires and tapes. In this method the silver billet containing the precursor material is transformed to the final shape using metallurgical deformation techniques such as wire drawing and flat rolling. In the present study, a modified version of the powder-in-tube technique was adopted where the silver billet was reduced in size by groove rolling instead of wire drawing. Microstructural analysis during the initial deformation stage revealed crack formation in the superconductor core. Stress conditions during groove rolling were analysed and appropriate changes were incorporated in the deformation process. After groove rolling the wires were flat rolled to a final thickness of 250 icons/Journals/Common/mu" ALT="mu" ALIGN="TOP"/>m. Subsequent thermomechanical treatment resulted in tapes with critical current density of icons/Journals/Common/approx" ALT="approx" ALIGN="TOP"/>19700 A cm-2 (critical current of icons/Journals/Common/approx" ALT="approx" ALIGN="TOP"/>40 A).

  7. Optimization of selective emitter fabrication method for solar cells using a laser grooving.

    Science.gov (United States)

    Jung, W W; Kim, S C; Jung, S W; Moon, I Y; Kumar, K; Lee, Y W; Kim, S Y; Ju, M K; Han, S K; Yi, J

    2011-05-01

    In this paper, screen-printing laser grooved buried contact (LGBC) method was applied, which is compatible with the existing screen-printed solar cell equipment and facilities. Experiments were performed in order to optimize short circuit current (I(sc)), open circuit voltage (V(oc)) and fill factor of high efficiency solar cells. To enhance I(sc), V(oc) and efficiency, heavy doping was performed at low sheet resistance in the laser grooved region of the cell. In contrast, light doping was carried out at a high sheet resistance in the non-laser grooved region. To increase fill factor, porous silicon found on the wafer after dipping in an HF solution to remove SiN(x), was cleared. The fabricated screen-printing LGBC solar cell using a 125 mm x 125 mm single crystalline silicon wafer exhibited an efficiency of 17.2%. The results show that screen-printing LGBC method can be applied for high efficiency solar cells.

  8. Development of a high resolution gamma camera system using finely grooved GAGG scintillator

    Science.gov (United States)

    Yamamoto, Seiichi; Kataoka, Jun; Oshima, Tsubasa; Ogata, Yoshimune; Watabe, Tadashi; Ikeda, Hayato; Kanai, Yasukazu; Hatazawa, Jun

    2016-06-01

    High resolution gamma cameras require small pixel scintillator blocks with high light output. However, manufacturing a small pixel scintillator block is difficult when the pixel size becomes small. To solve this limitation, we developed a high resolution gamma camera system using a finely grooved Ce-doped Gd3Al2Ga3O12 (GAGG) plate. Our gamma camera's detector consists of a 1-mm-thick finely grooved GAGG plate that is optically coupled to a 1-in. position sensitive photomultiplier tube (PSPMT). The grooved GAGG plate has 0.2×0.2 mm pixels with 0.05-mm wide slits (between the pixels) that were manufactured using a dicing saw. We used a Hamamatsu PSPMT with a 1-in. square high quantum efficiency (HQE) PSPMT (R8900-100-C12). The energy resolution for the Co-57 gamma photons (122 keV) was 18.5% FWHM. The intrinsic spatial resolution was estimated to be 0.7-mm FWHM. With a 0.5-mm diameter pinhole collimator mounted to its front, we achieved a high resolution, small field-of-view gamma camera. The system spatial resolution for the Co-57 gamma photons was 1.0-mm FWHM, and the sensitivity was 0.0025%, 10 mm from the collimator surface. The Tc-99m HMDP administered mouse images showed the fine structures of the mouse body's parts. Our developed high resolution small pixel GAGG gamma camera is promising for such small animal imaging.

  9. Blockade of the BAK hydrophobic groove by inhibitory phosphorylation regulates commitment to apoptosis.

    Directory of Open Access Journals (Sweden)

    Abul Azad

    Full Text Available The BCL-2 family protein BAK is a key regulator of mitochondrial apoptosis. BAK activation first involves N-terminal conformational changes that lead to the transient exposure of the BAK BH3 domain that then inserts into a hydrophobic groove on another BAK molecule to form symmetric dimers. We showed recently that post-translational modifications are important in the regulation of BAK conformational change and multimerization, with dephosphorylation at tyrosine 108 constituting an initial step in the BAK activation process. We now show that dephosphorylation of serine 117 (S117, located in the BAK hydrophobic groove, is also critical for BAK activation to proceed to completion. Phosphorylation of BAK at S117 has two important regulatory functions: first, it occludes the binding of BH3-containing peptides that bind to BAK causing activation and cytochrome c release from mitochondria; second, it prevents BAK-BH3:BAK-Groove interactions that nucleate dimer formation for subsequent multimerization. Hence, BH3-mediated BAK conformational change and subsequent BAK multimerization for cytochrome c release and cell death is intimately linked to, and dependent on, dephosphorylation at S117. Our study reveals important novel mechanistic and structural insights into the temporal sequence of events governing the process of BAK activation in commitment to cell death and how they are regulated.

  10. Computational Fluid Dynamic Simulation on NACA 0026 Airfoil with V-Groove Riblets

    Directory of Open Access Journals (Sweden)

    M.I Ghazali

    2016-08-01

    Full Text Available The aims of this research is to look into the percentage drag reduction on a NACA 0026 airfoil with V-Groove riblets installed around at some locations around its surface. NACA 0026 is a symmetrical airfoil mostly used as turbine blade and aircraft wing. Research on drag reduction by using riblets on the surface was introduced by NASA Langley Research Centre in 1970s. There are many types of riblet designed in this research area such as V groove, segmented blade and continuous sawtooth. This research used NACA 0026 with external geometry 500 mm spans, 615 mm chord and 156 mm thickness. V-groove riblets with 1 mm pitch and 1 mm high and 30 mm width are attached at peak points of the airfoil profile. The CFD simulation used ANSYS Fluent to analyze the velocity, pressure gradient, turbulent kinetic energy and vortex development. The result shows the percentage in drag reduction compared to clean surface for the zero angle of attack is 11.8% and 300 angle of attack is 1.64%. By this condition the airfoil will have better motion performance in their applications.

  11. Regenerated collagen fibers with grooved surface texture: Physicochemical characterization and cytocompatibility

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiang [Engineering Research Center of Technical Textiles, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Wu, Tong [College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620 (China); Wang, Wei [Engineering Research Center of Technical Textiles, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Huang, Chen, E-mail: hc@dhu.edu.cn [Engineering Research Center of Technical Textiles, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China); Jin, Xiangyu [Engineering Research Center of Technical Textiles, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620 (China)

    2016-01-01

    A novel type of protein fibers, regenerated collagen fibers (RC) from cattle skin, was prepared through wet-spinning. Due to the combined effect of solvent exchange and subsequent drawing process, the fibers were found to have a grooved surface texture. The grooves provided not only ordered topographical cues, but also increased surface area. Protein content of the RC fibers was confirmed by Fourier Transform infrared spectroscopy (FTIR) and ninhydrin color reaction. The fibers could be readily fabricated into nonwovens or other textiles, owning to their comparable physical properties to other commercialized fibers. Cell growth behavior on RC nonwovens suggested both early adhesion and prompt proliferation. The high moisture regain, good processability, along with the excellent cytocompatibility indicated that the RC fibers and nonwovens developed in this study might offer a good candidate for biomedical and healthcare applications. - Highlights: • Wet-spun regenerated collagen fibers having aligned surface grooves • Comparable physiochemical properties to commercialized fibers • Readily processed into nonwovens • Excellent cytocompatibility with prompt cell adhesion and proliferation.

  12. The Small Signal Analysis of a Centered Dielectric-Rod Loaded, Arbitrarily-Shaped Helical Groove Traveling-Wave-Tube

    Science.gov (United States)

    Wei, Yanyu; Liu, Hongtao; He, Jun; Gong, Yubin; Yue, Lingna; Wang, Wenxiang; Park, Gun-Sik

    2007-12-01

    Properties of traveling wave-beam interaction in a centered dielectric-rod loaded, arbitrarily-shaped helical groove slow-wave structure (SWS) are investigated for a thin annular electron beam. The “hot” dispersion equation is obtained by means of the self-consistent field theory, and the small signal analysis is carried out including the effects of the dielectric-rod parameters and the groove shapes. The numerical results show that the bandwidth of the helical groove TWT is expanded by loading dielectric-rod, however, the small-signal gain is reduced; and when the groove shape changes from the swallow-tail shape to the triangle shape, the working frequency increases , while the peak gain decreases.

  13. High quality broadband spatial reflections of slow Rayleigh surface acoustic waves modulated by a graded grooved surface

    KAUST Repository

    Xu, Yanlong

    2015-01-21

    We report high quality broadband spatial reflections of Rayleigh surface acoustic waves (SAWs) through a graded grooved surface. High quality means that no wave is allowed to transmit and the incident wave is nearly all reflected to the input side. The graded grooved surface is structured by drilling one dimensional array of graded grooves with increased depths on a flat surface. We investigate SAW dispersion relations, wave field distribution at several typical SAW wavelengths, and time evolution of a Gaussian pulse through the graded grooved surface. Results show that the input broadband Rayleigh SAWs can be slowed, spatially enhanced and stopped, and finally reflected to the input side. The study suggests that engraving the flat surface can be used as an efficient and economical way to manipulate Rayleigh SAWs, which has potential application in novel SAW devices such as filters, reflectors, sensors, energy harvesters, and diodes.

  14. Field Observations of Wave-Driven Circulation over Spur and Groove Formations on a Coral Reef (NCEI Accession 0123612)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Spur and groove (SAG) formations are found on the forereefs of many coral reefs worldwide. Modeling results have shown that SAG formations together with shoaling...

  15. Design and experimental study on Fresnel lens of the combination of equal-width and equal-height of grooves

    Science.gov (United States)

    Guo, Limin; Liu, Youqiang; Huang, Rui; Wang, Zhiyong

    2017-06-01

    High concentrating PV systems rely on large Fresnel lens that must be precisely oriented in the direction of the Sun to maintain high concentration ratio. We propose a new Fresnel lens design method combining equal-width and equal-height of grooves in this paper based on the principle of focused spot maximum energy. In the ring band near the center of Fresnel lens, the design with equal-width grooves is applied, and when the given condition is reached, the design with equal-height grooves is introduced near the edges of the Fresnel lens, which ensures all the lens grooves are planar. In this paper, we establish a Fresnel lens design example model by Solidworks, and simulate it with the software ZEMAX. An experimental test platform is built to test, and the simulation correctness is proved by experiments. Experimental result shows the concentrating efficiency of this example is 69.3%, slightly lower than the simulation result 75.1%.

  16. 7.35% efficiency rear-irradiated flexible dye-sensitized solar cells by sealing liquid electrolyte in a groove.

    Science.gov (United States)

    Wang, Xiaopeng; Tang, Qunwei; He, Benlin; Li, Ru; Yu, Liangmin

    2015-01-11

    We report the feasibility of assembling rear-irradiated flexible dye-sensitized solar cells employing a transparent Ni-Se alloy counter electrode along with a groove stored TiO2 and liquid electrolyte. The flexible device with the NiSe counter electrode and anode at a groove depth of 36 μm yielded a maximum efficiency of 7.35%.

  17. Depth prediction model of nano-grooves fabricated by AFM-based multi-passes scratching method

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Yanquan; Yan, Yongda, E-mail: yanyongda@hit.edu.cn; Yu, Bowen; Li, Jiran; Zhang, Qi; Hu, Zhenjiang; Zhao, Xuesen

    2014-09-15

    Highlights: • An AFM-based depth prediction model of nano-grooves for the atomic force microscopy (AFM)-based multi-passes scratching method is given. • The effect of the tip geometry is considered in the theoretical model. • A correction factor is introduced into the two-passes scratching model and the prediction error of the correction model is less than 10%. - Abstract: This paper proposes a nano-groove depth prediction model for the atomic force microscopy (AFM)-based multi-passes scratching method in which the AFM tip is considered as a cone with a spherical apex. The relationship between the normal load applied on the sample and the depth of the machined nano-groove is systematically investigated for the multi-passes scratching process. Nano-grooves are fabricated with several normal loads and two passes scratches on a 2A12 aluminum alloy surface to verify the developed models. Results show that the hardness may become larger near the machined region after one pass scratching test and a correction factor is introduced into the two passes scratching model which is as a function of the first pass machined depths of the nano-grooves. Based on the correction model, several nano-grooves with an expected depth are machined with different normal loads for each pass in the two passes scratching tests and the difference between the experiment results and the expected values is less than 10%. Actually, to machine a nano-groove with a desired depth, this method has the potential to distribute the appropriate normal load applied for each pass to reduce the tip wear and be used for nano-groove depth correction using the multi passes scratching technique.

  18. Successful treatment of a radicular groove by intentional replantation and Emdogain therapy: four years follow-up.

    Science.gov (United States)

    Al-Hezaimi, Khalid; Naghshbandi, Jafar; Simon, James H S; Rotstein, Ilan

    2009-03-01

    Radicular groove is an anatomical malformation that often causes severe periodontal defects. Treatments of such an anomaly present a clinical challenge to the operator. Presented is a case of successful treatment of radicular groove associated with a maxillary lateral incisor of a 15-year-old girl. A combination of endodontics, intentional replantation, and Emdogain therapy was used. At 4-year follow-up, the patient was comfortable and complete resolution of the periapical pathology was evident.

  19. An innovative approach in the management of palatogingival groove using Biodentine™ and platelet-rich fibrin membrane

    OpenAIRE

    Dexton Antony Johns; Vasundhara Yayathi Shivashankar; Shobha, K; Manu Johns

    2014-01-01

    Palatogingival groove is an anatomical malformation that often causes severe periodontal defects. Treatments of such an anomaly present a clinical challenge to the operator. Careful endodontic and periodontal procedures may restore the form and function. In the present case; root canal therapy, apicectomy, and sealing of the groove with Biodentine TM were done. Bone graft was placed followed by platelet-rich fibrin (PRF) membrane. This treatment modality resulted in gain in attachment, reduct...

  20. Endodontic and periodontal management of a severely affected maxillary lateral incisor having combined mucosal fenestration and palatogingival groove

    OpenAIRE

    Sarang Sharma; Dhirendra Srivastava; Vishal Sood; Priya Yadav

    2015-01-01

    Mucosal fenestrations, wherein the tooth root apices are clinically discernible in the oral cavity subsequent to loss of overlying alveolar bone and mucosa, are rare pathologic entities. Palato gingival grooves- anatomic aberrations are also infrequent occurrences that notoriously predispose to periodontal pathologies of varying extent. Both conditions independently are known to popularly affect maxillary lateral incisors. Coexistent fenestration defect and palato gingival groove in the same ...

  1. V-shaped ligand 1,3-bis(1-ethylbenzimidazol-2-yl)-2-thiapropane and manganese(II), cobalt(II) and copper(II) complexes: Synthesis, crystal structure, DNA-binding properties and antioxidant activities.

    Science.gov (United States)

    Wu, Huilu; Yang, Zaihui; Wang, Fei; Peng, Hongping; Zhang, Han; Wang, Cuiping; Wang, Kaitong

    2015-07-01

    A V-shaped ligand 1,3-bis(1-ethylbenzimidazol-2-yl)-2-thiapropane (bebt) and its transition metal complexes, [Mn(bebt)(pic)2]·CH3OH (pic=picrate) 1, [Co(bebt)2](pic)22 and [Cu(bebt)2](pic)2·2DMF 3, have been synthesized and characterized. The coordinate forms of complexes 1 and 2 are basically alike, which can be described as six-coordinated distorted octahedron. The geometric structure around Cu(II) atom can be described as distorted tetrahedral in complex 3. The DNA-binding properties of the ligand bebt and complexes have been investigated by electronic absorption, fluorescence, and viscosity measurements. The results suggest that bebt and complexes bind to DNA via an intercalative binding mode and the order of the binding affinity is 1<2<3

  2. A seven-coordinated manganese(II) complex with V-shaped ligand bis(N-benzylbenzimidazol-2-ylmethyl)benzylamine: synthesis, structure, DNA-binding properties and antioxidant activities.

    Science.gov (United States)

    Wu, Huilu; Yuan, Jingkun; Bai, Ying; Wang, Hua; Pan, Guolong; Kong, Jin

    2012-11-05

    A manganese(II) complex of the type, [MnL(pic)(2)]·H(2)O, was obtained by the reaction of the V-shaped ligand bis(N-benzylbenzimidazol-2-ylmethyl)benzylamine (L) with Mn(pic)(2) (pic=picrate). The ligand L and Mn(II) complex were confirmed on the basis of elemental analysis, molarconductivities, (1)H NMR, IR, UV-vis spectra and X-ray crystallography. Single-crystal X-ray revealed that central Mn(II) atom is seven-coordinate with a MnN(3)O(4) environment, in which ligand L acts as a tridentate N-donor. The remaining coordination sites were occupied by four O atoms afforded by two picrate anion. Interaction of the free ligand L and Mn(II) complex with DNA were investigated by spectrophotometric methods and viscosity measurements. The results suggested that both ligand L and Mn(II) complex bind to DNA in an intercalative binding mode, and DNA-binding affinity of the Mn(II) complex is stronger than that of ligand L. Moreover, antioxidant assay in vitro shows the Mn(II) complex possesses significant antioxidant activities.

  3. Transport in a grooved perfusion flat-bed bioreactor for cell therapy applications.

    Science.gov (United States)

    Horner, M; Miller, W M; Ottino, J M; Papoutsakis, E T

    1998-01-01

    This study considers the transport of oxygen (a growth-associated solute) and lactate (a metabolic byproduct) in a flat-bed perfusion chamber modified to retain cells through the addition of grooves, perpendicular to the direction of flow, at the chamber bottom. The chamber has been successfully applied to hematopoietic cell culture and may be useful for other basic and applied biomedical applications. The objective of this study is to characterize the culture environment in terms of solute transport under various operational conditions. This will allow one to improve the design and operating strategy of the perfusion system for maximizing cell numbers. The system is numerically simulated using the finite element package FIDAP. The reaction kinetics describing oxygen uptake by cells are simplified to zero order to give an upper bound for the oxygen consumption. A flat-bed chamber without grooves is considered here as a benchmark. We show that the growth environment is not oxygen limited (local oxygen concentration above 10 microM) for a variety of flow rates and culture conditions (qO2 = 0.1 micromol/(10(6) cells h)). With a medium flow rate of 2.5 mL/min through the reactor, the model predicts that the 29-cm2 reactor can support at least 33.4 x 10(6) total cells when the inlet medium is in equilibrium with high (20%) oxygen concentration. The culture becomes oxygen limited however for the same flow rate for low (5%) oxygen concentration and can only support 7.2 x 10(6) total cells. Comparison of grooved vs nongrooved chambers reveals that the presence of grooves only affects solute transport on a local scale. This result is attributed to the small size (200 microgram) of the cavities relative to the chamber dimensions. The comparison also yields an empirical relation that allows for rapid estimation of oxygen and lactate concentrations in the grooves using only the numerical simulation of the simpler nongrooved chamber. Finally, our investigation shows that, while

  4. RANS simulations of the U and V grooves effect in the subcritical flow over four rotated circular cylinders

    Institute of Scientific and Technical Information of China (English)

    ALONZO-GARCA A; GUTIRREZ-TORRES C del C; JIMNEZ BERNAL J A; MOLLINEDO-PONCE de LEN H R; MARTINEZ-DELGADILLO S A; BARBOSA-SALDAA J G

    2015-01-01

    This paper presents a CFD study about the effect of the V and U grooves in the flow over four cylinders in diamond shape configuration at subcritical flow conditions(Re=41000). Thek-ε Realizable turbulence model was implemented to fully structured hexahedral grids with near-wall refinements. Results showed that the numerical model was able to reproduce the impinging flow pattern and the repulsive forces present in the lateral cylinders of the smooth cylinder array. As a consequence of the flow alignment induced by the grooves, a jet-flow is formed between the lateral cylinders, which could cause an important vortex induced vibration effect especially in the rear cylinder. The magnitudes of the shear stresses at the valleys and peaks for the V grooved cylinders were lower than those of the U grooved cylinders, but the separation points were delayed due the U grooves presence. It is discussed the presence of a blowing effect caused by counter-rotating eddies located near the grooves peaks that cause a decrease of the shear stresses in the valleys, and promote them at the peaks.

  5. CO2 Corrosion and Grooving Corrosion Behavior of the ERW Joint of the Q125 Grade Tube Steel

    Institute of Scientific and Technical Information of China (English)

    Li-dong WANG; Feng-lei LIU; Qing-yun ZHAO; Hui-bin WU

    2015-01-01

    In order to investigate the CO2 corrosion behavior and the grooving corrosion susceptibility of electric resistance welded tubes of the Q125 grade, the high temperature and high pressure autoclave was employed to conduct CO2 corrosion experiments for the welded joint. The mechanisms of grooving corrosion and the factors inlfuencing grooving corrosion susceptibility were identiifed by electrochemical measurement, microstructure observation, residual stress examination, micro-region composition and orientation analysis. The CO2 corrosion results show that the corrosion resistance of the base material is the best, followed by heat-affected zone and the welded seam is the worst. The grooving corrosion occurred in the welded seam, and the grooving corrosion susceptibility of welded seam is relativity high. The dominated reason for the grooving corrosion of the electric resistance welded jointis the notable inclusions consisting of MnS as the main content in the welded seam.The proportion of high-angle grain bound-aries in the welding zone is higher than that of base metal and the heat affected zone, which plays an important role in the corrosion behavior of the welded seam.

  6. Transmittance of a subwavelength aperture flanked by a finite groove array \\\\ placed near the focus of a conventional lens

    CERN Document Server

    Villate-Guío, F; Martín-Moreno, L

    2014-01-01

    One-dimensional light harvesting structures illuminated by a conventional lens are studied in this paper. Our theoretical study shows that high transmission efficiencies are obtained when the structure is placed near the focal plane of the lens. The considered structure is a finite slit-groove array (SGA) with a given number of grooves that are symmetrically distributed with respect to a central slit. The SGA is nano-patterned on an opaque metallic film. It is found that a total transmittance of 80% is achieved even for a single slit when (i) Fabry-Perot like modes are excited inside the slit and (ii) the effective cross section of the aperture becomes of the order of the full width at half maximum of the incident beam. A further enhancement of 8% is produced by the groove array. The optimal geometry for the groove array consists of a moderate number of grooves ($ \\geq 4$) at either side of the slit, separated by a distance of half the incident wavelength $\\lambda$. Grooves should be deeper (with depth $\\geq ...

  7. Numerical Study on the Effect of Single Shallow Circumferential Groove Casing Treatment on the Flow Field and the Stability of a Transonic Compressor

    Directory of Open Access Journals (Sweden)

    Mohsen Agha Seyed Mirzabozorg

    2017-01-01

    Full Text Available The present research investigates the effect of the location and the width of single shallow circumferential groove casing treatment on the flow field and the stability improvement of NASA Rotor 37 utilizing the help of computational fluid dynamics. At first, steady state simulation of Rotor37 was presented for smooth casing (without groove. Then, forty five various grooved casing were simulated and compared with the smooth casing. The results indicated that narrow grooves had slight effect on the adiabatic efficiency but as the width of the groove was increased, a decline in efficiency was observed. The investigation on the stall margin revealed that narrow grooves next to the leading edge could improve the stall margin by a reduction in the size of vortex breakdown zone. Medium-width grooves displayed an effective role in delaying the separation- produced by shock wave and boundary layer interaction- on the blade suction side near the casing. This type of grooves could improve the stall margin more than narrow grooves when located on the top of separation zone near the blade suction side. Wide grooves had negative effect on the stall margin and caused a significant drop in the efficiency and the total pressure ratio of the compressor.

  8. MORPHOMETRIC ANALYSIS OF VERTICAL GROOVE ON ANTERIOR SURFACE OF TIBIAL LATERAL CONDYLE AND ITS RELATION WITH SQUATTING

    Directory of Open Access Journals (Sweden)

    Narinder

    2015-05-01

    Full Text Available Seventy dry tibiae of adult and unknown sex were collected from the department of Anatomy Government Medical College Jammu. The region under the course of the ligamentum patellae of every tibia was carefully examined and studied for the presence or absence of a vertical groove and its characteristics like shape, length and depth were noted. In India, one of the commonest mode of sitting is squatting. Squatters are known to show certain adap tational features in the lower extremities like vertical groove on the anterior surface of lateral condyle of tibia. This groove is produced on the tibia by pressure of the tendon of quadriceps femoris (ligamentum patellae. The pressure of the tendon of q uadriceps femoris occurs due to great deal of flexion of knee joint, occuring during squatting. Squatting is one of the frequently used exercise in the field of strength and conditioning. It is also an integral component in the sport of competitive weight lifting and power lifting and regarded as a supreme test of lower body strength. (1,2 INTRODUCTION: A vertical groove is present is present on the anterior surface of tibial lateral condyle in squatters. In India most of the people have a habit of sitting down by squatting. During squatting there is excessive flexion of the knee joint which exerts a great deal of pressure on the strong tendon of quadriceps femoris (ligamentum patellae which is inserted on the tibial tuberosity. The pressure so exerted lead s to the formation of a groove on the unattached part of the ligamentum patella. This vertical groove so formed is also called as quadracipital groove. (3 It is shallow but distinct with a prominent lateral lip and extends proximally in a vertical directio n. It is inverted “J” shaped as described by Hughes and Sunderland 1946. (4 The lateral lip is prominent due to lateral angulation between femur and tibia. If the groove is absent then either the person is a non - squatter (eg Europeans or is weak

  9. Research on the Driven Head's Elliptic Motion of the V-Shape Linear Ultrasonic Motor%V形直线超声波电动机运动分析和实验

    Institute of Scientific and Technical Information of China (English)

    许海; 李志荣

    2012-01-01

    The V-shape linear ultrasonic motor was large thrust, high efficiency by making full use of the piezoelectric ceramic d33 effect. The author developed this type of prototype, analyzed the motor symmetric and anti-symmetry modal excitation process, and the elliptic movement of driven head in actual work process, and proved the ellipse was inclined. The angle of the inclined ellipse was not only depended on the longitudinal vibration of the Langevin vibrators, but also the installation angle θ. The installation angle d affected the maximum speed and the maximum output thrust of linear ultrasonic motor. This angle should be fully guarantee accuracy in design and installation.%试制了V型直线超声波电动机样机,分析了该电机实际工作状态下对称和反对称模态的激发过程;对实际工作过程中驱动足的椭圆运动进行了分析,得出电机实际工作时驱动足的椭圆运动轨迹为一斜椭圆.斜椭圆的轨迹不仅与两个兰杰文振子的纵向振幅有关还和安装角θ角有关.通过理论分析可知,安装角θ直接影响到电机的最大速度和电机最大输出推力.该角度在设计和安装时应该充分保证精度.

  10. Investigations of the performance of grooved electrodes thermionic converters at collector temperatures up to 1023 K

    Energy Technology Data Exchange (ETDEWEB)

    Momozaki, Y.; El-Genk, M.S. [New Mexico Univ., Albuquerque, NM (United States). Dept. of Chemical and Nuclear Engineering

    2004-05-01

    The performances of grooved emitter (GE), grooved collector (GC) and grooved electrodes (GEL) thermionic converters are investigated, and the results are compared with those of an identical converter with smooth electrodes (SEL), which is tested at the same conditions. These converters, with planar polycrystalline molybdenum electrodes and a 0.5 mm inter-electrode gap, are tested at emitter temperatures, T{sub E}=1473-1673 K, collector temperatures, T{sub C}=773-1023 K and Cs pressures, P{sub Cs} = 10-500 Pa. The grooved electrodes have concentric macro-grooves 0.5 mm wide, 0.5 mm deep and 1.0 mm apart. Measured and calculated performance parameters include ignition voltage, V{sub IG}, barrier index, V{sub B}, electric power density, P{sub D} and conversion efficiency,{eta}, as functions of the cesium pressure and electrodes temperatures. V{sub IG} of the GC converter is smaller than that of the SEL converter by up to {approx}0.9 V for P{sub Cs}=20-100 Pa. V{sub B} for the SEL converter is always lowest, except at T{sub E}= 1673 K and T{sub C}=1023 K, indicating that grooved electrode(s) are effective in reducing V{sub B} only at high electrodes temperatures. The GE converter has the lowest P{sub D} and {eta}, followed by the GEL converter, GC converter and, finally, the SEL converter, except for T{sub E}=1473 K and T{sub C}=773 K and for T{sub E}=1673 K and T{sub C}=1023 K. P{sub D} and {eta} for the SEL converter at the optimum T{sub C} (873 K) are 3.74 W{sub e}/cm{sup 2} and 17.0%, respectively, and they decrease to 1.61 W{sub e}/cm{sup 2} and 10.4%, respectively, as T{sub C} increases by 150 to 1023 K. The corresponding P{sub D} and {eta} for the GC converter decrease from 2.56 W{sub e}/cm{sup 2} and 14.7% at T{sub C}=873 K to 2.38 W{sub e}/cm{sup 2} and 14.3%, respectively, at T{sub C}=1023 K. Those for the GE converter decrease from 2.18 W{sub e}/cm{sup 2} and 12.9% at T{sub C}=873 K to 1.56 W{sub e}/cm{sup 2} and 11.0%, respectively, at T{sub C}=1023 K. For

  11. The Effect of Shoe Sole Tread Groove Depth on the Gait Parameters during Walking on Dry and Slippery Surface

    Directory of Open Access Journals (Sweden)

    SF Tabatabai Ghomshe

    2013-01-01

    Full Text Available Background: Prevention of slipping accidents requires provision of adequate friction through the use of suitable combinations of footwear and underfoot surfaces. Shoe sole tread groove is one of the important factors on friction coefficient during walking.Objective: To measure the effect of different shoe sole tread groove depths and different surfaces on the required quotient of friction (Q, heel strike velocity and occurrence time of ground reaction forces (GRF in stance phase during walking on slippery and dry surfaces.Methods: In this semi-experimental study, 22 healthy men were studied under different conditions. The studied independent variables were shoe groove depths (included 1, 2.5 and 5 mm and type of walking surface (dry and slippery. Biomechanical gait analysis was carried out with 396 single steps. Data were collected by motion analysis system and two force platform.Results: The occurrence time of GRF was significantly faster on dry surface than slippery surface (p<0.01. Q was significantly lower on slippery surface and with groove depths of 1 and 2.5 mm. The highest value of Q was observed with the deepest groove depth of 5 mm. Heel strike velocity did not differ significantly in the 6 conditions tested.Conclusion: Tread groove depth is a significant factor affecting the Q at the shoes-surface interface on dry and slippery floors. It seems that deeper groove is more appropriate for maintaining the stability during walking. The walking surface affects the occurrence time of GRF; the force components occur sooner on the dry than slippery surface.

  12. Bifurcation and chaos analysis of nonlinear rotor system with axial-grooved gas-lubricated journal bearing support

    Science.gov (United States)

    Zhang, Yongfang; Hei, Di; Lü, Yanjun; Wang, Quandai; Müller, Norbert

    2014-03-01

    Axial-grooved gas-lubricated journal bearings have been widely applied to precision instrument due to their high accuracy, low friction, low noise and high stability. The rotor system with axial-grooved gas-lubricated journal bearing support is a typical nonlinear dynamic system. The nonlinear analysis measures have to be adopted to analyze the behaviors of the axial-grooved gas-lubricated journal bearing-rotor nonlinear system as the linear analysis measures fail. The bifurcation and chaos of nonlinear rotor system with three axial-grooved gas-lubricated journal bearing support are investigated by nonlinear dynamics theory. A time-dependent mathematical model is established to describe the pressure distribution in the axial-grooved compressible gas-lubricated journal bearing. The time-dependent compressible gas-lubricated Reynolds equation is solved by the differential transformation method. The gyroscopic effect of the rotor supported by gas-lubricated journal bearing with three axial grooves is taken into consideration in the model of the system, and the dynamic equation of motion is calculated by the modified Wilson- θ-based method. To analyze the unbalanced responses of the rotor system supported by finite length gas-lubricated journal bearings, such as bifurcation and chaos, the bifurcation diagram, the orbit diagram, the Poincaré map, the time series and the frequency spectrum are employed. The numerical results reveal that the nonlinear gas film forces have a significant influence on the stability of rotor system and there are the rich nonlinear phenomena, such as the periodic, period-doubling, quasi-periodic, period-4 and chaotic motion, and so on. The proposed models and numerical results can provide a theoretical direction to the design of axial-grooved gas-lubricated journal bearing-rotor system.

  13. Pressure drop and cavitation investigations on static helical-grooved square, triangular and curved cavity liquid labyrinth seals

    Energy Technology Data Exchange (ETDEWEB)

    Asok, S.P., E-mail: asoksp@yahoo.co [Department of Mechanical Engineering, Mepco Schlenk Engineering College (MSEC), Sivakasi, Tamilnadu 626005 (India); Sankaranarayanasamy, K. [National Institute of Technology, Trichy (India); Sundararajan, T. [Indian Institute of Technology Madras, Chennai (India); Vaidyanathan, G. [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam (India); Kumar, K. Udhaya [Department of Mechanical Engineering, MSEC, Sivakasi (India)

    2011-03-15

    Research highlights: Design and testing of newer and novel helical-grooved profiles of labyrinths capable of ensuring high pressure drops even at low liquid flow rates. Implementation of genetic algorithm in the optimization of labyrinth seal through surrogate modelling means. Application of CFD in three-dimensional fluid flow and cavitation analysis for static helical grooved labyrinth seals. - Abstract: Sodium cooled Fast Breeder Reactors (FBR) form the second stage of India's Nuclear power programme. Through a narrow annular space in the grid plate assembly of a prototype FBR, a very low leakage flow of liquid metal sodium should pass, experiencing a stipulated high pressure drop, and without much cavitation. To achieve this, a suitable labyrinth seal is required to be developed for use in the annulus. Water is employed as the model testing liquid which is estimated to experience a pressure drop ratio of 10.5 at the rated leakage flow. Previously studied circular or sinusoidal-grooved square, triangular or curved cavity labyrinth seals were unable to meet this value. In the present work, Computational Fluid Dynamics (CFD) analyses are carried out on Helical-grooved Square cavity Labyrinth Seals (HSLS), using commercial code Fluent. It is found that the geometrical configuration of the grooves plays a major role on the pressure drop. Experimental results reveal close agreement with CFD predictions. An optimal configuration of this square cavity seal is identified by applying genetic algorithm (GA) using commercial packages. It meets just about 24% of the targeted value. Later, using parametric CFD analyses, a Helical-grooved Triangular cavity Labyrinth Seal (HTLS) and different Helical-grooved Curved cavity Labyrinth Seals (HCLS) are analysed. The most favourable profile is tested and found to reach the required pressure drop. CFD cavitation analyses predict the intensity of cavitation in these seals to be below prohibitive levels.

  14. In and out of the minor groove: interaction of an AT-rich DNA with the drug CD27

    Energy Technology Data Exchange (ETDEWEB)

    Acosta-Reyes, Francisco J. [Universitat Politécnica de Catalunya, Diagonal 647, 08028 Barcelona (Spain); Dardonville, Christophe [Instituto de Química Médica, IQM–CSIC, Juan de la Cierva 3, 28006 Madrid (Spain); Koning, Harry P. de; Natto, Manal [University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland (United Kingdom); Subirana, Juan A.; Campos, J. Lourdes, E-mail: lourdes.campos@upc.edu [Universitat Politécnica de Catalunya, Diagonal 647, 08028 Barcelona (Spain)

    2014-06-01

    New features of an antiprotozoal DNA minor-groove binding drug, which acts as a cross-linking agent, are presented. It also fills the minor groove of DNA completely and prevents the access of proteins. These features are also expected for other minor-groove binding drugs when associated with suitable DNA targets. The DNA of several pathogens is very rich in AT base pairs. Typical examples include the malaria parasite Plasmodium falciparum and the causative agents of trichomoniasis and trypanosomiases. This fact has prompted studies of drugs which interact with the minor groove of DNA, some of which are used in medical practice. Previous studies have been performed almost exclusively with the AATT sequence. New features should be uncovered through the study of different DNA sequences. In this paper, the crystal structure of the complex of the DNA duplex d(AAAATTTT){sub 2} with the dicationic drug 4, 4′-bis(imidazolinylamino)diphenylamine (CD27) is presented. The drug binds to the minor groove of DNA as expected, but it shows two new features that have not previously been described: (i) the drugs protrude from the DNA and interact with neighbouring molecules, so that they may act as cross-linking agents, and (ii) the drugs completely cover the whole minor groove of DNA and displace bound water. Thus, they may prevent the access to DNA of proteins such as AT-hook proteins. These features are also expected for other minor-groove binding drugs when associated with all-AT DNA. These findings allow a better understanding of this family of compounds and will help in the development of new, more effective drugs. New data on the biological interaction of CD27 with the causative agent of trichomoniasis, Trichomonas vaginalis, are also reported.

  15. Development of a high resolution gamma camera system using finely grooved GAGG scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Seiichi [Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine (Japan); Kataoka, Jun; Oshima, Tsubasa [Research Institute for Science and Engineering, Waseda University (Japan); Ogata, Yoshimune [Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine (Japan); Watabe, Tadashi; Ikeda, Hayato; Kanai, Yasukazu; Hatazawa, Jun [Osaka University Graduate School of Medicine (Japan)

    2016-06-11

    High resolution gamma cameras require small pixel scintillator blocks with high light output. However, manufacturing a small pixel scintillator block is difficult when the pixel size becomes small. To solve this limitation, we developed a high resolution gamma camera system using a finely grooved Ce-doped Gd{sub 3}Al{sub 2}Ga{sub 3}O{sub 12} (GAGG) plate. Our gamma camera's detector consists of a 1-mm-thick finely grooved GAGG plate that is optically coupled to a 1-in. position sensitive photomultiplier tube (PSPMT). The grooved GAGG plate has 0.2×0.2 mm pixels with 0.05-mm wide slits (between the pixels) that were manufactured using a dicing saw. We used a Hamamatsu PSPMT with a 1-in. square high quantum efficiency (HQE) PSPMT (R8900-100-C12). The energy resolution for the Co-57 gamma photons (122 keV) was 18.5% FWHM. The intrinsic spatial resolution was estimated to be 0.7-mm FWHM. With a 0.5-mm diameter pinhole collimator mounted to its front, we achieved a high resolution, small field-of-view gamma camera. The system spatial resolution for the Co-57 gamma photons was 1.0-mm FWHM, and the sensitivity was 0.0025%, 10 mm from the collimator surface. The Tc-99m HMDP administered mouse images showed the fine structures of the mouse body's parts. Our developed high resolution small pixel GAGG gamma camera is promising for such small animal imaging.

  16. Into the groove: instructive silk-polypyrrole films with topographical guidance cues direct DRG neurite outgrowth.

    Science.gov (United States)

    Hardy, John G; Khaing, Zin Z; Xin, Shangjing; Tien, Lee W; Ghezzi, Chiara E; Mouser, David J; Sukhavasi, Rushi C; Preda, Rucsanda C; Gil, Eun S; Kaplan, David L; Schmidt, Christine E

    2015-01-01

    Instructive biomaterials capable of controlling the behaviour of the cells are particularly interesting scaffolds for tissue engineering and regenerative medicine. Novel biomaterials are particularly important in societies with rapidly aging populations, where demand for organ/tissue donations is greater than their supply. Herein we describe the preparation of electrically conductive silk film-based nerve tissue scaffolds that are manufactured using all aqueous processing. Aqueous solutions of Bombyx mori silk were cast on flexible polydimethylsiloxane substrates with micrometer-scale grooves on their surfaces, allowed to dry, and annealed to impart β-sheets to the silk which assures that the materials are stable for further processing in water. The silk films were rendered conductive by generating an interpenetrating network of polypyrrole and polystyrenesulfonate in the silk matrix. Films were incubated in an aqueous solution of pyrrole (monomer), polystyrenesulfonate (dopant) and iron chloride (initiator), after which they were thoroughly washed to remove low molecular weight components (monomers, initiators, and oligomers) and dried, yielding conductive films with sheet resistances of 124 ± 23 kΩ square(-1). The micrometer-scale grooves that are present on the surface of the films are analogous to the natural topography in the extracellular matrix of various tissues (bone, muscle, nerve, skin) to which cells respond. Dorsal root ganglions (DRG) adhere to the films and the grooves in the surface of the films instruct the aligned growth of processes extending from the DRG. Such materials potentially enable the electrical stimulation (ES) of cells cultured on them, and future in vitro studies will focus on understanding the interplay between electrical and topographical cues on the behaviour of cells cultured on them.

  17. Numerical Investigation of Inlet Distortion on an Axial Flow Compressor Rotor with Circumferential Groove Casing Treatment

    Institute of Scientific and Technical Information of China (English)

    Huang Jian; Wu Hu

    2008-01-01

    On the base of an assumed steady inlet circumferential total pressure distortion, three-dimensional time-dependent numerical simulations are conducted on an axial flow subsonic compressor rotor. The performances and flow fields of a compressor rotor, either casing treated or untreated, are investigated in detail either with or without inlet pressure distortion. Results show that the circumferential groove casing treatment can expand the operating range of the compressor rotor either with or without inlet pressure distortion at the expense of a drop in peak isentropic efficiency. The casing treatment is capable of weakening or even removing the tip leakage vortex effectively either with or without inlet distortion. In clean inlet circumstances, the enhancement and forward movement of tip leakage vortex cause the untreated compressor rotor to stall. By contrast, with circumferential groove casing, the serious flow separation on the suction surface leads to aerodynamic stalling eventually. In the presence of inlet pressure distortion, the blade loading changes from passage to passage as the distorted inflow sector is traversed. Similar to the clean inlet circumstances, with a smooth wall casing, the enhancement and forward movement of tip leakage vortex are still the main factors which lead to the compressor rotor stalling eventu-ally. When the rotor works under near stall conditions, the blockage resulting from the tip leakage vortex in all the passages is very seri-ous. Especially in several passages, flow-spillage is observed. Compared to the clean inlet circumstances, circumferential groove casing treatment can also eliminate the low energy zone in the outer end wall region effectively.

  18. 管道沟槽式连接制作及安装过程中的质量控制%Pipe Groove Connection the Quality Control in the Production and Installation Process of Pipe Groove Connection

    Institute of Scientific and Technical Information of China (English)

    孙强

    2014-01-01

    The pipe groove connection is widely applied in the electromechanical installation project. In order to ensure the quality of groove connection pipe instal ation, this article carries on the analysis from various aspects of the quality, pipe groove, pipe fit ings and pipe instal ation of the grooved pipe fit ings, and summarizes how to control the grooved piping instal ation quality in the construction process.%管道沟槽连接在机电安装工程中的应用越来越广,为保证沟槽连接管道安装的质量,本文从沟槽管件的质量、管道沟槽、管件安装及管道安装等各方面进行了分析。并总结出了在施工过程中,如何控制沟槽连接管道的安装质量。

  19. A novel radiant source for infrared calibration by using a grooved surface

    Institute of Scientific and Technical Information of China (English)

    Hong Zhang; Jingmin Dai

    2006-01-01

    @@ A radiant source with a large aperture at 5-95 ℃ in the wavelength bands of 8-12μm for calibrating infrared imaging systems has been designed. The effective emissivity of its flat bottom with concentric V-grooves was evaluated by the Monte-Carlo method whose correctness was tested and accuracy was discussed. The structure of the source was completed by incorporating the simulation results with the blackbody cavity effect. The source was certificated via an optical measurement system. The source can provide a consistent radiant flux with temperature uniformity of ±0.1 ℃ over an area of diameter of φ80 mm.

  20. Optical polarizer/isolator based on a rectangular waveguide with helical grooves

    CERN Document Server

    Shvets, G

    2006-01-01

    A chirality-based approach to making a one-way waveguide that can be used as an optical isolator or a polarizer is described. The waveguide is rectangular, and chirality is introduced by making slanted rectangular grooves on the waveguide walls. Chirality of the waveguide manifests as a strong circular dichroism, and is responsible for transmitting one circular polarization of light and reflecting the other. Optical isolation of the propagating circular polarization is accomplished when the chiral waveguide is placed in front of a non-chiral optical device. Even the crudest implementations of chirality are shown to exhibit significant circular dichroism.

  1. Slowing surface plasmon polaritons on plasmonic coupled cavities by tuning grating grooves

    Science.gov (United States)

    Balci, Sinan; Kocabas, Askin; Kocabas, Coskun; Aydinli, Atilla

    2010-09-01

    We investigate slow surface plasmon polaritons (SPPs) in plasmonic waveguiding bands formed by coupled plasmonic cavities on Moiré surfaces. We demonstrate controlling the group velocity and dispersion of the SPPs by varying the depth of the plasmonic Bragg grating groove. Changing the grating depth results in modification of coupling coefficients between the cavities and hence the SPPs group velocity is altered. Variation in the group velocity and dispersion of SPPs can be measured with polarization dependent spectroscopic reflection measurements. Dispersion of SPPs has been calculated by finite-difference time-domain method in agreement with the experimental data.

  2. Technical Characteristics of a Novel Helical-Groove Traveling-Wave Tube Structure

    Science.gov (United States)

    Wallett, Thomas M.; Vaden, Karl R.; Freeman, Jon; Qureshi, A. Haq

    1998-01-01

    Experimental measurements of the dispersion characteristics of a C-band helix structure were carried out and compared to the dispersion characteristics found from a helix model using the three-dimensional electromagnetic computer code MAFIA. A conceptually novel design comprising a helical thread of the same pitch and inner diameter in a cylindrical waveguide also were calculated using the MAFIA code. The helical-groove structure exhibits a smaller bandwidth but at a much higher frequency range than the traditional helical structure for similar physical dimensions. It is physically more robust in construction. The interaction impedance also compares favorably with those of the conventional structure.

  3. Konno procedure using atrioventricular groove patch plasty after arterial switch operation.

    Science.gov (United States)

    Kosaka, Yoshimichi; Kurosawa, Hiromi; Nagatsu, Masayoshi

    2004-11-01

    A patient with transposition of the great arteries accompanied by Shaher type 9 coronary anatomy experienced the development of progressive neoaortic valvular regurgitation with a small annulus, supravalvular stenosis, and neopulmonary valvular and supravalvular stenoses 15 years after an arterial switch operation. To implant a prosthetic valve clinically adequate in size, the Konno procedure was necessary. However, the right coronary anatomy precluded the original Konno procedure. My colleagues and I accomplished neoaortic anterior annular enlargement in this case by using atrioventricular groove patch plasty without jeopardizing the right coronary artery, and this resulted in a satisfactory outcome.

  4. DNA minor groove binding of small molecules: Experimental and computational evidence

    Indian Academy of Sciences (India)

    Prateek Pandya; Md Maidul Islam; G Suresh Kumar; B Jayaram; Surat Kumar

    2010-03-01

    Eight indole derivatives were studied for their DNA binding ability using fluorescence quenching and molecular docking methods. These indole compounds have structural moieties similar as in few indole alkaloids. Experimental and theoretical studies have suggested that indole derivatives bind in the minor groove of DNA. Thermodynamic profiles of DNA complexes of indole derivatives were obtained from computational methods. The complexes were largely stabilized by H-bonding and van der Waal’s forces with positive entropy values. Indole derivatives were found to possess some Purine (Pu) - Pyrimidine (Py) specificity with DNA sequences. The results obtained from experimental and computational methods showed good agreement with each other, supported by their correlation constant values.

  5. Experimental and Numerical Study on Heat Transfer Enhancement of a Rectangular Channel with Discontinuous Crossed Ribs and Grooves

    Institute of Scientific and Technical Information of China (English)

    唐新宜; 朱冬生

    2012-01-01

    Experimental and numerical investigations have been conducted to study turbulent flow of water and heat transfer characteristics in a rectangular channel with discontinuous crossed ribs and grooves.The tests investigated the overall heat transfer performance and friction factor in ribbed and ribbed-grooved channels with rib angle of 30°.The experimental results show that the overall thermo-hydraulic performance for ribbed-grooved channel is increased by 10%-13.6% when compared to ribbed channel.The investigation on the effects of different rib angles and rib pitches on heat transfer characteristics and friction factor in ribbed-grooved channel was carried out using Fluent with SST(shear-stress transport) k-ω turbulence model.The numerical results indicate that the case for rib angle of 45° shows the best overall thermo-hydraulic performance,about 18%-36% higher than the case for rib angle of 0°.In addition,the flow patterns and local heat transfer characteristics for ribbed and ribbed-grooved channels based on the numerical simulation were also analyzed to reveal the mechanism of heat transfer enhancement.

  6. Numerical simulation of grooving method for floor heave control in soft rock roadway

    Institute of Scientific and Technical Information of China (English)

    Sun Jin; Wang Lianguo

    2011-01-01

    Grooving method can restrain the deformation and destruction of surrounding rock by transferring the maximum stress to deep rock, bringing about the effective control for floor heave in soft rock roadway.Based on this important effect, and to discuss the relationship between cutting parameters and pressurerelief effect, this paper carried out a numerical simulation of grooving along bottom slab and two sides of gateway with finite difference software FLAC2D. The results show that the control effect on floor heave in soft rock tunnel can be improved by selecting appropriate cutting parameters. Appropriately increasing the crevice depth in the middle of the floor can improve the stress state of bottom slab by stress transfer.So the floor heave can be more effectively controlled. To lengthen the crevice in the comers of roadway can simultaneously transfer the maximum stresses of bottom slab and two sides to deep rock, And promote the pressure-relief effect. Extending the crevice length and crevice width on both sides within a certain range can decrease the stress concentration in the corners of roadway, and reduce the deformation of two sides. The cutting position beneficial to restrain the floor heave is close to the bottom slab.

  7. Detailed heat transfer measurements of impinging jet arrays issued from grooved surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Su, Lo May; Chang, Shyy Woei [Department of Marine Engineering National Kaohsiung Institute of Marine Technology, Kaohsiung, Taiwan (China)

    2002-07-01

    Heat transfer augmentation of impinging jet-array with very small separation distances (S/D{sub j}<1) is attempted by using the grooved orifice plate through which the nozzles with different diameters are fitted. The combined effects of groove and nozzle-size distribution in an array have demonstrated considerable influences on heat transfers via their impacts on inter-jet reactions. With a specified coolant flow rate; the detailed heat transfer distributions over the impinging surfaces of three tested arrays are compared to reveal the optimal selections of separation distance and array configuration. Heat transfer modifications caused by varying jet Reynolds number (Re) and separation distance (S/D{sub j}) over the ranges of 1000{<=}Re{<=}4000 and 0.1{<=}S/D{sub j}{<=}8 are examined for each test array. In conformity with the experimentally revealed heat transfer physics, a regression-type analysis is performed to develop the correlations of spatially-averaged Nusselt numbers, which permit the individual and interactive effect of Re and S/D{sub j} to be evaluated. (authors)

  8. Mechanical grooving effect on the gettering efficiency of crystalline silicon based solar cells

    Science.gov (United States)

    Zarroug, Ahmed; Hamed, Zied Ben; Derbali, Lotfi; Ezzaouia, Hatem

    2017-04-01

    This paper examines a gettering process of Czochralski silicon (CZ) via mechanical texture, followed by two step heat treatment in the presence of porous silicon layer (PSL) under oxygen flow gas. It is shown that a process with PS has a positive trend of improvement in the electronic quality, and found to be more efficient when used in combination with mechanical grooving. We obtained a significant increase of the effective minority carrier lifetime and majority charge carriers mobility. Thus, there is an apparent decrease in the resistivity. These parameters were estimated through a The Quasi-Steady-State Photo-Conductance technique (QSSPC), the van Der Pauw method and Hall Effect. Particularly, we have made obvious that the large enhancement of the electronic quality of the wafers can be related to the presence of grooves, the influence during which the gettering process is of importance to overcome the unexpected saturation phenomena. The current voltage I-V characteristics of all samples had been measured under illumination. They were shown to enhance the photovoltaic properties of solar cells.

  9. DAPI binding to the DNA minor groove: a continuum solvent analysis.

    Science.gov (United States)

    De Castro, L F Pineda; Zacharias, M

    2002-01-01

    A continuum solvent model based on the generalized Born (GB) or finite-difference Poisson-Boltzmann (FDPB) approaches has been employed to compare the binding of 4'-6-diamidine-2-phenyl indole (DAPI) to the minor groove of various DNA sequences. Qualitative agreement between the results of GB and FDPB approaches as well as between calculated and experimentally observed trends regarding the sequence specificity of DAPI binding to B-DNA was obtained. Calculated binding energies were decomposed into various contributions to solvation and DNA-ligand interaction. DNA conformational adaptation was found to make a favorable contribution to the calculated total interaction energy but did not change the DAPI binding affinity ranking of different DNA sequences. The calculations indicate that closed complex formation is mainly driven by nonpolar contributions and was found to be disfavored electrostatically due to a desolvation penalty that outbalances the attractive Coulomb interaction. The calculated penalty was larger for DAPI binding to GC-rich sequences compared with AT-rich target sequences and generally larger for the FDPB vs the GB continuum model. A radial interaction profile for DAPI at different distances from the DNA minor groove revealed an electrostatic energy minimum a few Angstroms farther away from the closed binding geometry. The calculated electrostatic interaction up to this distance is attractive and it may stabilize a nonspecific binding arrangement.

  10. Grooves to tubes: evolution of the venom delivery system in a Late Triassic "reptile"

    Science.gov (United States)

    Mitchell, Jonathan S.; Heckert, Andrew B.; Sues, Hans-Dieter

    2010-12-01

    Venom delivery systems occur in a wide range of extant and fossil vertebrates and are primarily based on oral adaptations. Teeth range from unmodified (Komodo dragons) to highly specialized fangs similar to hypodermic needles (protero- and solenoglyphous snakes). Developmental biologists have documented evidence for an infolding pathway of fang evolution, where the groove folds over to create the more derived condition. However, the oldest known members of venomous clades retain the same condition as their extant relatives, resulting in no fossil evidence for the transition. Based on a comparison of previously known specimens with newly discovered teeth from North Carolina, we describe a new species of the Late Triassic archosauriform Uatchitodon and provide detailed analyses that provide evidence for both venom conduction and document a complete structural series from shallow grooves to fully enclosed tubular canals. While known only from teeth, Uatchitodon is highly diagnostic in possessing compound serrations and for having two venom canals on each tooth in the dentition. Further, although not a snake, Uatchitodon sheds light on the evolutionary trajectory of venom delivery systems in amniotes and provide solid evidence for venom conduction in archosaur-line diapsids.

  11. Acute radial nerve entrapment at the spiral groove: detection by DTI-based neurography

    Energy Technology Data Exchange (ETDEWEB)

    Jengojan, Suren; Breitenseher, Julia; Weber, Michael; Prayer, Daniela; Kasprian, Gregor [Medical University of Vienna, Department of Biomedical Imaging and Image-guided Therapy, Division of Neuro- and Musculosceletal Radiology, Vienna (Austria); Kovar, Florian [Medical University of Vienna, Department of Trauma-Surgery, Vienna (Austria)

    2015-06-01

    This study evaluated the potential of three-tesla diffusion tensor imaging (DTI) and tractography to detect changes of the radial (RN) and median (MN) nerves during transient upper arm compression by a silicon ring tourniquet. Axial T2-weighted and DTI sequences (b = 700 s/mm{sup 2}, 16 gradient encoding directions) of 13 healthy volunteers were obtained. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of the MN and RN were measured at the spiral groove and further visualized in 3D by deterministic tractography (thresholds: FA =.15, angle change = 27 ). Local/lesional RN FA values increased (p = 0.001) and ADC values decreased (p = 0.02) during a 20-min upper arm compression, whereas no significant FA (p = 0.49) or ADC (p = 0.73) changes of the MN were detected. There were no T2-w nerve signal changes or alterations of nerve trajectories in 3D. Acute nerve compression of the RN leads to changes of its three-tesla DTI metrics. Peripheral nerve DTI provides non-invasive insights into the ''selective'' vulnerability of the RN at the spiral groove. (orig.)

  12. Chaotic Behaviour Investigation of a Front Opposed-Hemispherical Spiral-Grooved Air Bearing System

    Directory of Open Access Journals (Sweden)

    Cheng-Chi Wang

    2017-01-01

    Full Text Available In recent years, spiral-grooved air bearing systems have attracted much attention and are especially useful in precision instruments and machines with spindles that rotate at high speed. Load support can be multidirectional and this type of bearing can also be very rigid. Studies show that some of the design problems encountered are dynamic and include critical speed, nonlinearity, gas film pressure, unbalanced rotors, and even poor design, all of which can result in the generation of chaotic aperiodic motion and instability under certain conditions. Such irregular motion on a large scale can cause severe damage to a machine or instrument. Therefore, understanding the conditions under which aperiodic behaviour and vibration arise is crucial for prevention. In this study, numerical analysis, including the Finite Difference and Differential Transformation Methods, is used to study these effects in detail in a front opposed-hemispherical spiral-grooved air bearing system. It was found that different rotor masses and bearing number could cause undesirable behaviour including periodic, subperiodic, quasi-periodic, and chaotic motion. The results obtained in this study can be used as a basis for future bearing system design and the prevention of instability.

  13. Microelectroforming and evaluation of honeycomb-groove nozzle plates of piezoelectric actuators for microspray generation

    Science.gov (United States)

    Chen, Chin-Tai; Huang, Cheng-Chih

    2016-07-01

    Microspray generation by microfluidic nozzles comprising piezoelectric actuators featuring honeycombed grooves for antistiction was investigated. Microfluidic nozzles with 15-μm diameter were fabricated by the electroforming of nickel (Ni) with an estimated total deposition thickness of 40 μm. These nozzles were formed on the Ni plate in arrays of 31, 61, and 151; all nozzles were surrounded by a network array of honeycombed grooves with a line width of 30 μm. The piezoelectric actuators were bonded to the nozzle plates and filled with water to generate microsprays. The actuators were driven at electrical voltages of 40 to 142 V at 94 to 103 kHz, in which spray jets with volumetric rates of 4 to 65 ml/h were simply achieved and analyzed, agreeing with the proposed theory in the study. The use of particle image velocimetry (1500 fps) revealed that the turbulent flow of droplets from the sprays created strong recirculating vortices for a short time (0 to 12 ms). In addition, we experimentally demonstrated turbulence of droplets created at an average speed of 2.9±0.3 m/s, illustrating instable vortex-like motion. Hence the influence of turbulence on a variety of applications such as printing and cooling should be further concerned and investigated in the future.

  14. Treatment of an intrabony osseous lesion associated with a palatoradicular groove

    Directory of Open Access Journals (Sweden)

    A Suchetha

    2012-01-01

    Full Text Available Various root developmental anomalies like palatoradicular groove (PRG have been associated with worsening of periodontal condition. The aim of the present case report is to describe the regenerative surgical treatment of periodontal and osseous lesion associated with the subgingival extension of PRG. A 23-year-old female patient reported with pain in upper incisor teeth region. On clinical and radiological examination, a deep endosseous defect was found distal to maxillary right lateral incisor that was etiologically associated with the presence of a PRG. Treatment procedures consisted of: Regenerative periodontal therapy using Guided tissue regeneration (GTR and hydroxyapatite (HA bone graft and 2 flattening of the radicular portion of the palatal groove. The clinical examination at 1 year revealed shallow residual probing depth (3 mm and no increase in gingival recession. The radiographic examination showed reduction in the radiolucency suggesting bone fill. A PRG may serve as a pathway for the development of a periodontal osseous defect. The combination of GTR and HA may be clinically and radiographically efficacious in the treatment of such a defect.

  15. Geometries of Chip Groove%排屑槽的几何形状

    Institute of Scientific and Technical Information of China (English)

    曹伟

    2015-01-01

    The shape, the cutting force and tool geome try pro perties mainly influence the swarf discharging slot generated chip. One purpose of the study on chip groove geometries is to make the chip continue to curl up in front of the tool. If the chip groove geometries are suitable for the processing of materials and operating conditions, the chip is usually not bump in the workpiece machining surface, or below the blade of the knife rod side, broken in a turnback, it is effective to control chip.%排屑槽的几何形状主要影响所生成切屑的形状、切削力和刀具性能。研究排屑槽几何形状的目的之一是要使切屑在经过刀具前面时能不断卷曲起来。如果排屑槽的几何形状适合于所加工的材料和操作条件,则切屑通常是碰击在工件的未加工面上或刀片下方的刀杆侧上,并且在转一圈后就断了,这是有效的控制切屑。

  16. Reduction of absorption loss in multicrystalline silicon via combination of mechanical grooving and porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Ben Rabha, Mohamed; Mohamed, Seifeddine Belhadj; Dimassi, Wissem; Gaidi, Mounir; Ezzaouia, Hatem; Bessais, Brahim [Laboratoire de Photovoltaique, Centre de Recherches et des Technologies de l' Energie, Technopole de Borj-Cedria, BP 95, 2050 Hammam-Lif (Tunisia)

    2011-03-15

    Surface texturing of silicon wafer is a key step to enhance light absorption and to improve the solar cell performances. While alkaline-texturing of single crystalline silicon wafers was well established, no efficient chemical solution has been successfully developed for multicrystalline silicon wafers. Thus, the use of alternative new methods for effective texturization of multicrystalline silicon is worth to be investigated. One of the promising texturing techniques of multicrystalline silicon wafers is the use of mechanical grooves. However, most often, physical damages occur during mechanical grooves of the wafer surface, which in turn require an additional step of wet processing-removal damage. Electrochemical surface treatment seems to be an adequate solution for removing mechanical damage throughout porous silicon formation. The topography of untreated and porous silicon-treated mechanically textured surface was investigated using scanning electron microscopy (SEM). As a result of the electrochemical surface treatment, the total reflectivity drops to about 5% in the 400-1000 nm wavelength range and the effective minority carrier diffusion length enhances from 190 {mu}m to about 230 {mu}m (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Large critical current density improvement in Bi-2212 wires through the groove-rolling process

    Science.gov (United States)

    Malagoli, A.; Bernini, C.; Braccini, V.; Romano, G.; Putti, M.; Chaud, X.; Debray, F.

    2013-04-01

    Recently there has been a growing interest in Bi-2212 superconductor round wire for high magnetic field use despite the fact that an increase of the critical current is still needed to boost its successful use in such applications. Recent studies have demonstrated that the main obstacle to current flow, especially in long wires, is the residual porosity inside these powder-in-tube processed conductors that develops from bubble agglomeration when the Bi-2212 melts. In this work we tried to overcome this issue affecting the wire densification by changing the deformation process. Here we show the effects of groove rolling versus the drawing process on the critical current density JC and on the microstructure. In particular, groove-rolled multifilamentary wires show a JC increased by a factor of about 3 with respect to drawn wires prepared with the same Bi-2212 powder and architecture. We think that this approach in the deformation process is able to produce the required improvements both because the superconducting properties are enhanced and because it makes the fabrication process faster and cheaper.

  18. Microjetting from grooved surfaces in metallic samples subjected to laser driven shocks

    Energy Technology Data Exchange (ETDEWEB)

    Rességuier, T. de, E-mail: resseguier@ensma.fr [Institut PPRIME, UPR 3346, CNRS, ENSMA, Université de Poitiers, 1 ave. Clément Ader, 86961 Futuroscope Cedex (France); Lescoute, E.; Sollier, A.; Prudhomme, G.; Mercier, P. [CEA, DAM, DIF, 91297 Arpajon (France)

    2014-01-28

    When a shock wave propagating in a solid sample reflects from a free surface, geometrical effects predominantly governed by the roughness and defects of that surface may lead to the ejection of tiny jets that may breakup into high velocity, approximately micrometer-size fragments. This process referred to as microjetting is a major safety issue for engineering applications such as pyrotechnics or armour design. Thus, it has been widely studied both experimentally, under explosive and impact loading, and theoretically. In this paper, microjetting is investigated in the specific loading conditions associated to laser shocks: very short duration of pressure application, very high strain rates, small spatial scales. Material ejection from triangular grooves in the free surface of various metallic samples is studied by combining transverse optical shadowgraphy and time-resolved velocity measurements. The influences of the main parameters (groove angle, shock pressure, nature of the metal) on jet formation and ejection velocity are quantified, and the results are compared to theoretical estimates.

  19. Microjetting from grooved surfaces in metallic samples subjected to laser driven shocks

    Science.gov (United States)

    de Rességuier, T.; Lescoute, E.; Sollier, A.; Prudhomme, G.; Mercier, P.

    2014-01-01

    When a shock wave propagating in a solid sample reflects from a free surface, geometrical effects predominantly governed by the roughness and defects of that surface may lead to the ejection of tiny jets that may breakup into high velocity, approximately micrometer-size fragments. This process referred to as microjetting is a major safety issue for engineering applications such as pyrotechnics or armour design. Thus, it has been widely studied both experimentally, under explosive and impact loading, and theoretically. In this paper, microjetting is investigated in the specific loading conditions associated to laser shocks: very short duration of pressure application, very high strain rates, small spatial scales. Material ejection from triangular grooves in the free surface of various metallic samples is studied by combining transverse optical shadowgraphy and time-resolved velocity measurements. The influences of the main parameters (groove angle, shock pressure, nature of the metal) on jet formation and ejection velocity are quantified, and the results are compared to theoretical estimates.

  20. Optical spectroscopy of GaAs/AlGaAs V-groove quantum wires Quantum wells

    CERN Document Server

    Roshan, R

    2001-01-01

    In this thesis we report on optical spectroscopy of GaAs/AIGaAs quantum wires (QWRs), grown on pre-patterned semi-insulating GaAs (100) substrates by low-pressure metal organic vapour phase epitaxy (LP-MOVPE). Crescent-shaped quantum wires develop at the bottom of the grooves by self-organisation when a GaAs quantum well embedded in Al sub 0 sub . sub 3 Ga sub 0 sub . sub 7 As barriers was overgrown on the patterned surface. The overgrowth also resulted in the formation of vertical quantum wells (VQWs) in the AIGaAs barriers and sidewall quantum wells (SQWs) on the (111) surfaces that define the grooves. A narrow constriction (pinch-off) separates the QWRs from the side walls and provides two-dimensional confinement in them. Several types of wire arrangements are investigated in detail which includes single QWR, vertical stacked QWRs, lateral arrays of wires with sub-mu m pitch and gated QWRs. Both conventional far-field and near-field spectroscopic techniques are used to study these wires. A low-temperature ...

  1. Grooved nanowires from self-assembling hairpin molecules for solar cells.

    Science.gov (United States)

    Tevis, Ian D; Tsai, Wei-Wen; Palmer, Liam C; Aytun, Taner; Stupp, Samuel I

    2012-03-27

    One of the challenges facing bulk heterojunction organic solar cells is obtaining organized films during the phase separation of intimately mixed donor and acceptor components. We report here on the use of hairpin-shaped sexithiophene molecules to generate by self-assembly grooved nanowires as the donor component in bulk heterojunction solar cells. Photovoltaic devices were fabricated via spin-casting to produce by solvent evaporation a percolating network of self-assembled nanowires and fullerene acceptors. Thermal annealing was found to increase power conversion efficiencies by promoting domain growth while still maintaining this percolating network of nanostructures. The benefits of self-assembly and grooved nanowires were examined by building devices from a soluble sexithiophene derivative that does not form one-dimensional structures. In these systems, excessive phase separation caused by thermal annealing leads to the formation of defects and lower device efficiencies. We propose that the unique hairpin shape of the self-assembling molecules allows the nanowires as they form to interact well with the fullerenes in receptor-ligand type configurations at the heterojunction of the two domains, thus enhancing device efficiencies by 23%.

  2. Functional morphology of unguiculiform papillae of the reticular groove in the ruminant stomach.

    Science.gov (United States)

    Teixeira, Althen F; Kühnel, Wolfgang; Vives, Patricia; Wedel, Thilo

    2009-11-01

    The arrangement of the ruminant stomach in four gastric compartments with specialized mucosal papillae along the gastric groove (GG) has been previously described. However, a debate remains about functional implications of these morphological pecularities. This study was aimed to elucidate the relation between the papillar morphology and its putative functions. The GG was obtained from adult bovine stomachs (n=10) and subdivided into (1) proximal, (2) middle, (3) distal portion of the reticular groove (RG) and (4) the area of the reticulo-omasal sphincter (ROS). The specimens were processed for scanning electron microscopy and stereomicroscopy to analyze the density, shape and location of the papillae. Whereas the proximal portion of the RG was characterized by small (1.5mm), conically shaped, smooth papillae, the middle portion exhibited larger papillae (4mm) with sharp borders covered by keratin. Towards the ROS the papillae further increased in size (3-11mm) and showed compound or single processes resembling the shape of arrows, twisted hooks or thorns (unguiculliform papillae). At the ROS the unguiculliform papillae were distributed in clusters groups and along the border of the sphincter. Due to their peculiar morphological features it is suggested that unguiculliform papillae functions as a filter barrier preventing the passage of large-sized food particles into the omasum and avoiding subsequent obstruction of both the RG and the ROS. The data give further evidence that unguiculliform papillae are actively involved in the complex mechanisms of food processing taking place within the ruminant pluricavity stomach.

  3. Probing the equatorial groove of the hookworm protein and vaccine candidate antigen, Na-ASP-2.

    Science.gov (United States)

    Mason, Lyndel; Tribolet, Leon; Simon, Anne; von Gnielinski, Natascha; Nienaber, Lisa; Taylor, Paul; Willis, Charlene; Jones, Malcolm K; Sternberg, Paul W; Gasser, Robin B; Loukas, Alex; Hofmann, Andreas

    2014-05-01

    Hookworm activation-associated secreted proteins can be structurally classified into at least three different groups. The hallmark feature of Group 1 activation-associated secreted proteins is a prominent equatorial groove, which is inferred to form a ligand binding site. Furthermore, a conserved tandem histidine motif is located in the centre of the groove and believed to provide or support a yet to be determined catalytic activity. Here, we report three-dimensional crystal structures of Na-ASP-2, an L3-secreted activation-associated secreted protein from the human hookworm Necator americanus, which demonstrate transition metal binding ability of the conserved tandem histidine motif. We further identified moderate phosphohydrolase activity of recombinant Na-ASP-2, which relates to the tandem histidine motif. By panning a random 12-mer peptide phage library, we identified a peptide with high similarity to the human calcium-activated potassium channel SK3, and confirm binding of the synthetic peptide to recombinant Na-ASP-2 by differential scanning fluorimetry. Potential binding modes of the peptide to Na-ASP-2 were studied by molecular dynamics simulations which clearly identify a preferred topology of the Na-ASP-2:SK3 peptide complex. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Dislocation density analyses of multi-crystalline silicon during the directional solidification process with bottom grooved furnace

    Science.gov (United States)

    Karuppasamy, P.; Srinivasan, M.; Aravinth, K.; Ramasamy, P.

    2016-05-01

    A transient global model was used to investigate the effect of bottom grooved furnace upon the directional solidification (DS) process of multicrystalline silicon (mc-Si). The computations were carried out on a 2D axisymmetric model using the finite volume method. The temperature distribution, crystal-melt (c-m) interface and dislocation density were simulated. The modified heat exchanger block system was used for controlling the temperature gradient at the bottom of the crucible. The obtained results shows convex shape of the c-m interface. The dislocation density was reduced while using the bottom grooved furnace. This work was carried out for the different groove of radius 30 and 60 mm of the heat exchanger block.

  5. A monofunctional platinum complex coordinated to a rhodium metalloinsertor selectively binds mismatched DNA in the minor groove.

    Science.gov (United States)

    Weidmann, Alyson G; Barton, Jacqueline K

    2015-10-05

    We report the synthesis and characterization of a bimetallic complex derived from a new family of potent and selective metalloinsertors containing an unusual Rh-O axial coordination. This complex incorporates a monofunctional platinum center containing only one labile site for coordination to DNA, rather than two, and coordinates DNA nonclassically through adduct formation in the minor groove. This conjugate displays bifunctional, interdependent binding of mismatched DNA via metalloinsertion at a mismatch as well as covalent platinum binding. DNA sequencing experiments revealed that the preferred site of platinum coordination is not the traditional N7-guanine site in the major groove, but rather N3-adenine in the minor groove. The complex also displays enhanced cytotoxicity in mismatch repair-deficient and mismatch repair-proficient human colorectal carcinoma cell lines compared to the chemotherapeutic cisplatin, and it triggers cell death via an apoptotic pathway, rather than the necrotic pathway induced by rhodium metalloinsertors.

  6. Numerical study of the collar wave characteristics and the effects of grooves in acoustic logging while drilling

    Science.gov (United States)

    Yang, Yufeng; Guan, Wei; Hu, Hengshan; Xu, Minqiang

    2017-05-01

    Large-amplitude collar wave covering formation signals is still a tough problem in acoustic logging-while-drilling (LWD) measurements. In this study, we investigate the propagation and energy radiation characteristics of the monopole collar wave and the effects of grooves on reducing the interference to formation waves by finite-difference calculations. We found that the collar wave radiates significant energy into the formation by comparing the waveforms between a collar within an infinite fluid, and the acoustic LWD in different formations with either an intact or a truncated collar. The collar wave recorded on the outer surface of the collar consists of the outward-radiated energy direct from the collar (direct collar wave) and that reflected back from the borehole wall (reflected collar wave). All these indicate that the significant effects of the borehole-formation structure on collar wave were underestimated in previous studies. From the simulations of acoustic LWD with a grooved collar, we found that grooves broaden the frequency region of low collar-wave excitation and attenuate most of the energy of the interference waves by multireflections. However, grooves extend the duration of the collar wave and convert part of the collar-wave energy originally kept in the collar into long-duration Stoneley wave. Interior grooves are preferable to exterior ones because both the low-frequency and the high-frequency parts of the collar wave can be reduced and the converted inner Stoneley wave is relatively difficult to be recorded on the outer surface of the collar. Deeper grooves weaken the collar wave more greatly, but they result in larger converted Stoneley wave especially for the exterior ones. The interference waves, not only the direct collar wave but also the reflected collar wave and the converted Stoneley waves, should be overall considered for tool design.

  7. Molecular Probing of the HPV-16 E6 Protein Alpha Helix Binding Groove with Small Molecule Inhibitors.

    Directory of Open Access Journals (Sweden)

    Anne Rietz

    Full Text Available The human papillomavirus (HPV HPV E6 protein has emerged as a central oncoprotein in HPV-associated cancers in which sustained expression is required for tumor progression. A majority of the E6 protein interactions within the human proteome use an alpha-helix groove interface for binding. The UBE3A/E6AP HECT domain ubiquitin ligase binds E6 at this helix-groove interface. This enables formation of a trimeric complex with p53, resulting in destruction of this tumor suppressor. While recent x-ray crystal structures are useful, examples of small molecule probes that can modulate protein interactions at this interface are limited. To develop insights useful for potential structure-based design of ligands for HPV E6, a series of 2,6-disubstituted benzopyranones were prepared and tested as competitive antagonists of E6-E6AP helix-groove interactions. These small molecule probes were used in both binding and functional assays to evaluate recognition features of the E6 protein. Evidence for an ionic functional group interaction within the helix groove was implicated by the structure-activity among the highest affinity ligands. The molecular topographies of these protein-ligand interactions were evaluated by comparing the binding and activities of single amino acid E6 mutants with the results of molecular dynamic simulations. A group of arginine residues that form a rim-cap over the E6 helix groove offer compensatory roles in binding and recognition of the small molecule probes. The flexibility and impact on the overall helix-groove shape dictated by these residues offer new insights for structure-based targeting of HPV E6.

  8. Ultrastructure of the harmful unarmored dinoflagellate Cochlodinium polykrikoides (Dinophyceae) with reference to the apical groove and flagellar apparatus

    DEFF Research Database (Denmark)

    Iwataki, Mitsunori; Hansen, Gert; Moestrup, Øjvind;

    2010-01-01

    The external and internal ultrastructure of the harmful unarmored dinoflagellate Cochlodinium polykrikoides Margalef has been examined with special reference to the apical groove and three-dimensional structure of the flagellar apparatus. The apical groove is U-shaped and connected to the anterior...... sulcal extension on the dorsal side of the epicone. The eyespot is located dorsally and composed of two layers of globules situated within the chloroplast. A narrow invagination of the plasma membrane is associated with the eyespot. The nuclear envelope has normal nuclear pores similar to other...

  9. An innovative approach in the management of palatogingival groove using Biodentine™ and platelet-rich fibrin membrane

    Science.gov (United States)

    Johns, Dexton Antony; Shivashankar, Vasundhara Yayathi; Shobha, K; Johns, Manu

    2014-01-01

    Palatogingival groove is an anatomical malformation that often causes severe periodontal defects. Treatments of such an anomaly present a clinical challenge to the operator. Careful endodontic and periodontal procedures may restore the form and function. In the present case; root canal therapy, apicectomy, and sealing of the groove with Biodentine™ were done. Bone graft was placed followed by platelet-rich fibrin (PRF) membrane. This treatment modality resulted in gain in attachment, reduction in pocket depth, and deposition of bone in the osseous defect. A 24 month follow-up is included. PMID:24554867

  10. An innovative approach in the management of palatogingival groove using Biodentine™ and platelet-rich fibrin membrane.

    Science.gov (United States)

    Johns, Dexton Antony; Shivashankar, Vasundhara Yayathi; Shobha, K; Johns, Manu

    2014-01-01

    Palatogingival groove is an anatomical malformation that often causes severe periodontal defects. Treatments of such an anomaly present a clinical challenge to the operator. Careful endodontic and periodontal procedures may restore the form and function. In the present case; root canal therapy, apicectomy, and sealing of the groove with Biodentine™ were done. Bone graft was placed followed by platelet-rich fibrin (PRF) membrane. This treatment modality resulted in gain in attachment, reduction in pocket depth, and deposition of bone in the osseous defect. A 24 month follow-up is included.

  11. [Treatment of advanced periodontal and periapical lesion caused by malformed lingual groove with guided tissue regeneration: report of one case].

    Science.gov (United States)

    Yu, Yi-ming; Sun, Qing-Feng; Yang, Pi-shan

    2005-08-01

    This paper reported one case with severe periodontal lesions caused by malformed lingual groove treated by guided tissue regeneration. The periodontal lesion was exposed palatally after the tooth had been treated with root canal therapy, the alveolar bone and the root surface was prepared, an unabsorbable member of e-PTFE was placed into the wound,and removed after 4 weeks, the patient was followed up for 3 years. The lesion recovered well three years after the operation, all of the periodontal tissue was in a healthy condition. It is advisable that guided periodontal tissue regeneration can be used as a new method to treat periodontal destruction induced by malformed lingual groove.

  12. Anatomia do sulco da artéria vertebral Vertebral artery groove anatomy

    Directory of Open Access Journals (Sweden)

    Max Franco de Carvalho

    2009-01-01

    Full Text Available INTRODUÇÃO: Diversas técnicas cirúrgicas têm sido realizadas na região craniocervical devido a diversas patologias. Durante o acesso cirúrgico a essa região existe um risco potencial de lesão iatrogênica da artéria vertebral, relacionado ao acesso lateral amplo e à avaliação inadequada da anatomia local. Variações no trajeto da artéria vertebral ocasionam maior risco de lesão vascular. O estudo pré-operatório por imagem da anatomia da artéria vertebral e do seu sulco tem sido realizado para aumentar a segurança cirúrgica. OBJETIVO: Estudar a morfometria da artéria vertebral no atlas através da tomografia computadorizada do sulco da artéria vertebral (SAV em 30 atlas isolados de cadáveres. MATERIAIS E MÉTODOS: O SAV e suas relações com a linha média foram avaliados através de oito medidas lineares e duas angulares, bilateralmente. A média, valor máximo e mínimo, e desvio padrão foram calculados para cada parâmetro. RESULTADOS: O SAV apresentou uma maior largura e maior espessura do lado esquerdo (pINTRODUCTION: Several surgical techniques have been carried through in the skull-cervical region due to various pathologies. During the surgical access to this region, a potential risk of iatrogenic injury of the vertebral artery exists, related to extended lateral access and the inadequate evaluation of the local anatomy. Variations in the groove of the vertebral artery lead to a greater risk of vascular injury during surgery. Preoperative image study of the vertebral artery anatomy and its groove has been realized to enhance surgical safety. OBJECTIVE: to study the morphometry of atlas vertebral artery on computed tomography scan images of the vertebral artery groove (VAG in 30 dry atlas. METHODS: VAG and its relationship with the midline were evaluated through eight linear and two angular measures, bilaterally. The average, maximum and minimum values, and standard deviation were calculated for each parameter

  13. Effect of axial groove and resin luting cements on the retention of complete cast metal crowns

    Directory of Open Access Journals (Sweden)

    K Rajkumar

    2009-01-01

    Full Text Available Background : The design of the tooth preparation and the cementing medium are important consid-erations in the retention of crowns and fixed partial dentures. The purpose of this invitro study was to determine the effect of axial groove on the retention of complete cast metal crowns using two resin luting cements. Methods: Forty freshly extracted intact human molar teeth were prepared in their long axis to receive complete cast metal crowns. The specimens were randomly divided into two groups (one control and one study group. An axial groove of uniform size and shape was made on the prepared teeth under the study group. Axial surface area of prepared teeth specimens was measured. Complete cast metal crowns were fabricated for each specimen. Specimens of each group were divided into subgroups of 10 samples and were cemented with two resin luting cements, RelyX Unicem® and Calibra®, re-spectively. The cemented crowns were loaded in tension using a Universal Instron testing machine. The maximal tensile strength was recorded. Data were compared using the Mann-Whitney U test (α=0.05. Results: No significant differences in the tensile stress values were noted between the control (mean: 5.76±0.392 MPa and study (mean: 5.93±0.751 MPa groups cemented with RelyX Unicem. No sig-nificant differences in the tensile stress values were noted between the control (mean: 4.92±0.641 MPa and study (mean: 5.15 ±0.478 MPa groups cemented with Calibra. However, significant dif-ference in the tensile stress values was found between the two resin cements in the control and study groups. Conclusion: Axial groove placed in tooth preparations for resin bonded complete cast metal crowns had no statistically significant effect on retention. The use of (RelyX Unicem® yielded greater reten-tion values when compared to Calibra®.

  14. New insight into the molecular mechanisms of the biological effects of DNA minor groove binders.

    Directory of Open Access Journals (Sweden)

    Xinbo Zhang

    Full Text Available BACKGROUND: Bisbenzimides, or Hoechst 33258 (H258, and its derivative Hoechst 33342 (H342 are archetypal molecules for designing minor groove binders, and widely used as tools for staining DNA and analyzing side population cells. They are supravital DNA minor groove binders with AT selectivity. H342 and H258 share similar biological effects based on the similarity of their chemical structures, but also have their unique biological effects. For example, H342, but not H258, is a potent apoptotic inducer and both H342 and H258 can induce transgene overexpression in in vitro studies. However, the molecular mechanisms by which Hoechst dyes induce apoptosis and enhance transgene overexpression are unclear. METHODOLOGY/PRINCIPAL FINDINGS: To determine the molecular mechanisms underlying different biological effects between H342 and H258, microarray technique coupled with bioinformatics analyses and multiple other techniques has been utilized to detect differential global gene expression profiles, Hoechst dye-specific gene expression signatures, and changes in cell morphology and levels of apoptosis-associated proteins in malignant mesothelioma cells. H342-induced apoptosis occurs in a dose-dependent fashion and is associated with morphological changes, caspase-3 activation, cytochrome c mitochondrial translocation, and cleavage of apoptosis-associated proteins. The antagonistic effect of H258 on H342-induced apoptosis indicates a pharmacokinetic basis for the two dyes' different biological effects. Differential global gene expression profiles induced by H258 and H342 are accompanied by unique gene expression signatures determined by DNA microarray and bioinformatics software, indicating a genetic basis for their different biological effects. CONCLUSIONS/SIGNIFICANCE: A unique gene expression signature associated with H342-induced apoptosis provides a new avenue to predict and classify the therapeutic class of minor groove binders in the drug

  15. Variation of chemical composition of high strength low alloy steels with different groove sizes in multi-pass conventional and pulsed current gas metal arc weld depositions

    Directory of Open Access Journals (Sweden)

    K. Devakumaran

    2015-06-01

    Full Text Available 25 mm thick micro-alloyed HSLA steel plate is welded by multi-pass GMAW and P-GMAW processes using conventional V-groove and suitably designed narrow gap with 20 mm (NG-20 and 13 mm (NG-13 groove openings. The variation of weld metal chemistry in the multi pass GMA and P-GMA weld depositions are studied by spark emission spectroscopy. It is observed that the narrow groove GMA weld joint shows significant variation of weld metal chemistry compared to the conventional V-groove GMA weld joint since the dilution of base metal extends from the deposit adjacent to groove wall to weld center through dissolution by fusion and solid state diffusion. Further, it is noticed that a high rate of metal deposition along with high velocity of droplet transfer in P-GMAW process enhances the dilution of weld deposit and accordingly varies the chemical composition in multi-pass P-GMA weld deposit. Lower angle of attack to the groove wall surface along with low heat input in NG-13 weld groove minimizes the effect of dissolution by fusion and solid state diffusion from the deposit adjacent to groove wall to weld center. This results in more uniform properties of NG-13 P-GMA weld in comparison to those of NG-20 and CG welds.

  16. An Improved Design of Spiral Groove Mechanical Seal%螺旋槽机械密封的改进设计

    Institute of Scientific and Technical Information of China (English)

    周剑锋; 顾伯勤; 陈晔

    2007-01-01

    The coupling effect among the flow of fluid film, the frictional heat of fluid film and the thermal deformation of sealing rings is inherent in mechanical seals. The frictional heat transfer analysis was carried out to optlmize the geometrical parameters of the sealing rings, such as the length, the inner radius and the outer radius. The geometrical parameters of spiral grooves, such as the spiral angle, the end radius, the groove depth, the ratio of the groove width to the weir width and the number of the grooves, were optimized by regarding the maximum bearing force of fluid film as the optimization objective with the coupling effect considered. The depth of spiral groove was designed to gradually increase from the end radius of spiral groove to the outer radius of end face in order to decrease the weakening effect of thermal deformation on the hydrodynamic effect of spiral grooves. The end faces of sealing rings were machined to form a divergent gap at inner radius, and a parallel gap will form to reduce the leakage rate when the thermal deformation takes place. The improved spiral groove mechanical seal possesses good heat transfer performance and sealing ability.

  17. Minimization of the Ohmic Loss of Grooved Polarizer Mirrors in High-Power ECRH Systems

    Science.gov (United States)

    Wagner, D.; Leuterer, F.; Kasparek, W.; Stober, J.

    2016-10-01

    A set of two corrugated polarizer mirrors is typically used in high-power electron cyclotron resonance heating (ECRH) systems to provide the required polarization of the ECRH output beam. The ohmic losses of these mirrors can significantly exceed the losses of plane mirrors depending on the polarization of the incident beam with respect to the orientation of the grooves. Since polarizer mirrors incorporated into miter bends of a corrugated waveguide line are limited in size, active water cooling can become critical in high-power cw systems like the one for ITER. The ohmic loss of polarizer mirrors has been investigated experimentally at high power. A strategy to minimize the losses for given mirror geometries has been found.

  18. [Psychopathology and neuro-ophthalmology in meningioma of the olfactory groove].

    Science.gov (United States)

    Lange, E; Bräunig, K P; Fötzsch, R

    1982-01-01

    In 14 patients with a surgically nad histopathologically verified meningioma of the olfactory nerve groove (OGM) (12 women, 2 men), clinical findings and diagnosis were analysed, especially with respect to neuropathology and psychopathology. The apodictic theorem that an OGM leads to a Foster-Kennedy syndrome as well as to a psychopathological orbital brain syndrome cannot be maintained. The Foster-Kennedy syndrome does not occur in a characteristically high incidence, and psychopathologically an orbital brain syndrome can only be diagnosed in case of an anterior location of the OGM. The more the OGM shows starting point or growth development to or from the anterior chiasmal angle, the more is resembles that psychopathological syndrome that we have found and described for the meningioma of the Tuberculus sellae.

  19. Combined endodontic therapy and periapical surgery with MTA and bone graft in treating palatogingival groove.

    Science.gov (United States)

    Mittal, Mudit; Vashisth, Pallavi; Arora, Rachita; Dwivedi, Swati

    2013-04-18

    A 37-year-old male patient reported to our department with chief complaint of pain and pus discharge from the labial marginal gingiva in the maxillary right lateral incisor region since last 4 months. Clinically, the tooth was hypersensitive to percussion and palpation but failed to respond to pulp sensitivity testing. After periodontal probing, a palatal groove was observed which started at the cingulum and travelled apically and laterally, associated with a pocket depth of 8 mm. Occlusal radiograph showed circumscribed radiolucency measuring 5 mm×7 mm in diameter at the apex of the tooth. A clinical diagnosis of chronic apical abscess was established. The case was treated with a combination of mineral trioxide aggregate and bone graft. At the 6-month follow-up visit, the tooth showed progressive healing without sinus track and sulcular bleeding.

  20. GaAs Solar Cells on V-Grooved Silicon via Selective Area Growth: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Warren, Emily L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jain, Nikhil [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tamboli, Adele C [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Vaisman, Michelle [Yale University; Li, Qiang [Hong Kong University of Science and Technology; Lau, Kei May [Hong Kong University of Science and Technology

    2017-08-31

    Interest in integrating III-Vs onto Si has recently resurged as a promising pathway towards high-efficiency, low-cost tandem photovoltaics. Here, we present a single junction GaAs solar cell grown monolithically on polished Si (001) substrates using V-grooves, selective area growth, and aspect ratio trapping to mitigate defect formation without the use of expensive, thick graded buffers. The GaAs is free of antiphase domains and maintains a relatively low TDD of 4x107 cm-2, despite the lack of a graded buffer. This 6.25 percent-efficient demonstration solar cell shows promise for further improvements to III-V/Si tandems to enable cost-competitive photovoltaics.

  1. Optimizing the subwavelength grating of L-band Annular Groove Phase Masks for high coronagraphic performance

    CERN Document Server

    Catalan, Ernesto Vargas; Forsberg, Pontus; Jolivet, Aïssa; Baudoz, Pierre; Carlomagno, Brunella; Delacroix, Christian; Habraken, Serge; Mawet, Dimitri; Surdej, Jean; Absil, Olivier; Karlsson, Mikael

    2016-01-01

    Context. The Annular Groove Phase Mask (AGPM) is one possible implementation of the vector vortex coronagraph, where the helical phase ramp is produced by a concentric subwavelength grating. For several years, we have been manufacturing AGPMs by etching gratings into synthetic diamond substrates using inductively coupled plasma etching. Aims. We aim to design, fabricate, optimize, and evaluate new L-band AGPMs that reach the highest possible coronagraphic performance, for applications in current and forthcoming infrared high-contrast imagers. Methods. Rigorous coupled wave analysis (RCWA) is used for designing the subwavelength grating of the phase mask. Coronagraphic performance evaluation is performed on a dedicated optical test bench. The experimental results of the performance evaluation are then used to accurately determine the actual profile of the fabricated gratings, based on RCWA modeling. Results. The AGPM coronagraphic performance is very sensitive to small errors in etch depth and grating profile....

  2. Mechanical grooving of oxidized porous silicon to reduce the reflectivity of monocrystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zarroug, A.; Dimassi, W.; Ouertani, R.; Ezzaouia, H. [Laboratoire de Photovoltaique, Centre des Recherches et des Technologies de l' Energie, BP. 95, Hammam-Lif 2050 (Tunisia)

    2012-10-15

    In this work, we are interested to use oxidized porous silicon (ox-PS) as a mask. So, we display the creating of a rough surface which enhances the absorption of incident light by solar cells and reduces the reflectivity of monocrystalline silicon (c-Si). It clearly can be seen that the mechanical grooving enables us to elaborate the texturing of monocrystalline silicon wafer. Results demonstrated that the application of a PS layer followed by a thermal treatment under O2 ambient easily gives us an oxide layer of uniform size which can vary from a nanometer to about ten microns. In addition, the Fourier transform infrared (FTIR) spectroscopy investigations of the PS layer illustrates the possibility to realize oxide layer as a mask for porous silicon. We found also that this simple and low cost method decreases the total reflectivity (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. THE MECHANISM OF FRICTION BETWEEN SURFACES WITH REGULAR MICRO GROOVES UNDER BOUNDARY LUBRICATION

    Directory of Open Access Journals (Sweden)

    Mykhaylo Pashechko

    2012-12-01

    Full Text Available The results of researches related to the influence of partially regular microrelief parameters on the adhesion component of the friction factor under boundary lubrication have been given. A special ring-on tape test rig is proposed in order to avoid errors during running-in process. Special technique is used to form sinusoidal microgrooves what helped to create a partially regular microrelief on the surface with controlled contour and nominal contact areas. Fatigue and deformation components of wear process are considered. We proved that microtexturing with proposed parameters decreases the adhesion component of friction and reduces the probability of microwelding. It has been shown that under boundary friction micro grooves are effective on precision surfaces with low roughness when lack of film and probability of seizure appear.

  4. Prediction of leakage and rotordynamic coefficients for the circumferential-groove pump seal using CFD analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Ho; Ha, Tae Woong [Gachon University, Seongnam (Korea, Republic of)

    2016-05-15

    The circumferential-groove seal is commonly used in various turbopumps to reduce leakage. The main goal of this paper is to develop the method of three-dimensional CFD analysis for determining leakage and rotordynamic coefficients of the circumferential-groovepump seal. A relative coordinate system was defined for steady-state simulation to calculate the velocity and pressure distributions of the seal clearance at each rotor whirl speed. Instead of setting the inlet and outlet pressures as the boundary conditions in the three dimensional CFD analysis, as it is more commonly done, we used the inlet velocity and outlet pressure obtained from a preliminary two dimensional CFD analysis. For prediction leakage, the presented analysis shows improvement from the bulk-flow model analysis. For the prediction of rotordynamic coefficients of K, k and C, the presented analysis provides results in closer agreement with the experimental values than those of the bulk-flow model analysis at several rotor speeds.

  5. Minimization of the Ohmic Loss of Grooved Polarizer Mirrors in High-Power ECRH Systems

    Science.gov (United States)

    Wagner, D.; Leuterer, F.; Kasparek, W.; Stober, J.

    2017-02-01

    A set of two corrugated polarizer mirrors is typically used in high-power electron cyclotron resonance heating (ECRH) systems to provide the required polarization of the ECRH output beam. The ohmic losses of these mirrors can significantly exceed the losses of plane mirrors depending on the polarization of the incident beam with respect to the orientation of the grooves. Since polarizer mirrors incorporated into miter bends of a corrugated waveguide line are limited in size, active water cooling can become critical in high-power cw systems like the one for ITER. The ohmic loss of polarizer mirrors has been investigated experimentally at high power. A strategy to minimize the losses for given mirror geometries has been found.

  6. Palatogingival groove mimicking as a mutilated root fracture in a maxillary lateral incisor: a case report.

    Science.gov (United States)

    Vasanth, Kumar; Kottoor, Jojo; Nandini, Suresh; Velmurugan, Natanasabapathy; Abarajithan, Mohan

    2014-01-01

    This article presents a case of a palatogingival groove (PPG) in tooth No. 12 that was misdiagnosed as a mutilated root fracture. A PPG is a developmental anomaly that predisposes a tooth to a severe periodontal defect. The initial diagnosis of mutilated root fracture on tooth No. 12 was made solely from radiographs that showed a vertical and horizontal radiolucent line with a radiolucent halo-shaped bone resorption in relation to the root apex. Transillumination, bite test, surgical visualization of the site, and the use of high-end diagnostic modalitieswere not considered prior to the final diagnosis. PPG was confirmed only after the tooth was extracted and observed under a dental operating microscope.

  7. Far-field characteristics of the square grooved-dielectric lens antenna for the terahertz band.

    Science.gov (United States)

    Pan, Wu; Zeng, Wei

    2016-09-10

    In order to improve the gain and directionality of a terahertz antenna, a square grooved-dielectric lens antenna based on a Fresnel zone plate is proposed. First, a diagonal horn, which is adopted as the primary feed antenna, is designed. Then, the far-field characteristics of the lens antenna are studied by using Fresnel-Kirchhoff diffraction theory and the paraxial approximation. The effects of the full-wave period, the focus diameter ratio, the subregion, and the dielectric substrate thickness on radiation characteristics are studied. The experimental results show that the proposed lens antenna has axisymmetric radiation patterns. The gain is over 26.1 dB, and the 3 dB main lobe beam width is lower than 5.6° across the operation band. The proposed lens antenna is qualified for applications in terahertz wireless communication systems.

  8. Deciphering the groove binding modes of tau-fluvalinate and flumethrin with calf thymus DNA

    Science.gov (United States)

    Tao, Mo; Zhang, Guowen; Pan, Junhui; Xiong, Chunhong

    2016-02-01

    Tau-fluvalinate (TFL) and flumethrin (FL), widely used in agriculture and a class of synthetic pyrethroid pesticides with a similar structure, may cause a potential security risk. Herein, the modes of binding in vitro of TFL and FL with calf thymus DNA (ctDNA) were characterized by fluorescence, UV-vis absorption, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy with the aid of viscosity measurements, melting analyses and molecular docking studies. The fluorescence titration indicated that both TFL and FL bound to ctDNA forming complexes through hydrogen bonding and van der Waals forces. The binding constants of TFL and FL with ctDNA were in the range of 104 L mol- 1, and FL exhibited a higher binding propensity than TFL. The iodide quenching effect, single/double-stranded DNA effects, and ctDNA melting and viscosity measurements demonstrated that the binding of both TFL and FL to ctDNA was groove mode. The FT-IR analyses suggested the A-T region of the minor groove of ctDNA as the preferential binding for TFL and FL, which was confirmed by the displacement assays with Hoechst 33258 probe, and the molecular docking visualized the specific binding. The changes in CD spectra indicated that both FL and TFL induced the perturbation on the base stacking and helicity of B-DNA, but the disturbance caused by FL was more obvious. Gel electrophoresis analyses indicated that both TFL and FL did not cause significant DNA cleavage. This study provides novel insights into the binding properties of TFL/FL with ctDNA and its toxic mechanisms.

  9. Structural, conformational and thermodynamic aspects of groove-directed-intercalation of flavopiridol into DNA.

    Science.gov (United States)

    Ray, Bhumika; Agarwal, Shweta; Lohani, Neelam; Rajeswari, Moganty R; Mehrotra, Ranjana

    2016-11-01

    Certain plant-derived alkaloids and flavonoids have shown propitious cytotoxic acitvity against different types of cancer, having deoxyribose nucleic acid (DNA) as their main cellular target. Flavopiridol, a semi-synthetic derivative of rohitukine (a natural compound isolated from Dysoxylum binectariferum plant), has attained much attention owing to its anticancer potential against various haematological malignancies and solid tumours. This work focuses on investigating interaction between flavopiridol and DNA at molecular level in order to decipher its underlying mechanism of action, which is not well understood. To define direct influence of flavopiridol on the structural, conformational and thermodynamic aspects of DNA, various spectroscopic and calorimetric techniques have been used. ATR-FTIR and SERS spectral outcomes indicate a novel insight into groove-directed-intercalation of flavopiridol into DNA via direct binding with nitrogenous bases guanine (C6=O6) and thymine (C2=O2) in DNA groove together with slight external binding to its sugar-phosphate backbone. Circular dichroism spectral analysis of flavopiridol-DNA complexes suggests perturbation in native B-conformation of DNA and its transition into C-form, which may be localized up to a few base pairs of DNA. UV-visible spectroscopic results illustrate dual binding mode of flavopiridol when interacts with DNA having association constant, Ka = 1.18 × 10(4) M(-1). This suggests moderate type of interaction between flavopiridol and DNA. Further, UV melting analysis also supports spectroscopic outcomes. Thermodynamically, flavopiridol-DNA complexation is an enthalpy-driven exothermic process. These conclusions drawn from this study could be helpful in unveiling mechanism of cytoxicity induced by flavopiridol that can be further applied in the development of flavonoid-based new chemotherapeutics with more specificity and better efficacy.

  10. Deciphering the groove binding modes of tau-fluvalinate and flumethrin with calf thymus DNA.

    Science.gov (United States)

    Tao, Mo; Zhang, Guowen; Pan, Junhui; Xiong, Chunhong

    2016-02-15

    Tau-fluvalinate (TFL) and flumethrin (FL), widely used in agriculture and a class of synthetic pyrethroid pesticides with a similar structure, may cause a potential security risk. Herein, the modes of binding in vitro of TFL and FL with calf thymus DNA (ctDNA) were characterized by fluorescence, UV-vis absorption, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy with the aid of viscosity measurements, melting analyses and molecular docking studies. The fluorescence titration indicated that both TFL and FL bound to ctDNA forming complexes through hydrogen bonding and van der Waals forces. The binding constants of TFL and FL with ctDNA were in the range of 10(4)Lmol(-1), and FL exhibited a higher binding propensity than TFL. The iodide quenching effect, single/double-stranded DNA effects, and ctDNA melting and viscosity measurements demonstrated that the binding of both TFL and FL to ctDNA was groove mode. The FT-IR analyses suggested the A-T region of the minor groove of ctDNA as the preferential binding for TFL and FL, which was confirmed by the displacement assays with Hoechst 33258 probe, and the molecular docking visualized the specific binding. The changes in CD spectra indicated that both FL and TFL induced the perturbation on the base stacking and helicity of B-DNA, but the disturbance caused by FL was more obvious. Gel electrophoresis analyses indicated that both TFL and FL did not cause significant DNA cleavage. This study provides novel insights into the binding properties of TFL/FL with ctDNA and its toxic mechanisms.

  11. Performance analysis of sandwiched flux-switching machines using V-shape permanent magnets%集成式“V”形永磁体磁通切换电机性能分析

    Institute of Scientific and Technical Information of China (English)

    莫丽红; 全力; 朱孝勇; 陈云云

    2015-01-01

    为提高永磁磁通切换电机中永磁体利用率,介绍了一种集成式“V”形永磁体磁通切换电机,分析了其结构特点,对电机绕组空载反电势、转矩特性、损耗以及效率等电磁性能进行了有限元分析并与常规12/10极磁通切换电机进行了比较。研究表明,相对于常规永磁磁通切换电机,该电机结构能有效提高永磁材料的利用率及功率密度。在相同线负荷下,该电机平均输出转矩提高了22.8%,转矩/永磁材料体积比值提高了26.3%,额定负载时输出功率能增加近24%,效率则下降2.1%。总体说来,该电机继承了永磁无刷类电机高效率、高转矩密度、高功率密度的特点,在电动汽车等新能源汽车领域具有应用前景。%In order to improve the PM usage efficiency in switched-flux permanent magnet machine, a new sandwiched switched-flux and V-shape permanent-magnet ( SSFVPM) machine was proposed and its to-pology was analyzed. Based on the finite element analysis ( FEA) , the back electromotive force ( EMF) , torque characteristics, total losses, and efficiency were investigated in details. The simulation results are compared with those of a conventional 12/10-pole flux-switching permanent-magnet ( FSPM) machine. It shows that the usage efficiency of magnets and power density are significantly increased. Compared with the conventional FSPM machine with the same electric loading, the average output torque and the ratio of torque/PM volume increase to 22. 8% and 26. 3% separately. Meanwhile, the efficiency of SSFVPM ma-chine shows a slight decrease of 2. 1%, while the output power increases nearly to 24%. Hence, the SS-FVPM machine still retains the merits of permanent magnet brushless machine of high efficiency, high torque density, and high power density, which makes the machine very promising for electric vehicles ( EVs) and other new energy electric vehicle applications.

  12. Fatigue growth of a surface crack in a V-shaped notched round bar under cyclic tension%反复张力下V形切口圆条的表面裂纹的疲劳扩展

    Institute of Scientific and Technical Information of China (English)

    Devi CHANDRA; Judha PURBOLAKSONO; Yusoff NUKMAN; Haw-ling LIEW; Singh RAMESH; Mohsen-abdel HASSAN

    2014-01-01

    This paper presents modeling results for fatigue crack growths of a semi-elliptical surface crack in a V-shaped notched round bar under uniform cyclic tension. All the analyses were carried out by using a software package featuring the boundary element method. The J-integral technique was used to compute the stress intensity factors (SIFs), and the NASGRO crack growth rate was chosen to simulate the fatigue crack growths. Mechanical and fracture properties of AZ-6A-T5 magnesium alloy were used for our analysis. Crack shape evolutions for different crack aspect ratios and the corresponding SIFs may be correlated to study the behavior of crack growths. An unstable crack growth was observed when the evolving crack aspect ratio was between 0.6 and 0.7. Careful consideration should be taken if the cylinder contains a defect which has a straight shape on the crack front or a smaller crack aspect ratio.%研究目的:在相同的反复张力下,研究V形切口圆条表面裂纹的疲劳扩展规律。  研究方法:1.构建V形切口圆条模型(图1),基于线性二次元将模型表面离散成一个个网格点(图2);2.以AZ-6A-T5镁合金为例,利用J积分计算应力强度因数,利用NASGRO裂纹增长率模拟裂纹的疲劳扩展;3.通过研究不同的裂纹纵横比和对应的应力强度因数之间的相关性来研究裂纹的扩展。  重要结论:1.在裂纹扩展时裂纹纵横比的初始值对断裂形状的发展有重要影响;2.裂纹纵横比对疲劳负荷寿命的作用比缺口半径更加明显;3.当裂纹前缘演变成一条直线形时可观察到不稳定的裂纹扩展;4.裂纹深度一定时,断裂纵横比越小,疲劳负荷寿命越短;5.当裂纹纵横比为0.6-0.7时,出现了不稳定的裂纹扩展。

  13. Endodontic and periodontal management of a severely affected maxillary lateral incisor having combined mucosal fenestration and palatogingival groove

    Directory of Open Access Journals (Sweden)

    Sarang Sharma

    2015-01-01

    Full Text Available Mucosal fenestrations, wherein the tooth root apices are clinically discernible in the oral cavity subsequent to loss of overlying alveolar bone and mucosa, are rare pathologic entities. Palato gingival grooves- anatomic aberrations are also infrequent occurrences that notoriously predispose to periodontal pathologies of varying extent. Both conditions independently are known to popularly affect maxillary lateral incisors. Coexistent fenestration defect and palato gingival groove in the same tooth is extremely rare and undoubtedly is a perfect combination to precipitate severe endodontic-periodontal consequences. In this report, a 34-year-old patient presented to the dental department with complaint of esthetics in relation to exposed root of right maxillary lateral incisor. On closer inspection, a palato gingival groove in addition to fenestration defect was evident on the root surface along with a periodontal pocket of >5 mm. An interdisciplinary treatment was instituted which included endodontic treatment followed by root end resection, osseous bone graft placement and guided tissue regeneration procedures for repair of mucosal fenestration defect. Debridement of the palatal pocket, with saucerization of the groove and restoration with glass ionomer cement were simultaneously employed to correct the palatal defect.

  14. Zooming into the binding groove of HLA molecules : which positions and which substitutions change peptide binding most?

    NARCIS (Netherlands)

    van Deutekom, Hanneke W M; Kesmir, C.

    2015-01-01

    Human leukocyte antigen (HLA) genes are the most polymorphic genes in the human genome. Almost all polymorphic residues are located in the peptide-binding groove, resulting in different peptide-binding preferences. Whether a single amino acid change can alter the peptide-binding repertoire of an HLA

  15. A finite element solution of the Reynolds equation of lubrication with film discontinuities: application to helical groove seals

    Science.gov (United States)

    Jarray, M.; Souchet, D.; Henry, Y.; Fatu, A.

    2017-02-01

    Helical groove seal, is one of the very few non-contact seals that have the capability to effectively seal a liquid. It finds use mainly in turbines and compressors. Although its reliability, this type of seals has not been investigated thoroughly because of its complex characteristics. This work presents a numerical analysis of a helical groove seal operating in laminar regime by means of solving the Reynolds equations for incompressible fluid film in steady state. Equations governing the fluid flow were solved by the finite element method. Although the simplifying assumptions of Reynolds model help to keep the computational time at an acceptable level, the inertia effects are neglected which may lead to unreliable results especially where the film thickness is discontinuous. The present approach, inspired by Arghir et al. [1] is able to take into account concentrated inertia effects, as described by a generalized Bernoulli equation. Comparisons made with the classical Reynolds model show that the film discontinuities should be taken into account when dealing with helically grooved seals. In addition, the leakage of fluid towards the air side was investigated for different parameters such as the groove angle and depth.

  16. Variation in number of trunk vertebrae and in count of costal grooves in salamanders of the family Hynobiidae

    NARCIS (Netherlands)

    Litvinchuk, S.N.; Borkin, L.J.

    2003-01-01

    Ten species from five genera of the family Hynobiidae were studied. The number of trunk vertebrae varied between 14 and 21, and the count of costal grooves ranged from 10 to 15. Both the within-species variation and the within-population variation were recorded in some species. In both kinds the val

  17. Sensitive detection of African swine fever virus using real-time PCR with a 5' conjugated minor groove binding probe

    DEFF Research Database (Denmark)

    McKillan, John; McMenamy, Michael; Hjertner, Bernt;

    2010-01-01

    The design of a 5′ conjugated minor groove binder (MGB) probe real-time PCR assay is described for the rapid, sensitive and specific detection of African swine fever virus (ASFV) DNA. The assay is designed against the 9GL region and is capable of detecting 20 copies of a DNA standard. It does...

  18. Sequence-specific high mobility group box factors recognize 10-12-base pair minor groove motifs

    DEFF Research Database (Denmark)

    van Beest, M; Dooijes, D; van De Wetering, M

    2000-01-01

    Sequence-specific high mobility group (HMG) box factors bind and bend DNA via interactions in the minor groove. Three-dimensional NMR analyses have provided the structural basis for this interaction. The cognate HMG domain DNA motif is generally believed to span 6-8 bases. However, alignment...

  19. Troxerutin, a natural flavonoid binds to DNA minor groove and enhances cancer cell killing in response to radiation.

    Science.gov (United States)

    Panat, Niranjan A; Singh, Beena G; Maurya, Dharmendra K; Sandur, Santosh K; Ghaskadbi, Saroj S

    2016-05-05

    Troxerutin, a flavonoid best known for its radioprotective and antioxidant properties is of considerable interest of study due to its broad pharmacological activities. The present study on troxerutin highlights its abilities to bind DNA and enhance cancer cell killing in response to radiation. Troxerutin showed strong binding with calf thymus DNA in vitro. Troxerutin-DNA interaction was confirmed by CD spectropolarimetry. The mode of binding of troxerutin to DNA was assessed by competing troxerutin with EtBr or DAPI, known DNA intercalator and a minor groove binder, respectively. DAPI fluorescence was drastically reduced with linear increase in troxerutin concentration suggesting possible binding of troxerutin to DNA minor groove. Further, computational studies of docking of troxerutin molecule on mammalian DNA also indicated possible troxerutin-DNA interaction at minor groove of DNA. Troxerutin was found to mainly localize in the nucleus of prostate cancer cells. It induced cytotoxicity in radioresistant (DU145) and sensitive (PC3) prostate cancer cells. When troxerutin pre-treated DU145 and PC3 cells were exposed to γ-radiation, cytotoxicity as estimated by MTT assay, was found to be further enhanced. In addition, the % subG1 population detected by propidium iodide staining also showed similar response when combined with radiation. A similar trend was observed in terms of ROS generation and DNA damage in DU145 cells when troxerutin and radiation were combined. DNA binding at minor groove by troxerutin may have contributed to strand breaks leading to increased radiation induced cell death.

  20. Odour sensitivity of antennal olfactory cells underlying grooved pegs of Anopheles gambiae s.s. and An. quadriannulatus

    NARCIS (Netherlands)

    van den Broek, IVF; den Otter, CJ

    2000-01-01

    In female mosquitoes of the anthropophilic species Anopheles gambiae Giles s.s. and the zoophilic An. quadriannulatus Theobald single sensillum recordings from grooved pegs were made. In both species, the majority of these sensilla responded to ammonium hydroxide, butylamine and propanoic acid, wher

  1. A simulation study of the micro-grooved electrode structure for back-contact back-junction silicon solar cell

    Science.gov (United States)

    Zhang, Bo; Yang, Jianfeng

    2015-01-01

    A micro-grooved electrode structure is investigated to illustrate its advantages when applied to the back-contact back-junction (BC-BJ) silicon solar cell. The finite element analysis shows that the micro-grooved electrodes enhances the photo-carrier collection and weakens the dependence of collection ability on pitch distance. The geometries of micro-groove are found to have little impact on the cell performance. These advantages open possibilities for the implementation of low cost fabrication methods. As a demonstration, a process involving laser doping and screen printing techniques are proposed and analyzed. The simulation results show that the laser induced lattice damage causes negligible deterioration of device electrical properties and the presence of parasitic metal insulator semiconductor structure near the screen printed electrodes actually leads to a performance improvement rather than degradation. Our preliminary results indicate that the micro-grooved electrode structure is promising for fabricating low cost high efficiency BC-BJ silicon solar cells.

  2. Effect of nitrogen-doped graphene nanofluid on the thermal performance of the grooved copper heat pipe

    DEFF Research Database (Denmark)

    Mehrali, Mohammad; Sadeghinezhad, Emad; Azizian, Reza

    2016-01-01

    Thermal performance of a grooved heat pipe using aqueous nitrogen-doped graphene (NDG) nanofluids was analysed. This study in particular focused on the effect of varying NDG nanosheets concentrations, heat pipe inclination angles and input heating powers. The results indicated that the inclination...

  3. Numerical Analysis of Rotating Pumping Flows in Inter-Coil Rotor Cavities and Short Cooling Grooves of a Generator

    Directory of Open Access Journals (Sweden)

    Wei Tong

    2001-01-01

    Full Text Available An important characteristic of wall rotating-driven flows is the tendency of fluid with high angular momentum to be flung radially outward. For a generator, the rotor rotating-driven flow, usually referred to as the rotating pumping flow, plays an important role in rotor winding cooling. In this study, three-dimensional numerical analyzes are presented for turbulent pumping flow in the inter-coil rotor cavity and short cooling grooves of a generator. Calculations of the flow field and the mass flux distribution through the grooves were carried out in a sequence of four related cases Under an isothermal condition: (a pumping flow, which is the self-generated flow resulted from the rotor pumping action; (b mixing flow, which is the combination of the ventilating flow and pumping flow, under a constant density condition; (c mixing flow, with density modeled by the ideal gas law; and (d mixing flow, with different pressure differentials applied on the system. The comparisons of the results from these cases can provide useful information regarding the impacts of the ventilating flow, gas density, and system pressure differential on the mass flux distribution in the short cooling grooves. Results show that the pumping effect is strong enough to generate the cooling flow for rotor winding cooling. Therefore, for small- or mid-size generators ventilation fans may be eliminated. It also suggests that increasing the chimney dimension can improve the distribution uniformity of mass flux through the cooling grooves.

  4. Plasmonic black metals via radiation absorption by two-dimensional arrays of ultra-sharp convex grooves

    DEFF Research Database (Denmark)

    Beermann, Jonas; Eriksen, René L.; Stær, Tobias Holmgaard;

    2014-01-01

    Plasmonic black surfaces formed by two-dimensional arrays of ultra-sharp convex metal grooves, in which the incident radiation is converted into gap surface plasmon polaritons (GSPPs) and subsequently absorbed (via adiabatic nanofocusing), are fabricated and investigated experimentally for gold...

  5. Heat transfer model of dropwise condensation and experimental validation for surface with coating and groove at low pressure

    Science.gov (United States)

    Lu, C.-H.; Beckmann, M.; Unz, S.; Gloess, D.; Frach, P.; Holst, E.; Lasagni, A.; Bieda, M.

    2016-01-01

    It is well known that dropwise condensation corresponds to a high heat transfer coefficient. The high performance enhancement of dropwise condensation in comparison to filmwise condensation is attributed to the ability of non-wetting droplets to be shed from the surface by gravity, therefore reducing the overall thermal resistance. The common treatments to carry out the hydrophobic surface for dropwise condensation are coating and structure. The improvement of heat transfer efficiency by combination of surface treatments with coating and groove structure has been proved compared of surface with single surface treatment by coating or groove structure. Based on this result, in this study presents a model developed to predict the heat transfer efficiency of dropwise condensation for surface with coating and groove structure features. The model is established by heat transfer though a single droplet with the drop size distribution. The heat transfer of single drop is not only analyzed as combination of thermal resistances, but also considered capillary effect of droplet due to groove geometry and properties of surface. In addition, the model results are validated with experimental data which is investigated by varied modification of vapor side metallic surface properties at low absolute pressure. It can be a reference to design industrial condensers of heat exchangers in the future. Further to optimize the surface properties and improve the higher heat transfer performance of dropwise condensation.

  6. Unusually strong binding to the DNA minor groove by a highly twisted benzimidazole diphenylether: induced fit and bound water.

    Science.gov (United States)

    Tanious, Farial A; Laine, William; Peixoto, Paul; Bailly, Christian; Goodwin, Kristie D; Lewis, Mark A; Long, Eric C; Georgiadis, Millie M; Tidwell, Richard R; Wilson, W David

    2007-06-12

    RT29 is a dicationic diamidine derivative that does not obey the classical "rules" for shape and functional group placement that are expected to result in strong binding and specific recognition of the DNA minor groove. The compound contains a benzimidazole diphenyl ether core that is flanked by the amidine cations. The diphenyl ether is highly twisted and gives the entire compound too much curvature to fit well to the shape of the minor groove. DNase I footprinting, fluorescence intercalator displacement studies, and circular dichroism spectra, however, indicate that the compound is an AT specific minor groove binding agent. Even more surprisingly, quantitative biosensor-surface plasmon resonance and isothermal titration calorimetric results indicate that the compound binds with exceptional strength to certain AT sequences in DNA with a large negative enthalpy of binding. Crystallographic results for the DNA complex of RT29 compared to calculated results for the free compound show that the compound undergoes significant conformational changes to enhance its minor groove interactions. In addition, a water molecule is incorporated directly into the complex to complete the compound-DNA interface, and it forms an essential link between the compound and base pair edges at the floor of the minor groove. The calculated DeltaCp value for complex formation is substantially less than the experimentally observed value, which supports the idea of water being an intrinsic part of the complex with a major contribution to the DeltaCp value. Both the induced fit conformational changes of the compound and the bound water are essential for strong binding to DNA by RT29.

  7. Heat transfer enhancement through inner grooved copper tubes with different tube parameters

    Directory of Open Access Journals (Sweden)

    M. M. Rahman, Y. M. Ling, G. W. Soon, G. A. Kuan

    2012-01-01

    Full Text Available This paper presents the evaluation of heat transfer coefficients for the flow of R22 through internally grooved copper tubes. A series of tests were conducted using two types of tubes namely Tube A and Tube B, which have different tube parameters. The straight and horizontal test section of the test apparatus with a length of 3.67 m was heated or cooled by water circulated in a surrounding annulus. Condensation tests were conducted at mass flux rates of 180 to 537 kg/m2s and the vapor qualities ranged from a nominal value of 83% at the test section inlet to 6% at the outlet. Evaporation tests were conducted at mass flux rates of 110 to 404 kg/m2s and the nominal vapor qualities at the inlet and outlet were 0 and 85%, respectively. For both the condensation and evaporation tests, the heat transfer coefficients are found to increase as the mass flux rate increases.

  8. Au-induced deep groove nanowire structure on the Ge(001) surface: DFT calculations

    Science.gov (United States)

    Tsay, Shiow-Fon

    2016-09-01

    The atomic geometry, stability, and electronic properties of self-organized Au induced nanowires on the Ge(001) surface are investigated based on the density-functional theory in GGA and the stoichiometry of Au. A giant Ge zigzag chain structure is suggested for 0.75 ML Au coverage, which displays c(8 × 2) deep groove zigzag nanowire structure simulated STM images. The top layer Ge and Au atomic disorder introduces the chevron units into the zigzag nanowire structure STM image as per the experimental observations. The zigzag Ge nanowire exhibits a semi-metallic characteristic, and the electric transport occurs in between the Ge zigzag nanowire and the subsurface. The system exhibits obvious electronic correlations among the Ge nanowire, the nano-facet Au trimers and the deeper layer Ge atoms, that play an important role in the electronic structure. At surface Brillouin zone boundaries, an anisotropic two-dimensional upward parabolic surface-state band is consistent with the ARPES spectra reported by Nakatsuji et al. [Phys. Rev. B 80, 081406(R) (2009); Phys. Rev. B 84, 115411 (2011)]; this electronic structure is different from the quasi-one-dimensional energy trough reported by Schäfer et al. [Phys. Rev. Lett. 101, 236802 (2008); Phys. Rev. B 83, 121411(R) (2011)].

  9. Experimental Investigation into the Tractive Prerolling Behavior of Balls in V-Grooved Tracks

    Directory of Open Access Journals (Sweden)

    Kris De Moerlooze

    2008-01-01

    Full Text Available In a rolling element system, the period of transition between motion commencement and the attainment of steady state, gross rolling, and termed prerolling is of common concern to many engineering applications. This region is marked by hysteresis friction behavior, with a characteristic friction-displacement curve, which is in particular relevant to motion characterization and control issues. In a previous paper, the authors carried out a theoretical analysis of tractive prerolling, leading to a model for simulating this phenomenon. The present paper is dedicated to the experimental investigation of tractive prerolling friction behavior, including validation of the theoretical model. Firstly, a kinematic analysis of the rolling motion in V-grooved tracks is carried out. Secondly, the influence of the normal load on the frictional behavior, in prerolling up to the attainment of gross rolling, is investigated on a dedicated test setup. Finally, the newly developed theoretical model is validated by comparison with the experimental results. Satisfactory agreement is obtained between theory and experiment.

  10. Annularly grooved membrane combined with rood beam piezoresistive pressure sensor for low pressure applications.

    Science.gov (United States)

    Li, Chuang; Cordovilla, Francisco; Ocaña, José L

    2017-03-01

    A novel structural piezoresistive pressure sensor with annularly grooved membrane combined with rood beam has been proposed for low pressure measurements based on silicon substrate. In this study, a design method, including the model design, dimensions optimization, and performance prediction of the novel structure sensor, is presented. The finite element method has been used to analyze the stress distribution of sensitive elements and the deflection of membrane. On the basis of simulation results, the relationships between structural dimension variables and mechanical performance are deduced, which make the fabrication processes more efficient. According to statistics theory, the coefficient of determination R(2) and residual sum of squares are introduced to indicate whether the fitting equations and curves match well with the simulation results. After that, a series of the optimal membrane dimensions are determined. Compared with other structural sensors, the optimized sensor achieves the best overall properties as it mitigates the contradiction between sensitivity and linearity. The reasons why the proposed sensor can maximize sensitivity and minimize nonlinearity are also discussed. By localizing more strain energy in the high concentrated stress profile and creating partially stiffened membrane, the proposed sensor has achieved a high sensitivity of 34.5 (mV/V)/psi and a low nonlinearity of 0.25% FSS. Thus, the proposed structure sensor will be a proper choice for low pressure applications less than 1 psi.

  11. Annularly grooved membrane combined with rood beam piezoresistive pressure sensor for low pressure applications

    Science.gov (United States)

    Li, Chuang; Cordovilla, Francisco; Ocaña, José L.

    2017-03-01

    A novel structural piezoresistive pressure sensor with annularly grooved membrane combined with rood beam has been proposed for low pressure measurements based on silicon substrate. In this study, a design method, including the model design, dimensions optimization, and performance prediction of the novel structure sensor, is presented. The finite element method has been used to analyze the stress distribution of sensitive elements and the deflection of membrane. On the basis of simulation results, the relationships between structural dimension variables and mechanical performance are deduced, which make the fabrication processes more efficient. According to statistics theory, the coefficient of determination R2 and residual sum of squares are introduced to indicate whether the fitting equations and curves match well with the simulation results. After that, a series of the optimal membrane dimensions are determined. Compared with other structural sensors, the optimized sensor achieves the best overall properties as it mitigates the contradiction between sensitivity and linearity. The reasons why the proposed sensor can maximize sensitivity and minimize nonlinearity are also discussed. By localizing more strain energy in the high concentrated stress profile and creating partially stiffened membrane, the proposed sensor has achieved a high sensitivity of 34.5 (mV/V)/psi and a low nonlinearity of 0.25% FSS. Thus, the proposed structure sensor will be a proper choice for low pressure applications less than 1 psi.

  12. Micro-Photoluminescence Confocal Mapping of Single V-Grooved GaAs Quantum Wire

    Institute of Scientific and Technical Information of China (English)

    HUANG Shao-Hua; CHEN Zhang-Hai; BAI Li-Hui; SHEN Xue-Chu; H. H. Tan; L. Fu; M. Fraser; C. Jagadish

    2006-01-01

    We perform the micro-photoluminescence measurement at low temperatures and a scanning optical mapping with high spatial resolution of a single V-grooved GaAs quantum wire modified by the selective ion-implantation and rapid thermally annealing. While the mapping shows the luminescences respectively from the quantum wires and from quantum well areas between quantum wires in general, the micro-photoluminescence at liquid He temperatures reveals a plenty of spectral structures of the PL band for a single quantum wire. The spectral structures are attributed to the inhomogeneity and non-uniformity of both the space structure and compositions of realwires as well as the defects nearby the interface between quantum wire and surrounding quantum well structures.All these make the excitons farther localized in quasi-zero-dimensional quantum potential boxes related to these non-uniformity and/or defects. The results also demonstrate the ability of micro-photoluminescence measurement and mapping for the characterization of both opto-electronic and structural properties of realquantum wires.

  13. Millimeter-wave phase resonances in compound reflection gratings with subwavelength grooves.

    Science.gov (United States)

    Beruete, Miguel; Navarro-Cía, Miguel; Skigin, Diana C; Sorolla, Mario

    2010-11-08

    Experimental evidence of phase resonances in a dual-period reflection structure comprising three subwavelength grooves in each period is provided in the millimeter-wave regime. We have analyzed and measured the response of these structures and show that phase resonances are characterized by a minimum in the reflected response, as predicted by numerical calculations. It is also shown that under oblique incidence these structures exhibit additional phase resonances not present for normal illumination because of the potentially permitted odd field distribution. A satisfactory agreement between the experimental and numerical reflectance curves is obtained. These results confirm the recent theoretical predictions of phase resonances in reflection gratings in the millimeter-wave regime, and encourage research in this subject due to the multiple potential applications, such as frequency selective surfaces, backscattering reduction and complex-surface-wave-based sensing. In addition, it is underlined here that the response becomes much more complex than the mere infinite analysis when one considers finite periodic structures as in the real experiment.

  14. Multi-wavelength microflow cytometer using groove-generated sheath flow.

    Science.gov (United States)

    Golden, Joel P; Kim, Jason S; Erickson, Jeffrey S; Hilliard, Lisa R; Howell, Peter B; Anderson, George P; Nasir, Mansoor; Ligler, Frances S

    2009-07-07

    A microflow cytometer was developed that ensheathed the sample (core) fluid on all sides and interrogated each particle in the sample stream at four different wavelengths. Sheathing was achieved by first sandwiching the core fluid with the sheath fluid laterally via fluid focusing. Chevron-shaped groove features fabricated in the top and bottom of the channel directed sheath fluid from the sides to the top and bottom of the channel, completely surrounding the sample stream. Optical fibers inserted into guide channels provided excitation light from diode lasers at 532 and 635 nm and collected the emission wavelengths. Two emission collection fibers were connected to PMTs through a multimode fiber splitter and optical filters for detection at 635 nm (scatter), 665 nm and 700 nm (microsphere identification) and 565 nm (phycoerythrin tracer). The cytometer was capable of discriminating microspheres with different amounts of the fluorophores used for coding and detecting the presence of a phycoerythrin antibody complex on the surface of the microspheres. Assays for Escherichia coli were compared with a commercial Luminex flow cytometer.

  15. Convex Grooves in Staggered Herringbone Mixer Improve Mixing Efficiency of Laminar Flow in Microchannel.

    Science.gov (United States)

    Kwak, Tae Joon; Nam, Young Gyu; Najera, Maria Alejandra; Lee, Sang Woo; Strickler, J Rudi; Chang, Woo-Jin

    2016-01-01

    The liquid streams in a microchannel are hardly mixed to form laminar flow, and the mixing issue is well described by a low Reynolds number scheme. The staggered herringbone mixer (SHM) using repeated patterns of grooves in the microchannel have been proved to be an efficient passive micro-mixer. However, only a negative pattern of the staggered herringbone mixer has been used so far after it was first suggested, to the best of our knowledge. In this study, the mixing efficiencies from negative and positive staggered herringbone mixer patterns as well as from opposite flow directions were tested to investigate the effect of the micro-structure geometry on the surrounding laminar flow. The positive herringbone pattern showed better mixing efficiency than the conventionally used negative pattern. Also, generally used forward flow gives better mixing efficiency than reverse flow. The mixing was completed after two cycles of staggered herringbone mixer with both forward and reverse flow in a positive pattern. The traditional negative pattern showed complete mixing after four and five cycles in forward and reverse flow direction, respectively. The mixing effect in all geometries was numerically simulated, and the results confirmed more efficient mixing in the positive pattern than the negative. The results can further enable the design of a more efficient microfluidic mixer, as well as in depth understanding of the phenomena of positive and negative patterns existing in nature with regards to the surrounding fluids.

  16. Influence of shock pressure and profile on the microjetting from a grooved Pb surface

    Science.gov (United States)

    Shao, Jian-Li; Wang, Pei; He, An-Min

    2017-01-01

    This work investigates the shock-induced microjetting from a grooved surface (10 nm, 120 degree) of low-melting metal Pb with molecular dynamics simulations. The microjetting processes under surface/release melting conditions are presented in detail, and some properties on the microjet mass and velocity are revealed for different shock pressure and profile cases. It is found that the increase of microjet mass with shock pressure experiences three stages: rapid increase (solid phase), slowdown increase (release melting) and almost no increase (shock melting). For all cases, the ratio of the maximal jetting velocity to the surface velocity approximately keeps a constant (1.5-1.55), but this value undergoes a degree of exponential decay with time for the solid release cases. In addition, the temperature of the microjet is found to be always above the melting point (zero pressure) and keep a continuous increase towards the microjet tip. When introducing slow decaying profiles, the microjet mass begins to increase with the decay rate, which is dominated by the deformation of bubble during pull-back. When the decay rate becomes fast enough, the microspall occurs as expected, meanwhile the microjet appears to reduce because of the shock energy reduction. But that cannot cut off the microjet completely. The velocity distribution along the loading direction shows two linear regions corresponding to the microspall and microjet, and the latter seems to have a greater velocity gradient.

  17. Toxoplasma gondii peptide ligands open the gate of the HLA class I binding groove.

    Science.gov (United States)

    McMurtrey, Curtis; Trolle, Thomas; Sansom, Tiffany; Remesh, Soumya G; Kaever, Thomas; Bardet, Wilfried; Jackson, Kenneth; McLeod, Rima; Sette, Alessandro; Nielsen, Morten; Zajonc, Dirk M; Blader, Ira J; Peters, Bjoern; Hildebrand, William

    2016-01-29

    HLA class I presentation of pathogen-derived peptide ligands is essential for CD8+ T-cell recognition of Toxoplasma gondii infected cells. Currently, little data exist pertaining to peptides that are presented after T. gondii infection. Herein we purify HLA-A*02:01 complexes from T. gondii infected cells and characterize the peptide ligands using LCMS. We identify 195 T. gondii encoded ligands originating from both secreted and cytoplasmic proteins. Surprisingly, T. gondii ligands are significantly longer than uninfected host ligands, and these longer pathogen-derived peptides maintain a canonical N-terminal binding core yet exhibit a C-terminal extension of 1-30 amino acids. Structural analysis demonstrates that binding of extended peptides opens the HLA class I F' pocket, allowing the C-terminal extension to protrude through one end of the binding groove. In summary, we demonstrate that unrealized structural flexibility makes MHC class I receptive to parasite-derived ligands that exhibit unique C-terminal peptide extensions.

  18. Optoelectronic enhancement of monocrystalline silicon solar cells by porous silicon-assisted mechanical grooving

    Energy Technology Data Exchange (ETDEWEB)

    Ben Rabha, Mohamed; Mohamed, Seifeddine Belhadj; Dimassi, Wissem; Gaidi, Mounir; Ezzaouia, Hatem; Bessais, Brahim [Laboratoire de Photovoltaique, Centre de Recherches et des Technologies de l' Energie, Technopole de Borj-Cedria, BP 95, 2050 Hammam-Lif (Tunisia)

    2011-03-15

    One of the most important factors influencing silicon solar cells performances is the front side reflectivity. Consequently, new methods for efficient reduction of this reflectivity are searched. This has always been done by creating a rough surface that enables incident light of being absorbed within the solar cell. Combination of texturization-porous silicon surface treatment was found to be an attractive technical solution for lowering the reflectivity of monocrystalline silicon (c-Si). The texturization of the monocrystalline silicon wafer was carried out by means of mechanical grooving. A specific etching procedure was then applied to form a thin porous silicon layer enabling to remove mechanical damages. This simple and low cost method reduces the total reflectivity from 29% to 7% in the 300 - 950 nm wavelength range and enhances the diffusion length of the minority carriers from 100 {mu}m to 790 {mu}m (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Current transport and microstructural development in BSCCO tapes and joints fabricated by groove rolling

    Science.gov (United States)

    Iyer, A. N.; Lu, W.; Mironova, M.; Vipulanandan, C.; Balachandran, U.; Salama, K.

    2000-02-01

    The powder-in-tube technique, which includes wire drawing and rolling, has been widely used to fabricate superconducting tapes for possible electric power applications. In the present study the starting billet was reduced in size by groove rolling instead of by wire drawing. To optimize the deformation and thermomechanical treatment processes, BSCCO wires of various dimensions were fabricated. The wires were flat rolled to a final thickness of 250 µm. Short-length tapes were subjected to a series of thermal and deformation steps. Phase development and microstructural development during the process were monitored by XRD, SEM and TEM. Current transport properties of the tapes were determined in the temperature range of 20-77 K in self-field. Thermomechanical treatment resulted in tapes with average critical current densities of 18 000 A cm-2 at 77 K. High-resolution electron microscopy revealed better texturing and grain structure at the superconductor-silver interface. Superconducting lap- and butt-joints have been formed by a chemical etching technique. Detailed microstructural and current transport properties of the joints have also been measured.

  20. Experimental investigation of turbulent flow past four grooved and smooth cylinders in an in-line square arrangement

    Directory of Open Access Journals (Sweden)

    Ladjedel O.

    2015-01-01

    Full Text Available An experimental study of turbulent flow past four cylinders in square arrangement with a space ratio of (T/D = P/D = 2.88 is performed. The investigation focuses on effects of Reynolds number and the shape of cylinders on the force and pressure coefficients of the cylinders. Two cases are investigated: four smooth cylinders (case1 and four grooved cylinders (case2. The cylinders are equipped with two grooves placed on the external surface at 90° and 270° degrees. The pressure distributions along the tubes (22 circumferential pressure taping were determined for a variation of the azimuthal angle from 0 to 360deg. The drag and lift forces are measured using the TE 44 balance. The results show a bistable flow often exists behind the downstream cylinders is observed. By rising the Reynolds number the pressure coefficient increases in the absolute value.