WorldWideScience

Sample records for hollow section columns

  1. Flexural stiffness of the composite steel and fibre-reinforced concrete circular hollow section column

    Science.gov (United States)

    Tretyakov, A.; Tkalenko, I.; Wald, F.; Novak, J.; Stefan, R.; Kohoutková, A.

    2017-09-01

    The recent development in technology of production and transportation of steel fibre-reinforced concrete enables its utilization in composite steel-concrete structures. This work is a part of a project which focuses on development of mechanical behaviour of circular hollow section (CHS) composite steel and fibre-concrete (SFRC) columns at elevate temperature. Research includes two levels of accuracy/complexity, allowing simplified or advanced approach for design that follows upcoming changes in European standard for composite member design in fire EN1994-1-2 [1]. One part is dedicated to determination and description of flexural stiffness of the SFRC CHS columns. To determinate flexural stiffness were prepared series of pure bending tests at elevated and ambient temperature. Presented paper focuses on the results of the tests and determination of flexural stiffness at ambient temperature. Obtained outputs were compared to data of existing studies about concrete-filled tube members with plain concrete and values analytically calculated according to the existing European standard EN1994-1-1 [2].

  2. Safety of carbon fibre reinforced plastic hollow sections in ...

    African Journals Online (AJOL)

    The use of steel hollow sections as compression members in structures has been a common practice. This study highlights the safety of using Carbon Fibre Reinforced Plastic (CFRP) hollow sections as compression structural members. The primary compression members in structures are columns and this study uses Finite ...

  3. Dynamic and Static Behavior of Hollow-Core FRP-Concrete-Steel and Reinforced Concrete Bridge Columns under Vehicle Collision

    Directory of Open Access Journals (Sweden)

    Omar I. Abdelkarim

    2016-12-01

    Full Text Available This paper presents the difference in behavior between hollow-core fiber reinforced polymer-concrete-steel (HC-FCS columns and conventional reinforced concrete (RC columns under vehicle collision in terms of dynamic and static forces. The HC-FCS column consisted of an outer FRP tube, an inner steel tube, and a concrete shell sandwiched between the two tubes. The steel tube was hollow inside and embedded into the concrete footing with a length of 1.5 times the tube diameter while the FRP tube stopped at the top of footing. The RC column had a solid cross-section. The study was conducted through extensive finite element impact analyses using LS-DYNA software. Nine parameters were studied including the concrete material model, unconfined concrete compressive strength, material strain rate, column height-to-diameter ratio, column diameter, column top boundary condition, axial load level, vehicle velocity, and vehicle mass. Generally, the HC-FCS columns had lower dynamic forces and higher static forces than the RC columns when changing the values of the different parameters. During vehicle collision with either the RC or the HC-FCS columns, the imposed dynamic forces and their equivalent static forces were affected mainly by the vehicle velocity and vehicle mass.

  4. Hollow-core FRP-concrete-steel bridge columns under extreme loading.

    Science.gov (United States)

    2015-04-01

    This report presents the behavior of hollow-core fiber reinforced polymer concrete - steel columns (HC-FCS) under : combined axial-flexural as well as vehicle collision loads. The HC-FCS column consists of a concrete wall sandwiched between an ou...

  5. Finite Element Studies on Hollow Steel Columns under Multi ...

    African Journals Online (AJOL)

    Herein, finite element (FE) modeling of the columns under multi-directional loading is conducted employing ABAQUS FE code in conjunction with the experimental results. To optimize on the program capabilities, the sensitivity of the developed model is appraised with regard to the effect of type of shell element, type of ...

  6. Tensile Strength of GFRP Reinforcing Bars with Hollow Section

    Directory of Open Access Journals (Sweden)

    Young-Jun You

    2015-01-01

    Full Text Available Fiber reinforced polymer (FRP has been proposed to replace steel as a reinforcing bar (rebar due to its high tensile strength and noncorrosive material properties. One obstacle in using FRP rebars is high price. Generally FRP is more expensive than conventional steel rebar. There are mainly two ways to reduce the cost. For example, one is making the price of each composition cost of FRP rebar (e.g., fibers, resin, etc. lower than steel rebar. Another is making an optimized design for cross section and reducing the material cost. The former approach is not easy because the steel price is very low in comparison with component materials of FRP. For the latter approach, the cost could be cut down by reducing the material cost. Therefore, an idea of making hollow section over the cross section of FRP rebar was proposed in this study by optimizing the cross section design with acceptable tensile performance in comparison with steel rebar. In this study, glass reinforced polymer (GFRP rebars with hollow section and 19 mm of outer diameter were manufactured and tested to evaluate the tensile performance in accordance with the hollowness ratio. From the test results, it was observed that the tensile strength decreased almost linearly with increase of hollowness ratio and the elastic modulus decreased nonlinearly.

  7. Thermal transient analysis of steel hollow sections exposed to fire

    Directory of Open Access Journals (Sweden)

    Lenka Lausova

    2016-03-01

    Full Text Available The paper describes a study of non-uniform temperature distribution across the section of steel structures where elevated temperature causes additive internal forces due to restrained conditions. The work provides comparison of a heat field at the time of fire in the non-protected steel hollow cross-sections of different sizes. The study compares simplified calculations according to valid standard and numerical simulations in finite element analysis of steel structures exposed to fire loading from three sides. Numerical thermal analysis is also compared with results obtained from the fire testing in VSB-Technical University of Ostrava.

  8. safety of carbon fibre reinforced plastic hollow sections in compression

    African Journals Online (AJOL)

    ADMINUSER

    2014-01-06

    Jan 6, 2014 ... researchers did a lot of work and study during the past few decades to investigate the durability of this ... performance of cross sections of columns subjected to combined shear and flexure stresses was ... models have been developed to describe the bond behaviour [11-14]. Other researches, primarily in ...

  9. Hydrodynamic effects of air sparging on hollow fiber membranes in a bubble column reactor.

    Science.gov (United States)

    Xia, Lijun; Law, Adrian Wing-Keung; Fane, Anthony G

    2013-07-01

    Air sparging is now a standard approach to reduce concentration polarization and fouling of membrane modules in membrane bioreactors (MBRs). The hydrodynamic shear stresses, bubble-induced turbulence and cross flows scour the membrane surfaces and help reduce the deposit of foulants onto the membrane surface. However, the detailed quantitative knowledge on the effect of air sparging remains lacking in the literature due to the complex hydrodynamics generated by the gas-liquid flows. To date, there is no valid model that describes the relationship between the membrane fouling performance and the flow hydrodynamics. The present study aims to examine the impact of hydrodynamics induced by air sparging on the membrane fouling mitigation in a quantitative manner. A modelled hollow fiber module was placed in a cylindrical bubble column reactor at different axial heights with the trans-membrane pressure (TMP) monitored under constant flux conditions. The configuration of bubble column without the membrane module immersed was identical to that studied by Gan et al. (2011) using Phase Doppler Anemometry (PDA), to ensure a good quantitative understanding of turbulent flow conditions along the column height. The experimental results showed that the meandering flow regime which exhibits high flow instability at the 0.3 m is more beneficial to fouling alleviation compared with the steady flow circulation regime at the 0.6 m. The filtration tests also confirmed the existence of an optimal superficial air velocity beyond which a further increase is of no significant benefit on the membrane fouling reduction. In addition, the alternate aeration provided by two air stones mounted at the opposite end of the diameter of the bubble column was also studied to investigate the associated flow dynamics and its influence on the membrane filtration performance. It was found that with a proper switching interval and membrane module orientation, the membrane fouling can be effectively

  10. The Fatigue Behaviour of T- and X-Joints Made of Square Hollow Sections

    NARCIS (Netherlands)

    Van Wingerde, A.M.

    1992-01-01

    This work presents the results of experimental and numerical research on the fatigue behaviour of T- and X-joints between square hollow sections of which the brace is welded to the face of the chord, without any additional stiffeners. The work has been carried out in the framework of the CIDECT

  11. Numerical and Experimental Determination of Strain (Stress) Concentration Factors of Welded Joints between Square Hollow Sections

    NARCIS (Netherlands)

    Puthli, R.S.; Wardenier, J.; De Koning, C.H.M.; Van Wingerde, A.M.; Van Dooren, F.J.

    1988-01-01

    This article presents methods of approach for finite element modelling of joints made of rectangular hollow steel sections where the brace members are welded to the face of the chord, to obtain strain (stress) concentration factors, SNCF (SCF). X, T and K type joints are considered. Simple modelling

  12. Experimental and Theoretical Analysis of Hollow Steel Columns Strengthening by CFRP

    Directory of Open Access Journals (Sweden)

    Keykha A.H.

    2015-09-01

    Full Text Available The need for strengthening and retrofitting is well known and extensive research is progressing in this field. The reasons for strengthening and retrofitting are numerous: increased loads, changes in use, deterioration, and so on. In recent years, the use of carbon fiber reinforced polymer (CFRP for strengthening has shown to be a competitive method, both regarding structural performance, and economical aspects. Extensive research has been carried out in this field. However, most of the research has been undertaken on concrete structures and for confinement, flexural, and shear strengthening. Limited research has been carried out on steel structures strengthened with CFRP. This paper presents axially loaded steel columns strengthened for increased load. The topic is studied theoretically and through laboratory tests. The theory covers analytical methods. Carbon fiber reinforced polymers has been used to strengthen the columns. The tests have been undertaken on full scale specimens, non-strengthened for reference, partially strengthened and fully strengthened

  13. Retrofitting of bridge hollow piers with CFRP

    OpenAIRE

    Pedro Delgado; Patrício Rocha; João Pedrosa; António Arêde; Nelson Vila Pouca; Miguel Santos; Aníbal Costa; Raimundo Delgado

    2007-01-01

    Hollow bridge piers generally have large section dimensions, with reinforcement barsspread along both wall faces. Unlike common solid section columns, quite often the shear effect hasgreat importance on the pier behavior. Therefore, it is of particular relevance that special attention isgiven to this issue when the assessment and retrofit of RC hollow section piers is envisaged. Representativeof typical bridge construction, RC piers were tested at LESE ¿ the Laboratory of Earthquakeand Struct...

  14. Production and cross-sectional characterization of aligned co-electrospun hollow microfibrous bulk assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Feng-Lei [Centre for Imaging Sciences, The University of Manchester, Manchester M13 9PT (United Kingdom); The School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); CRUK-EPSRC Cancer Imaging Centre in Cambridge and Manchester (United Kingdom); Parker, Geoff J.M., E-mail: geoff.parker@manchester.ac.uk [Centre for Imaging Sciences, The University of Manchester, Manchester M13 9PT (United Kingdom); CRUK-EPSRC Cancer Imaging Centre in Cambridge and Manchester (United Kingdom); Eichhorn, Stephen J. [College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF (United Kingdom); Hubbard Cristinacce, Penny L. [Centre for Imaging Sciences, The University of Manchester, Manchester M13 9PT (United Kingdom); School of Psychological Sciences, University of Manchester, Manchester M13 9PT (United Kingdom)

    2015-11-15

    The development of co-electrospun (co-ES) hollow microfibrous assemblies of an appreciable thickness is critical for many practical applications, including filtration membranes and tissue-mimicking scaffolds. In this study, thick uniaxially aligned hollow microfibrous assemblies forming fiber bundles and strips were prepared by co-ES of polycaprolactone (PCL) and polyethylene oxide (PEO) as shell and core materials, respectively. Hollow microfiber bundles were deposited on a fixed rotating disc, which resulted in non-controllable cross-sectional shapes on a macroscopic scale. In comparison, fiber strips were produced with tuneable thickness and width by additionally employing an x–y translation stage in co-ES. Scanning electron microscopy (SEM) images of cross-sections of fiber assemblies were analyzed to investigate the effects of production time (from 0.5 h to 12 h), core flow rate (from 0.8 mL/h to 2.0 mL/h) and/or translation speed (from 0.2 mm/s to 5 mm/s) on the pores and porosity. We observed significant changes in pore size and shape with core flow rate but the influence of production time varied; five strips produced under the same conditions had reasonably good size and porosity reproducibility; pore sizes didn't vary significantly from strip bottom to surface, although the porosity gradually decreased and then returned to the initial level. - Highlights: • Hollow microfibrous assemblies based on co-electrospinning are demonstrated. • The thickness and width of co-electrospun strips were controllable. • Cross-sections of fibres had non-normally distributed pore sizes and shapes. • Cross-sections were significantly influenced by production time and flow rate. • Co-electrospun strips had reasonably good reproducible cross-sections.

  15. Nuclear reactor control column

    Science.gov (United States)

    Bachovchin, Dennis M.

    1982-01-01

    The nuclear reactor control column comprises a column disposed within the nuclear reactor core having a variable cross-section hollow channel and containing balls whose vertical location is determined by the flow of the reactor coolant through the column. The control column is divided into three basic sections wherein each of the sections has a different cross-sectional area. The uppermost section of the control column has the greatest cross-sectional area, the intermediate section of the control column has the smallest cross-sectional area, and the lowermost section of the control column has the intermediate cross-sectional area. In this manner, the area of the uppermost section can be established such that when the reactor coolant is flowing under normal conditions therethrough, the absorber balls will be lifted and suspended in a fluidized bed manner in the upper section. However, when the reactor coolant flow falls below a predetermined value, the absorber balls will fall through the intermediate section and into the lowermost section, thereby reducing the reactivity of the reactor core and shutting down the reactor.

  16. Fire exposed steel columns with a thermal gradient over the cross-section

    NARCIS (Netherlands)

    Ojeda, O.D.; Maljaars, J.; Abspoel, R.

    2016-01-01

    Thermal gradients often occur in fire exposed structures. This paper considers thermal gradients over the cross-section of steel columns. By means of finite element simulations, the paper demonstrates that these gradients reduce the fiexural buckling resistance of the columns. This is due to the

  17. A Hollow-Waveguide Gas Correlation Radiometer for Ultra-Precise Column Measurements of Formaldehyde on Mars

    Science.gov (United States)

    Wilson, Emily L.; Neveu, Marc; Riris, Haris; Georgieva, Elena M.; Heaps, William S.

    2011-01-01

    We present preliminary results in the development of a miniaturized gas correlation radiometer that implements a hollow-core optical fiber (hollow waveguide) gas correlation cell. The substantial reduction in mass and volume of the gas correlation cell makes this technology appropriate for an orbital mission -- capable of pinpointing sources of trace gases in the Martian atmosphere. Here we demonstrate a formaldehyde (H2CO) sensor and report a detection limit equivalent to approximately 30 ppb in the Martian atmosphere. The relative simplicity of the technique allows it to be expanded to measure a range of atmospheric trace gases of interest on Mars such as methane (CH4), water vapour (H2O), deuterated water vapour (HDO), and methanol (CH3OH). Performance of a formaldehyde instrument in a Mars orbit has been simulated assuming a 3 meter long, 1000 micron inner diameter hollow-core fiber gas correlation cell, a 92.8 degree sun-synchronous orbit from 400 km with a horizontal sampling scale of 10 km x 10 km. Initial results indicate that for one second of averaging, a detection limit of 1 ppb is possible.

  18. Experimental engineering section off-gas decontamination facility's fractionator column: installation and performance

    Energy Technology Data Exchange (ETDEWEB)

    Gilliam, T. M.; Fowler, V. L.; Inman, D. J.

    1978-03-01

    A detailed description of the third column recently installed in the Experimental Engineering Section Off-Gas Decontamination Facility (EES-ODF) is presented. The EES-ODF is being used to provide engineering-scale experiments (nominal gas and liquid flows of 5 scfm and 0.5 gpm, respectively) in the development of the Krypton Absorption in Liquid CO/sub 2/ (KALC) process. A detailed discussion of the column's construction is provided. This discussion includes the peripherals associated with the column, such as refrigeration, heat exchangers, instrumentation, etc. The compressibility of Goodloe packing (the packing in the other columns) and the possible reduced throughput due to this compression have revealed the desirablility of a random (i.e., noncompressible) packing. Toward this end, the third column is packed with a new random packing (PRO-PAK). A preliminary comparison between this packing and the woven wire mesh packing (Goodloe) used in the other two columns has been made. Experiments comparing the throughput capacity indicate that the PRO-PAK packing has approximately 60% the capacity of Goodloe for a CO/sub 2/ system. When used as a fractionator or stripper with the basic O/sub 2/-Kr-CO/sub 2/ KALC system, the PRO-PAK column produced HTU values less than or equal to the GOODLOE columns under similar operating conditions.

  19. Study of scattering cross section of a plasma column using Green's function volume integral equation method

    Science.gov (United States)

    Soltanmoradi, Elmira; Shokri, Babak

    2017-05-01

    In this article, the electromagnetic wave scattering from plasma columns with inhomogeneous electron density distribution is studied by the Green's function volume integral equation method. Due to the ready production of such plasmas in the laboratories and their practical application in various technological fields, this study tries to find the effects of plasma parameters such as the electron density, radius, and pressure on the scattering cross-section of a plasma column. Moreover, the incident wave frequency influence of the scattering pattern is demonstrated. Furthermore, the scattering cross-section of a plasma column with an inhomogeneous collision frequency profile is calculated and the effect of this inhomogeneity is discussed first in this article. These results are especially used to determine the appropriate conditions for radar cross-section reduction purposes. It is shown that the radar cross-section of a plasma column reduces more for a larger collision frequency, for a relatively lower plasma frequency, and also for a smaller radius. Furthermore, it is found that the effect of the electron density on the scattering cross-section is more obvious in comparison with the effect of other plasma parameters. Also, the plasma column with homogenous collision frequency can be used as a better shielding in contrast to its inhomogeneous counterpart.

  20. Flexural Strength of Carbon Fiber Reinforced Polymer Repaired Cracked Rectangular Hollow Section Steel Beams

    Directory of Open Access Journals (Sweden)

    Tao Chen

    2015-01-01

    Full Text Available The flexural behavior of rectangular hollow section (RHS steel beams with initial crack strengthened externally with carbon fiber reinforced polymer (CFRP plates was studied. Eight specimens were tested under three-point loading to failure. The experimental program included three beams as control specimens and five beams strengthened with CFRP plates with or without prestressing. The load deflection curves were graphed and failure patterns were observed. The yield loads and ultimate loads with or without repairing were compared together with the strain distributions of the CFRP plate. It was concluded that yield loads of cracked beams could be enhanced with repairing. Meanwhile, the ultimate loads were increased to some extent. The effect of repair became significant with the increase of the initial crack depth. The failure patterns of the repaired specimens were similar to those of the control ones. Mechanical clamping at the CFRP plate ends was necessary to avoid premature peeling between the CFRP plate and the steel beam. The stress levels in CFRP plates were relatively low during the tests. The use of prestressing could improve the utilization efficiency of CFRP plates. It could be concluded that the patching repair could be used to restore the load bearing capacity of the deficient steel beams.

  1. Temperature Effect on O4 Cross Sections for Estimating its Slant Column Density by Using OMI

    Science.gov (United States)

    Park, S. S.; Takemura, T.; Kim, J.

    2016-12-01

    The slant column densities (SCDs) of oxygen dimers (O4) have sensitivities to the temperature-dependent O4 cross section used as the input to the radiative transfer model (RTM) calculation. In this study, the linearized pseudo-spherical vector discrete ordinate radiative transfer (VLIDORT) is used as a RTM, which is basically not taken account to the temperature dependence. The simulated SCDs are compared based on the databases between the temperature-independent cross section and the newly investigated temperature-dependent cross section. To adopt the temperature dependence of O4 cross section, the O4 cross section databases of 203 K and 293 K are used for the radiance simulation by interpolating atmospheric layer temperature. Based on the RTM simulation, the temperature-dependent cross section significantly affects the O4 SCD increasing. The O4 SCD is generally estimated 3.9% increase based on the observation geometries of the Ozone Monitoring Instrument (OMI), and the above O4 SCD increase corrects the 20% of total underestimation of the O4 SCD between observation and simulation. The O4 SCD variations due to the surface pressure and background aerosol effect are relatively insignificant as compared to those due to the temperature-dependent cross section. The temperature dependence of cross section makes closer to describe extinction intensities in the real atmosphere by the RTM calculation.

  2. Performance of externally CFRP confined RC columns with changes in thickness of the wrap, slenderness of the column and shape of the section

    Directory of Open Access Journals (Sweden)

    Gahmous M.

    2012-09-01

    Full Text Available The present study deals with the analysis of experimental results, in terms of load carrying capacity and strains, obtained from tests on reinforced concrete (RC columns, strengthened with external carbon fiber reinforced polymer (CFRP sheets. The experimental parameters include: number of wrap layers, slenderness of the columns (L/a or L/D and shape of the section (circular and square. A total of 48 specimens were subjected to axial compression. All test specimens were loaded to failure in axial compression. Compressive stress, axial and hoop strains have been recorded to evaluate the stress-strain relationship, ultimate strength, stiffness, and ductility of the specimens. Results clearly demonstrate that composite wrapping can enhance the structural performance of RC columns in terms of both maximum strength and ductility. The effects of test parameters are evidenced and compared.

  3. A new model for analyzing nonlinear torsion behavior of concrete filled steel tube columns with rectangular section

    Science.gov (United States)

    Wang, Yuhang; Nie, Jianguo; Fan, Jiansheng

    2016-06-01

    An experimental study on concrete filled steel tube columns with rectangular section subjected to compressionflexure-torsion combined action has been carried out. The failure modes and load-deformation hysteretic relations were obtained. Based on the principles of classical material mechanics, the relations between the torsion curvature of the section and the shear strain of the fiber on the section were established. Then the strain distribution on the rectangular section of concrete filled steel tube columns subjected to torsion was analyzed. The three-dimensional refined finite element model was also built, in order to make the precision verification. The matrix forms of the relation between the torsion curvature of the section and the shear strain of the fiber on the section were derived, and introduced into the fiber beam model considering nonlinear torsion effect on the section. The comparison between test results and calculation results showed that the fiber beam model considering nonlinear torsion effect had high modeling efficiency and solution precision for predicting the torsion behavior of concrete filled steel tube columns with rectangular sections, and was suitable for analyzing the dynamic response of various structures subjected to the combined cyclic load caused by the earthquake load.

  4. Cyclic performance and simplified pushover analyses of precast segmental concrete bridge columns with circular section

    Science.gov (United States)

    Bu, Zhanyu; Guo, Jian; Zheng, Rongyue; Song, Jianwei; Lee, George C.

    2016-06-01

    In recent years, precast segmental concrete bridge columns became prevalent because of the benefits of accelerated construction, low environmental impact, high quality and low life cycle costs. The lack of a detailed configuration and appropriate design procedure to ensure a comparable performance with monolithic construction has impeded this structural system from being widely used in areas of high seismicity. In this study, precast segmental bridge column cyclic loading tests were conducted to investigate the performance of unbonded post-tensioned segmental bridge columns. One monolithic and two precast segmental columns were tested. The precast segmental column exhibited minor damage and small residual displacement after the maximum 7% cyclic drift; energy dissipation (ED) can be enhanced byadding ED bars. The experimental results were modeled by a simplified pushover method (SPOM), as well as a fiber model (FIBM) finite element method. Forty-five cases of columns with different aspect ratios, axial load ratios and ED bar ratios were analyzed with the SPOM and FIBM, respectively. Using these parametric results, a simplified design method was suggested by regressive analysis. Satisfactory correlation was found between the experimental results and the simplified design method for precast segmental columns with different design parameters.

  5. Hollow Core?

    Science.gov (United States)

    Qiao, G. J.; Liu, J. F.; Wang, Yang; Wu, X. J.; Han, J. L.

    We carried out the Gaussian fitting to the profile of PSR B1237+25 and found that six components rather than five are necessary to make a good fit. In the central part, we found that the core emission is not filled pencil beam but is a small hollow cone. This implies that the impact angle could be $\\beta<0.5^\\circ$. The ``hollow core'' is in agreement with Inverse Compton Scattering model of radio pulsars.

  6. Experimental behaviour of beam-column connection using cold-formed steel sections with rectangular gusset-plate

    Science.gov (United States)

    Aminuddin, K. M.; Saggaff, Anis; Tahir, Mahmood Md

    2017-11-01

    Beam-to-column connections setting up as isolated joint of cold-formed steel sections were tested up to failure. This experiment was conducted to observe the behaviour of connection in term of strength, stiffness and ductility. The type of connection used was rectangular gusset plate which stiffen the beam-to-column connection. The behaviour of the proposed connection was expressed with Moment-Rotation curves plotted from the experiment test results. The capacity of connections on this research were done in two ways: theoretical calculation by adopting Eurocode 3 BS EN 1993-1-8:2005 and experimental test results. The theoretical calculation of the moment capacit y of the proposed connection has found (Mj) to be 10.78 kNm with joint stiffness (Sj) amount to 458.53 kNm/rad. The experimental test results has recorded that the Moment capacity (Mj) of 15.68 kNm with joint stiffness (Sj) of 1948.06 kNm/rad. The moment ratio of theoretical to experimental amount to 0.69. The joint stiffness ratio of theoretical to experimental amount to 0.24.

  7. Effects of abdominal hollowing during stair climbing on the activations of local trunk stabilizing muscles: a cross-sectional study.

    Science.gov (United States)

    Lee, Ah Young; Kim, Eun Hyuk; Cho, Yun Woo; Kwon, Sun Oh; Son, Su Min; Ahn, Sang Ho

    2013-12-01

    To examine using surface electromyography whether stair climbing with abdominal hollowing (AH) is better at facilitating local trunk muscle activity than stair climbing without AH. Twenty healthy men with no history of low back pain participated in the study. Surface electrodes were attached to the multifidus (MF), lumbar erector spinae, thoracic erector spinae, transverse abdominus - internal oblique abdominals (TrA-IO), external oblique abdominals (EO), and the rectus abdominis. Amplitudes of electromyographic signals were measured during stair climbing. Study participants performed maximal voluntary contractions (MVC) for each muscle in various positions to normalize the surface electromyography data. AH during stair climbing resulted in significant increases in normalized MVCs in both MFs and TrA-IOs (pclimbing with AH as compared with stair climbing without AH. Especially, right TrA-IO/EO and left TrA-IO/EO were significantly increased (pclimbing with AH activates local trunk stabilizing muscles better than stair climbing without AH. The findings suggest that AH during stair climbing contributes to trunk muscle activation and trunk stabilization.

  8. Influence of cross-sectional ratio of down comer to riser on the efficiency of liquid circulation in loop air lift bubble column

    Directory of Open Access Journals (Sweden)

    Yamamoto Tatsumi

    2017-01-01

    Full Text Available Loop type bubble columns have good performance of liquid circulation and mass transfer by airlift effect, where the liquid circulation time is an important measurable characteristic parameter. This parameter is affected by the column construction, the aspect ratio of the column, the cross-sectional area ratio of down comer to riser (R, and the superficial gas velocity in the riser (UGR. In this work, the mean gas holdup and the liquid circulation time (TC have been measured in four types of loop airlift type bubble column: concentric tube internal loop airlift type, rectangular internal loop airlift type, external loop airlift type, external loop airlift with separator. Air and tap water were used as gas and liquid phase, respectively. The results have demonstrated that the mean gas holdup in riser increases in proportion to UGR, and that it in downcomer changes according to the geometric parameters of each bubble column. TC has been found to conform to an empirical equation which depends on UGR and the length of draft tube or division plate in the region of 0.33 < R < 1.

  9. Influence of cross-sectional ratio of down comer to riser on the efficiency of liquid circulation in loop air lift bubble column

    Science.gov (United States)

    Yamamoto, Tatsumi; Kawasaki, Hiroyuki; Mori, Hidetoshi

    2017-11-01

    Loop type bubble columns have good performance of liquid circulation and mass transfer by airlift effect, where the liquid circulation time is an important measurable characteristic parameter. This parameter is affected by the column construction, the aspect ratio of the column, the cross-sectional area ratio of down comer to riser (R), and the superficial gas velocity in the riser (UGR). In this work, the mean gas holdup and the liquid circulation time (TC) have been measured in four types of loop airlift type bubble column: concentric tube internal loop airlift type, rectangular internal loop airlift type, external loop airlift type, external loop airlift with separator. Air and tap water were used as gas and liquid phase, respectively. The results have demonstrated that the mean gas holdup in riser increases in proportion to UGR, and that it in downcomer changes according to the geometric parameters of each bubble column. TC has been found to conform to an empirical equation which depends on UGR and the length of draft tube or division plate in the region of 0.33 < R < 1.

  10. Hollow MEMS

    DEFF Research Database (Denmark)

    Larsen, Peter Emil

    a hollow MEMS sensor has been designed, fabricated and tested. Combined density, viscosity, buoyant mass spectrometry and IR absorption spectroscopy are possible on liquid samples and micron sized suspended particles (e.g. single cells). Measurements are based on changes in the resonant behavior...... of these sensors. Optimization of the microfabrication process has led to a process yield of almost 100% .This is achieved despite the fact, that the process still offers a high degree of flexibility. By simple modifications the Sensor shape can be optimized for different size ranges and sensitivities...... technologies and pre-concentration approaches. A thorough theoretical analysis of the expected sensor responsivity and sensitivity is performed. Predictions made are confirmed by finite element simulations. Using these tools the sensor geometry is optimized for ideal performance in both mass density and IR...

  11. Effect of temperature-dependent cross sections on O4 slant column density estimation by a space-borne UV-visible hyperspectral sensor

    Science.gov (United States)

    Park, Sang Seo; Takemura, Toshihiko; Kim, Jhoon

    2017-03-01

    The sensitivities of oxygen dimer (O4) slant column densities (SCDs) were examined by applying temperature-dependent O4 cross sections using the radiative transfer model (RTM) calculation with the linearized pseudo-spherical vector discrete ordinate radiative transfer model. For the sensitivity study, we used a newly developed cross section database in place of the database used in the operational algorithm. Newly investigated O4 cross section databases for 203 K and 293 K were used for the radiance simulation by interpolating temperature for each atmospheric layer based on the vertical profile of standard atmosphere in the RTM. The effect of the temperature-dependent cross sections was a significant O4 SCD increase of 8.3% with dependence on satellite and solar viewing geometries. Furthermore, the O4 SCD generally increased by an estimated 3.9% based on the observation geometries of the Ozone Monitoring Instrument. For the long-term comparison, the O4 SCD estimated from the temperature-dependent cross sections corrects 20% of the total underestimation of O4 SCD between the observation and simulation. Although the surface pressure variation and background aerosol effect also correct the O4 SCD discrepancy, the effect of temperature-dependent cross sections was more important than the effects of surface pressure variation and background aerosols. Therefore, temperature dependence of the cross section in the RTM calculation is essential for the accurate simulation of O4 SCD.

  12. Evidence of fire resistance of hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Sørensen, Lars Schiøtt; Giuliani, Luisa

    Hollow-core slabs have during the past 50 years comprised a variety of different structures with different cross-sections and reinforcement. At present the extruded hollow-core slabs without cross-reinforcement in the bottom flange and usually round or oval longitudinal channels (holes...... is therefore going on in the Netherlands about the fire resistance of hollow-core slabs. In 2014 the producers of hollow-core slabs have published a report of a project called Holcofire containing a collection of 162 fire tests on hollow-core slabs giving for the first time an overview of the fire tests made....... The present paper analyses the evidence now available for assessment of the fire resistance of extruded hollow-core slabs. The 162 fire tests from the Holcofire report are compared against the requirements for testing from the product standard for hollow-core slabs EN1168 and knowledge about the possible...

  13. Hollow Prosthetic Eyes.

    Science.gov (United States)

    Worrell, Emma

    A new technique to produce hollow prostheses is presented. A small case series of patients utilized standard methods to fabricate hollow ocular prostheses where rehabilitation had proved difficult. This article describes the fabrication and results of hollow ocular prostheses. Each hollow eye was significantly reduced in weight, one-third lighter than the original weight, with the exact size, shape, and volume of the existing solid prosthesis. This simple design significantly reduced the weight of these eyes and revolutionized these patients' rehabilitation. Previously the solid prostheses overburdened the lower eyelids, causing discomfort, irritation, discharge, and reddening, whereas the new lightweight prostheses are unobtrusive, comfortable, and good aesthetically.

  14. A tapered hollow metallic microneedle array using backside exposure of SU-8

    Science.gov (United States)

    Kim, Kabseog; Park, Daniel S.; Lu, Hong M.; Che, Wooseong; Kim, Kyunghwan; Lee, Jeong-Bong; Ahn, Chong H.

    2004-04-01

    This paper presents a novel fabrication process for a tapered hollow metallic microneedle array using backside exposure of SU-8, and analytic solutions of critical buckling of a tapered hollow microneedle. An SU-8 mesa was formed on a Pyrex glass substrate and another SU-8 layer, which was spun on top of the SU-8 mesa, was exposed through the backside of the glass substrate. An array of SU-8 tapered pillar structures, with angles in the range of 3.1°-5°, was formed on top of the SU-8 mesa. Conformal electrodeposition of metal was carried out followed by a mechanical polishing using a planarizing polymeric layer. All organic layers were then removed to create a metallic hollow microneedle array with a fluidic reservoir on the backside. Both 200 µm and 400 µm tall, 10 by 10 arrays of metallic microneedles with inner diameters of the tip in the range of 33.6-101 µm and wall thickness of 10-20 µm were fabricated. Analytic solutions of the critical buckling of arbitrary-angled truncated cone-shaped columns are also presented. It was found that a single 400 µm tall hollow cylindrical microneedle made of electroplated nickel with a wall thickness of 20 µm, a tapered angle of 3.08° and a tip inner diameter of 33.6 µm has a critical buckling force of 1.8 N. This analytic solution can be used for square or rectangular cross-sectioned column structures with proper modifications.

  15. [Hollow foot in adults].

    Science.gov (United States)

    Braun, S

    1997-01-01

    Contrary to the general impression, the hollow foot is much more common than the flat foot. We distinguish three categories of hollow foot: varus hollow (clinical form I), valgus hollow (clinical form II), and pseudo-hollow (clinical form III). These three clinical forms have a common deviation dynamics, the consequence of shortening of the sural-Achilles-calcaneoplantar system. Metatarsalgia often precedes deformation of the front of the foot. Talalgia is linked to excess traction or to a conflict between the heel and the back of the shoe. Common therapy consists of plantar orthoses, eventually toe orthoses and orthopedic shoes. When surgery is used in the adult, it is generally not to correct excess cavus but to correct problems of the front of the foot such as hallux valgus, involvement of the second metatarsal bone (??), or toenails.

  16. Hollow circular-truncated cone resonator and its hollow variable biconical laser beam

    Science.gov (United States)

    Liu, Jinglun; Chen, Mei; Wang, Qionghua; Sun, Nianchun

    2014-05-01

    To obtain a hollow variable biconical laser beam (HVBLB), a CO2 laser having a hollow circular-truncated cone resonator (HCTCR) is presented. This HCTCR comprises a rotationally symmetric total-reflecting concave mirror at the bottom, a rotationally symmetric part-reflecting convex mirror at the top, and a hollow circular-truncated cone discharge tube at the middle. The cross section of this generated biconical laser beam changes from annulus to circular to annulus and the size of this cross section from big to small to large as the propagation distance increases. So, a kind of laser beam with variable center intensity from zero to peak value to zero is obtained and is known as HVBLB. Due to the inclusion of part of the hollow laser beam (HLB) and solid laser beam, this HVBLB requires no additional beam-shaping element and has broad applications such as optical trapping and commercial manufacturing.

  17. Creative columns

    National Research Council Canada - National Science Library

    Hoff, Diane

    2017-01-01

      Here, Hoff presents creative columns. As her seventh-graders began learning about ancient Greece in social studies, in art they observed ancient Greek architecture, paying attention to the orders of Pork, Ionic, and Corinthian...

  18. Effect of an Opening on Reinforced Concrete Hollow Beam Web Under Torsional, Flexural, and Cyclic Loadings

    OpenAIRE

    Jabbar, Sarah; Hejazi,Farzad; Mahmod,H. Mahir

    2016-01-01

    Abstract Hollow sections have been increasingly applied in the construction of buildings, bridges, offshore structures, and towers for passing electrical and mechanical pipes or other utilities. Torsion caused by external force is a weakness of hollow sections that is rarely investigated. In particular, the behavior of hollow sections with high-strength concrete (HSC) and ultra-high performance concrete (UHPC) remains poorly studied. This study aims to examine the behavior of a reinforced con...

  19. COLUMN TESSELLATIONS

    Directory of Open Access Journals (Sweden)

    Linh Ngoc Nguyen

    2015-06-01

    Full Text Available A new class of non facet-to-facet random tessellations in three-dimensional space is introduced -- the so-called column tessellations. The spatial construction is based on a stationary planar tessellation; each cell of the spatial tessellation is a prism whose base facet is  congruent to a cell of the planar tessellation. Thus intensities, topological and metric mean values of the spatial tessellation can be calculated from suitably chosen parameters of the planar tessellation.

  20. Hollow-Core Fiber Lamp

    Science.gov (United States)

    Yi, Lin (Inventor); Tjoelker, Robert L. (Inventor); Burt, Eric A. (Inventor); Huang, Shouhua (Inventor)

    2016-01-01

    Hollow-core capillary discharge lamps on the millimeter or sub-millimeter scale are provided. The hollow-core capillary discharge lamps achieve an increased light intensity ratio between 194 millimeters (useful) and 254 millimeters (useless) light than conventional lamps. The capillary discharge lamps may include a cone to increase light output. Hollow-core photonic crystal fiber (HCPCF) may also be used.

  1. How do Colluvial Hollows Fill?

    Science.gov (United States)

    Hales, T. C.; Parker, R.; Mudd, S. M.; Grieve, S. W. D.

    2016-12-01

    In humid, soil-mantled mountains shallow landslides commonly initiate in colluvial hollows, areas where convergent topography can lead to high pore pressures during storms. Immediately post-landslide initiation, a thin veneer of colluvial material accumulates by small-scale slumping from landslide headscarps. Thereafter colluvium accumulates in hollows primarily through creep-dominated processes like tree throw and animal burrowing, recording the hillslope sediment flux since the last landslide event. We measured the post-landslide hillslope sediment flux in 30 colluvial hollows in the southern Appalachians using radiocarbon measurements collected from soil pits excavated at the centre of steep, landslide-prone hollows. We collected material from the soil-saprolite/bedrock boundary at each location for radiocarbon dating and dated different chemical fractions of the soil (humic acid, humin, charcoal) in an attempt to bracket the "true" age of the soil. We calculated infilling rates of each hollow by measuring soil depths in cross-hollow transects and dividing this by the age of the hollow. The interquartile range of hollow basal ages is 2278-8184 cal. yrs B.P., demonstrating the long return period of landslides in most colluvial hollows. Hillslope erosion rates calculated assuming a linear diffusion transport law show that the transport coefficient (diffusivity) of the hollows varied by 4 orders of magnitude 10-5 to 10-1 m2 yr-1, despite the hollows being formed in regionally consistent geology and vegetation. Uncertainty in the dating and hollow geometry measurements can, at most, account for an order of magnitude of that variability. Our results show that hollows have a phase of rapid infilling that slows through time, consistent with previous observations. Despite this, the oldest hollows show several orders of magnitude variation in the transport coefficient, suggesting local, hollow scale variations in process significantly affect hillslope erosion rates.

  2. VELOCITY AND CONCENTRATION OF BUBBLES IN OZONIZATION COLUMNS WITH CROSS SECTIONS OF DIFFERENT SIZES VELOCIDAD Y CONCENTRACIÓN DE BURBUJAS EN COLUMNAS DE OZONIZACIÓN CON SECCIÓN TRANSVERSAL DE TAMAÑOS DIVERSOS

    Directory of Open Access Journals (Sweden)

    Marcio Ricardo Salla

    2008-12-01

    Full Text Available The size of the cross section of an ozonization column influences its hydrodynamic characteristics, which, on its turn, has effects on phenomena that depend on the relative movement between gas bubbles and liquid. To observe the influence of the cross sectional area on gas concentration and bubbles velocity, two columns were used. The first column had a square cross section with side of 0.19m and the second had a circular cross section with diameter of 0.10 m. The ascendant velocities of the bubbles and their concentration were measured in both columns and compared. The transversal spread of the plumes of bubbles was also quantified. The results show that the increase of the cross section of the column, in the proportion studied here, does not result in a similar increase of the cross section of the ascending plume of bubbles. Furthermore, the results of average velocities and concentrations obtained for the smallest cross section resulted independent of the liquid level in the column, while the results for the largest cross section showed to be dependent of this level. The ratio between the cross sectional areas of the larger and the smaller plumes of bubbles decreases for higher distances to the bottom of the columns.La sección transversal de una columna de ozonización posee influencia directa sobre las características hidrodinámicas de esa columna, lo que se refleja en los fenómenos que dependen de la transferencia de masa en la interfase gas-líquido. En este estudio se utilizaron dos columnas con secciones transversales diferentes cuanto a la forma y al tamaño. La primera con sección transversal cuadrada de 0,19m y la segunda con sección transversal circular de 0,10 m de diámetro. Se midieron las velocidades ascensionales de las burbujas y su concentración. Los resultados obtenidos muestran que el aumento de la sección transversal en la proporción aquí estudiada no conlleva un aumento semejante de la sección transversal de la

  3. Hollow Microporous Organic Capsules

    Science.gov (United States)

    Li, Buyi; Yang, Xinjia; Xia, Lingling; Majeed, Muhammad Irfan; Tan, Bien

    2013-01-01

    Fabrication of hollow microporous organic capsules (HMOCs) could be very useful because of their hollow and porous morphology, which combines the advantages of both microporous organic polymers and non-porous nanocapsules. They can be used as storage materials or reaction chambers while supplying the necessary path for the design of controlled uptake/release systems. Herein, the synthesis of HMOCs with high surface area through facile emulsion polymerization and hypercrosslinking reactions, is described. Due to their tailored porous structure, these capsules possessed high drug loading efficiency, zero-order drug release kinetics and are also demonstrated to be used as nanoscale reactors for the prepareation of nanoparticles (NPs) without any external stabilizer. Moreover, owing to their intrinsic biocompatibility and fluorescence, these capsules exhibit promising prospect for biomedical applications. PMID:23820511

  4. Hollow bunches production

    CERN Document Server

    Hancock, S

    2017-01-01

    Hollow bunches address the issue of high-brightnessbeams suffering from transverse emittance growth in a strongspace charge regime. During the Proton Synchrotron (PS)injection plateau, the negative space charge tune shift canpush the beam onto theQy=6integer resonance. Modify-ing the longitudinal bunch profile in order to reduce the peakline charge density alleviates the detrimental impact of spacecharge. To this end we first produce longitudinally hollowphase space distributions in the PS Booster by exciting aparametric resonance with the phase loop feedback system.These inherently flat bunches are then transferred to the PS,where the beam becomes less prone to the emittance growthcaused by the integer resonance.During the late 2016 machine development sessions inthe PS Booster we profited from solved issues from 2015and managed to reliably extract hollow bunches of1.3eVsmatched longitudinal area. Furthermore, first results to cre-ate hollow bunches with larger longitudinal emittances to-wards the LHC Inject...

  5. High strength and low weight hollow carbon fibres

    Science.gov (United States)

    Köhler, T.; Brüll, R.; Pursche, F.; Langgartner, J.; Seide, G.; Gries, T.

    2017-10-01

    Carbon fibres have strengths of 2.5 to 5 GPa in the fibre direction and an elastic modulus of 200 to 500 GPa. Carbon fibres have equal mechanical properties as steel but 20% of the weight. But the material is more expensive than steel. Therefore, they are only used in industry sectors where the benefits legitimate the high costs. The use of hollow rather than solid fibres allows an even lower weight of the components. At the same time, similar mechanical properties are achieved by the circular cross section. Carbon fibres are obtained from polyacrylonitrile fibers (PAN). These can be produced as hollow fibres. As a first step stabilization and carbonization of hollow PAN precursors is investigated to produce hollow carbon fibres.

  6. Birefringent hollow core fibers

    DEFF Research Database (Denmark)

    Roberts, John

    2007-01-01

    Hollow core photonic crystal fiber (HC-PCF), fabricated according to a nominally non-birefringent design, shows a degree of un-controlled birefringence or polarization mode dispersion far in excess of conventional non polarization maintaining fibers. This can degrade the output pulse in many...... and an increased overlap between the polarization modes at the glass interfaces. The interplay between these effects leads to a wavelength for optimum polarization maintenance, lambda(PM), which is detuned from the wavelength of highest birefringence. By a suitable fiber design involving antiresonance of the core...

  7. The use of NO2 absorption cross section temperature sensitivity to derive NO2 profile temperature and stratospheric–tropospheric column partitioning from visible direct-sun DOAS measurements

    Directory of Open Access Journals (Sweden)

    E. Spinei

    2014-12-01

    Full Text Available This paper presents a temperature sensitivity method (TESEM to accurately calculate total vertical NO2 column, atmospheric slant NO2 profile-weighted temperature (T, and to separate stratospheric and tropospheric columns from direct-sun (DS, ground-based measurements using the retrieved T. TESEM is based on differential optical absorption spectroscopy (DOAS fitting of the linear temperature-dependent NO2 absorption cross section, σ (T, regression model (Vandaele et al., 2003. Separation between stratospheric and tropospheric columns is based on the primarily bimodal vertical distribution of NO2 and an assumption that stratospheric effective temperature can be represented by temperature at 27 km ± 3 K, and tropospheric effective temperature is equal to surface temperature within 3–5 K. These assumptions were derived from the Global Modeling Initiative (GMI chemistry-transport model (CTM simulations over two northern midlatitude sites in 2011. TESEM was applied to the Washington State University Multi-Function DOAS instrument (MFDOAS measurements at four midlatitude locations with low and moderate NO2 anthropogenic emissions: (1 the Jet Propulsion Laboratory's Table Mountain Facility (JPL-TMF, CA, USA (34.38° N/117.68° W; (2 Pullman, WA, USA (46.73° N/117.17° W; (3 Greenbelt, MD, USA (38.99° N/76.84° W; and (4 Cabauw, the Netherlands (51.97° N/4.93° E during July 2007, June–July 2009, July–August and October 2011, November 2012–May 2013, respectively. NO2 T and total, stratospheric, and tropospheric NO2 vertical columns were determined over each site.

  8. 30 CFR 817.72 - Disposal of excess spoil: Valley fill/head-of-hollow fills.

    Science.gov (United States)

    2010-07-01

    ... functioning of the rock core shall be designed and constructed using current, prudent engineering practices...-hollow fills. 817.72 Section 817.72 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STANDARDS-UNDERGROUND MINING ACTIVITIES § 817.72 Disposal of excess spoil: Valley fill/head-of-hollow fills...

  9. 29 CFR 1926.756 - Beams and columns.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Beams and columns. 1926.756 Section 1926.756 Labor... (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Steel Erection § 1926.756 Beams and columns. (a.... (c) (1) Double connections at columns and/or at beam webs over a column. When two structural members...

  10. Preparation of porous hollow silica spheres via a layer-by-layer process and the chromatographic performance

    Science.gov (United States)

    Wei, Xiaobing; Gong, Cairong; Chen, Xujuan; Fan, Guoliang; Xu, Xinhua

    2017-03-01

    Hollow silica spheres possessing excellent mechanical properties were successfully prepared through a layer-by-layer process using uniform polystyrene (PS) latex fabricated by dispersion polymerization as template. The formation of hollow SiO2 micro-spheres, structures and properties were observed in detail by zeta potential, SEM, TEM, FTIR, TGA and nitrogen sorption porosimetry. The results indicated that the hollow spheres were uniform with particle diameter of 1.6 μm and shell thickness of 150 nm. The surface area was 511 m2/g and the pore diameter was 8.36 nm. A new stationary phase for HPLC was obtained by using C18-derivatized hollow SiO2 micro-spheres as packing materials and the chromatographic properties were evaluated for the separation of some regular small molecules. The packed column showed low column pressure, high values of efficiency (up to about 43 000 plates/m) and appropriate asymmetry factors.

  11. Mercury's Hollows: New Information on Distribution and Morphology from MESSENGER Observations at Low Altitude

    Science.gov (United States)

    Blewett, D. T.; Stadermann, A. C.; Chabot, N. L.; Denevi, B. W.; Ernst, C. M.; Peplowski, P. N.

    2014-12-01

    MESSENGER's orbital mission at Mercury led to the discovery of an unusual landform not known from other airless rocky bodies of the Solar System. Hollows are irregularly shaped, shallow, rimless depressions, often occurring in clusters and with high-reflectance interiors and halos. The fresh appearance of hollows suggests that they are relatively young features. For example, hollows are uncratered, and talus aprons downslope of hollows in certain cases appear to be covering small impact craters (100-200 in diameter). Hence, some hollows may be actively forming at present. The characteristics of hollows are suggestive of formation via destruction of a volatile-bearing phase (possibly one or more sulfides) through solar heating, micrometeoroid bombardment, and/or ion impact. Previous analysis showed that hollows are associated with low-reflectance material (LRM), a color unit identified from global color images. The material hosting hollows has often been excavated from depth by basin or crater impacts. Hollows are small features (tens of meters to several kilometers), so their detection and characterization with MESSENGER's global maps have been limited. MESSENGER's low-altitude orbits provide opportunities for collection of images at high spatial resolutions, which reveal new occurrences of hollows and offer views of hollows with unprecedented detail. As of this writing, we have examined more than 21,000 images with pixel sizes images. Locations of the hollows (e.g., crater floor, rim, central peak, plains) were recorded. Shadow-length measurements were made on 280 images, yielding the depths of 1343 individual hollows. The mean depth is 30 m, with a standard deviation of 17 m. We also explored correlations between the geographic locations of hollows and maps provided by the MESSENGER geochemical sensors (X-Ray, Gamma-Ray, and Neutron Spectrometers), including the abundances of Al/Si, Ca/Si, Fe/Si, K, Mg/Si, and S/Si, as well as total neutron cross-section. No

  12. Prediction of Stress Concentration Factors in Unlapped Square Hollow

    African Journals Online (AJOL)

    The paper sets out to discover numerically the effect of brace spacing on stress concentrations in welded square hollow section 'K' joints. Thin shell theory and isoparametric formulation are employed to obtain equilibrium equations, which were solved by the frontal solution code developed for this purpose. Thereafter, the ...

  13. Synthesis, Properties, and Applications of Hollow Micro-/Nanostructures.

    Science.gov (United States)

    Wang, Xiaojing; Feng, Ji; Bai, Yaocai; Zhang, Qiao; Yin, Yadong

    2016-09-28

    In this Review, we aim to provide an updated summary of the research related to hollow micro- and nanostructures, covering both their synthesis and their applications. After a brief introduction to the definition and classification of the hollow micro-/nanostructures, we discuss various synthetic strategies that can be grouped into three major categories, including hard templating, soft templating, and self-templating synthesis. For both hard and soft templating strategies, we focus on how different types of templates are generated and then used for creating hollow structures. At the end of each section, the structural and morphological control over the product is discussed. For the self-templating strategy, we survey a number of unconventional synthetic methods, such as surface-protected etching, Ostwald ripening, the Kirkendall effect, and galvanic replacement. We then discuss the unique properties and niche applications of the hollow structures in diverse fields, including micro-/nanocontainers and reactors, optical properties and applications, magnetic properties, energy storage, catalysis, biomedical applications, environmental remediation, and sensors. Finally, we provide a perspective on future development in the research relevant to hollow micro-/nanostructures.

  14. Research on Configurations of Thermally Integrated Distillation Column(TIDC)

    Science.gov (United States)

    Sun, Lanyi; Li, Jun; Liu, Xuenuan; Li, Qingsong

    Taking a C3 distillation column as the base case, possible configurations for Thermally Integrated Distillation Columns (TIDC) are proposed and compared to a conventional column and a column with a vapor recompression system (VRC). Thermal efficiency of the TIDC appears to be strongly sensitive to column configuration and a highly efficient asymmetrical configuration with stripping section stages thermally interconnected with the same number of stages in the upper part of the rectifying section emerges as the most promising option. The relationships among pressure ratio of rectifying section to stripping section and energy consumption were also discussed.

  15. Switching a Nanocluster Core from Hollow to Non-hollow

    KAUST Repository

    Bootharaju, Megalamane Siddaramappa

    2016-03-24

    Modulating the structure-property relationship in atomically precise nanoclusters (NCs) is vital for developing novel NC materials and advancing their applications. While promising biphasic ligand-exchange (LE) strategies have been developed primarily to attain novel NCs, understanding the mechanistic aspects involved in tuning the core and the ligand-shell of NCs in such biphasic processes is challenging. Here, we design a single phase LE process that enabled us to elucidate the mechanism of how a hollow NC (e.g., [Ag44(SR)30]4-, -SR: thiolate) converts into a non-hollow NC (e.g., [Ag25(SR)18]-), and vice versa. Our study reveals that the complete LE of the hollow [Ag44(SPhF)30]4- NCs (–SPhF: 4-fluorobenzenethiolate) with incoming 2,4-dimethylbenzenethiol (HSPhMe2) induced distortions in the Ag44 structure forming the non-hollow [Ag25(SPhMe2)18]- by a disproportionation mechanism. While the reverse reaction of [Ag25(SPhMe2)18]- with HSPhF prompted an unusual dimerization of Ag25, followed by a rearrangement step that reproduces the original [Ag44(SPhF)30]4-. Remarkably, both the forward and the backward reactions proceed through similar size intermediates that seem to be governed by the boundary conditions set by the thermodynamic and electronic stability of the hollow and non-hollow metal cores. Furthermore, the resizing of NCs highlights the surprisingly long-range effect of the ligands which are felt by atoms far deep in the metal core, thus opening a new path for controlling the structural evolution of nanoparticles.

  16. The Electrospun Ceramic Hollow Nanofibers

    Directory of Open Access Journals (Sweden)

    Shahin Homaeigohar

    2017-11-01

    Full Text Available Hollow nanofibers are largely gaining interest from the scientific community for diverse applications in the fields of sensing, energy, health, and environment. The main reasons are: their extensive surface area that increases the possibilities of engineering, their larger accessible active area, their porosity, and their sensitivity. In particular, semiconductor ceramic hollow nanofibers show greater space charge modulation depth, higher electronic transport properties, and shorter ion or electron diffusion length (e.g., for an enhanced charging–discharging rate. In this review, we discuss and introduce the latest developments of ceramic hollow nanofiber materials in terms of synthesis approaches. Particularly, electrospinning derivatives will be highlighted. The electrospun ceramic hollow nanofibers will be reviewed with respect to their most widely studied components, i.e., metal oxides. These nanostructures have been mainly suggested for energy and environmental remediation. Despite the various advantages of such one dimensional (1D nanostructures, their fabrication strategies need to be improved to increase their practical use. The domain of nanofabrication is still advancing, and its predictable shortcomings and bottlenecks must be identified and addressed. Inconsistency of the hollow nanostructure with regard to their composition and dimensions could be one of such challenges. Moreover, their poor scalability hinders their wide applicability for commercialization and industrial use.

  17. Modelling Pesticide Leaching At Column, Field and Catchment Scales Ii. Influence of Soil Variability On Small Scale Transfer Properties

    Science.gov (United States)

    Roulier, S.; Jarvis, N.

    The aim of this study was to investigate the differences in small scale transfer prop- erties in relation to variability of soil characteristics in a small undulating agricultural catchment (Vemmenhög, 9 km2), where texture and organic C content are strongly related to landscape position (see Gärdenäs et al., this session). Undisturbed soil col- umn samples (20 cm diameter, 20 cm height) were taken at two locations (4 columns at each location): on a hilltop (high clay content), and in a hollow (high C content). Transient leaching experiments for a tracer and a herbicide (MCPA) were carried out in two steps. After a first application of solute and pesticide the columns were ex- posed to natural rainfall. After one pore volume of drainage had flowed through the columns, they were transferred indoors. A second dose of tracer and pesticide was applied, and the columns were irrigated with half a pore volume of natural rainwa- ter. The breakthrough curves obtained for the hilltop columns showed strong evidence of macroporous flow. The flux concentrations and the resident concentration at the end of the experiment measured for the hollow columns suggested that the loss of pesticide from those columns is little. The MACRO model and the inverse modelling package SUFI were used to estimate the small scale parameters for water transfer, so- lute transport, and pesticide. Good agreement was obtained between model and data. Macroporous flow and diffusive transport through hilltop columns was highlighted by the high calibrated values of the effective diffusion pathlength and the dispersivity. As a consequence of the significant organic C content in the hollows, the value of the degradation rate coefficient for hollow columns was important. In both hilltop and hollow columns, the variation of the degradation rate coefficient between the first and the second application of MCPA showed the ability of the micro-organisms to adapt to the pesticide.

  18. Investigation of monolithic capillary columns based on ethylene glycol dimethacrylate in gas chromatography

    Science.gov (United States)

    Korolev, A. A.; Shiryaeva, V. E.; Popova, T. P.; Kurganov, A. A.

    2010-09-01

    The influence of the conditions of the synthesis of polymer monoliths based on ethylene glycol dimethacrylate on the properties of monolithic capillary columns for gas chromatography was investigated. It was established that the time of polymerization, the temperature of synthesis, and the composition of the polymerization mixture have a strong effect on the dynamic and chromatographic properties of the columns. It was concluded that monolithic capillary columns synthesized under optimum conditions are characterized by a height equivalent to a theoretical plate of 30-40 μm, which is considerably less than that for traditional hollow capillary columns of the same diameter.

  19. Hollow waveguide for urology treatment

    Science.gov (United States)

    Jelínková, H.; Němec, M.; Koranda, P.; Pokorný, J.; Kőhler, O.; Drlík, P.; Miyagi, M.; Iwai, K.; Matsuura, Y.

    2010-02-01

    The aim of our work was the application of the special sealed hollow waveguide system for the urology treatment - In our experimental study we have compared the effects of Ho:YAG (wavelength 2100 nm) and Er:YAG (wavelength 2940 nm) laser radiation both on human urinary stones (or compressed plaster samples which serve as a model) fragmentation and soft ureter tissue incision in vitro. Cyclic Olefin Polymer - coated silver (COP/Ag) hollow glass waveguides with inner and outer diameters 700 and 850 μm, respectively, were used for the experiment. To prevent any liquid to diminish and stop the transmission, the waveguide termination was utilized.

  20. Quartz antenna with hollow conductor

    Science.gov (United States)

    Leung, Ka-Ngo; Benabou, Elie

    2002-01-01

    A radio frequency (RF) antenna for plasma ion sources is formed of a hollow metal conductor tube disposed within a glass tube. The hollow metal tubular conductor has an internal flow channel so that there will be no coolant leakage if the outer glass tube of the antenna breaks. A portion of the RF antenna is formed into a coil; the antenna is used for inductively coupling RF power to a plasma in an ion source chamber. The antenna is made by first inserting the metal tube inside the glass tube, and then forming the glass/metal composite tube into the desired coil shape.

  1. Hollow Force, Hollow Metaphor: Assessing The Current Defense Drawdown

    Science.gov (United States)

    2016-04-04

    of a period of war and the threats diminish and everyone starts cutting the hell out of the defense budget….we are not going to hollow out the force...and tactical unit performance at the National Training Center. Henderson concluded that structural barriers and adopted practices in the new All

  2. Modeling Stone Columns

    OpenAIRE

    Castro Gonzalez, Jorge

    2017-01-01

    This paper reviews the main modeling techniques for stone columns, both ordinary stone columns and geosynthetic-encased stone columns. The paper tries to encompass the more recent advances and recommendations in the topic. Regarding the geometrical model, the main options are the "unit cell", longitudinal gravel trenches in plane strain conditions, cylindrical rings of gravel in axial symmetry conditions, equivalent homogeneous soil with improved properties and three-dimensional models, eith...

  3. Slender CRC Columns

    DEFF Research Database (Denmark)

    Aarup, Bendt; Jensen, Lars Rom; Ellegaard, Peter

    2005-01-01

    CRC is a high-performance steel fibre reinforced concrete with a typical compressive strength of 150 MPa. Design methods for a number of structural elements have been developed since CRC was invented in 1986, but the current project set out to further investigate the range of columns for which...... current design guides can be used. The columns tested had a slenderness varying from 1.11 to 12.76 and a reinforcement ratio (area of rebar to area of concrete) ranging from 0 to 8.8 %. A total of 77 tests were carried out - 61 columns were tested in ambient conditions and 16 columns were tested...

  4. Inflatable Column Structure

    Science.gov (United States)

    Hedgepeth, J. M.

    1985-01-01

    Lightweight structural member easy to store. Billowing between circumferential loops of fiber inflated column becomes series of cells. Each fiber subjected to same tension along entire length (though tension is different in different fibers). Member is called "isotensoid" column. Serves as jack for automobiles or structures during repairs. Also used as support for temporary bleachers or swimming pools.

  5. JCE Feature Columns

    Science.gov (United States)

    Holmes, Jon L.

    1999-05-01

    The Features area of JCE Online is now readily accessible through a single click from our home page. In the Features area each column is linked to its own home page. These column home pages also have links to them from the online Journal Table of Contents pages or from any article published as part of that feature column. Using these links you can easily find abstracts of additional articles that are related by topic. Of course, JCE Online+ subscribers are then just one click away from the entire article. Finding related articles is easy because each feature column "site" contains links to the online abstracts of all the articles that have appeared in the column. In addition, you can find the mission statement for the column and the email link to the column editor that I mentioned above. At the discretion of its editor, a feature column site may contain additional resources. As an example, the Chemical Information Instructor column edited by Arleen Somerville will have a periodically updated bibliography of resources for teaching and using chemical information. Due to the increase in the number of these resources available on the WWW, it only makes sense to publish this information online so that you can get to these resources with a simple click of the mouse. We expect that there will soon be additional information and resources at several other feature column sites. Following in the footsteps of the Chemical Information Instructor, up-to-date bibliographies and links to related online resources can be made available. We hope to extend the online component of our feature columns with moderated online discussion forums. If you have a suggestion for an online resource you would like to see included, let the feature editor or JCE Online (jceonline@chem.wisc.edu) know about it. JCE Internet Features JCE Internet also has several feature columns: Chemical Education Resource Shelf, Conceptual Questions and Challenge Problems, Equipment Buyers Guide, Hal's Picks, Mathcad

  6. Hollow micro string based calorimeter device

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a micron-scale calorimeter and a calorimetry method utilizing the micron-scale calorimeter. In accordance with the invention, there is provided a micron-scale calorimeter comprising a micro-channel string, being restrained at at least two longitudinally distanced...... positions so as to form a free released double clamped string in-between said two longitudinally distanced positions said micro-channel string comprising a microfluidic channel having a closed cross section and extending in the longitudinal direction of the hollow string, acoustical means adapted...... to oscillate the string at different frequencies by emitting sound waves towards the string, optical means adapted to detect oscillating frequencies of the string, and controlling means controlling the strength and frequency of the sound wave emitted by the acoustical means and receiving a signal from...

  7. Fabrication of Metallic Hollow Nanoparticles

    Science.gov (United States)

    Kim, Jae-Woo (Inventor); Choi, Sr., Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2016-01-01

    Metal and semiconductor nanoshells, particularly transition metal nanoshells, are fabricated using dendrimer molecules. Metallic colloids, metallic ions or semiconductors are attached to amine groups on the dendrimer surface in stabilized solution for the surface seeding method and the surface seedless method, respectively. Subsequently, the process is repeated with additional metallic ions or semiconductor, a stabilizer, and NaBH.sub.4 to increase the wall thickness of the metallic or semiconductor lining on the dendrimer surface. Metallic or semiconductor ions are automatically reduced on the metallic or semiconductor nanoparticles causing the formation of hollow metallic or semiconductor nanoparticles. The void size of the formed hollow nanoparticles depends on the dendrimer generation. The thickness of the metallic or semiconductor thin film around the dendrimer depends on the repetition times and the size of initial metallic or semiconductor seeds.

  8. Biaxial bending of slender HSC columns and tubes filled with concrete under short- and long-term loads: I Theory

    Directory of Open Access Journals (Sweden)

    Jose A. Rodríguez-Gutiérrez

    2014-07-01

    Full Text Available An analytical method that calculates both the short- and long-term response of slender columns made of high-strength concrete (HSC and tubes filled with concrete with generalized end conditions and subjected to transverse loads along the span and axial load at the ends (causing a single or double curvature under uniaxial or biaxial bending is presented. The proposed method, which is an extension of a method previously developed by the authors, is capable of predicting not only the complete load-rotation and load-deflection curves (both the ascending and descending parts but also the maximum load capacity. The columns that can be analyzed include solid and hollow (rectangular, circular, oval, C-, T-, L-, or any arbitrary shape cross sections and columns made of circular and rectangular steel tubes filled with HSC. The fiber method is used to calculate the moment-curvature diagrams at different levels of the applied axial load (i.e., the M-P-φ curves, and the Gauss method of integration (for the sum of the contributions of the fibers parallel to the neutral axis is used to calculate the lateral rotations and deflections along the column span. Long-term effects, such as creep and shrinkage of the concrete, are also included. However, the effects of the shear deformations and torsion along the member are not included. The validity of the proposed method is presented in a companion paper and compared against the experimental results for over seventy column specimens reported in the technical literature by different researchers.

  9. Modeling of column apparatus processes

    CERN Document Server

    Boyadjiev, Christo; Boyadjiev, Boyan; Popova-Krumova, Petya

    2016-01-01

    This book presents a new approach for the modeling of chemical and interphase mass transfer processes in industrial column apparatuses, using convection-diffusion and average-concentration models. The convection-diffusion type models are used for a qualitative analysis of the processes and to assess the main, small and slight physical effects, and then reject the slight effects. As a result, the process mechanism can be identified. It also introduces average concentration models for quantitative analysis, which use the average values of the velocity and concentration over the cross-sectional area of the column. The new models are used to analyze different processes (simple and complex chemical reactions, absorption, adsorption and catalytic reactions), and make it possible to model the processes of gas purification with sulfur dioxide, which form the basis of several patents.

  10. Confinement less spectral behavior in hollow-core Bragg fibers

    DEFF Research Database (Denmark)

    Foroni, M.; Passaro, D.; Poli, F.

    2007-01-01

    The influence of each cross-section geometric parameter on hollow-core Bragg fiber guiding properties has been numerically investigated. Fabricated fibers have been modeled, giving insight into the spectral behavior of the confinement loss. It has been verified that, by changing the amount...... of silica and air in the fiber cladding, it is possible to change the reflection conditions undergone by the field within the core, thus shifting the confinement loss spectrum....

  11. Space Charge Mitigation With Longitudinally Hollow Bunches

    CERN Multimedia

    Oeftiger, Adrian; Rumolo, Giovanni

    2016-01-01

    Hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

  12. Space charge mitigation with longitudinally hollow bunches

    CERN Document Server

    AUTHOR|(CDS)2088716; Hancock, Steven; Rumolo, Giovanni; CERN. Geneva. ATS Department

    2016-01-01

    Suitably, hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

  13. Method to fabricate hollow microneedle arrays

    Energy Technology Data Exchange (ETDEWEB)

    Kravitz, Stanley H. (Placitas, NM); Ingersoll, David (Albuquerque, NM); Schmidt, Carrie (Los Lunas, NM); Flemming, Jeb (Albuquerque, NM)

    2006-11-07

    An inexpensive and rapid method for fabricating arrays of hollow microneedles uses a photoetchable glass. Furthermore, the glass hollow microneedle array can be used to form a negative mold for replicating microneedles in biocompatible polymers or metals. These microneedle arrays can be used to extract fluids from plants or animals. Glucose transport through these hollow microneedles arrays has been found to be orders of magnitude more rapid than natural diffusion.

  14. Microminiature gas chromatographic column

    Science.gov (United States)

    Donaldson, R. W., Jr.

    1972-01-01

    Techniques commonly used for fabrication of integrated circuits are utilized to produce long capillary tubes for microminiature chromatographs. Method involves bonding of flat silicon plate to top of spirally grooved silicon chip to close groove and form capillary column.

  15. Behavior of reinforced concrete columns strenghtened by partial jacketing

    Directory of Open Access Journals (Sweden)

    D. B. FERREIRA

    Full Text Available This article presents the study of reinforced concrete columns strengthened using a partial jacket consisting of a 35mm self-compacting concrete layer added to its most compressed face and tested in combined compression and uniaxial bending until rupture. Wedge bolt connectors were used to increase bond at the interface between the two concrete layers of different ages. Seven 2000 mm long columns were tested. Two columns were cast monolithically and named PO (original column e PR (reference column. The other five columns were strengthened using a new 35 mm thick self-compacting concrete layer attached to the column face subjected to highest compressive stresses. Column PO had a 120mm by 250 mm rectangular cross section and other columns had a 155 mm by 250mm cross section after the strengthening procedure. Results show that the ultimate resistance of the strengthened columns was more than three times the ultimate resistance of the original column PO, indicating the effectiveness of the strengthening procedure. Detachment of the new concrete layer with concrete crushing and steel yielding occurred in the strengthened columns.

  16. Towards Atomic Column-by-Column Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pennycook, S.J.; Rafferty, B.

    1998-09-06

    The optical arrangement of the scanning transmission electron microscope (STEM) is ideally suited for performing analysis of individual atomic columns in materials. Using the incoherent Z-contrast image as a reference, and arranging incoherent conditions also for the spectroscopy, a precise correspondence is ensured between features in the inelastic image and elastic signals. In this way the exact probe position needed to maximise the inelastic signal from a selected column can be located and monitored during the analysis using the much higher intensity elastic signal. Although object functions for EELS are typically less than 1 {Angstrom} full width at half maximum, this is still an order of magnitude larger than the corresponding object functions for elastic (or diffuse) scattering used to form the Z-contrast image. Therefore the analysis is performed with an effective probe that is significantly broader than that used for the reference Z-contrast image. For a 2.2 {Angstrom} probe the effective probe is of the order of 2.5 {Angstrom}, while for a 1.3 {Angstrom} probe the effective probe is 1.6 {Angstrom}. Such increases in effective probe size can significantly reduce or even eliminate contrast between atomic columns that are visible in the image. However, this is only true if we consider circular collector apertures. Calculations based upon the theory of Maslen and Rossouw (Maslen and Rossouw 1984; Rossouw and Maslen 1984) show that employing an annular aperture can reduce the FWHM of the inelastic object function down to values close 0.1 {Angstrom}. With practical aperture sizes it should be possible to achieve this increased spatial resolution without loosing too much signal.

  17. Hollow system with fin. Transient Green function method combination for two hollow cylinders

    Directory of Open Access Journals (Sweden)

    Buikis Andris

    2017-01-01

    Full Text Available In this paper we develop mathematical model for three dimensional heat equation for the system with hollow wall and fin and construct its analytical solution for two hollow cylindrical sample. The method of solution is based on Green function method for one hollow cylinder. On the conjugation conditions between both hollow cylinders we construct solution for system wall with fin. As result we come to integral equation on the surface between both hollow cylinders. Solution is obtained in the form of second kind Fredholm integral equation. The generalizing of Green function method allows us to use Green function method for regular non-canonical domains.

  18. Hollow nanocrystals and method of making

    Science.gov (United States)

    Alivisatos, A Paul [Oakland, CA; Yin, Yadong [Moreno Valley, CA; Erdonmez, Can Kerem [Berkeley, CA

    2011-07-05

    Described herein are hollow nanocrystals having various shapes that can be produced by a simple chemical process. The hollow nanocrystals described herein may have a shell as thin as 0.5 nm and outside diameters that can be controlled by the process of making.

  19. The use of hollow cathodes in deposition processes: A critical review

    Energy Technology Data Exchange (ETDEWEB)

    Muhl, Stephen, E-mail: muhl@unam.mx; Pérez, Argelia

    2015-03-31

    of electrons (we will call this a hollow cathode arc or HCA). The accepted explanation for the HCD phenomenon involves the existence of high-energy “pendulum” electrons, which are reflected from the sheaths on either side of the cathode; the long trajectory of this electron is understood to produce a large number of secondary electrons, with this resulting in the high plasma density and plasma current. We describe the structure of a parallel-plate discharge, particularly the gas phase and cathode surface excitation and ionization collision processes. Using this description, we discuss some of the problems associated with the conventional hollow cathode model and we propose a new explanation that has important implications for the physics and applications of hollow cathodes. In the last section of this review, we describe how hollow cathodes have and can be used to deposit thin films and nanostructured coatings. We provide an extensive and approximately chronological listing of how hollow cathodes have been successfully used to deposit materials, mainly by sputtering and plasma enhanced chemical vapour deposition based techniques. - Highlights: • We describe the discrepancies of the pendulum model of the hollow cathode plasma. • We present a model of the hollow cathode discharge based on doubly-charged ions. • The secondary electron yield of Ar{sup ++} from the cathode is about 4 times that of Ar{sup +}. • Plasma generation of Ar{sup ++} and the secondary electron emission are quasi-resonant. • A very high density hollow cathode discharge in pure hydrogen is not possible.

  20. Columns in Clay

    Science.gov (United States)

    Leenhouts, Robin

    2010-01-01

    This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…

  1. Practical column design guide

    CERN Document Server

    Nitsche, M

    2017-01-01

    This book highlights the aspects that need to be considered when designing distillation columns in practice. It discusses the influencing parameters as well as the equations governing them, and presents several numerical examples. The book is intended both for experienced designers and for those who are new to the subject.

  2. Hollow Micro-/Nanostructures: Synthesis and Applications

    KAUST Repository

    Lou, Xiong Wen (David)

    2008-11-03

    Hollow micro-nanostructures are of great interest in many current and emerging areas of technology. Perhaps the best-known example of the former is the use of fly-ash hollow particles generated from coal power plants as partial replacement for Portland cement, to produce concrete with enhanced strength and durability. This review is devoted to the progress made in the last decade in synthesis and applications of hollow micro-nanostructures. We present a comprehensive overview of synthetic strategies for hollow structures. These strategies are broadly categorized into four themes, which include well-established approaches, such as conventional hard-templating and soft-templating methods, as well as newly emerging methods based on sacrificial templating and template-free synthesis. Success in each has inspired multiple variations that continue to drive the rapid evolution of the field. The Review therefore focuses on the fundamentals of each process, pointing out advantages and disadvantages where appropriate. Strategies for generating more complex hollow structures, such as rattle-type and nonspherical hollow structures, are also discussed. Applications of hollow structures in lithium batteries, catalysis and sensing, and biomedical applications are reviewed. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA,.

  3. Analyzing Dendritic Morphology in Columns and Layers.

    Science.gov (United States)

    Ting, Chun-Yuan; McQueen, Philip G; Pandya, Nishith; McCreedy, Evan S; McAuliffe, Matthew; Lee, Chi-Hon

    2017-03-23

    In many regions of the central nervous systems, such as the fly optic lobes and the vertebrate cortex, synaptic circuits are organized in layers and columns to facilitate brain wiring during development and information processing in developed animals. Postsynaptic neurons elaborate dendrites in type-specific patterns in specific layers to synapse with appropriate presynaptic terminals. The fly medulla neuropil is composed of 10 layers and about 750 columns; each column is innervated by dendrites of over 38 types of medulla neurons, which match with the axonal terminals of some 7 types of afferents in a type-specific fashion. This report details the procedures to image and analyze dendrites of medulla neurons. The workflow includes three sections: (i) the dual-view imaging section combines two confocal image stacks collected at orthogonal orientations into a high-resolution 3D image of dendrites; (ii) the dendrite tracing and registration section traces dendritic arbors in 3D and registers dendritic traces to the reference column array; (iii) the dendritic analysis section analyzes dendritic patterns with respect to columns and layers, including layer-specific termination and planar projection direction of dendritic arbors, and derives estimates of dendritic branching and termination frequencies. The protocols utilize custom plugins built on the open-source MIPAV (Medical Imaging Processing, Analysis, and Visualization) platform and custom toolboxes in the matrix laboratory language. Together, these protocols provide a complete workflow to analyze the dendritic routing of Drosophila medulla neurons in layers and columns, to identify cell types, and to determine defects in mutants.

  4. Energy-dependent expansion of .177 caliber hollow-point air gun projectiles.

    Science.gov (United States)

    Werner, Ronald; Schultz, Benno; Bockholdt, Britta; Ekkernkamp, Axel; Frank, Matthias

    2017-05-01

    Amongst hundreds of different projectiles for air guns available on the market, hollow-point air gun pellets are of special interest. These pellets are characterized by a tip or a hollowed-out shape in their tip which, when fired, makes the projectiles expand to an increased diameter upon entering the target medium. This results in an increase in release of energy which, in turn, has the potential to cause more serious injuries than non-hollow-point projectiles. To the best of the authors' knowledge, reliable data on the terminal ballistic features of hollow-point air gun projectiles compared to standard diabolo pellets have not yet been published in the forensic literature. The terminal ballistic performance (energy-dependent expansion and penetration) of four different types of .177 caliber hollow-point pellets discharged at kinetic energy levels from approximately 3 J up to 30 J into water, ordnance gelatin, and ordnance gelatin covered with natural chamois as a skin simulant was the subject of this investigation. Energy-dependent expansion of the tested hollow-point pellets was observed after being shot into all investigated target media. While some hollow-point pellets require a minimum kinetic energy of approximately 10 J for sufficient expansion, there are also hollow-point pellets which expand at kinetic energy levels of less than 5 J. The ratio of expansion (RE, calculated by the cross-sectional area (A) after impact divided by the cross-sectional area (A 0) of the undeformed pellet) of hollow-point air gun pellets reached values up of to 2.2. The extent of expansion relates to the kinetic energy of the projectile with a peak for pellet expansion at the 15 to 20 J range. To conclude, this work demonstrates that the hollow-point principle, i.e., the design-related enlargement of the projectiles' frontal area upon impact into a medium, does work in air guns as claimed by the manufacturers.

  5. Hollow Core, Whispering Gallery Resonator Sensors

    CERN Document Server

    Ward, Jonathan M; Chormaic, Síle Nic

    2014-01-01

    A review of hollow core whispering gallery resonators (WGRs)is given. After a short introduction to the topic of whispering gallery resonators we provide a description of whispering gallery modes in hollow or liquid core WGRs. Next, whispering gallery mode (WGM) sensing mechanisms are outlined and some fabrication methods for microbubbles, microcapillaries and other tubular WGM devices are discussed. We then focus on the most common applications of hollow core WGRs, namely refractive index and temperature sensing, gas sensing, force sensing, biosensing, and lasing. The review highlights some of the key papers in this field and gives the reader a general overview of the current state-of-the-art.

  6. Hollow fiber membrane contactors for CO2 capture: modeling and up-scaling to CO2 capture for an 800 MWe coal power station

    NARCIS (Netherlands)

    Kimball, E.; Al-Azki, A.; Gomez, A.; Goetheer, E.L.V.; Booth, N.; Adams, D.; Ferre, D.

    2014-01-01

    A techno-economic analysis was completed to compare the use of Hollow Fiber Membrane Modules (HFMM) with the more conventional structured packing columns as the absorber in amine-based CO2capture systems for power plants. In order to simulate the operation of industrial scale HFMMsystems, a

  7. Development of Dynamic Models for a Reactive Packed Distillation Column

    OpenAIRE

    Abdulwahab GIWA; Süleyman KARACAN

    2012-01-01

    This work has been carried out to develop dynamic models for a reactive packed distillation column using the production of ethyl acetate as the case study. The experimental setup for the production of ethyl acetate was a pilot scale packed column divided into condenser, rectification, acetic acid feed, reaction, ethanol feed, stripping and reboiler sections. The reaction section was filled with Amberlyst 15 catalyst while the rectification and the stripping sections were both filled raschig r...

  8. Nine Words - Nine Columns

    DEFF Research Database (Denmark)

    Trempe Jr., Robert B.; Buthke, Jan

    2016-01-01

    This book records the efforts of a one-week joint workshop between Master students from Studio 2B of Arkitektskolen Aarhus and Master students from the Harbin Institute of Technology in Harbin, China. The workshop employed nine action words to instigate team-based investigation into the effects o...... as formwork for the shaping of wood veneer. The resulting columns ‘wear’ every aspect of this design pipeline process and display the power of process towards an architectural resolution....

  9. Analysis of Reinforced Concrete Hollow Piers Behavior: Benefits of FRP Confinement

    Directory of Open Access Journals (Sweden)

    Gian Piero Lignola

    2009-07-01

    Full Text Available Reliable stress-strain behavior of concrete is necessary particularly when a member is subjected to combine bending and axial load and confinement effects should be accounted for. A unified theory for confinement of circular hollow sections is proposed herein, that can be extended to the case of solid and noncircular sections. The main aim of the model is to trace step-by-step the evolution of the three dimensional stresses in confined concrete and confining devices (i.e. FRP externally bonded jackets. The iterative model is able to estimate confinement effectiveness and to plot stress-strain relationships, which are different in the case of solid and hollow sections. Through the proposed improved model, a simplified closed form solution has been also derived to directly determine ultimate confined concrete properties and stress-strain curves. At present, theoretical results based on the proposed concrete circular hollow sections confinement model, in satisfactory agreement with the experimental data available in scientific literature, show that FRP jacketing can enhance the ultimate load and ductility significantly, also in the case of hollow concrete cross sections.

  10. Behavior of Columns During Earthquakes

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The behavior of columns during earthquakes is very important since column failures may lead to additional structural failures and result in total building collapses....

  11. Plasma Emission Characteristics from a High Current Hollow Cathode in an Ion Thruster Discharge Chamber

    Science.gov (United States)

    Foster, John E.; Patterson, Michael J.

    2002-01-01

    The presence of energetic ions produced by a hollow cathodes operating at high emission currents (greater than 5A) has been documented in the literature. In order to further elucidate these findings, an investigation of a high current cathode operating in an ion thruster discharge chamber has been undertaken. Using Langmuir probes, a low energy charged particle analyzer and emission spectroscopy, the behavior of the near-cathode plasma and the emitted ion energy distribution was characterized. The presence of energetic ions was confirmed. It was observed that these ions had energies in excess of the discharge voltage and thus cannot be simply explained by ions falling out of plasma through a potential difference of this order. Additionally, evidence provided by Langmuir probes suggests the existence of a double layer essentially separating the hollow cathode plasma column from the main discharge. The radial potential difference associated with this double layer was measured to be of order the ionization potential.

  12. PROBABILISTIC FAILURE ANALYSIS OF A SOLID TIMBER COLUMN

    African Journals Online (AJOL)

    2012-11-03

    Nov 3, 2012 ... In this paper, a reliability evaluation of a solid timber column of square cross section subjected to axial and lateral loading in ... reliability evaluation, solid timber column, Eurocode, axial loading, slenderness ratio. 1. Introduction. The quality of an .... joint probability function. Fx(x) = P (nn i=1 {Xi ≤ xi}).

  13. Column: Every Last Byte

    Directory of Open Access Journals (Sweden)

    Simson Garfinkel

    2011-06-01

    Full Text Available Inheritance powder is the name that was given to poisons, especially arsenic, that were commonly used in the 17th and early 18th centuries to hasten the death of the elderly. For most of the 17th century, arsenic was deadly but undetectable, making it nearly impossible to prove that someone had been poisoned. The first arsenic test produced a gas—hardly something that a scientist could show to a judge. Faced with a growing epidemic of poisonings, doctors and chemists spent decades searching for something better.(see PDF for full column

  14. of reinforced concrete columns

    Directory of Open Access Journals (Sweden)

    Anna Szcześniak

    2015-09-01

    Full Text Available The paper presents the modification of the dynamic relaxation method in order to increase its effectiveness in the range of the post-critical analysis. For this purpose, the arc-length parameter on the equilibrium path was introduced into the computational procedure. The additional constraints equation that combines increment of load parameter and the vector of displacement increments with the arc-length increment on the solution path was incorporated to analysis of the equations of motion. Solution of nonlinear equilibrium equations is obtained recursively in subsequent pseudo-time instants. The proposed method allows for tracking the global softening phenomenon of the structural element in the post-critical range, which leads to failure. We ran numerical experiments for the reinforced concrete eccentrically loaded column. Our comparative analysis with previously published numerical results demonstrated that the proposed computational method is effective.[b]Keywords[/b]: reinforced concrete columns, dynamic relaxation method, arc-length method, load-carrying capacity

  15. Fire Response of Concrete Filled Hollow Steel Sections

    DEFF Research Database (Denmark)

    Nyman, Simon; Virdi, Kuldeep

    2011-01-01

    Advanced and simplified methods of analysis and design for the fire resistance of structural elements and assemblages of structures have been developed in recent years. Some simplified methods for the fire design of concrete filled tubes have appeared in Eurocode 4 part 1.2. Experience to date in...

  16. Method for the production of fabricated hollow microspheroids

    Energy Technology Data Exchange (ETDEWEB)

    Wickramanayake, Shan; Luebke, David R.

    2015-06-09

    The method relates to the fabrication of a polymer microspheres comprised of an asymmetric layer surrounding a hollow interior. The fabricated hollow microsphere is generated from a nascent hollow microsphere comprised of an inner core of core fluid surrounded by a dope layer of polymer dope, where the thickness of the dope layer is at least 10% and less than 50% of the diameter of the inner core. The nascent hollow microsphere is exposed to a gaseous environment, generating a vitrified hollow microsphere, which is subsequently immersed in a coagulation bath. Solvent exchange produces a fabricated hollow microsphere comprised of a densified outer skin surrounding a macroporous inner layer, which surrounds a hollow interior. In an embodiment, the polymer is a polyimide or a polyamide-imide, and the non-solvent in the core fluid and the coagulation bath is water. The fabricated hollow microspheres are particularly suited as solvent supports for gas separation processes.

  17. Column-to-column packing variation of disposable pre-packed columns for protein chromatography.

    Science.gov (United States)

    Schweiger, Susanne; Hinterberger, Stephan; Jungbauer, Alois

    2017-12-08

    In the biopharmaceutical industry, pre-packed columns are the standard for process development, but they must be qualified before use in experimental studies to confirm the required performance of the packed bed. Column qualification is commonly done by pulse response experiments and depends highly on the experimental testing conditions. Additionally, the peak analysis method, the variation in the 3D packing structure of the bed, and the measurement precision of the workstation influence the outcome of qualification runs. While a full body of literature on these factors is available for HPLC columns, no comparable studies exist for preparative columns for protein chromatography. We quantified the influence of these parameters for commercially available pre-packed and self-packed columns of disposable and non-disposable design. Pulse response experiments were performed on 105 preparative chromatography columns with volumes of 0.2-20ml. The analyte acetone was studied at six different superficial velocities (30, 60, 100, 150, 250 and 500cm/h). The column-to-column packing variation between disposable pre-packed columns of different diameter-length combinations varied by 10-15%, which was acceptable for the intended use. The column-to-column variation cannot be explained by the packing density, but is interpreted as a difference in particle arrangement in the column. Since it was possible to determine differences in the column-to-column performance, we concluded that the columns were well-packed. The measurement precision of the chromatography workstation was independent of the column volume and was in a range of±0.01ml for the first peak moment and±0.007 ml 2 for the second moment. The measurement precision must be considered for small columns in the range of 2ml or less. The efficiency of disposable pre-packed columns was equal or better than that of self-packed columns. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

  18. SPIRAL CONTACTOR FOR SOLVENT EXTRACTION COLUMN

    Science.gov (United States)

    Cooley, C.R.

    1961-06-13

    The patented extraction apparatus includes a column, perforated plates extending across the column, liquid pulse means connected to the column, and an imperforate spiral ribbon along the length of the column.

  19. European Analytical Column

    DEFF Research Database (Denmark)

    Karlberg, B.; Grasserbauer, M.; Andersen, Jens Enevold Thaulov

    2009-01-01

    The European Analytical Column has once more invited a guest columnist to give his views on various matters related to analytical chemistry in Europe. This year, we have invited Professor Manfred Grasserbauer of the Vienna University of Technology to present some of the current challenges...... for European analytical chemistry. During the period 2002–07, Professor Grasserbauer was Director of the Institute for Environment and Sustainability, Joint Research Centre of the European Commission (EC), Ispra, Italy. There is no doubt that many challenges exist at the present time for all of us representing...... a major branch of chemistry, namely analytical chemistry. The global financial crisis is affecting all branches of chemistry, but analytical chemistry, in particular, since our discipline by tradition has many close links to industry. We have already noticed decreased industrial commitment with respect...

  20. Column: File Cabinet Forensics

    Directory of Open Access Journals (Sweden)

    Simson Garfinkel

    2011-12-01

    Full Text Available Researchers can spend their time reverse engineering, performing reverse analysis, or making substantive contributions to digital forensics science. Although work in all of these areas is important, it is the scientific breakthroughs that are the most critical for addressing the challenges that we face.Reverse Engineering is the traditional bread-and-butter of digital forensics research. Companies like Microsoft and Apple deliver computational artifacts (operating systems, applications and phones to the commercial market. These artifacts are bought and used by billions. Some have evil intent, and (if society is lucky, the computers end up in the hands of law enforcement. Unfortunately the original vendors rarely provide digital forensics tools that make their systems amenable to analysis by law enforcement. Hence the need for reverse engineering.(see PDF for full column

  1. Transmission properties of hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Falk, Charlotte Ijeoma; Hald, Jan; Petersen, Jan C.

    2010-01-01

    Variations in optical transmission of four types of hollow-core photonic bandgap fibers are measured as a function of laser frequency. These variations influence the potential accuracy of gas sensors based on molecular spectroscopy in hollow-core fibers.......Variations in optical transmission of four types of hollow-core photonic bandgap fibers are measured as a function of laser frequency. These variations influence the potential accuracy of gas sensors based on molecular spectroscopy in hollow-core fibers....

  2. Adiabatic Rearrangement of Hollow PV Towers

    Directory of Open Access Journals (Sweden)

    Eric A Hendricks

    2010-10-01

    Full Text Available Diabatic heating from deep moist convection in the hurricane eyewall produces a towering annular structure of elevated potential vorticity (PV. This structure has been referred to as a hollow PV tower. The sign reversal of the radial gradient of PV satisfies the Charney-Stern necessary condition for combined barotropic-baroclinic instability. For thin enough annular structures, small perturbations grow exponentially, extract energy from the mean flow, and lead to hollow tower breakdown, with significant vortex structural and intensity change. The three-dimensional adiabatic rearrangements of two prototypical hurricane-like hollow PV towers (one thick and one thin are examined in an idealized framework. For both hollow towers, dynamic instability causes air parcels with high PV to be mixed into the eye preferentially at lower levels, where unstable PV wave growth rates are the largest. Little or no mixing is found to occur at upper levels. The mixing at lower and middle levels is most rapid for the breakdown of the thin hollow tower, consistent with previous barotropic results. For both hollow towers, this advective rearrangement of PV affects the tropical cyclone structure and intensity in a number of ways. First, the minimum central pressure and maximum azimuthal mean velocity simultaneously decrease, consistent with previous barotropic results. Secondly, isosurfaces of absolute angular momentum preferentially shift inward at low levels, implying an adiabatic mechanism by which hurricane eyewall tilt can form. Thirdly, a PV bridge, similar to that previously found in full-physics hurricane simulations, develops as a result of mixing at the isentropic levels where unstable PV waves grow most rapidly. Finally, the balanced mass field resulting from the PV rearrangement is warmer in the eye between 900 and 700 hPa. The location of this warming is consistent with observed warm anomalies in the eye, indicating that in certain instances the hurricane

  3. Tin-wall hollow ceramic spheres from slurries. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, A.T.; Cochran, J.K.

    1992-12-31

    The overall objective of this effort was to develop a process for economically fabricating thin-wall hollow ceramic spheres from conventional ceramic powders using dispersions. This process resulted in successful production of monosized spheres in the mm size range which were point contact bonded into foams. Thin-wall hollow ceramic spheres of small (one to five millimeter) diameter have novel applications as high-temperature insulation and light structural materials when bonded into monolithic foams. During Phase 1 of this program the objective as to develop a process for fabricating thin-wall hollow spheres from powder slurries using the coaxial nozzle fabrication method. Based on the success during Phase 1, Phase 2 was revised to emphasize the assessment of the potential structural and insulation applications for the spheres and modeling of the sphere formation process was initiated. As more understanding developed, it was clear that to achieve successful structural application, the spheres had to be bonded into monolithic foams and the effort was further expanded to include both bonding into structures and finite element mechanical modeling which became the basis of Phase 3. Successful bonding techniques and mechanical modeling resulted but thermal conductivities were higher than desired for insulating activities. In addition, considerable interest had been express by industry for the technology. Thus the final Phase 4 concentrated on methods to reduce thermal conductivity by a variety of techniques and technology transfer through individualized visits. This program resulted in three Ph.D. theses and 10 M.S. theses and they are listed in the appropriate technical sections.

  4. Computational predictions of zinc oxide hollow structures

    Science.gov (United States)

    Tuoc, Vu Ngoc; Huan, Tran Doan; Thao, Nguyen Thi

    2018-03-01

    Nanoporous materials are emerging as potential candidates for a wide range of technological applications in environment, electronic, and optoelectronics, to name just a few. Within this active research area, experimental works are predominant while theoretical/computational prediction and study of these materials face some intrinsic challenges, one of them is how to predict porous structures. We propose a computationally and technically feasible approach for predicting zinc oxide structures with hollows at the nano scale. The designed zinc oxide hollow structures are studied with computations using the density functional tight binding and conventional density functional theory methods, revealing a variety of promising mechanical and electronic properties, which can potentially find future realistic applications.

  5. Microfabricated hollow microneedle array using ICP etcher

    Energy Technology Data Exchange (ETDEWEB)

    Ji Jing [Mechanical Engineering National University of Singapore, 119260, Singapore (Singapore); Tay, Francis E H [Mechanical Engineering National University of Singapore, 119260, Singapore (Singapore); Miao Jianmin [MicroMachines Center, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore)

    2006-04-01

    This paper presents a developed process for fabrication of hollow silicon microneedle arrays. The inner hollow hole and the fluidic reservoir are fabricated in deep reactive ion etching. The profile of outside needles is achieved by the developed fabrication process, which combined isotropic etching and anisotropic etching with inductively coupled plasma (ICP) etcher. Using the combination of SF{sub 6}/O{sub 2} isotropic etching chemistry and Bosch process, the high aspect ratio 3D and high density microneedle arrays are fabricated. The generated needle external geometry can be controlled by etching variables in the isotropic and anisotropic cases.

  6. Microfabricated hollow microneedle array using ICP etcher

    Science.gov (United States)

    Ji, Jing; Tay, Francis E. H.; Miao, Jianmin

    2006-04-01

    This paper presents a developed process for fabrication of hollow silicon microneedle arrays. The inner hollow hole and the fluidic reservoir are fabricated in deep reactive ion etching. The profile of outside needles is achieved by the developed fabrication process, which combined isotropic etching and anisotropic etching with inductively coupled plasma (ICP) etcher. Using the combination of SF6/O2 isotropic etching chemistry and Bosch process, the high aspect ratio 3D and high density microneedle arrays are fabricated. The generated needle external geometry can be controlled by etching variables in the isotropic and anisotropic cases.

  7. Bioreactor design considerations for hollow organs.

    Science.gov (United States)

    Fish, Jeff; Halberstadt, Craig; McCoy, Darell W; Robbins, Neil

    2013-01-01

    There are many important considerations in the design, construction, and use of a bioreactor for growing hollow organs such as vessels, gastrointestinal tissue, esophagus, and others. The growth of new organs requires a specialized container that provides sterility and an environment conducive to cell-seeding and attachment onto a three-dimensional bioabsorbable porous scaffold, incubation, maturation, and shipping for implantation. The materials' selection, dimensions, manufacturing, testing, and use of the bioreactor are all factors that should be considered in designing a bioreactor for the development of hollow organs.

  8. Scaffold Characteristics for Functional Hollow Organ Regeneration

    Directory of Open Access Journals (Sweden)

    Daniel Eberli

    2010-01-01

    Full Text Available Many medical conditions require surgical reconstruction of hollow organs. Tissue engineering of organs and tissues is a promising new technique without harvest site morbidity. An ideal biomaterial should be biocompatible, support tissue formation and provide adequate structural support. It should degrade gradually and provide an environment allowing for cell-cell interaction, adhesion, proliferation, migration, and differentiation. Although tissue formation is feasible, functionality has never been demonstrated. Mainly the lack of proper innervation and vascularisation are hindering contractility and normal function. In this chapter we critically review the current state of engineering hollow organs with a special focus on innervation and vascularisation.

  9. The Hollow-Face Illusion in Infancy: Do Infants See a Screen Based Rotating Hollow Mask as Hollow?

    Directory of Open Access Journals (Sweden)

    Aki Tsuruhara

    2011-06-01

    Full Text Available We investigated whether infants experience the hollow-face illusion using a screen-based presentation of a rotating hollow mask. In experiment 1 we examined preferential looking between rotating convex and concave faces. Adults looked more at the concave—illusory convex—face which appears to counter rotate. Infants of 7- to 8-month-old infants preferred the convex face, and 5- to 6-month-olds showed no preference. While older infants discriminate, their preference differed from that of adults possibly because they don't experience the illusion or counter rotation. In experiment 2 we tested preference in 7- to 8-month-olds for angled convex and concave static faces both before and after habituation to the stimuli shown in experiment 1. The infants showed a novelty preference for the static shape opposite to the habituation stimulus, together with a general preference for the static convex face. This shows that they discriminate between convex and concave faces and that habituation to either transfers across a change in view. Seven- to eight-month-olds have been shown to discriminate direction of rigid rotation on the basis of perspective changes. Our results suggest that this, perhaps together with a weaker bias to perceive faces as convex, allows these infants to see the screen-based hollow face as hollow even though adults perceive it as convex.

  10. A review on process intensification in internally heat-integrated distillation columns

    NARCIS (Netherlands)

    Kiss, Anton Alexandru; Olujic, Zarko

    2014-01-01

    Internally heat-integrated distillation column (HIDiC) is the most radical approach of a heat pump design, making efficient use of internal heat-integration: the rectifying section of a distillation column operating at a higher pressure becomes the heat source, while the stripping part of the column

  11. Seeding the m = 0 instability in dense plasma focus Z-pinches with a hollow anode

    CERN Document Server

    Liu, J X; McMahon, M; Tummel, K; Cooper, C; Higginson, D; Shaw, B; Povilus, A; Link, A; Schmidt, A

    2016-01-01

    The dense plasma focus (DPF) is a classic Z-pinch plasma device that has been studied for decades as a radiation source. The formation of the m = 0 plasma instability during the compression phase is linked to the generation of high-energy charged particle beams, which, when operated in deuterium, lead to beam-target fusion reactions and the generation of neutron yield. In this paper, we present a technique of seeding the m = 0 instability by employing a hollow in the anode. As the plasma sheath moves along the anode's hollow structure, a low density perturbation is formed and this creates a non-uniform plasma column which is highly unstable. Dynamics of the low density perturbation and preferential seeding of the m = 0 instability were studied in detail with fully kinetic plasma simulations performed in the Large Scale Plasma particle-in-cell code as well as with a simple snowplow model. The simulations showed that by employing an anode geometry with appropriate inner hollow radius, the neutron yield of the D...

  12. HETP evaluation of structured packing distillation column

    Directory of Open Access Journals (Sweden)

    A. E. Orlando Jr.

    2009-09-01

    Full Text Available Several tests with a hydrocarbon mixture of known composition (C8-C14, obtained from DETEN Chemistry S.A., have been performed in a laboratory distillation column, having 40mm of nominal diameter and 2.2m high, with internals of Sulzer DX gauze stainless steel structured packing. The main purpose of this work was to evaluate HETP of a structured packing laboratory scale distillation column, operating continuously. Six HETP correlations available in the literature were compared in order to find out which is the most appropriate for structured packing columns working with medium distillates. Prior to the experimental tests, simulation studies using commercial software PRO/II® were performed in order to establish the optimum operational conditions for the distillation, especially concerning operating pressure, top and bottom temperatures, feed location and reflux ratio. The results of PRO/II® were very similar to the analysis of the products obtained during continuous operation, therefore permitting the use of the properties calculated by that software on the theoretical models investigated. The theoretical models chosen for HETP evaluation were: Bravo, Rocha and Fair (1985; Rocha, Bravo and Fair (1993, 1996; Brunazzi and Pagliant (1997; Carlo, Olujić and Pagliant (2006; Olujić et al., (2004. Modifications concerning calculation of specific areas were performed on the correlations in order to fit them for gauze packing HETP evaluation. As the laboratory distillation column was operated continuously, different HETP values were found by the models investigated for each section of the column. The low liquid flow rates in the top section of the column are a source of error for HETP evaluation by the models; therefore, more reliable HETP values were found in the bottom section, in which liquid flow rates were much greater. Among the theoretical models, Olujić et al. (2004 has shown good results relative to the experimental tests. In addition, the

  13. Hollow fibre supported liquid membrane extraction of ...

    African Journals Online (AJOL)

    A simple sample pre-treatment method utilizing hollow fibre supported liquid membrane (HFSLM) was carried out on pharmaceuticals samples comprising of cough syrups (CS1 and CS2) and an anti-inflammatory product (AI). The active ingredients targeted in the extraction process were diphenylhydramine (DPH), ...

  14. Electromagnetic and microwave absorbing properties of hollow ...

    Indian Academy of Sciences (India)

    A mass of hollow carbon nanospheres (HCNSs) was fabricated by chemical vapour deposition of methane over Ni/Al2O3 catalyst at 600 °C. The products were ... Airworthiness Certification Technology Research and Management Centre, Civil Aviation University of China, Tianjin 300 300, China; School of Materials Science ...

  15. Safety barriers and lighting columns.

    NARCIS (Netherlands)

    Schreuder, D.A.

    1972-01-01

    Problems arising from the sitting of lighting columns on the central reserve are reviewed, and remedial measures such as break-away lighting supports and installation of safety fences on the central reserve on both sides of the lighting columns are examined.

  16. Developing the bundled glass column

    NARCIS (Netherlands)

    Oikonomopoulou, F.; Bristogianni, T; Veer, F.A.; Nijsse, R.; da Sousa Cruz, Paulo J.

    In this paper a bundled glass column is presented as a promising solution for a completely transparent, almost dematerialized structural compressive element. The aim is to ob-tain a glass column that can safely carry loads, achieve a high visual result and be relatively eas-ily manufactured.

  17. Comparative analysis of thermal behavior in hollow nuclear fuel pellets

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Beatriz M. dos; Alvim, Antonio C.M., E-mail: bmachado@nuclear.ufrj.br, E-mail: aalvim@gmail.com [Coordenacao de Pos-Graduacao e Pesquisa de Engenharia (PEN/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear

    2017-11-01

    The increase in energy demand in Brazil and in the world is a real problem and several solutions are being considered to mitigate it. Maximization of energy generation, within the safety standards of fuel resources already known, is one of them. In this respect, nuclear energy is a crucial technology to sustain energy demand on several countries. Performances of a solid cylindrical and an annular rod have been verified and compared; where it has been proven that the annular rod can reach a higher nominal power in relation to the solid one. In this paper, the temperature profiles of two distinct nuclear fuel pellets, one of them annular and the other in the shape of a hollow biconcave disc (like the cross section of a red blood cell), were compared to analyze the efficiency and safety of both. The finite differences method allowed the evaluation of the thermal behavior of these pellets, where one specific physical condition was analyzed, regarding convection and conduction at the lateral edges. The results show that the temperature profile of the hollow biconcave disc pellet is lower, about 70 deg C below, when compared to the temperature profile of the annular pellet, considering the same simulation parameters for both pellets. (author)

  18. Mush Column Magma Chambers

    Science.gov (United States)

    Marsh, B. D.

    2002-12-01

    Magma chambers are a necessary concept in understanding the chemical and physical evolution of magma. The concept may well be similar to a transfer function in circuit or time series analysis. It does what needs to be done to transform source magma into eruptible magma. In gravity and geodetic interpretations the causative body is (usually of necessity) geometrically simple and of limited vertical extent; it is clearly difficult to `see' through the uppermost manifestation of the concentrated magma. The presence of plutons in the upper crust has reinforced the view that magma chambers are large pots of magma, but as in the physical representation of a transfer function, actual magma chambers are clearly distinct from virtual magma chambers. Two key features to understanding magmatic systems are that they are vertically integrated over large distances (e.g., 30-100 km), and that all local magmatic processes are controlled by solidification fronts. Heat transfer considerations show that any viable volcanic system must be supported by a vertically extensive plumbing system. Field and geophysical studies point to a common theme of an interconnected stack of sill-like structures extending to great depth. This is a magmatic Mush Column. The large-scale (10s of km) structure resembles the vertical structure inferred at large volcanic centers like Hawaii (e.g., Ryan et al.), and the fine scale (10s to 100s of m) structure is exemplified by ophiolites and deeply eroded sill complexes like the Ferrar dolerites of the McMurdo Dry Valleys, Antarctica. The local length scales of the sill reservoirs and interconnecting conduits produce a rich spectrum of crystallization environments with distinct solidification time scales. Extensive horizontal and vertical mushy walls provide conditions conducive to specific processes of differentiation from solidification front instability to sidewall porous flow and wall rock slumping. The size, strength, and time series of eruptive behavior

  19. Completing electron scattering studies with the inert gas column:e - Rn scattering and Ionization

    CERN Document Server

    Joshi, Foram M; Chaudhari, Asha S; Modi, Hitesh S; Pindaria, Manish J

    2016-01-01

    Interest in the inert or noble- gas atoms in general arises because they are ideal as test systems for various theoretical models of electron scattering and also since their interaction processes serve as reference for the determination of instrumental responses in electron scattering experiments. The ionization cross section data of ground state inert gas atoms He through Xe are considered to be benchmark data. Our aim in this paper is to provide theoretical results on electron scattering with Radon atoms, as it would complete the studies on the entire inert gas column. That is possible with this particular column only, in view of the preceding literature on He through Xe . Inert gas radon is radioactive, and would be a difficult target for electron scattering experiments. In the present calculations, the complications arising from radioactivity are not considered. We provide hitherto unavailable cross sections on atomic radon, and also provide opportunity of the comparison of electron impact cross sections ...

  20. Packing: do you really need it in heat transfer section of distillation column?; E realmente necessario o uso de recheio em secoes de troca termica de colunas de destilacao?

    Energy Technology Data Exchange (ETDEWEB)

    Waintraub, Silvia [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES); Torres, Glaucia Alves da Silva [PETROBRAS, Rio de Janeiro, RJ (Brazil); Barbarela, Bruno de Almeida; Guimaraes, Flavio Martins de Queiroz [Chemtech, A Siemens Company, Sao Paulo, SP (Brazil)

    2004-07-01

    Recent studies and some designs have shown a great advantage of using empty spray sections in some regions of towers, such as gas oil pump around in vacuum towers and wash oil chambers in coker main fractionator. The main advantages are the pressure drop reduction that implies in an increase of vaporization and in the distillates yields, besides the reduction in both maintenance and investment costs. Plant tests were conducted in vacuum towers from PETROBRAS refineries, and the results were modeled with CFD in order to evaluate the performance of these empty spray sections. Radial temperature surveys were collected at several levels to allow the determination of the distribution quality profile and the height necessary to exchange the desired heat amount. Vapor maldistribution , the influence of vapor velocity (C factor) and the use of more than one level of distributors were also studied. (author)

  1. Column-Oriented Database Systems (Tutorial)

    NARCIS (Netherlands)

    D. Abadi; P.A. Boncz (Peter); S. Harizopoulos

    2009-01-01

    textabstractColumn-oriented database systems (column-stores) have attracted a lot of attention in the past few years. Column-stores, in a nutshell, store each database table column separately, with attribute values belonging to the same column stored contiguously, compressed, and densely packed, as

  2. Conceptual design of hollow electron lenses for beam halo control in the Large Hadron Collider

    Energy Technology Data Exchange (ETDEWEB)

    Stancari, Giulio [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Previtali, Valentina [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Valishev, Alexander [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Bruce, Roderik [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Redaelli, Stefano [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Rossi, Adriana [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Salvachua Ferrando, Belen [European Organization for Nuclear Research (CERN), Geneva (Switzerland)

    2014-06-26

    Collimation with hollow electron beams is a technique for halo control in high-power hadron beams. It is based on an electron beam (possibly pulsed or modulated in intensity) guided by strong axial magnetic fields which overlaps with the circulating beam in a short section of the ring. The concept was tested experimentally at the Fermilab Tevatron collider using a hollow electron gun installed in one of the Tevatron electron lenses. We are proposing a conceptual design for applying this technique to the Large Hadron Collider at CERN. A prototype hollow electron gun for the LHC was built and tested. The expected performance of the hollow electron beam collimator was based on Tevatron experiments and on numerical tracking simulations. Halo removal rates and enhancements of halo diffusivity were estimated as a function of beam and lattice parameters. Proton beam core lifetimes and emittance growth rates were checked to ensure that undesired effects were suppressed. Hardware specifications were based on the Tevatron devices and on preliminary engineering integration studies in the LHC machine. Required resources and a possible timeline were also outlined, together with a brief discussion of alternative halo-removal schemes and of other possible uses of electron lenses to improve the performance of the LHC.

  3. Electrospun manganese-cobalt oxide hollow nanofibres synthesized via combustion reactions and their lithium storage performance

    Science.gov (United States)

    Hwang, Soo Min; Kim, So Yeun; Kim, Jae-Geun; Kim, Ki Jae; Lee, Jong-Won; Park, Min-Sik; Kim, Young-Jun; Shahabuddin, Mohammed; Yamauchi, Yusuke; Kim, Jung Ho

    2015-04-01

    Mesoporous hollow fibres of MnCo2O4 and CoMn2O4 were synthesized by electrospinning and highly exothermic oxygen-mediated combustion reactions during calcination, in which the heating rate affected the final fibre morphology (e.g., single- or double-shell). The anodes consisting of hollow fibres showed excellent electrochemical properties for lithium-ion batteries.Mesoporous hollow fibres of MnCo2O4 and CoMn2O4 were synthesized by electrospinning and highly exothermic oxygen-mediated combustion reactions during calcination, in which the heating rate affected the final fibre morphology (e.g., single- or double-shell). The anodes consisting of hollow fibres showed excellent electrochemical properties for lithium-ion batteries. Electronic supplementary information (ESI) available: Experimental section; additional thermal analyses; XRD patterns; SEM and TEM results; N2 adsorption isotherms; differential capacity plots of galvanostatic voltage profiles and coulombic efficiency during cycling. See DOI: 10.1039/c5nr01145k

  4. Conceptual design of hollow electron lenses for beam halo control in the Large Hadron Collider

    CERN Document Server

    Stancari, Giulio; Valishev, Alexander; Bruce, Roderik; Redaelli, Stefano; Rossi, Adriana; Salvachua Ferrando, Belen

    2014-01-01

    Collimation with hollow electron beams is a technique for halo control in high-power hadron beams. It is based on an electron beam (possibly pulsed or modulated in intensity) guided by strong axial magnetic fields which overlaps with the circulating beam in a short section of the ring. The concept was tested experimentally at the Fermilab Tevatron collider using a hollow electron gun installed in one of the Tevatron electron lenses. Within the US LHC Accelerator Research Program (LARP) and the European FP7 HiLumi LHC Design Study, we are proposing a conceptual design for applying this technique to the Large Hadron Collider at CERN. A prototype hollow electron gun for the LHC was built and tested. The expected performance of the hollow electron beam collimator was based on Tevatron experiments and on numerical tracking simulations. Halo removal rates and enhancements of halo diffusivity were estimated as a function of beam and lattice parameters. Proton beam core lifetimes and emittance growth rates were check...

  5. Mathematical modeling of liquid/liquid hollow fiber membrane contactor accounting for interfacial transport phenomena: Extraction of lanthanides as a surrogate for actinides

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, J.D.

    1994-08-04

    This report is divided into two parts. The second part is divided into the following sections: experimental protocol; modeling the hollow fiber extractor using film theory; Graetz model of the hollow fiber membrane process; fundamental diffusive-kinetic model; and diffusive liquid membrane device-a rigorous model. The first part is divided into: membrane and membrane process-a concept; metal extraction; kinetics of metal extraction; modeling the membrane contactor; and interfacial phenomenon-boundary conditions-applied to membrane transport.

  6. Active Disturbance Rejection Control of a Heat Integrated Distillation Column

    DEFF Research Database (Denmark)

    Al-Kalbani, Fahad; Zhang, Jie; Bisgaard, Thomas

    2016-01-01

    Heat integrated distillation column (HiDC) is the most energy efficient distillation approach making efficient utilization of internal heat integration through heat pump. The rectifying section acts as a heat source with high pressure, while the stripping section operates as a heat sink with low...

  7. Experimental analysis of reinforcing columns of reinforced concrete, with anchor steel bolts

    Directory of Open Access Journals (Sweden)

    A. C. MESQUITA

    Full Text Available Abstract This article presents a columns reinforcement experimental study, with the use of anchor steel bolts and fill with self-compacting concrete. Were tested five columns of reinforced concrete subjected to flexion-compression: two columns were used as reference, and a cross-section equal to 120 x 250 mm; with a monolithic section equal to 155 x 250 mm cross section of the same reinforced columns and three which were initially molded with a 120 x 250 mm section and subsequently received a layer of 35 mm thick self-compacting concrete in the compressed side. Despite the studs do not present break, there was peeling of the reinforcement layer. The results indicate the possibility of using this method in reinforcing structural rehabilitation of reinforced concrete columns, with increase in load capacity on average equal to 403% in relation to the column reference.

  8. Water Column Sonar Data Collection

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The collection and analysis of water column sonar data is a relatively new avenue of research into the marine environment. Primary uses include assessing biological...

  9. Surface functionalized hollow silica particles and composites

    KAUST Repository

    Rodionov, Valentin

    2017-05-26

    Composition comprising hollow spherical silica particles having outside particle walls and inside particle walls, wherein the particles have an average particle size of about 10 nm to about 500 nm and an average wall thickness of about 10 nm to about 50 nm; and wherein the particles are functionalized with at least one organic functional group on the outside particle wall, on the inside particle wall, or on both the outside and inside particle walls, wherein the organic functional group is in a reacted or unreacted form. The organic functional group can be epoxy. The particles can be mixed with polymer precursor or a polymer material such as epoxy to form a prepreg or a nanocomposite. Lightweight but strong materials can be formed. Low loadings of hollow particles can be used.

  10. Mesoporous hollow spheres from soap bubbling.

    Science.gov (United States)

    Yu, Xianglin; Liang, Fuxin; Liu, Jiguang; Lu, Yunfeng; Yang, Zhenzhong

    2012-02-01

    The smaller and more stable bubbles can be generated from the large parent bubbles by rupture. In the presence of a bubble blowing agent, hollow spheres can be prepared by bubbling a silica sol. Herein, the trapped gas inside the bubble acts as a template. When the porogen, i.e., other surfactant, is introduced, a mesostructured shell forms by the co-assembly with the silica sol during sol-gel process. Morphological evolution emphasizes the prerequisite of an intermediate interior gas flow rate and high exterior gas flow rate for hollow spheres. The method is valid for many compositions from inorganic, polymer to their composites. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. Space Charge Mitigation by Hollow Bunches

    CERN Multimedia

    Oeftiger, AO

    2014-01-01

    To satisfy the requirements of the HL-LHC (High Luminosity Large Hadron Collider), the LHC injector chain will need to supply a higher brightness, i.e. deliver the same transverse beam emittances \\epsilon_{x,y} while providing a higher intensity N. However, a larger number of particles per bunch enhances space charge effects. One approach to mitigate the impact of space charge is to change the longitudinal phase space distribution: hollow bunches feature a depleted bunch centre and a densely populated periphery. Thus, the spatial line density maximum is depressed which ultimately decreases the tune spread imposed by space charge. Therefore, a higher intensity can be accepted while keeping the same overall space charge tune shift. 3 different methods to create hollow bunches in the PSBooster are simulated.

  12. Critical factors in displacement ductility assessment of high-strength concrete columns

    Science.gov (United States)

    Taheri, Ali; Moghadam, Abdolreza S.; Tasnimi, Abass Ali

    2017-12-01

    Ductility of high-strength concrete (HSC) columns with rectangular sections was assessed in this study by reviewing experimental data from the available literature. Up to 112 normal weights concrete columns with strength in the range of 50-130 MPa were considered and presented as a database. The data included the results of column testes under axial and reversed lateral loading. Displacement ductility of HSC columns was evaluated in terms of their concrete and reinforcement strengths, bar arrangement, volumetric ratio of transverse reinforcement, and axial loading. The results indicated that the confinement requirements and displacement ductility in HSC columns are more sensitive than those in normal strength concrete columns. Moreover, ductility is descended by increasing concrete strength. However, it was possible to obtain ductile behavior in HSC columns through proper confinement. Furthermore, this study casts doubt about capability of P/ A g f c' ratio that being inversely proportional to displacement ductility of HSC columns.

  13. Critical factors in displacement ductility assessment of high-strength concrete columns

    Science.gov (United States)

    Taheri, Ali; Moghadam, Abdolreza S.; Tasnimi, Abass Ali

    2017-09-01

    Ductility of high-strength concrete (HSC) columns with rectangular sections was assessed in this study by reviewing experimental data from the available literature. Up to 112 normal weights concrete columns with strength in the range of 50-130 MPa were considered and presented as a database. The data included the results of column testes under axial and reversed lateral loading. Displacement ductility of HSC columns was evaluated in terms of their concrete and reinforcement strengths, bar arrangement, volumetric ratio of transverse reinforcement, and axial loading. The results indicated that the confinement requirements and displacement ductility in HSC columns are more sensitive than those in normal strength concrete columns. Moreover, ductility is descended by increasing concrete strength. However, it was possible to obtain ductile behavior in HSC columns through proper confinement. Furthermore, this study casts doubt about capability of P/A g f c' ratio that being inversely proportional to displacement ductility of HSC columns.

  14. Silica hollow spheres with nano-macroholes like diatomaceous earth.

    Science.gov (United States)

    Fujiwara, Masahiro; Shiokawa, Kumi; Sakakura, Ikuko; Nakahara, Yoshiko

    2006-12-01

    Artificial synthesis of hollow cell walls of diatoms is an ultimate target of nanomaterial science. The addition of some water-soluble polymers such as sodium polymethacrylate to a solution of water/oil/water emulsion system, which is an essential step of the simple synthetic procedure of silica hollow spheres (microcapsules), led to the formation of silica hollow spheres with nano-macroholes (>100 nm) in their shell walls, the morphologies of which are analogous to those of diatom earth.

  15. Review of Synthetic Methods to Form Hollow Polymer Nanocapsules

    Energy Technology Data Exchange (ETDEWEB)

    Barker, Madeline T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-03-13

    Syntactic foams have grown in interest due to the widened range of applications because of their mechanical strength and high damage tolerance. In the past, hollow glass or ceramic particles were used to create the pores. This paper reviews literature focused on the controlled synthesis of hollow polymer spheres with diameters ranging from 100 –200 nm. By using hollow polymer spheres, syntactic foams could reach ultra-low densities.

  16. Pinhole Viewing Strengthens the Hollow-Face Illusion

    OpenAIRE

    Koessler, Trent; Hill, Harold

    2015-01-01

    A hollow (concave) mask appears convex when viewed from beyond a certain distance even when viewed stereoscopically—this is the hollow-face illusion. At close viewing distances, the same mask is seen as hollow even when disparity information is eliminated by monocular viewing. A potential source of nonpictorial, monocular information that favors a veridical percept at close distances is accommodation in conjunction with focus blur. In this article, we used pinhole viewing to minimize this pot...

  17. Magnetic and Optical Properties of Submicron-Size Hollow Spheres

    Directory of Open Access Journals (Sweden)

    Hirofumi Yoshikawa

    2010-02-01

    Full Text Available Magnetic hollow spheres with a controlled diameter and shell thickness have emerged as an important class of magnetic nanomaterials. The confined hollow geometry and pronouncedly curved surfaces induce unique physical properties different from those of flat thin films and solid counterparts. In this paper, we focus on recent progress on submicron-size spherical hollow magnets (e.g., cobalt- and iron-based materials, and discuss the effects of the hollow shape and the submicron size on magnetic and optical properties.

  18. Finite Element Modelling of Cold Formed Stainless Steel Columns

    Directory of Open Access Journals (Sweden)

    M. Macdonald

    2005-01-01

    Full Text Available This paper describes the results obtained from a finite element investigation into the load capacity of column members of lipped channel cross-section, cold formed from Type 304 stainless steel, subjected to concentric and eccentric compression loading. The main aims of this investigation were to determine the effects which the non-linearity of the stress-strain behaviour of the material would have on the column behaviour under concentric or eccentric loading. Stress-strain curves derived from tests and design codes are incorporated into non-linear finite element analyses of eccentrically loaded columns and the results obtained are compared with those obtained on the basis of experiments on stainless steel channel columns with the same properties and dimensions. Comparisons of the finite element results and the test results are also made with existing design specifications and conclusions are drawn on the basis of the comparisons. 

  19. Spectral Clustering of Hermean craters hollows

    Science.gov (United States)

    Lucchetti, Alice; Pajola, Maurizio; Cremonese, Gabriele; Carli, Cristian; Marzo, Giuseppe; Roush, Ted

    2017-04-01

    The Mercury Dual Imaging System (MDIS, Hawkins et al., 2007) onboard NASA MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft, provided high-resolution images of "hollows", i.e. shallow, irregular, rimless, flat-floored depressions with bright interiors and halos, often found on crater walls, rims, floors and central peaks (Blewett et al., 2011, 2013). The formation mechanism of these features was suggested to be related to the depletion of subsurface volatiles (Blewett et al., 2011, Vaughan et al., 2012). To understand the hollows' mineralogical composition, which can provide new insights on Mercury's surface characterization, we applied a spectral clustering method to different craters where hollows are present. We chose, as first test case, the 20 km wide Dominici crater due to previous multiple spectral detection (Vilas et al., 2016). We used the MDIS WAC dataset covering Dominici crater with a scale of 935 m/pixel through eight filters, ranging from 0.433 to 0.996 μm. First, the images have been photometrically corrected using the Hapke parameters (Hapke et al., 2002) derived in Domingue et al. (2015). We then applied a statistical clustering over the entire dataset based on a K-means partitioning algorithm (Marzo et al., 2006). This approach was developed and evaluated by Marzo et al. (2006, 2008, 2009) and makes use of the Calinski and Harabasz criterion (Calinski, T., Harabasz, J., 1974) to identify the intrinsically natural number of clusters, making the process unsupervised. The natural number of ten clusters was identified and spectrally separates the Dominici surrounding terrains from its interior, as well as the two hollows from their edges. The units located on the brightest part of the south wall/rim of Dominici crater clearly present a wide absorption band between 0.558 and 0.828 μm. Hollows surrounding terrains typically present a red slope in the VNIR with a possible weak absorption band centered at 0.748

  20. Hollow-Fiber Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Bue, Grant; Trevino, Luis; Tsioulos, Gus; Mitchell, Keith; Settles, Joseph

    2013-01-01

    The hollow-fiber spacesuit water membrane evaporator (HoFi SWME) is being developed to perform the thermal control function for advanced spacesuits and spacecraft to take advantage of recent advances in micropore membrane technology in providing a robust, heat-rejection device that is less sensitive to contamination than is the sublimator. After recent contamination tests, a commercial-off-the-shelf (COTS) micro porous hollow-fiber membrane was selected for prototype development as the most suitable candidate among commercial hollow-fiber evaporator alternatives. An innovative design that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape, was developed into a full-scale prototype for the spacesuit application. Vacuum chamber testing has been performed to characterize heat rejection as a function of inlet water temperature and water vapor back-pressure, and to show contamination resistance to the constituents expected to be found in potable water produced by the wastewater reclamation distillation processes. Other tests showed tolerance to freezing and suitability to reject heat in a Mars pressure environment. In summary, HoFi SWME is a lightweight, compact evaporator for heat rejection in the spacesuit that is robust, contamination- insensitive, freeze-tolerant, and able to reject the required heat of spacewalks in microgravity, lunar, and Martian environments. The HoFi is packaged to reject 810 W of heat through 800 hours of use in a vacuum environment, and 370 W in a Mars environment. The device also eliminates free gas and dissolved gas from the coolant loop.

  1. Co-Flow Hollow Cathode Technology

    Science.gov (United States)

    Hofer, Richard R.; Goebel, Dan M.

    2011-01-01

    Hall thrusters utilize identical hollow cathode technology as ion thrusters, yet must operate at much higher mass flow rates in order to efficiently couple to the bulk plasma discharge. Higher flow rates are necessary in order to provide enough neutral collisions to transport electrons across magnetic fields so that they can reach the discharge. This higher flow rate, however, has potential life-limiting implications for the operation of the cathode. A solution to the problem involves splitting the mass flow into the hollow cathode into two streams, the internal and external flows. The internal flow is fixed and set such that the neutral pressure in the cathode allows for a high utilization of the emitter surface area. The external flow is variable depending on the flow rate through the anode of the Hall thruster, but also has a minimum in order to suppress high-energy ion generation. In the co-flow hollow cathode, the cathode assembly is mounted on thruster centerline, inside the inner magnetic core of the thruster. An annular gas plenum is placed at the base of the cathode and propellant is fed throughout to produce an azimuthally symmetric flow of gas that evenly expands around the cathode keeper. This configuration maximizes propellant utilization and is not subject to erosion processes. External gas feeds have been considered in the past for ion thruster applications, but usually in the context of eliminating high energy ion production. This approach is adapted specifically for the Hall thruster and exploits the geometry of a Hall thruster to feed and focus the external flow without introducing significant new complexity to the thruster design.

  2. Hollow Electron Lens Simulation for the SPS

    CERN Document Server

    Previtali, V; Stancari, G; Valishev, A

    2013-01-01

    The hardware of the Tevatron hollow electron lens, which has been used in the past for collimation purposes, is presently available. Possible applications of similar devices in the LHC are under evaluation, but a realistic date for installation of electron lenses in the LHC would be not earlier than the machine shutdown scheduled for 2018. We investigated the possibility of beam tests with the available hardware in the meantime in the SPS. This article aims to answer this question by presenting the results of dedicated numerical simulations

  3. Casting of particle-based hollow shapes

    Science.gov (United States)

    Menchhofer, Paul

    1995-01-01

    A method for the production of hollow articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is coated onto a prewarmed continuous surface in a relatively thin layer so that the slurry is substantially uniformly coated on the surface. The heat of the prewarmed surface conducts to the slurry to initiate a reaction which causes the slurry to set or harden in a shape conforming to the surface. The hardened configurations may then be sintered to consolidate the particles and provide a high density product.

  4. Porous-wall hollow glass microspheres as carriers for biomolecules

    Science.gov (United States)

    Li, Shuyi; Dynan, William S; Wicks, George; Serkiz, Steven

    2013-09-17

    The present invention includes compositions of porous-wall hollow glass microspheres and one or more biomolecules, wherein the one or more biomolecules are positioned within a void location within the hollow glass microsphere, and the use of such compositions for the diagnostic and/or therapeutic delivery of biomolecules.

  5. Wet spinning of asymmetric hollow fibre membranes for gas separation

    NARCIS (Netherlands)

    van 't Hof, Jacob Adriaan

    1988-01-01

    This thesis describes the spinning and characterizatin of hollow fibre membranes for gas separation. The type of fibres studied here are made by a wet spinning process. A homogeneous solution is prepared, consisting of a polymer in a suitable organic solvent, and extruded as a hollow fibre. Both the

  6. Fabrication of Closed Hollow Bulb Obturator Using Thermoplastic Resin Material

    Directory of Open Access Journals (Sweden)

    Bidhan Shrestha

    2015-01-01

    Full Text Available Purpose. Closed hollow bulb obturators are used for the rehabilitation of postmaxillectomy patients. However, the time consuming process, complexity of fabrication, water leakage, and discoloration are notable disadvantages of this technique. This paper describes a clinical report of fabricating closed hollow bulb obturator using a single flask and one time processing method for an acquired maxillary defect. Hard thermoplastic resin sheet has been used for the fabrication of hollow bulb part of the obturator. Method. After fabrication of master cast conventionally, bulb and lid part of the defect were formed separately and joined by autopolymerizing acrylic resin to form one sized smaller hollow body. During packing procedure, the defect area was loaded with heat polymerizing acrylic resin and then previously fabricated smaller hollow body was adapted over it. The whole area was then loaded with heat cure acrylic. Further processes were carried out conventionally. Conclusion. This technique uses single flask which reduces laboratory time and makes the procedure simple. The thickness of hollow bulb can be controlled and light weight closed hollow bulb prosthesis can be fabricated. It also minimizes the disadvantages of closed hollow bulb obturator such as water leakage, bacterial infection, and discoloration.

  7. optimizing compression zone of flanged hollow cored concrete ...

    African Journals Online (AJOL)

    eobe

    effective flange width and the hollow core position in the compression zone of a plain concrete beam with a point loaded at .... OPTIMIZING COMPRESSION ZONE OF FLANGED HOLLOW CORED CONCRETE BEAMS USING MOMENT OF INERTIA THEORY, ... chi-square test, a correction factor was obtained using.

  8. Compact High Current Rare-Earth Emitter Hollow Cathode for Hall Effect Thrusters

    Science.gov (United States)

    Hofer, Richard R. (Inventor); Goebel, Dan M. (Inventor); Watkins, Ronnie M. (Inventor)

    2012-01-01

    An apparatus and method for achieving an efficient central cathode in a Hall effect thruster is disclosed. A hollow insert disposed inside the end of a hollow conductive cathode comprises a rare-earth element and energized to emit electrons from an inner surface. The cathode employs an end opening having an area at least as large as the internal cross sectional area of the rare earth insert to enhance throughput from the cathode end. In addition, the cathode employs a high aspect ratio geometry based on the cathode length to width which mitigates heat transfer from the end. A gas flow through the cathode and insert may be impinged by the emitted electrons to yield a plasma. One or more optional auxiliary gas feeds may also be employed between the cathode and keeper wall and external to the keeper near the outlet.

  9. Guiding Properties of Silica/Air Hollow-Core Bragg Fibers

    DEFF Research Database (Denmark)

    Foroni, Matteo; Passaro, Davide; Poli, Federica

    2008-01-01

    The guiding properties of realistic silica/air hollow-core Bragg fibers have been investigated by calculating the dispersion curves, the confinement loss spectrum and the field distribution of the guided modes through a full-vector modal solver based on the finite element method. In particular......, the silica bridge influence on the fundamental mode has been analyzed, by comparing the properties of an ideal structure, without the silica nano-supports, and of two realistic fibers, with squared off and rounded air-holes. Simulation results have demonstrated the presence of anti-crossing points...... on the guiding properties of each geometric characteristic in the hollow-core Bragg fiber cross-section has been deeply investigated, thus showing which parameter it is better to change in order to properly modify the loss values or its spectral behaviour. Moreover, in order to improve the loss properties...

  10. Bubble columns : Structures or stability?

    NARCIS (Netherlands)

    Harteveld, W.K.

    2005-01-01

    The aim of the thesis is to contribute to the understanding of the hydrodynamics of the gravity driven bubbly flow that can be found in bubble columns. Special attention is paid to the large scale structures that have a strong impact on several key parameters such as the degree of mixing, mass and

  11. Editorial/Associate Editor's Column

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 2. Editorial / Associate Editor's Column. Rajaram Nityananda. Editorial Volume 5 Issue 2 February 2000 pp 1-1. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/005/02/0001-0001. Author Affiliations.

  12. Growth of hollow cell spheroids in microbead templated chambers.

    Science.gov (United States)

    Wang, Eddie; Wang, Dong; Geng, Andrew; Seo, Richard; Gong, Xiaohua

    2017-10-01

    Cells form hollow, spheroidal structures during the development of many tissues, including the ocular lens, inner ear, and many glands. Therefore, techniques for in vitro formation of hollow spheroids are valued for studying developmental and disease processes. Current in vitro methods require cells to self-organize into hollow morphologies; we explored an alternative strategy based on cell growth in predefined, spherical scaffolds. Our method uses sacrificial, gelatin microbeads to simultaneously template spherical chambers within a hydrogel and deliver cells into the chambers. We use mouse lens epithelial cells to demonstrate that cells can populate the internal surfaces of the chambers within a week to create numerous hollow spheroids. The platform supports manipulation of matrix mechanics, curvature, and biochemical composition to mimic in vivo microenvironments. It also provides a starting point for engineering organoids of tissues that develop from hollow spheroids. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. A 200 W Hall thruster with hollow indented anode

    Science.gov (United States)

    Ding, Yongjie; Sun, Hezhi; Wei, Liqiu; Li, Peng; Su, Hongbo; Peng, Wuji; Yu, Daren

    2017-10-01

    A hollow indented anode is proposed for increasing the neutral gas density in a discharge channel, in order to improve the performance of the thruster. The experimental results show that a hollow indented anode structure can effectively improve the performance, compared to a hollow straight anode under similar operating conditions, in terms of thrust, propellant utilization, ionization rate, and anode efficiency. Furthermore, simulations show that the indented anode can effectively increase the neutral gas density in a discharge channel and on the centerline of the channel, compared to a hollow straight anode. In addition, it can increase the ionization rate in the channel and the pre-ionization in the anode. Therefore, the hollow indented anode could be considered as an important design idea for improving thruster performance.

  14. Hollow fiber bioreactor technology for tissue engineering applications.

    Science.gov (United States)

    Eghbali, Hadis; Nava, Michele M; Mohebbi-Kalhori, Davod; Raimondi, Manuela T

    2016-01-01

    Hollow fiber bioreactors are the focus of scientific research aiming to mimic physiological vascular networks and engineer organs and tissues in vitro. The reason for this lies in the interesting features of this bioreactor type, including excellent mass transport properties. Indeed, hollow fiber bioreactors allow limitations to be overcome in nutrient transport by diffusion, which is often an obstacle to engineer sizable constructs in vitro. This work reviews the existing literature relevant to hollow fiber bioreactors in organ and tissue engineering applications. To this purpose, we first classify the hollow fiber bioreactors into 2 categories: cylindrical and rectangular. For each category, we summarize their main applications both at the tissue and at the organ level, focusing on experimental models and computational studies as predictive tools for designing innovative, dynamic culture systems. Finally, we discuss future perspectives on hollow fiber bioreactors as in vitro models for tissue and organ engineering applications.

  15. Self-templated chemically stable hollow spherical covalent organic framework

    Science.gov (United States)

    Kandambeth, Sharath; Venkatesh, V.; Shinde, Digambar B.; Kumari, Sushma; Halder, Arjun; Verma, Sandeep; Banerjee, Rahul

    2015-04-01

    Covalent organic frameworks are a family of crystalline porous materials with promising applications. Although active research on the design and synthesis of covalent organic frameworks has been ongoing for almost a decade, the mechanisms of formation of covalent organic frameworks crystallites remain poorly understood. Here we report the synthesis of a hollow spherical covalent organic framework with mesoporous walls in a single-step template-free method. A detailed time-dependent study of hollow sphere formation reveals that an inside-out Ostwald ripening process is responsible for the hollow sphere formation. The synthesized covalent organic framework hollow spheres are highly porous (surface area ~1,500 m2 g-1), crystalline and chemically stable, due to the presence of strong intramolecular hydrogen bonding. These mesoporous hollow sphere covalent organic frameworks are used for a trypsin immobilization study, which shows an uptake of 15.5 μmol g-1 of trypsin.

  16. Long-term evaluation of hollow screw and hollow cylinder dental implants : Clinical and radiographic results after 10 years

    NARCIS (Netherlands)

    Telleman, Gerdien; Meijer, Henny J. A.; Raghoebar, Gerry M.

    Background: In 1988, an implant manufacturer offered a new dental implant system, with a wide choice of hollow cylinder (HC) and hollow screw (HS) implants. The purpose of this retrospective study of HS and HC implants was to evaluate clinical and radiographic parameters of peri-implant tissue and

  17. [Recovery of zinc ion and cadmium ion with hollow fiber membrane extraction].

    Science.gov (United States)

    Wang, Y; Luo, G; Wang, Y; Wu, Z; Dai, Y

    2001-09-01

    The efficiency of hollow fiber membrane solvent extraction for the system of Meaq/bis(2-ethylhexyl) phosphate in heptane(Me = Cd2+, Zn2+) was studied for wastewater treatment and hydrometallurgy. It was found that the two phases velocity, the initial concentration and the pH value of the aqueous phase greatly influenced the extraction ratio. For very dilute solution with concentration lower than 500 mg/L, the mass transfer resistance was mainly in aqueous phase. When the aqueous phase concentration was relative higher than that of dilute solution, all the individual mass transfer resistances would not be ignored. For the concentrated solution, the mass transfer in the organic phase and the diffusion in membrane pores controlled the transport process. In the back extraction, the mass transfer resistance lied in the organic phase and the diffusion in membrane pores. The experimental results showed that it was possible that the extraction percentage achieved 90% when the metal ion concentration was lower than 400 mg/L. When the cadmium concentration was lower than 200 mg/L, its concentration can decrease 2 orders by extraction in a single-pass flow mode. The values of (HTU)w were between 15 cm and 30 cm, which was much lower than those of traditional extraction columns. The results indicated that membrane extraction with hollow fiber modules could efficiently remove or recover metal ions in the aqueous phases.

  18. Metal-Matrix/Hollow-Ceramic-Sphere Composites

    Science.gov (United States)

    Baker, Dean M.

    2011-01-01

    A family of metal/ceramic composite materials has been developed that are relatively inexpensive, lightweight alternatives to structural materials that are typified by beryllium, aluminum, and graphite/epoxy composites. These metal/ceramic composites were originally intended to replace beryllium (which is toxic and expensive) as a structural material for lightweight mirrors for aerospace applications. These materials also have potential utility in automotive and many other terrestrial applications in which there are requirements for lightweight materials that have high strengths and other tailorable properties as described below. The ceramic component of a material in this family consists of hollow ceramic spheres that have been formulated to be lightweight (0.5 g/cm3) and have high crush strength [40.80 ksi (.276.552 MPa)]. The hollow spheres are coated with a metal to enhance a specific performance . such as shielding against radiation (cosmic rays or x rays) or against electromagnetic interference at radio and lower frequencies, or a material to reduce the coefficient of thermal expansion (CTE) of the final composite material, and/or materials to mitigate any mismatch between the spheres and the matrix metal. Because of the high crush strength of the spheres, the initial composite workpiece can be forged or extruded into a high-strength part. The total time taken in processing from the raw ingredients to a finished part is typically 10 to 14 days depending on machining required.

  19. Hollow Pollen Shells to Enhance Drug Delivery

    Science.gov (United States)

    Diego-Taboada, Alberto; Beckett, Stephen T.; Atkin, Stephen L.; Mackenzie, Grahame

    2014-01-01

    Pollen grain and spore shells are natural microcapsules designed to protect the genetic material of the plant from external damage. The shell is made up of two layers, the inner layer (intine), made largely of cellulose, and the outer layer (exine), composed mainly of sporopollenin. The relative proportion of each varies according to the plant species. The structure of sporopollenin has not been fully characterised but different studies suggest the presence of conjugated phenols, which provide antioxidant properties to the microcapsule and UV (ultraviolet) protection to the material inside it. These microcapsule shells have many advantageous properties, such as homogeneity in size, resilience to both alkalis and acids, and the ability to withstand temperatures up to 250 °C. These hollow microcapsules have the ability to encapsulate and release actives in a controlled manner. Their mucoadhesion to intestinal tissues may contribute to the extended contact of the sporopollenin with the intestinal mucosa leading to an increased efficiency of delivery of nutraceuticals and drugs. The hollow microcapsules can be filled with a solution of the active or active in a liquid form by simply mixing both together, and in some cases operating a vacuum. The active payload can be released in the human body depending on pressure on the microcapsule, solubility and/or pH factors. Active release can be controlled by adding a coating on the shell, or co-encapsulation with the active inside the shell. PMID:24638098

  20. Low-frequency flute instabilities of a hollow cathode arc discharge - Theory and experiment.

    Science.gov (United States)

    Ilic, D. B.; Rognlien, T. D.; Self, S. A.; Crawford, F. W.

    1973-01-01

    The characteristics of two low-frequency electrostatic flute instabilities of a low-pressure hollow cathode arc discharge are reported. Mode I has azimuthal mode number m = 1, and occurs when the radial electric field is negative (directed inward), while mode II has m = - 1 and occurs when the field is positive. The radial electric field is controlled by varying the potential of a secondary anode cylinder located close to the outer discharge radius. A linear perturbation analysis, based on the two-fluid equations, is given for a low-beta, collisionless, cylindrical plasma column, immersed in a uniform axial magnetic field, having a Gaussian density profile and an arbitrary radial electric field profile. Reasonable correlation between theory and experiment is demonstrated for both modes.

  1. Note: Hollow cathode lamp with integral, high optical efficiency isolation valve: a modular vacuum ultraviolet source.

    Science.gov (United States)

    Roberts, F Sloan; Anderson, Scott L

    2013-12-01

    The design and operating conditions of a hollow cathode discharge lamp for the generation of vacuum ultraviolet radiation, suitable for ultrahigh vacuum (UHV) application, are described in detail. The design is easily constructed, and modular, allowing it to be adapted to different experimental requirements. A thin isolation valve is built into one of the differential pumping stages, isolating the discharge section from the UHV section, both for vacuum safety and to allow lamp maintenance without venting the UHV chamber. The lamp has been used both for ultraviolet photoelectron spectroscopy of surfaces and as a "soft" photoionization source for gas-phase mass spectrometry.

  2. Note: Hollow cathode lamp with integral, high optical efficiency isolation valve: A modular vacuum ultraviolet source

    Energy Technology Data Exchange (ETDEWEB)

    Sloan Roberts, F.; Anderson, Scott L. [Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, Utah 84112 (United States)

    2013-12-15

    The design and operating conditions of a hollow cathode discharge lamp for the generation of vacuum ultraviolet radiation, suitable for ultrahigh vacuum (UHV) application, are described in detail. The design is easily constructed, and modular, allowing it to be adapted to different experimental requirements. A thin isolation valve is built into one of the differential pumping stages, isolating the discharge section from the UHV section, both for vacuum safety and to allow lamp maintenance without venting the UHV chamber. The lamp has been used both for ultraviolet photoelectron spectroscopy of surfaces and as a “soft” photoionization source for gas-phase mass spectrometry.

  3. Strengthening Techniques of RC Columns Using Fibre Reinforced Polymeric Materials

    Directory of Open Access Journals (Sweden)

    Ciprian Cozmanciuc

    2009-01-01

    Full Text Available Fibre reinforced composite materials are becoming more frequently used in civil engineering structures. One of the most practical applications of these new materials concerns the strengthening of reinforced concrete columns by means of confinement with fibre composite sheets. In the literature, various theoretical models have been proposed to describe the behaviour of confined concrete columns. The principal advantages of this technique are the high strength-to-weight ratio, good fatigue properties, non-corroding characteristics of the fibre reinforced polymers (FRP, and the facility of its application. The maximum efficiency of confining systems using FRP materials is reached in case of columns with circular cross-section and is explained by the fact that the entire section of the column is involved into the confinement effect. Rectangular confining reinforcement is less efficient as the confinement action is mostly located at the corners This paper reveals the most utilized techniques of performing composite confining systems for reinforced concrete columns, with their advantages and also disadvantages.

  4. Simplified analysis of filled steel tubular stub columns under ...

    African Journals Online (AJOL)

    Instead, a simple summation of the strength of components forming the composite section is found to rationally predict the stub column strength. However, continued research is still required to accurately predict the effects of confinement, on the steel tube and on the fill material, hence expressions for the proportion of load ...

  5. The selection of small forest hollows for pollen analysis in boreal and temperate forest regions

    DEFF Research Database (Denmark)

    Overballe-Petersen, Mette V; Bradshaw, Richard H.W.

    2011-01-01

    Small forest hollows represent a specialised site type for pollen analysis, since they mainly record the vegetation within an approximate radius of 20-100 m from the hollow. We discuss how to choose the most appropriate small forest hollow for pollen analysis. Hollow size, site topography, location...

  6. Enhancing Thermodynamic Efficiency of Energy Intensive Distillation Columns via Internal Heat Integration

    OpenAIRE

    Olujić, Ž.; Sun, L.; Gadalla, M.; de Rijke, A.; Jansens, P.J.

    2008-01-01

    As demonstrated in the present simulation study, taking propylene/propane splitter as base case, an internally heat integrated distillation column (HIDiC), with rectification section operating at higher pressure and temperature than the stripping section, offers significant potential for energy saving compared to energy requirements associated with operation of conventional and heat-pump assisted distillation columns. The rectification section of a propylene/propane splitter contains us...

  7. Formation map of air-liquid hollow profile under microgravity

    Energy Technology Data Exchange (ETDEWEB)

    Ohira, Y.; Kuga, Y.; Ando, K. [Muroran Institute of Technology, Hokkaido (Japan). Dept. of Applied Chemistry; Idogawa, K.; Fukuda, T. [Hokkaido National Industrial Research Institute, Hokkaido (Japan)

    2000-04-01

    From the viewpoint of oxygen recovery and supply in a space station, the formation of an air-liquid hollow profile which has a suitable interface shape to cultivate microalgae under microgravity conditions is experimentally investigated. The air-liquid interface profiles in a rotating vessel were observed and recorded. The effects of the modified Weber number and modified Reynolds number on formation of the air-liquid hollow profile were experimentally investigated. We developed a basis for judging conditions forming the air-liquid hollow profile from the video images. When the volume ratio of the liquid/vessel is 0.60 and the modified Weber number is greater than 2.2, it is found that the air-liquid hollow profile forms and is independent of the modified Reynolds number. From the experimental results using liquids with different surface tension, the validity of using the modified Weber number is confirmed as a dimensionless number for judging the formation of the air-liquid hollow profile. It is experimentally found that the formation conditions for the air-liquid hollow profile under microgravity can be determined by the modified Weber number and the volume ratio of the liquid/vessel. In a map of the volume ratio of the liquid/vessel vs. the modified Weber number, the discrimination of the formation of the air-liquid hollow profile is performed by a line experimentally obtained in this study. (author)

  8. Improved Rare-Earth Emitter Hollow Cathode

    Science.gov (United States)

    Goebel, Dan M.

    2011-01-01

    An improvement has been made to the design of the hollow cathode geometry that was created for the rare-earth electron emitter described in Compact Rare Earth Emitter Hollow Cathode (NPO-44923), NASA Tech Briefs, Vol. 34, No. 3 (March 2010), p. 52. The original interior assembly was made entirely of graphite in order to be compatible with the LaB6 material, which cannot be touched by metals during operation due to boron diffusion causing embrittlement issues in high-temperature refractory materials. Also, the graphite tube was difficult to machine and was subject to vibration-induced fracturing. This innovation replaces the graphite tube with one made out of refractory metal that is relatively easy to manufacture. The cathode support tube is made of molybdenum or molybdenum-rhenium. This material is easily gun-bored to near the tolerances required, and finish machined with steps at each end that capture the orifice plate and the mounting flange. This provides the manufacturability and robustness needed for flight applications, and eliminates the need for expensive e-beam welding used in prior cathodes. The LaB6 insert is protected from direct contact with the refractory metal tube by thin, graphite sleeves in a cup-arrangement around the ends of the insert. The sleeves, insert, and orifice plate are held in place by a ceramic spacer and tungsten spring inserted inside the tube. To heat the cathode, an insulating tube is slipped around the refractory metal hollow tube, which can be made of high-temperature materials like boron nitride or aluminum nitride. A screw-shaped slot, or series of slots, is machined in the outside of the ceramic tube to constrain a refractory metal wire wound inside the slot that is used as the heater. The screw slot can hold a single heater wire that is then connected to the front of the cathode tube by tack-welding to complete the electrical circuit, or it can be a double slot that takes a bifilar wound heater with both leads coming out

  9. Axisymmetric Vibration of Piezo-Lemv Composite Hollow Multilayer Cylinder

    Directory of Open Access Journals (Sweden)

    E. S. Nehru

    2012-01-01

    Full Text Available Axisymmetric vibration of an infinite piezolaminated multilayer hollow cylinder made of piezoelectric layers of 6 mm class and an isotropic LEMV (Linear Elastic Materials with Voids layers is studied. The frequency equations are obtained for the traction free outer surface with continuity conditions at the interfaces. Numerical results are carried out for the inner, middle, and outer hollow piezoelectric layers bonded by LEMV (It is hypothetical material layers and the dispersion curves are compared with that of a similar 3-layer model and of 3 and 5 layer models with inner, middle, and outer hollow piezoelectric layers bonded by CFRP (Carbon fiber reinforced plastics.

  10. Hollow fiber membranes and methods for forming same

    Science.gov (United States)

    Bhandari, Dhaval Ajit; McCloskey, Patrick Joseph; Howson, Paul Edward; Narang, Kristi Jean; Koros, William

    2016-03-22

    The invention provides improved hollow fiber membranes having at least two layers, and methods for forming the same. The methods include co-extruding a first composition, a second composition, and a third composition to form a dual layer hollow fiber membrane. The first composition includes a glassy polymer; the second composition includes a polysiloxane; and the third composition includes a bore fluid. The dual layer hollow fiber membranes include a first layer and a second layer, the first layer being a porous layer which includes the glassy polymer of the first composition, and the second layer being a polysiloxane layer which includes the polysiloxane of the second composition.

  11. Development of hollow electron beams for proton and ion collimation

    CERN Document Server

    Stancari, G.; Kuznetsov, G.; Shiltsev, V.; Still, D.A.; Valishev, A.; Vorobiev, L.G.; Assmann, R.; Kabantsev, A.

    2010-01-01

    Magnetically confined hollow electron beams for controlled halo removal in high-energy colliders such as the Tevatron or the LHC may extend traditional collimation systems beyond the intensity limits imposed by tolerable material damage. They may also improve collimation performance by suppressing loss spikes due to beam jitter and by increasing capture efficiency. A hollow electron gun was designed and built. Its performance and stability were measured at the Fermilab test stand. The gun will be installed in one of the existing Tevatron electron lenses for preliminary tests of the hollow-beam collimator concept, addressing critical issues such as alignment and instabilities of the overlapping proton and electron beams

  12. Development of hollow electron beams for proton and ion collimation

    CERN Document Server

    Stancari, G; Kuznetsov, G; Shiltsev, V; Still, D A; Valishev, A; Vorobiev, L G; Assmann, R; Kabantsev, A

    2012-01-01

    Magnetically confined hollow electron beams for controlled halo removal in high-energy colliders such as the Tevatron or the LHC may extend traditional collimation systems beyond the intensity limits imposed by tolerable material damage. They may also improve collimation performance by suppressing loss spikes due to beam jitter and by increasing capture efficiency. A hollow electron gun was designed and built. Its performance and stability were measured at the Fermilab test stand. The gun will be installed in one of the existing Tevatron electron lenses for preliminary tests of the hollow-beam collimator concept, addressing critical issues such as alignment and instabilities of the overlapping proton and electron beams.

  13. Permeability of Hollow Microspherical Membranes to Helium

    Science.gov (United States)

    Zinoviev, V. N.; Kazanin, I. V.; Pak, A. Yu.; Vereshchagin, A. S.; Lebiga, V. A.; Fomin, V. M.

    2016-01-01

    This work is devoted to the study of the sorption characteristics of various hollow microspherical membranes to reveal particles most suitable for application in the membrane-sorption technologies of helium extraction from a natural gas. The permeability of the investigated sorbents to helium and their impermeability to air and methane are shown experimentally. The sorption-desorption dependences of the studied sorbents have been obtained, from which the parameters of their specific permeability to helium are calculated. It has been established that the physicochemical modification of the original particles exerts a great influence on the coefficient of the permeability of a sorbent to helium. Specially treated cenospheres have displayed high efficiency as membranes for selective extraction of helium.

  14. Hollow-tip scanning photoelectron microscopy

    Science.gov (United States)

    Cherkun, A. P.; Mironov, B. N.; Aseyev, S. A.; Chekalin, S. V.

    2014-07-01

    A new type of microscopy based on scanning in vacuum by a beam of charged particles transmitted through a hollow probe has been implemented. This approach provides controllable motion of spatially localized ion, electron, molecular (atomic), and soft X-ray beams and investigation of the surface in the shear force mode. In the photoelectron mode, in which electrons are transmitted through a 2-μm quartz capillary, a surface profile of gadolinium irradiated by 400-nm femtosecond laser pulses has been visualized with a subwave spatial resolution. The new method of microscopy opens an opportunity of investigations in the field of nanometer local photodesorption of molecular ions (one of the last ideas of V.S. Letokhov).

  15. Two-piece hollow bulb obturator

    Directory of Open Access Journals (Sweden)

    Subramaniam Elangovan

    2011-01-01

    Full Text Available There are various types of obturator fabrication achievable by prosthodontist. Maxillectomy, which is a term used by head and neck surgeons and prosthodontists to describe the partial or total removal of the maxilla in patients suffering from benign or malignant neoplasms is a defect for which to provide an effective obturator is a difficult task for the maxillofacial prosthodontist. Multidisciplinary treatment planning is essential to achieve adequate retention and function for the prosthesis. Speech is often unintelligible as a result of the marked defects in articulation and nasal resonance. This paper describes how to achieve the goal for esthetics and phonetics and also describes the fabrication of a hollow obturator by two piece method, which is simple and maybe used as definitive obturator for maximum comfort of the patient.

  16. Barium Depletion in Hollow Cathode Emitters

    Science.gov (United States)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2009-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the ow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  17. Axisymmetric collapses of granular columns

    Science.gov (United States)

    Lube, Gert; Huppert, Herbert E.; Sparks, R. Stephen J.; Hallworth, Mark A.

    2004-06-01

    Experimental observations of the collapse of initially vertical columns of small grains are presented. The experiments were performed mainly with dry grains of salt or sand, with some additional experiments using couscous, sugar or rice. Some of the experimental flows were analysed using high-speed video. There are three different flow regimes, dependent on the value of the aspect ratio a {=} h_i/r_i, where h_i and r_i are the initial height and radius of the granular column respectively. The differing forms of flow behaviour are described for each regime. In all cases a central, conically sided region of angle approximately 59(°) , corresponding to an aspect ratio of 1.7, remains undisturbed throughout the motion. The main experimental results for the final extent of the deposit and the time for emplacement are systematically collapsed in a quantitative way independent of any friction coefficients. Along with the kinematic data for the rate of spread of the front of the collapsing column, this is interpreted as indicating that frictional effects between individual grains in the bulk of the moving flow only play a role in the last instant of the flow, as it comes to an abrupt halt. For a {reach r_infty is given by t_infty {=} 3(h_i/g)(1/2} {=} 3(r_i/g)({1/2}a^{1/2)) , where g is the gravitational acceleration. The insights and conclusions gained from these experiments can be applied to a wide range of industrial and natural flows of concentrated particles. For example, the observation of the rapid deposition of the grains can help explain details of the emplacement of pyroclastic flows resulting from the explosive eruption of volcanoes.

  18. Experimental analysis of reinforced concrete columns strengthened with Self-Compacting concrete

    Directory of Open Access Journals (Sweden)

    M. Y. M. Omar

    Full Text Available This paper presents the results of reinforced concrete columns strengthened by addition of a self-compacting concrete overlay at the compressed and at the tensioned face of the member, with and without addition of longitudinal steel bars. Eight columns were submit- ted to loading with an initial eccentricity of 60 mm . These columns had 120 mm x 250 mm of rectangular cross section, 2000 mm in length and four longitudinal reinforcement steel bars with 10 mm in diameter. Reference columns P1 and P2 were tested to failure without any type of rehabilitation. Columns P3 to P8 were loaded to a predefined load (close to the initial yield point of tension reinforce- ment, then unloaded and strengthened for a subsequent test until failure. Results showed that the method of rehabilitation used was effective, increasing the loading capacity of the strengthened pieces by 2 to 5 times the ultimate load of the reference column.

  19. Electron and ion kinetics in a micro hollow cathode discharge

    Energy Technology Data Exchange (ETDEWEB)

    Kim, G J; Iza, F; Lee, J K [Electronics and Electrical Engineering Department, Pohang University of Science and Technology, Pohang, 790-784 (Korea, Republic of)

    2006-10-21

    Electron and ion kinetics in a micro hollow cathode discharge are investigated by means of two-dimensional axisymmetric particle-in-cell Monte Carlo collision simulations. Argon discharges at 10 and 300 Torr are studied for various driving currents. Electron and ion energy probability functions (IEPF) are shown at various times and locations to study the spatio-temporal behaviour of the discharge. The electron energy probability function (EEPF) evolves from the Druyvesteyn type in the early stages of the discharge into a two (or three) temperature distribution when steady state is reached. In steady state, secondary electrons accelerated across the cathode fall populate the high energy tail of the EEPF while the low energy region is populated by trapped electrons. The IEPF evolves from a Maxwellian in the negative glow (bulk) to a two temperature distribution on the cathode surface. The overpopulation of low energy ions near the cathode surface is attributed to a larger collision cross section for low energy ions and ionization within the cathode fall.

  20. Synthesis, characterization and properties of hollow nickel phosphide nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Ni Yonghong; Tao Ali; Hu Guangzhi; Cao Xiaofeng; Wei Xianwen; Yang Zhousheng [College of Chemistry and Materials Science, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, Wuhu 241000 (China)

    2006-10-14

    Nickel phosphide (Ni{sub 12}P{sub 5}) hollow nanospheres with a mean diameter of 100 nm and a shell thickness of 15-20 nm have been successfully prepared by a hydrothermal-microemulsion route, using NaH{sub 2}PO{sub 2} as a phosphorus source. XRD, EDS (HR)TEM, SEM and the SAED pattern were used to characterize the final product. Experiments showed that the as-prepared nickel phosphide hollow nanospheres could selectively catalytically degrade some organic dyes such as methyl red and Safranine T under 254 nm UV light irradiation. At the same time, the nickel phosphide hollow nanospheres showed a stronger ability to promote electron transfer between the glass-carbon electrode and adrenalin than nickel phosphide honeycomb-like particles prepared by a simple hydrothermal route. A possible formation process for nickel phosphide hollow nanospheres was suggested based on the experimental results.

  1. Hollow Au–Ag Alloy Nanorices and Their Optical Properties

    Directory of Open Access Journals (Sweden)

    Keke Yu

    2017-09-01

    Full Text Available Hollow noble metal nanoparticles have excellent performance not only in surface catalysis but also in optics. In this work, the hollow Au–Ag alloy nanorices are fabricated by the galvanic replacement reaction. The dark-field spectrum points out that there is a big difference in the optical properties between the pure Ag nanorices and the hollow alloy nanorices that exhibit highly tunable localized surface plasmon resonances (LSPR and that possess larger radiative damping, which is also indicated by the finite element method. Furthermore, the surface enhanced Raman scattering (SERS and oxidation test indicate that hollow Au–Ag alloy nanorices show good anti-oxidation and have broad application prospects in surface-plasmon-related fields.

  2. Polyazole hollow fiber membranes for direct contact membrane distillation

    KAUST Repository

    Maab, Husnul

    2013-08-07

    Porous hollow fiber membranes were fabricated from fluorinated polyoxadiazole and polytriazole by a dry-wet spinning method for application in desalination of Red Sea water by direct contact membrane distillation (DCMD). The data were compared with commercially available hollow fiber MD membranes prepared from poly(vinylidene fluoride). The membranes were characterized by electron microscopy, liquid entry pressure (LEP), and pore diameter measurements. Finally, the hollow fiber membranes were tested for DCMD. Salt selectivity as high as 99.95% and water fluxes as high as 35 and 41 L m -2 h-1 were demonstrated, respectively, for polyoxadiazole and polytriazole hollow fiber membranes, operating at 80 C feed temperature and 20 C permeate. © 2013 American Chemical Society.

  3. Fabrication and formation mechanism of poly (L-lactic acid ultrafine multi-porous hollow fiber by electrospinning

    Directory of Open Access Journals (Sweden)

    Q. Z. Yu

    2013-01-01

    Full Text Available Poly(L-lactic acid (PLLA ultrafine multi-porous hollow fibers are fabricated by electrospinning with methylene dichloride as solvent. The Kirkendall effect has been widely applied for the fabrication of hollow structure in metals and inorganic materials. In this study, a conceptual extension is proposed for the formation mechanism: the development of porous hollow fiber undergoes three stages. The initial stage is the generation of small voids or pits on the surface of the fiber via surface diffusion and phase separation; the second stage is the formation of multi-pores penetrating the core of the fiber through the interaction of Kirkendall effect, surface diffusion and phase separation; the third stage is dominated by surface diffusion of the core material along the pore surface. To explore the formation conditions, the factors including ambient temperature, relativity humidity (R. H., molecular weight and fiber diameter are studied. The longitudinal and cross sectional morphologies of these fibers are examined by scanning electron micrograph (SEM. The results show that the prerequisite for the formation of uniform porous hollow PLLA fibers include moderate ambient temperature (10~20°C and appropriate molecular weight for the PLLA, as well as the diameter of the fiber in the range of several micrometers to about 100 nanometers.

  4. Laser-plasma-based linear collider using hollow plasma channels

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, C.B., E-mail: CBSchroeder@lbl.gov; Benedetti, C.; Esarey, E.; Leemans, W.P.

    2016-09-01

    A linear electron–positron collider based on laser-plasma accelerators using hollow plasma channels is considered. Laser propagation and energy depletion in the hollow channel is discussed, as well as the overall efficiency of the laser-plasma accelerator. Example parameters are presented for a 1-TeV and 3-TeV center-of-mass collider based on laser-plasma accelerators.

  5. Thin-walled reinforcement lattice structure for hollow CMC buckets

    Energy Technology Data Exchange (ETDEWEB)

    de Diego, Peter

    2017-06-27

    A hollow ceramic matrix composite (CMC) turbine bucket with an internal reinforcement lattice structure has improved vibration properties and stiffness. The lattice structure is formed of thin-walled plies made of CMC. The wall structures are arranged and located according to high stress areas within the hollow bucket. After the melt infiltration process, the mandrels melt away, leaving the wall structure to become the internal lattice reinforcement structure of the bucket.

  6. Flat Bunches with a Hollow Distribution for Space Charge Mitigation

    CERN Document Server

    Oeftiger, Adrian; Findlay, Alan James; Hancock, Steven; Rumolo, Giovanni

    2016-01-01

    Longitudinally hollow bunches provide one means to mitigate the impact of transverse space charge. The hollow distributions are created via dipolar parametric excitation during acceleration in CERN's Proton Synchrotron Booster. We present simulation work and beam measurements. Particular emphasis is given to the alleviation of space charge effects on the long injection plateau of the downstream Proton Synchrotron machine, which is the main goal of this study.

  7. Highly efficient fluorescence sensing with hollow core photonic crystal fibers

    DEFF Research Database (Denmark)

    Smolka, Stephan; Barth, Michael; Benson, Oliver

    2008-01-01

    We investigate hollow core photonic crystal fibers for ultra-sensitive fluorescence detection by selectively infiltrating the central hole with fluorophores. Dye concentrations down to 10(-9) M can be detected using only nanoliter sample volumes.......We investigate hollow core photonic crystal fibers for ultra-sensitive fluorescence detection by selectively infiltrating the central hole with fluorophores. Dye concentrations down to 10(-9) M can be detected using only nanoliter sample volumes....

  8. Liquid Temperature Measurements Using Two Different Tunable Hollow Prisms.

    Science.gov (United States)

    Calixto, Sergio; Rosete-Aguilar, Martha; Torres-Gomez, Ismael

    2017-01-29

    This paper describes the design, fabrication, and testing of two hollow prisms. One is a prism with a grating glued to its hypotenuse. This ensemble, prism + grating, is called a grism. It can be applied as an on-axis tunable spectrometer. The other hollow prism is a constant deviation one called a Pellin-Broca. It can be used as a tunable dispersive element in a spectrometer with no moving parts. The application of prisms as temperature sensors is shown.

  9. 3D hollow nanostructures as building blocks for multifunctional plasmonics

    KAUST Repository

    De Angelis, Francesco De

    2013-08-14

    We present an advanced and robust technology to realize 3D hollow plasmonic nanostructures which are tunable in size, shape, and layout. The presented architectures offer new and unconventional properties such as the realization of 3D plasmonic hollow nanocavities with high electric field confinement and enhancement, finely structured extinction profiles, and broad band optical absorption. The 3D nature of the devices can overcome intrinsic difficulties related to conventional architectures in a wide range of multidisciplinary applications. © 2013 American Chemical Society.

  10. Development of gamma column scanner

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Bum; Jung, Sung Hee; Jun, Jong Kyu; Kim, Jin Sup

    2004-11-01

    Distillation column is important unit in petro-chemical industries, and its on-line diagnose is important. To get density profile measured by the radiation transmitted through column is well method for on-line diagnose to find out missing tray or flooding. In many cases the distance from radiation detector to detection circuit is up to 100m long. Conventional radiation detection method that is to transmit analog signal by co axial cable directly to detection circuit couldn't give good result because of its long cable. In this case the system is sensitive to electric noise because of long cable and interface between the radiation circuit and the controller for mechanical system. The radiation detection system introduced here is using digital modulated signal and loop coil to transmit signal instead of slip ring and analog signal. In detail detection part of automatic gamma scanner consists of high voltage circuit, PHA circuit FSK modem and battery. This method isolates power system and gives good solution for automatic gamma scanning by isolating the controlling circuit of mechanical system from radiation detecting circuit which is sensitive to noise.

  11. Column-like structures following the course of dentinal tubules in bovine, red deer, and rat teeth.

    Science.gov (United States)

    Hals, E; Dyngeland, T

    1988-12-01

    A material of bovine, red deer, and rat incisors was investigated, with emphasis on the bovine teeth. Both ground sections and paraffin wax sections of demineralized material were used. The sections were investigated by ordinary and polarized light microscopy and contact microradiography. In the bulk of the dentin irregular column-like light structures, alternating with largely similar, but dark, columns, followed the course of the dentinal tubules from the pulpal border to just below the mantle dentin. Each column, 10-100 micron in diameter, contained a highly varying number of tubules. The difference between light and dark columns was mainly related to the intertubular dentin of the globules of which they were composed. Light columns were slightly more mineralized than the dark ones and seemed to contain fewer GAGs, but more glycoproteins. A difference in fiber direction between light and dark columns was also evident. To the authors' knowledge these structures have not attracted the attention of previous workers.

  12. Oscillating water column structural model

    Energy Technology Data Exchange (ETDEWEB)

    Copeland, Guild [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bull, Diana L [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jepsen, Richard Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gordon, Margaret Ellen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    An oscillating water column (OWC) wave energy converter is a structure with an opening to the ocean below the free surface, i.e. a structure with a moonpool. Two structural models for a non-axisymmetric terminator design OWC, the Backward Bent Duct Buoy (BBDB) are discussed in this report. The results of this structural model design study are intended to inform experiments and modeling underway in support of the U.S. Department of Energy (DOE) initiated Reference Model Project (RMP). A detailed design developed by Re Vision Consulting used stiffeners and girders to stabilize the structure against the hydrostatic loads experienced by a BBDB device. Additional support plates were added to this structure to account for loads arising from the mooring line attachment points. A simplified structure was designed in a modular fashion. This simplified design allows easy alterations to the buoyancy chambers and uncomplicated analysis of resulting changes in buoyancy.

  13. Vibroacoustic response of an eccentric hollow cylinder

    Science.gov (United States)

    Hasheminejad, Seyyed M.; Mousavi-akbarzadeh, Hessam

    2012-07-01

    The linear 3D elasticity theory in conjunction with the classical method of separation of variables and the translational addition theorem for cylindrical wave functions are employed to investigate the three-dimensional steady-state sound radiation characteristics of an arbitrarily thick eccentric hollow cylinder of infinite length, submerged in an unbounded ideal acoustic medium, and subjected to arbitrary time-harmonic on-surface mechanical drives. The spatial Fourier transform along the shell axis and Fourier series expansion in the circumferential direction are utilized to obtain a formal integral expression for the radiated pressure field in the frequency domain. The method of stationary phase is subsequently implemented to evaluate the integral for an observation point in the far field. The analytical results are illustrated with numerical examples in which air-filled water-submerged concentric and eccentric steel cylinders are driven by harmonic concentrated radial and transverse surface loads. Effects of excitation and cylinder eccentricity on the far-field radiated pressure amplitudes/directivities are discussed and contributions from pseudo-Rayleigh, whispering gallery, and axially guided waves are examined through selected spatial dispersion patterns. Limiting cases are considered and the validity of results is established with the aid of a commercial finite element package as well as by comparison with the data in the existing literature.

  14. Hollow plasmonic antennas for broadband SERS spectroscopy

    Directory of Open Access Journals (Sweden)

    Gabriele C. Messina

    2015-02-01

    Full Text Available The chemical environment of cells is an extremely complex and multifaceted system that includes many types of proteins, lipids, nucleic acids and various other components. With the final aim of studying these components in detail, we have developed multiband plasmonic antennas, which are suitable for highly sensitive surface enhanced Raman spectroscopy (SERS and are activated by a wide range of excitation wavelengths. The three-dimensional hollow nanoantennas were produced on an optical resist by a secondary electron lithography approach, generated by fast ion-beam milling on the polymer and then covered with silver in order to obtain plasmonic functionalities. The optical properties of these structures have been studied through finite element analysis simulations that demonstrated the presence of broadband absorption and multiband enhancement due to the unusual geometry of the antennas. The enhancement was confirmed by SERS measurements, which showed a large enhancement of the vibrational features both in the case of resonant excitation and out-of-resonance excitation. Such characteristics indicate that these structures are potential candidates for plasmonic enhancers in multifunctional opto-electronic biosensors.

  15. Reluctance Machine for a Hollow Cylinder Flywheel

    Directory of Open Access Journals (Sweden)

    Magnus Hedlund

    2017-03-01

    Full Text Available A hollow cylinder flywheel rotor with a novel outer rotor switched reluctance machine (SRM mounted on the interior rim is presented, with measurements, numerical analysis and analytical models. Practical experiences from the construction process are also discussed. The flywheel rotor does not have a shaft and spokes and is predicted to store 181 Wh / kg at ultimate tensile strength (UTS according to simulations. The novel SRM is an axial flux machine, chosen due to its robustness and tolerance for high strain. The computed maximum tip speed of the motor at UTS is 1050 m / s . A small-scale proof-of-concept electric machine prototype has been constructed, and the machine inductance has been estimated from measurements of voltage and current and compared against results from analytical models and finite element analysis (FEA. The prototype measurements were used to simulate operation during maximal speed for a comparison towards other high-speed electric machines, in terms of tip speed and power. The mechanical design of the flywheel was performed with an analytical formulation assuming planar stress in concentric shells of orthotropic (unidirectionally circumferentially wound carbon composites. The analytical approach was verified with 3D FEA in terms of stress and strain.

  16. Analysis of the behavior of reinforced concrete columns strengthened with sleeve wedge bolts and a self compacting concrete layer

    Directory of Open Access Journals (Sweden)

    M. G. Marques

    Full Text Available Strengthening of reinforced concrete columns by jacketing is one of the most common structural rehabilitation techniques in Brazil. For adequate performance, it is necessary, among others, to avoid detachment of the new concrete layer (strengthening material from the old concrete substrate when the strengthened member is again in service conditions. This paper describes the test results of eight reinforced concrete rectangular columns subjected to combined compression and one-axis bending to evaluate the efficiency of using sleeve wedge bolts across the new concrete/old concrete interface to avoid detachment. The strengthening technique, in this case, consists of adding a layer of self-compacting concrete to one face of the column. Two columns tested were monolithic and named PO (original column e PR (reference column. The other six columns were strengthened using a new 35 mm thick self-compacting concrete layer attached to the column face subjected to highest compressive stresses. Column PO had a 120mm by 250 mm rectangular cross section and its results gave information about column behavior without the use of strengthening. Column PR had a 155mm by 250 mm rectangular cross section and its cross section dimensions matched the strengthened columns but it was cast monolithically. To improve bond conditions between the existing concrete and the new concrete, the concrete surface was roughened and the outermost aggregate was exposed using hydro jetting. Holes along the concrete surface were made to insert the wedge bolts responsible for increasing the bond between the two concrete surfaces. The difference among the six strengthened columns was the position and amount of bolts used. Results indicate that the position and amount of the bolts alters significantly the strength capacity of the columns, since premature rupture by concrete detachment was delayed.

  17. GPR Diagnostics of columns in archaeological contexts

    Science.gov (United States)

    Soldovieri, Francesco; Masini, Nicola; Persico, Raffaele; Catapano, Ilaria

    2017-04-01

    In the last decade the use of Ground Penetrating radar (GPR) applied to cultural heritage has been strongly increasing thanks to both technological development of sensors and softwares for data processing and cultural reasons such as the increasing awareness of conservators and archaeologist of the benefits of this method in terms of reduction of costs and time and risk associated with restoration works. This made GPR a mature technique for investigating different types of works of art and building elements of historical interest, including masonry structures, frescoes, mosaics [1-3], in the context of scientific projects, decision support activities aimed at the diagnosis of decay pathologies, and educational activities. One of the most complex building elements to be investigated by GPR are the columns both for the geometry of the object and for the several expected features to be detected including fractures, dishomogeneities and metallic connection elements. The work deals with the Ground Penetrating Radar diagnostic surveys at the prestigious archaeological site of Pompei. In particular, GPR surveys were carried out in two different areas, Palestra Grande and Tempio di Giove. The first campaign was carried out also as educational activity of the "International School "GEOPHYSICS AND REMOTE SENSING FOR ARCHAEOLOGY". The School aimed at giving the opportunity to scholars, PhD students, researchers and specialists in Geophysics, Remote Sensing and Archaeology to deepen their knowledge and expertise with geophysical and remote sensing techniques for archaeology and cultural heritage documentation and management. This survey was carried on two kinds of columns, with circular and rectangular section in order to detect possible hidden defects affecting their integrity. The second survey was carried out at Tempio di Giove, on request of the Soprintendenza Pompei, in order to gain information about the presence of reinforcement structures, which may be put inside the

  18. Soil column leaching of pesticides.

    Science.gov (United States)

    Katagi, Toshiyuki

    2013-01-01

    In this review, I address the practical and theoretical aspects of pesticide soil mobility.I also address the methods used to measure mobility, and the factors that influence it, and I summarize the data that have been published on the column leaching of pesticides.Pesticides that enter the unsaturated soil profile are transported downwards by the water flux, and are adsorbed, desorbed, and/or degraded as they pass through the soil. The rate of passage of a pesticide through the soil depends on the properties of the pesticide, the properties of the soil and the prevailing environmental conditions.Because large amounts of many different pesticides are used around the world, they and their degradates may sometimes contaminate groundwater at unacceptable levels.It is for this reason that assessing the transport behavior and soil mobility of pesticides before they are sold into commerce is important and is one indispensable element that regulators use to assess probable pesticide safety. Both elementary soil column leaching and sophisticated outdoor lysimeter studies are performed to measure the leaching potential for pesticides; the latter approach more reliably reflects probable field behavior, but the former is useful to initially profile a pesticide for soil mobility potential.Soil is physically heterogeneous. The structure of soil varies both vertically and laterally, and this variability affects the complex flow of water through the soil profile, making it difficult to predict with accuracy. In addition, macropores exist in soils and further add to the complexity of how water flow occurs. The degree to which soil is tilled, the density of vegetation on the surface, and the type and amounts of organic soil amendments that are added to soil further affect the movement rate of water through soil, the character of soil adsorption sites and the microbial populations that exist in the soil. Parameters that most influence the rate of pesticide mobility in soil are

  19. Methodological analysis of gamma tomography system for large random packed columns

    Energy Technology Data Exchange (ETDEWEB)

    Vasquez, Pablo A.S.; De Mesquita, Carlos H. [Instituto de Pesquisas Energeticas e Nucleares-IPEN/CNEN-SP, Prof. Lineu Prestes, 2242-Cidade Universitaria, 05508-900, Sao Paulo (Brazil); LeRoux, Galo A.C. [Departamento de Engenharia Quimica, Escola Politecnica da Universidade de Sao Paulo, Prof. Luciano Gualberto, Trav. 3, 380-Cidade Universitaria, 05508-900, Sao Paulo (Brazil); Hamada, Margarida M. [Instituto de Pesquisas Energeticas e Nucleares-IPEN/CNEN-SP, Prof. Lineu Prestes, 2242-Cidade Universitaria, 05508-900, Sao Paulo (Brazil)], E-mail: mmhamada@ipen.br

    2010-04-15

    Gamma ray tomography experiments have been carried out to detect spatial patterns in the porosity in a 0.27 m diameter column packed with steel Rashig rings of different sizes: 12.6, 37.9, and 76 mm. using a first generation CT system. A fast Fourier transform tomographic reconstruction algorithm has been used to calculate the spatial variation over the column cross section. Cross-sectional gas porosity and solid holdup distribution were determinate. The values of cross-sectional average gas porosity were {epsilon}=0.849, 0.938 and 0.966 for the 12.6, 37.9, and 76 mm rings, respectively. Radial holdup variation within the packed bed has been determined. The variation of the circumferentially averaged gas holdup in the radial direction indicates that the porosity in the column wall region is a somewhat higher than that in the bulk region, due to the effect of the column wall.

  20. Hollow fiber based quantum cascade laser spectrometer for fast and sensitive drug identification

    Science.gov (United States)

    Herbst, J.; Scherer, B.; Ruf, A.; Erb, J.; Lambrecht, A.

    2012-01-01

    Sensitive and fast identification of drugs or drug precursors is important and necessary in scenarios like baggage or container check by customs or police. Fraunhofer IPM is developing a laser spectrometer using external cavity quantum cascade lasers (EC-QCL) to obtain mid-infrared (IR) absorption spectra in the wavelength range of the specific vibrational bands of amphetamines and their precursors. The commercial EC-QCL covers a tuning range of about 225 cm-1 within 1.4 s. The system could be used for different sample types like bulk samples or liquid solutions. A sampling unit evaporates the sample. Because of small sample amounts a 3 m long hollow fiber with an inner volume smaller than 1ml is used as gas cell and wave guide for the laser beam. This setup is suitable as a detector of a gas chromatograph instead of a standard detector (TCD or FID). The advantage is the selective identification of drugs by their IR spectra in addition to the retention time in the gas chromatographic column. In comparison to Fourier Transform IR systems the EC-QCL setup shows a good mechanical robustness and has the advantage of a point light source. Because of the good fiber incoupling performance of the EC-QCL it is possible to use hollow fibers. So, a good absorption signal is achieved because of the long optical path in the small cell volume without significant dilution. In first laboratory experiments a detection limit in the microgram range for pseudo ephedrine is achieved.

  1. Hollow proppants and a process for their manufacture

    Science.gov (United States)

    Jones, Arfon H.; Cutler, Raymond A.

    1985-01-01

    Hollow, fine-grained ceramic proppants are less expensive and improve fracture control when compared to conventional proppants (dense alumina, mullite, bauxite, zirconia, etc.). Hollow proppants of the present invention have been fabricated by spray drying, followed by sintering in order to obtain a dense case and a hollow core. These proppants generally have high sphericity and roundness (Krumbein sphericity and roundness greater than 0.8), have diameters on average between 2250 and 125 .mu.m, depending on proppant size required, and have strength equal to or greater than that of sand. The hollow core, the size of which can be controlled, permits better fracture control in hydraulic fracturing treatments since the proppant can be transported in lower viscosity fluids. Hollow proppants produced at the same cost/weight as conventional proppants also provide for lower costs, since less weight is required to fill the same volume. The fine-grained (preferably less than 5 .mu.m in diameter) ceramic case provides the strength necessary to withstand closure stresses and prevent crushing.

  2. Heat Transfer Study of Heat-Integrated Distillation Column (HIDiC) Using Simulation Techniques

    Science.gov (United States)

    Pulido, Jeffrey León; Martínez, Edgar Leonardo; Wolf, Maria Regina; Filho, Rubens Maciel

    2011-08-01

    Separation processes is largely used in petroleum refining and alcohol industries. Distillation columns consume a huge amount of energy in industrial process. Therefore, the concept of Heat-Integrated Distillation Column (HIDiC) was studied using simulation techniques in order to overcome this drawback. In this configuration the column is composed for two concentric sections called rectifying and stripping. The heat transfer is conducted from the rectifying section (which works at higher pressure and temperature) to the stripping section (which works at lower pressure and temperature) using the heat present in the process and decreasing the energy charge required by the reboiler. The HIDiC column offers great potential to reduce energy consumption compared to conventional columns. However, the complexity of the internal configuration requires the development of rigorous works that enable a better understanding of the column operation. For this reason, techniques of simulation were used through of computational software. The current work presents a heat transfer study in a concentric stage of a HIDiC column. The results obtained by Aspen Plus and CFD simulation showed the internal heat transfer in a concentric tray as a promissory configuration in order to decrease energy consumption in distillation processes.

  3. Family Bovidae (Hollow-horned Ruminants)

    Science.gov (United States)

    Groves, Colin P.; Leslie, David M.; Huffman, Brent A.; Valdez, Raul; Habibi, Khushal; Weinberg, Paul; Burton, James; Jarman, Peter; Robichaud, William

    2015-01-01

    Probably the single most eye-catching aspect of the current volume is the explosion of species recognized in the family Bovidae (Hollow-horned Ruminants). In 2005, the third edition of Mammal Species of the World listed 143 species in 50 genera of Bovidae. That list, prepared by the late Peter Grubb, was somewhat traditional and provisional, as he was engaged with his long-time colleague, Colin Groves, in a substantial revision of ungulate taxonomy. Their work, which will be published later this year, is the culmination of years of study of this important and wide-ranging family by these two venerable authorities. Colin Groves is the lead author for Bovidae in this volume of HMW, and in it we recognize all 279 species in 54 genera that are documented in his and Peter Grubb’s ground-breaking work.At the root of this expanded number of recognized species is our changing view of the modern species concept. Like a growing number of taxonomists, Groves favors a phylogenetic species concept, which he defines as the smallest population or aggregation of populations that has fixed heritable differences from other such populations or aggregations. This is in contrast to the traditional biological species concept, which requires reproductive isolation between such populations. The difficulty in determining that reproductive isolation led to an underrepresentation of the number of species in many groups. Clearly there remain problems in determining which differences between populations are heritable, and the system used here undoubtedly will continue to be tweaked as our understanding grows. For now, this greatly expanded version of Bovidae species limits seems the best answer. One of the goals of HMW is to provide an up-to-date summary of the conservation status for every species of mammal, and this expanded species concept better enables us to explore the true conservation situation of each.

  4. Column: Factors Affecting Data Decay

    Directory of Open Access Journals (Sweden)

    Kevin Fairbanks

    2012-06-01

    Full Text Available In nuclear physics, the phrase decay rate is used to denote the rate that atoms and other particles spontaneously decompose. Uranium-235 famously decays into a variety of daughter isotopes including Thorium and Neptunium, which themselves decay to others. Decay rates are widely observed and wildly different depending on many factors, both internal and external. U-235 has a half-life of 703,800,000 years, for example, while free neutrons have a half-life of 611 seconds and neutrons in an atomic nucleus are stable.We posit that data in computer systems also experiences some kind of statistical decay process and thus also has a discernible decay rate. Like atomic decay, data decay fluctuates wildly. But unlike atomic decay, data decay rates are the result of so many different interplaying processes that we currently do not understand them well enough to come up with quantifiable numbers. Nevertheless, we believe that it is useful to discuss some of the factors that impact the data decay rate, for these factors frequently determine whether useful data about a subject can be recovered by forensic investigation.(see PDF for full column

  5. Hollow volcanic tumulus caves of Kilauea Caldera, Hawaii County, Hawaii

    Directory of Open Access Journals (Sweden)

    William R. Halliday

    1998-01-01

    Full Text Available In addition to lava tube caves with commonly noted features, sizable subcrustal spaces of several types exist on the floor of Kilauea Caldera. Most of these are formed by drainage of partially stabilized volcanic structures enlarged or formed by injection of very fluid lava beneath a plastic crust. Most conspicuous are hollow tumuli, possibly first described by Walker in 1991. Walker mapped and described the outer chamber of Tumulus E-I Cave. Further exploration has revealed that it has a hyperthermic inner room beneath an adjoining tumulus with no connection evident on the surface. Two lengthy, sinuous hollow tumuli also are present in this part of the caldera. These findings support Walkers conclusions that hollow tumuli provide valuable insights into tumulus-forming mechanisms, and provide information about the processes of emplacement of pahoehoe sheet flows.

  6. Hollow Silica: A novel Material for Methane Storage

    Directory of Open Access Journals (Sweden)

    Chari Vangala Dhanunjana

    2015-11-01

    Full Text Available Methane gas storage in the form of Methane Hydrate (MH in hollow silica was studied and compared with solid silica and pure water systems. The gas hydrate growth/dissociation was monitored by following the pressure (gas intake – temperature variations in a classical isochoric process. The effect of stirring on the hydrate formation kinetics and yield was clearly evidenced in the case of solid and pure water systems, whereas it did not show any influence in hollow silica; and in fact, the yields remained identical in both stirring and non-stirring experiments. Approximately 3.6 m.mol of methane per gram of water was consumed as MH in the hollow silica matrix and the formation kinetics was extremely fast (~180 min. However, the methane gas conversion into MH in solid silica and pure water systems was ~ 10 times higher in a stirred reactor when compared with a non-stirred system.

  7. Fabrication of Polyacrylonitrile Hollow Fiber Membranes from Ionic Liquid Solutions

    KAUST Repository

    Kim, Dooli

    2015-10-08

    The interest in green processes and products has increased to reduce the negative impact of many industrial processes to the environment. Solvents, which play a crucial role in the fabrication of membranes, need to be replaced by sustainable and less toxic solvent alternatives for commonly used polymers. The purpose of this study is the fabrication of greener hollow fiber membranes based on polyacrylonitrile (PAN), substituting dimethylformamide (DMF) by less toxic mixtures of ionic liquids (IL) and dimethylsulfoxide (DMSO). A thermodynamic analysis was conducted, estimating the Gibbs free energy of mixing to find the most convenient solution compositions. Hollow fiber membranes were manufactured and optimized. As a result, a uniform pattern and high porosity were observed in the inner surface of the membranes prepared from the ionic liquid solutions. The membranes were coated with a polyamide layer by interfacial polymerization the hollow fiber membranes were applied in forward osmosis experiments by using sucrose solutions as draw solution.

  8. Sharp tipped plastic hollow microneedle array by microinjection moulding

    Science.gov (United States)

    Yung, K. L.; Xu, Yan; Kang, Chunlei; Liu, H.; Tam, K. F.; Ko, S. M.; Kwan, F. Y.; Lee, Thomas M. H.

    2012-01-01

    A method of producing sharp tipped plastic hollow microneedle arrays using microinjection moulding is presented in this paper. Unlike traditional approaches, three mould inserts were used to create the sharp tips of the microneedles. Mould inserts with low surface roughness were fabricated using a picosecond laser machine. Sharp tipped plastic hollow microneedles 500 µm in height were fabricated using a microinjection moulding machine developed by the authors’ group. In addition, the strength of the microneedle was studied by simulation and penetration experiments. Results show that the microneedles can penetrate into skin, delivering liquid successfully without any breakage or severe deformation. Techniques presented in this paper can be used to fabricate sharp tipped plastic hollow microneedle arrays massively with low cost.

  9. Hollow-core photonic-crystal fibres for laser dentistry

    Energy Technology Data Exchange (ETDEWEB)

    Konorov, Stanislav O [Physics Department, International Laser Center, M V Lomonosov Moscow State University, Vorob' evy gory, 119899 Moscow (Russian Federation); Mitrokhin, Vladimir P [Physics Department, International Laser Center, M V Lomonosov Moscow State University, Vorob' evy gory, 119899 Moscow (Russian Federation); Fedotov, Andrei B [Physics Department, International Laser Center, M V Lomonosov Moscow State University, Vorob' evy gory, 119899 Moscow (Russian Federation); Sidorov-Biryukov, Dmitrii A [Physics Department, International Laser Center, M V Lomonosov Moscow State University, Vorob' evy gory, 119899 Moscow (Russian Federation); Beloglazov, Valentin I [Technology and Equipment for Glass Structures Institute, pr. Stroitelei 1, 410044 Saratov (Russian Federation); Skibina, Nina B [Technology and Equipment for Glass Structures Institute, pr. Stroitelei 1, 410044 Saratov (Russian Federation); Wintner, Ernst [Institut fuer Photonik, Technische Universitaet Wien, Gusshausstrasse 27/387, 1040 Wien (Austria); Scalora, Michael [Weapons Sciences Directorate, US Army Aviation and Missile Command Huntsville, AL 35898-5000 (United States); Zheltikov, Aleksei M [Physics Department, International Laser Center, M V Lomonosov Moscow State University, Vorob' evy gory, 119899 Moscow (Russian Federation)

    2004-04-07

    Hollow-core photonic-crystal fibres (PCFs) for the delivery of high-fluence laser radiation capable of ablating tooth enamel are developed. Sequences of picosecond pulses of 1.06 {mu}m Nd:YAG-laser radiation with a total energy of about 2 mJ are transmitted through a hollow-core photonic-crystal fibre with a core diameter of approximately 14 {mu}m and are focused on a tooth surface in vitro to ablate dental tissue. The hollow-core PCF is shown to support the single-fundamental-mode regime for 1.06 {mu}m laser radiation, serving as a spatial filter and allowing the laser beam quality to be substantially improved. The same fibre is used to transmit emission from plasmas produced by laser pulses on the tooth surface in the backward direction for detection and optical diagnostics.

  10. Fire resistance of extruded hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Sørensen, Lars Schiøtt; Giuliani, Luisa

    2017-01-01

    Purpose – Prefabricated extruded hollow-core slabs are preferred building components for floor structures in several countries. It is therefore important to be able to document the fire resistance of these slabs proving fulfilment of standard fire resistance requirements of 60 and 120 min found...... in most national building regulations. The paper aims to present a detailed analysis of the mechanisms responsible for the loss of loadbearing capacity of hollow-core slabs when exposed to fire. Design/methodology/approach – Furthermore, it compares theoretica calculation and assessment according...... to the structural codes with data derived from a standard fire test and from a thorough examination of the comprehensive test documentation available on fire exposed hollow-core slabs. Findings – Mechanisms for loss of load-bearing capacity are clarified, and evidence of the fire resistance is found. Originality...

  11. Fire resistance of extruded hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Giuliani, Luisa; Sørensen, Lars Schiøtt

    2016-01-01

    Prefabricated extruded hollow-core slabs are preferred building components for floor structures in several countries. It is therefore important to be able to document the fire resistance of these slabs proving fulfilment of standard fire resistance requirements of 60- and 120 minutes found in most...... national building regulations. The paper presents a detailed analysis of the mechanisms responsible for the loss of load-bearing capacity of hollow-core slabs when exposed to fire. Furthermore, it compares theoretical calculation and assessment according to the structural codes with data derived from...... a standard fire test and from a thorough examination of the comprehensive test documentation available on fire exposed hollow-core slabs. Mechanisms for loss of load-bearing capacity are clarified, and evidence of the fire resistance is found. For the first time the mechanisms responsible for loss of load...

  12. Strain sensor based on hollow microsphere Fabry-Perot cavity

    Science.gov (United States)

    Monteiro, Catarina S.; Silva, Susana O.; Frazão, Orlando

    2017-08-01

    Fusion splicing technique was explored for the fabrication of two sensing structures based on hollow microsphere Fabry- Perot cavity. The first sensor proposed was fabricated with a hollow microsphere tip, working as a probe sensor. This structure was studied for lateral load pressure, yielding a 1.56 +/- 0.01 nm/N sensitivity. The second sensing structure relied on an in-line hollow microsphere, which allowed the detection of lateral load, with a sensitivity of 2.62 +/- 0.02 nm/N. Furthermore, the proposed structure enabled strain sensing, with a sensitivity of 4.66 +/- 0.03 pm/μɛ. The two sensing structures were subjected to temperature, presenting low thermal cross-sensitivity.

  13. Hollow micro/nanomaterials as nanoreactors for photocatalysis

    Directory of Open Access Journals (Sweden)

    Xiaobo Li

    2013-10-01

    Full Text Available Learning from nature, one of the most prominent goals of photocatalysis is to assemble multifunctional photocatalytic units in an integrated, high performance device that is capable of using solar energy to produce “solar hydrogen” from aqueous media. By analogy with natural systems it is clear that scaffolds with multi-scale structural architectures are necessary. In this perspective, recent progress related to the use of hollow micro/nanomaterials as nanoreactors for photocatalysis is discussed. Organised, multi-scale assemblies of photocatalytic units on hollow scaffolds is an emerging area that shows much promise for the synthesis of high performance photocatalysts. Not only do improved transport and diffusion characteristics play an import role, but increased electron/hole separation lifetimes as well as improved light harvesting characteristics by the hollow structures also do so and are touched upon in this short perspective.

  14. Pressure effects in hollow and solid iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Silva, N.J.O., E-mail: nunojoao@ua.pt [Departamento de Física and CICECO, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Saisho, S.; Mito, M. [Faculty of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550 (Japan); Millán, A.; Palacio, F. [Instituto de Ciencia de Materiales de Aragón, CSIC - Universidad de Zaragoza. Departamento de Física de la Materia Condensada, Facultad de Ciencias, 50009 Zaragoza (Spain); Cabot, A. [Universitat de Barcelona and Catalonia Energy Research Institute, Barcelona (Spain); Iglesias, Ò.; Labarta, A. [Departament de Física Fonamental, Universitat de Barcelona and Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain)

    2013-06-15

    We report a study on the pressure response of the anisotropy energy of hollow and solid maghemite nanoparticles. The differences between the maghemite samples are understood in terms of size, magnetic anisotropy and shape of the particles. In particular, the differences between hollow and solid samples are due to the different shape of the nanoparticles and by comparing both pressure responses it is possible to conclude that the shell has a larger pressure response when compared to the core. - Highlights: ► Study of the pressure response of core and shell magnetic anisotropy. ► Contrast between hollow and solid maghemite nanoparticles. ► Disentanglement of nanoparticles core and shell magnetic properties.

  15. Dynamic Effects of Diabatization in Distillation Columns

    DEFF Research Database (Denmark)

    Bisgaard, Thomas; Huusom, Jakob Kjøbsted; Abildskov, Jens

    2012-01-01

    The dynamic eects of diabatization in distillation columns are investigated in simulation with primary focus on the heat-integrated distillation column (HIDiC). A generic, dynamic, rst-principle model has been formulated, which is exible to describe various diabatic distillation congurations. Dyn...

  16. Biomimetic Branched Hollow Fibers Templated by Self-assembled Fibrous Polyvinylpyrrolidone (PVP) Structures in Aqueous Solution

    Science.gov (United States)

    Qiu, Penghe; Mao, Chuanbin

    2010-01-01

    Branched hollow fibers are common in nature, but to form artificial fibers with a similar branched hollow structure is still a challenge. We discovered that polyvinylpyrrolidone (PVP) could self-assemble into branched hollow fibers in an aqueous solution after aging the PVP solution for about two weeks. Based on this finding, we demonstrated two approaches by which the self-assembly of PVP into branched hollow fibers could be exploited to template the formation of branched hollow inorganic fibers. First, inorganic material such as silica with high affinity against the PVP could be deposited on the surface of the branched hollow PVP fibers to form branched hollow silica fibers. To extend the application of PVP self-assembly in templating the formation of hollow branched fibers, we then adopted a second approach where the PVP molecules bound to inorganic nanoparticles (using gold nanoparticles as a model) co-self-assemble with the free PVP molecules in an aqueous solution, resulting in the formation of the branched hollow fibers with the nanoparticles embedded in the PVP matrix constituting the walls of the fibers. Heating the resultant fibers above the glass transition temperature of PVP led to the formation of branched hollow gold fibers. Our work suggests that the self-assembly of the PVP molecules in the solution can serve as a general method for directing the formation of branched hollow inorganic fibers. The branched hollow fibers may find potential applications in microfluidics, artificial blood vessel generation, and tissue engineering. PMID:20158250

  17. Soliton formation in hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper

    2009-01-01

    The formation of solitons upon compression of linearly chirped pulses in hollow-core photonic bandgap fibers is investigated numerically. The dependence of soliton duration on the chirp and power of the input pulse and on the dispersion slope of the fiber is investigated, and the validity...... of an approximate scaling relation is tested. It is concluded that compression of input pulses of several ps duration and sub-MW peak power can lead to a formation of solitons with ∼100 fs duration and multi-megawatt peak powers. The dispersion slope of realistic hollow-core fibers appears to be the main obstacle...

  18. Preparation and Electrochemical Properties of Silver Doped Hollow Carbon Nanofibers

    Directory of Open Access Journals (Sweden)

    LI Fu

    2016-11-01

    Full Text Available Silver doped PAN-based hollow carbon nanofibers were prepared combining co-electrospinning with in situ reduction technique subsequently heat treatment to improve the electrochemical performances of carbon based supercapacitor electrodes. The morphology, structure and electrochemical performances of the resulted nanofiber were studied. The results show that the silver nanoparticles can be doped on the surface of hollow carbon nanofibers and the addition of silver favors the improvement of the electrochemical performances, exhibiting the enhanced reversibility of electrode reaction and the capacitance and the reduced charge transfer impedance.

  19. Antiresonant hollow core fiber with seven nested capillaries

    DEFF Research Database (Denmark)

    Antonio-Lopez, Jose E.; Habib, Selim; Van Newkirk, Amy

    2016-01-01

    We report an antiresonant hollow core fiber formed of 7 non-touching capillaries with inner tubes. The fiber has a core diameter of ∼33μm and a core wall of ∼780nm of thickness. We demonstrate robust single mode operation at 1064nm and broad transmission bandwidth.......We report an antiresonant hollow core fiber formed of 7 non-touching capillaries with inner tubes. The fiber has a core diameter of ∼33μm and a core wall of ∼780nm of thickness. We demonstrate robust single mode operation at 1064nm and broad transmission bandwidth....

  20. Hollow-core fibers for high power pulse delivery

    DEFF Research Database (Denmark)

    Michieletto, Mattia; Lyngsø, Jens K.; Jakobsen, Christian

    2016-01-01

    We investigate hollow-core fibers for fiber delivery of high power ultrashort laser pulses. We use numerical techniques to design an anti-resonant hollow-core fiber having one layer of non-touching tubes to determine which structures offer the best optical properties for the delivery of high power......-core fiber. The three fibers are characterized experimentally for the delivery of 22 picosecond pulses at 1032nm. We demonstrate flexible, diffraction limited beam delivery with output average powers in excess of 70W. (C) 2016 Optical Society of America...

  1. Raman lasing in a hollow, bottle-like microresonator

    CERN Document Server

    Ooka, Yuta; Ward, Jonathan; Chromaic, Síle Nic

    2015-01-01

    We report on the fabrication of an ultrahigh quality factor, bottle-like microresonator from a hollow microcapillary, and the realisation of Raman lasing therein at pump wavelengths of $1.55~\\mathrm{\\mu m}$ and $780~\\mathrm{nm}$. Third-order cascaded Raman lasing was observed when pumped at $780~\\mathrm{nm}$. The aerostatic pressure tunability of the Raman laser was also investigated. Thence, we demonstrate that a high dynamic range, high resolution pressure sensor can be realised using the Raman spectrum of the hollow, bottle-like microresonator.

  2. Aminosilane-Functionalized Hollow Fiber Sorbents for Post-Combustion CO 2 Capture

    KAUST Repository

    Li, Fuyue Stephanie

    2013-07-03

    Increasing carbon dioxide emissions are generally believed to contribute to global warming. Developing new materials for capturing CO2 emitted from coal-fired plants can potentially mitigate the effect of these CO 2 emissions. In this study, we developed and optimized porous hollow fiber sorbents with both improved sorption capacities and rapid sorption kinetics by functionalizing aminosilane (N-(2-aminoethyl)-3- aminoisobutyldimethylmethoxysilane) to cellulose acetate hollow fibers as a "proof of concept". A lumen-side barrier layer was also developed in the aminosilane-functionalized cellulose acetate fiber sorbent to allow for facile heat exchange without significant mass transfer with the bore-side heat transfer fluid. The functionalized cellulose acetate fiber sorbents were characterized by pressure decay sorption measurements, multicomponent column chromatography, FT-IR, elemental analysis, and scanning electron microscopy. The carbon dioxide sorption capacity at 1 atm is 0.73 mmol/g by using the pressure decay apparatus. Multicomponent column chromatography measurements showed that aminosilane functionalized cellulose acetate fiber sorbent has a CO2 sorption capacity of 0.23 mmol/g at CO2 partial pressure 0.1 atm and 35 C in simulated flue gas. While this capacity is low, our proof of concept positions the technology to move forward to higher capacity with work that is underway. The presence of silicon and nitrogen elements in the elemental analysis confirmed the success of grafting along with FT-IR spectra which showed the absorbance peak (∼810 cm-1) for Si-C stretching. A cross-linked Neoprene material was used to form the lumen-side barrier layer. Preliminary data showed the required reduction in gas permeance to eliminate mixing between shell side and bore side fluid flows. Specifically the permeance was reduced from 10 000 GPUs for the neat fibers to 6.6 ± 0.1 and 3.3 ± 0.3 GPUs for the coated fibers. The selected lumen layer formation materials

  3. A Comparative Study of Hollow Copper Sulfide Nanoparticles and Hollow Gold Nanospheres on Degradability and Toxicity

    Science.gov (United States)

    Guo, Liangran; Panderi, Irene; Yan, Daisy D.; Szulak, Kevin; Li, Yajuan; Chen, Yi-Tzai; Ma, Hang; Niesen, Daniel B.; Seeram, Navindra; Ahmed, Aftab; Yan, Bingfang; Pantazatos, Dionysios; Lu, Wei

    2013-01-01

    Gold and copper nanoparticles have been widely investigated for photothermal therapy of cancer. However, degradability and toxicity of these nanoparticles remain concerns. Here, we compare hollow CuS nanoparticles (HCuSNPs) with hollow gold nanospheres (HAuNS) in similar particle sizes and morphology following intravenous administration to mice. The injected pegylated HCuSNPs (PEG-HCuSNPs) are eliminated through both hepatobiliary (67 percentage of injected dose, %ID) and renal (23 %ID) excretion within one month post injection. By contrast, 3.98 %ID of Au is excreted from liver and kidney within one month after i.v. injection of pegylated HAuNS (PEG-HAuNS). Comparatively, PEG-HAuNS are almost non-metabolizable, while PEG-HCuSNPs are considered biodegradable nanoparticles. PEG-HCuSNPs do not show significant toxicity by histological or blood chemistry analysis. Principal component analysis and 2-D peak distribution plots of data from matrix-assisted laser desorption ionization-time of flight imaging mass spectrometry (MALDI-TOF IMS) of liver tissues demonstrated a reversible change in the proteomic profile in mice receiving PEG-HCuSNPs. This is attributed to slow dissociation of Cu ion from CuS nanoparticles along with effective Cu elimination for maintaining homeostasis. Nonetheless, an irreversible change in the proteomic profile is observed in the liver from mice receiving PEG-HAuNS by analysis of MALDI-TOF IMS data, probably due to the non-metabolizability of Au. This finding correlates with the elevated serum lactate dehydrogenase at 3 months after PEG-HAuNS injection, indicating potential long-term toxicity. The comparative results between the two types of nanoparticles will advance the development of HCuSNPs as a new class of biodegradable inorganic nanomaterials for photothermal therapy. PMID:24053214

  4. Design of reinforced areas of concrete column using quadratic polynomials

    Science.gov (United States)

    Arif Gunadi, Tjiang; Parung, Herman; Rachman Djamaluddin, Abd; Arwin Amiruddin, A.

    2017-11-01

    Designing of reinforced concrete columns mostly carried out by a simple planning method which uses column interaction diagram. However, the application of this method is limited because it valids only for certain compressive strenght of the concrete and yield strength of the reinforcement. Thus, a more applicable method is still in need. Another method is the use of quadratic polynomials as a basis for the approach in designing reinforced concrete columns, where the ratio of neutral lines to the effective height of a cross section (ξ) if associated with ξ in the same cross-section with different reinforcement ratios is assumed to form a quadratic polynomial. This is identical to the basic principle used in the Simpson rule for numerical integral using quadratic polynomials and had a sufficiently accurate level of accuracy. The basis of this approach to be used both the normal force equilibrium and the moment equilibrium. The abscissa of the intersection of the two curves is the ratio that had been mentioned, since it fulfill both of the equilibrium. The application of this method is relatively more complicated than the existing method but provided with tables and graphs (N vs ξN ) and (M vs ξM ) so that its used could be simplified. The uniqueness of these tables are only distinguished based on the compresssive strength of the concrete, so in application it could be combined with various yield strenght of the reinforcement available in the market. This method could be solved by using programming languages such as Fortran.

  5. Behaviour of axially and eccentrically loaded short columns reinforced with GFRP bars

    Science.gov (United States)

    Sreenath, S.; Balaji, S.; Saravana Raja Mohan, K.

    2017-07-01

    The corrosion of steel reinforcing bars is a predominant factor in limiting the life expectancy of Reinforced Cement Concrete (RCC) structures. Corrosion resistant Fibre Reinforced Polymer (FRP) bars can be an effective alternative to steel bars in this context. Recent investigations reported the flexural behaviour of RCC beams reinforced with Glass Fibre Reinforced Polymer (GFRP) bars. This study is meant to investigate the suitability of Sand Coated GFRP reinforcement bars in short square columns which when loaded axially and loaded with a minimum eccentricity. Standard tests to assess mechanical properties of GFRP bars and pullout test to quantify the bond strength between the bars and concrete were conducted. GFRP reinforced column specimens with a cross-sectional dimension of 100mm X 100mm and of length 1000mm were cast and tested under axial and eccentric loading. The assessed load carrying capacity was compared with that of conventional steel reinforced columns of the same size. The yield load and ultimate load at failure withstood by the steel reinforced columns were considerably more than that of GFRP reinforced columns. The energy absorption capacity of GFRP reinforced columns was also poor compared to steel reinforced columns. Both the columns exhibited nearly the same ductile behaviour. Hence GFRP reinforcements are not recommendable for compression members.

  6. Application of a new vertical profiling tool (ESASS) for sampling groundwater quality during hollow-stem auger drilling

    Science.gov (United States)

    Harte, Philip T.; Flanagan, Sarah M.

    2011-01-01

    A new tool called ESASS (Enhanced Screen Auger Sampling System) was developed by the U.S. Geological Survey. The use of ESASS, because of its unique U.S. patent design (U.S. patent no. 7,631,705 B1), allows for the collection of representative, depth-specific groundwater samples (vertical profiling) in a quick and efficient manner using a 0.305-m long screen auger during hollow-stem auger drilling. With ESASS, the water column in the flights above the screen auger is separated from the water in the screen auger by a specially designed removable plug and collar. The tool fits inside an auger of standard inner diameter (82.55 mm). The novel design of the system constituted by the plug, collar, and A-rod allows the plug to be retrieved using conventional drilling A-rods. After retrieval, standard-diameter (50.8 mm) observation wells can be installed within the hollow-stem augers. Testing of ESASS was conducted at one waste-disposal site with tetrachloroethylene (PCE) contamination and at two reference sites with no known waste-disposal history. All three sites have similar geology and are underlain by glacial, stratified-drift deposits. For the applications tested, ESASS proved to be a useful tool in vertical profiling of groundwater quality. At the waste site, PCE concentrations measured with ESASS profiling at several depths were comparable (relative percent difference nitrate and nitrite) over short (0.61 m) distances.

  7. Review of design codes of concrete encased steel short columns under axial compression

    Directory of Open Access Journals (Sweden)

    K.Z. Soliman

    2013-08-01

    Full Text Available In recent years, the use of encased steel concrete columns has been increased significantly in medium-rise or high-rise buildings. The aim of the present investigation is to assess experimentally the current methods and codes for evaluating the ultimate load behavior of concrete encased steel short columns. The current state of design provisions for composite columns from the Egyptian codes ECP203-2007 and ECP-SC-LRFD-2012, as well as, American Institute of Steel Construction, AISC-LRFD-2010, American Concrete Institute, ACI-318-2008, and British Standard BS-5400-5 was reviewed. The axial capacity portion of both the encased steel section and the concrete section was also studied according to the previously mentioned codes. Ten encased steel concrete columns have been investigated experimentally to study the effect of concrete confinement and different types of encased steel sections. The measured axial capacity of the tested ten composite columns was compared with the values calculated by the above mentioned codes. It is concluded that non-negligible discrepancies exist between codes and the experimental results as the confinement effect was not considered in predicting both the strength and ductility of concrete. The confining effect was obviously influenced by the shape of the encased steel section. The tube-shaped steel section leads to better confinement than the SIB section. Among the used codes, the ECP-SC-LRFD-2012 led to the most conservative results.

  8. The Influence of Heat Transfer Irreversibilities on the Optimal Performance of Diabatic Distillation Columns

    Science.gov (United States)

    Schaller, M.; Hoffmann, K. H.; Rivero, R.; Andresen, B.; Salamon, P.

    2002-09-01

    A distillation column with the possibility of heat exchange on every tray (a fully diabatic column) is optimized in the sense of minimizing its total entropy production. This entropy production counts the interior losses due to heat and mass flow as well as the entropy generated in the heat exchangers. It is observed that the optimal heating distribution, i.e. the heat exchange required on each tray, is essentially the same for all trays in the stripping and rectification sections, respectively. This makes a column design with consecutive interior heat exchanger and only one exterior supply for each of the two sections very appealing. The result is only slightly dependent on the heat transfer law considered. In the limit of an infinite number of trays even this column with resistance to transfer of heat becomes reversible.

  9. Generation of surface-wave microwave microplasmas in hollow-core photonic crystal fiber based on a split-ring resonator.

    Science.gov (United States)

    Vial, Florian; Gadonna, Katell; Debord, Benoît; Delahaye, Frédéric; Amrani, Foued; Leroy, Olivier; Gérôme, Frédéric; Benabid, Fetah

    2016-05-15

    We report on a new and highly compact scheme for the generation and sustainment of microwave-driven plasmas inside the core of an inhibited coupling Kagome hollow-core photonic crystal fiber. The microwave plasma generator consists of a split-ring resonator that efficiently couples the microwave field into the gas-filled fiber. This coupling induces the concomitant generation of a microwave surface wave at the fiber core surround and a stable plasma column confined in the fiber core. The scheme allowed the generation of several centimeters long argon microplasma columns with a very low excitation power threshold. This result represents an important step toward highly compact plasma lasers or plasma-based photonic components.

  10. Housing shortages in urban regions: aggressive interactions at tree hollows in forest remnants.

    Directory of Open Access Journals (Sweden)

    Adrian Davis

    Full Text Available Urbanisation typically results in a reduction of hollow-bearing trees and an increase in the density of particularly species, potentially resulting in an increased level of competition as cavity-nesting species compete for a limited resource. To improve understanding of hollow usage between urban cavity-nesting species in Australia, particularly parrots, we investigated how the hollow-using assemblage, visitation rate, diversity and number of interactions varied between hollows within urban remnant forest and continuous forest. Motion-activated video cameras were installed, via roped access to the canopy, and hollow usage was monitored at 61 hollows over a two-year period. Tree hollows within urban remnants had a significantly different assemblage of visitors to those in continuous forest as well as a higher rate of visitation than hollows within continuous forest, with the rainbow lorikeet making significantly more visitations than any other taxa. Hollows within urban remnants were characterised by significantly higher usage rates and significantly more aggressive interactions than hollows within continuous forest, with parrots responsible for almost all interactions. Within urban remnants, high rates of hollow visitation and both interspecific and intraspecific interactions observed at tree hollows suggest the number of available optimal hollows may be limiting. Understanding the usage of urban remnant hollows by wildlife, as well as the role of parrots as a potential flagship for the conservation of tree-hollows, is vital to prevent a decrease in the diversity of urban fauna, particularly as other less competitive species risk being outcompeted by abundant native species.

  11. Collapse of tall granular columns in fluid

    Science.gov (United States)

    Kumar, Krishna; Soga, Kenichi; Delenne, Jean-Yves

    2017-06-01

    Avalanches, landslides, and debris flows are geophysical hazards, which involve rapid mass movement of granular solids, water, and air as a multi-phase system. In order to describe the mechanism of immersed granular flows, it is important to consider both the dynamics of the solid phase and the role of the ambient fluid. In the present study, the collapse of a granular column in fluid is studied using 2D LBM - DEM. The flow kinematics are compared with the dry and buoyant granular collapse to understand the influence of hydrodynamic forces and lubrication on the run-out. In the case of tall columns, the amount of material destabilised above the failure plane is larger than that of short columns. Therefore, the surface area of the mobilised mass that interacts with the surrounding fluid in tall columns is significantly higher than the short columns. This increase in the area of soil - fluid interaction results in an increase in the formation of turbulent vortices thereby altering the deposit morphology. It is observed that the vortices result in the formation of heaps that significantly affects the distribution of mass in the flow. In order to understand the behaviour of tall columns, the run-out behaviour of a dense granular column with an initial aspect ratio of 6 is studied. The collapse behaviour is analysed for different slope angles: 0°, 2.5°, 5° and 7.5°.

  12. Applicability analysis of hexahedral hollow profiles as component elements of supporting systems for gondola cars

    Directory of Open Access Journals (Sweden)

    O. V. Fomin

    2014-12-01

    Full Text Available Purpose. The purpose of work is presentation of features and results of the conducted works on determination of introduction expedience of hexahedral hollow profiles as the component elements of the modern supporting systems of railway freight gondola cars. Methodology. During the research an introduction methodology of different types of profiles as alternative to the existent supporting elements of the body module for freight car was used. This methodology had been developed by the author before. It is oriented to the reduction in material consumption and providing of strength requirements and operating reliability of the car design under study. The developed methodology includes the procedures of admissible values calculation of the resistance moments of the section of the hexahedral hollow profile, which is being introduced. It also includes the determination of optimum (i.e. characterized by the minimum material consumption when meeting the durability requirements values of height and minimum thickness of profile in the conditions of construction limitations. At the same time the admissible resistance moments are calculated as such, which are equal to the value of existent implementation of supporting element or as such that are determined taking into account the surplus design reserve. The first direction is applied in this work. Findings. As a result of the conducted research the introduction expedience of hexahedral hollow profiles as vertical rods of the lateral and latitude belts of the walls of the butt-end freight gondola cars is grounded and the optimum parameters of such replacements are determined. Originality. The problem of the use expedience of hexahedral hollow profiles as the supporting elements of the freight gondola cars bodies was first considered in the article. To solve this problem the mathematical models describing the dependence of basic strength and mass indexes of the proper profiles on varying the geometrical

  13. Experimental and Numerical Investigation of the Effect of Process Conditions on Residual Wall Thickness and Cooling and Surface Characteristics of Water-Assisted Injection Molded Hollow Products

    Directory of Open Access Journals (Sweden)

    Hyungpil Park

    2015-01-01

    Full Text Available Recently, water-assisted injection molding was employed in the automobile industry to manufacture three-dimensional hollow tube-type products with functionalities. However, process optimization is difficult in the case of water-assisted injection molding because of the various rheological interactions between the injected water and the polymer. In this study, the boiling phenomenon that occurs because of the high melt temperature when injecting water and the molding characteristics of the hollow section during the water-assisted injection process were analyzed by a water-assisted injection molding analysis. In addition, the changes in the residual wall thickness accompanying changes in the process conditions were compared with the analysis results by considering water-assisted injection molding based on gas-assisted injection molding. Furthermore, by comparing the cooling characteristics and inner wall surface qualities corresponding to the formation of the hollow section by gas and water injections, a water-assisted injection molding technique was proposed for manufacturing hollow products with functionality.

  14. Single column locking plate fixation is inadequate in two column acetabular fractures. A biomechanical analysis

    Directory of Open Access Journals (Sweden)

    Bellino Michael J

    2010-05-01

    Full Text Available Abstract Background The objective of this study was to determine whether one can achieve stable fixation of a two column (transverse acetabular fracture by only fixing a single column with a locking plate and unicortical locking screws. We hypothesized that a locking plate applied to the anterior column of a transverse acetabular fracture would create a construct that is more rigid than a non-locking plate, and that this construct would be biomechanically comparable to two column fixation. Methods Using urethane foam models of the pelvis, we simulated transverse acetabular fractures and stabilized them with 1 an anterior column plate with bicortical screws, 2 an anterior locking plate with unicortical screws, 3 an anterior plate and posterior column lag screw, and 4 a posterior plate with an anterior column lag screw. These constructs were mechanically loaded on a servohydraulic material testing machine. Construct stiffness and fracture displacement were measured. Result and Discussion We found that two column fixation is 54% stiffer than a single column fixation with a conventional plate with bicortical screws. There was no significant difference between fixation with an anterior column locking plate with unicortical screws and an anterior plate with posterior column lag screw. We detected a non-significant trend towards more stiffness for the anterior locking plate compared to the anterior non-locking plate. Conclusion In conclusion, a locking plate construct of the anterior column provides less stability than a traditional both column construct with posterior plate and anterior column lag screw. However, the locking construct offers greater strength than a non-locking, bicortical construct, which in addition often requires extensive contouring and its application is oftentimes accompanied by the risk of neurovascular damage.

  15. Dynamic effects of diabatization in distillation columns

    DEFF Research Database (Denmark)

    Bisgaard, Thomas; Huusom, Jakob Kjøbsted; Abildskov, Jens

    2013-01-01

    The dynamic effects of diabatization in distillation columns are investigated in simulation emphasizing the heat-integrated distillation column (HIDiC). A generic, dynamic, first-principle model has been formulated, which is flexible enough to describe various diabatic distillation configurations....... Dynamic Relative Gain Array and Singular Value Analysis have been applied in a comparative study of a conventional distillation column and a HIDiC. The study showed increased input-output coupling due to diabatization. Feasible SISO control structures for the HIDiC were also found and control...

  16. optimizing compression zone of flanged hollow cored concrete ...

    African Journals Online (AJOL)

    eobe

    effective flange width and the hollow core position in the compression zone of a plain concrete beam with a point ... rectangular concrete beam to the topmost fiber could ... concrete. The results obtained by finite element solution showed good agreement with experimental results. In an investigation of thirty-nine reinforced.

  17. Highly permeable and mechanically robust silicon carbide hollow fiber membranes

    NARCIS (Netherlands)

    de Wit, Patrick; Kappert, Emiel; Lohaus, T.; Wessling, Matthias; Nijmeijer, Arian; Benes, Nieck Edwin

    2015-01-01

    Silicon carbide (SiC) membranes have shown large potential for applications in water treatment. Being able to make these membranes in a hollow fiber geometry allows for higher surface-to-volume ratios. In this study, we present a thermal treatment procedure that is tuned to produce porous silicon

  18. Morphology conserving aminopropyl functionalization of hollow silica nanospheres in toluene

    Science.gov (United States)

    Dobó, Dorina G.; Berkesi, Dániel; Kukovecz, Ákos

    2017-07-01

    Inorganic nanostructures containing cavities of monodisperse diameter distribution find applications in e.g. catalysis, adsorption and drug delivery. One of their possible synthesis routes is the template assisted core-shell synthesis. We synthesized hollow silica spheres around polystyrene cores by the sol-gel method. The polystyrene template was removed by heat treatment leaving behind a hollow spherical shell structure. The surface of the spheres was then modified by adding aminopropyl groups. Here we present the first experimental evidence that toluene is a suitable alternative functionalization medium for the resulting thin shells, and report the comprehensive characterization of the amino-functionalized hollow silica spheres based on scanning electron microscopy, transmission electron microscopy, N2 adsorption, FT-IR spectroscopy, Raman spectroscopy and electrokinetic potential measurement. Both the presence of the amino groups and the preservation of the hollow spherical morphology were unambiguously proven. The introduction of the amine functionality adds amphoteric character to the shell as shown by the zeta potential vs. pH function. Unlike pristine silica particles, amino-functionalized nanosphere aqueous sols can be stable at both acidic and basic conditions.

  19. Formation and Stability of Hollow MgO Nanoshells

    NARCIS (Netherlands)

    Krishnan, G.; Palasantzas, G.; Kooi, B.J.

    High temperature annealing of gas phase synthesized Mg nanoparticles surrounded by an MgO shell leads to formation of hollow MgO nanoshells due to the evaporation assisted Kirkendall effect. Under electron beam exposure in TEM, the (220) MgO facets reduce their high surface energy by forming cube

  20. Facile synthesis of ZnO hollow fibres

    Indian Academy of Sciences (India)

    WINTEC

    Abstract. In this paper, cotton fibres were used as bio-template to successfully synthesize new ceramic mate- rials, ZnO hollow fibres and in an effort to explore the synthesis condition, and simplify the synthesis procedure. In this synthesis, a direct thermal decomposition of zinc acetate dihydrate coated on the surface of ...

  1. Characterization of silane coated hollow sphere alumina-reinforced ...

    Indian Academy of Sciences (India)

    Silane coated hollow sphere alumina ceramic particles were moulded with ultra high molecular weight polyethylene (UHMWPE) to form a series of composites with alumina weight percent in the range from 15 to 50. The composites were prepared in a cylindrical mould using powder-processing technique. The composites ...

  2. Hollow cathode heater development for the Space Station plasma contactor

    Science.gov (United States)

    Soulas, George C.

    1993-01-01

    A hollow cathode-based plasma contactor has been selected for use on the Space Station. During the operation of the plasma contactor, the hollow cathode heater will endure approximately 12000 thermal cycles. Since a hollow cathode heater failure would result in a plasma contactor failure, a hollow cathode heater development program was established to produce a reliable heater design. The development program includes the heater design, process documents for both heater fabrication and assembly, and heater testing. The heater design was a modification of a sheathed ion thruster cathode heater. Three heaters have been tested to date using direct current power supplies. Performance testing was conducted to determine input current and power requirements for achieving activation and ignition temperatures, single unit operational repeatability, and unit-to-unit operational repeatability. Comparisons of performance testing data at the ignition input current level for the three heaters show the unit-to-unit repeatability of input power and tube temperature near the cathode tip to be within 3.5 W and 44 degrees C, respectively. Cyclic testing was then conducted to evaluate reliability under thermal cycling. The first heater, although damaged during assembly, completed 5985 ignition cycles before failing. Two additional heaters were subsequently fabricated and have completed 3178 cycles to date in an on-going test.

  3. EM-wave absorption properties of hollow spiral iron particles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenqiang, E-mail: zwqcau@gmail.com [College of Engineering, China Agricultural University, Beijing 100083 (China); Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China); Zhang, Deyuan [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China)

    2015-12-15

    Hollow iron spiral particles were fabricated successfully by thermal decomposition method, and they were heat-treated at different temperatures in N{sub 2} atmosphere. The electromagnetic wave absorption properties of hollow iron spiral particles were investigated ranging between 1 GHz and 18 GHz. The results indicated that the phase structures of the particles changed from amorphous to nanocrystal with the treating temperature rising, also causing the significant change in electromagnetic parameters and the reflection loss. The reflection loss could reach −33 dB at 16.2 GHz, indicating that the hollow iron spiral particles had the potential to be used in prepare the a high property EM-wave absorber. - Highlights: • Hollow iron spiral particles were fabricated by thermal decomposition method. • The particles changed from amorphous to nanocrystals with heat-treatment. • Particles’ EM-parameters have a great change after high temperature heat-treatment. • RL results show the particles have potential to be high property EM-wave absorber.

  4. Synthesis of Porous Inorganic Hollow Fibers without Harmful Solvents

    NARCIS (Netherlands)

    Shukla, Sushumna; de Wit, Patrick; Luiten-Olieman, Maria W.J.; Kappert, Emiel; Nijmeijer, Arian; Benes, Nieck Edwin

    2015-01-01

    A route for the fabrication of porous inorganic hollow fibers with high surface-area-to-volume ratio that avoids harmful solvents is presented. The approach is based on bio-ionic gelation of an aqueous mixture of inorganic particles and sodium alginate during wet spinning. In a subsequent thermal

  5. Fabrication of polystyrene hollow microspheres as laser fusion ...

    Indian Academy of Sciences (India)

    Centre for Advanced Technology (CAT), Indore 452 013, India. MS received 26 June 2001; revised 7 December 2001. Abstract. Inertial confinement fusion, frequently referred to as ICF, inertial fusion, or laser fu- sion, is a means of producing energy by imploding small hollow microspheres containing thermo- nuclear fusion ...

  6. Fabrication of polystyrene hollow microspheres as laser fusion ...

    Indian Academy of Sciences (India)

    Inertial confinement fusion, frequently referred to as ICF, inertial fusion, or laser fusion, is a means of producing energy by imploding small hollow microspheres containing thermonuclear fusion fuel. Polymer microspheres, which are used as fuel containers, can be produced by solution-based micro-encapsulation technique ...

  7. Silicon micromachined hollow microneedles for transdermal liquid transfer

    NARCIS (Netherlands)

    Gardeniers, Johannes G.E.; Berenschot, Johan W.; de Boer, Meint J.; Yeshurun, Y.; Hefetz, M.; van 't Oever, R.; van den Berg, Albert

    2002-01-01

    This paper presents an improved design and fabrication process [ 13 for hollow micro needles with the proper mechanical strength and sharpness to be applied for painless transdermal transfer of liquids. Tests have shown that liquids like blood are drawn into the needle by capillary forces, reducing

  8. Ferroelectric hollow particles obtained by solid-state reaction

    Energy Technology Data Exchange (ETDEWEB)

    Buscaglia, Maria Teresa; Buscaglia, Vincenzo; Viviani, Massimo; Nanni, Paolo [Institute of Energetics and Interphases, National Research Council, Via De Marini 6, I-16149 Genoa (Italy); Dondero, Giovanni [Institute for Macromolecular Studies, National Research Council, Via De Marini 6, I-16149 Genoa (Italy); Roehrig, Serge; Ruediger, Andreas [Institute of Solid State Research, Centre of Nanoelectronic Systems for Information Technology, Research Centre Juelich, 52425 Juelich (Germany)], E-mail: v.buscaglia@ge.ieni.cnr.it

    2008-06-04

    Hollow particles of barium titanate were obtained by a two-step process combining colloidal chemistry and solid-state reaction. BaCO{sub 3} crystals (size {approx}1 {mu}m) suspended in a peroxy-Ti(IV) aqueous solution were coated with an amorphous TiO{sub 2} shell using a precipitation process. Calcination of the BaCO{sub 3}-TiO{sub 2} core-shell particles at 700 deg. C resulted in the formation of BaTiO{sub 3} hollow particles (shell thickness of {approx}70 nm) which retain the morphology of the BaCO{sub 3} crystals. Formation of the cavity occurs because out-diffusion of the core phase is much faster than in-diffusion of the shell material. X-ray diffraction (XRD) and Raman spectroscopy indicate that the hollow particles possess a tetragonal ferroelectric structure with axial ratio c/a = 1.005. Piezoresponse force microscopy has shown strong piezoactivity and 180 deg. ferroelectric domains. The process described provides a general route to fabricate hollow ferroelectric structures of several compounds.

  9. Ferroelectric hollow particles obtained by solid-state reaction.

    Science.gov (United States)

    Buscaglia, Maria Teresa; Buscaglia, Vincenzo; Viviani, Massimo; Dondero, Giovanni; Röhrig, Serge; Rüdiger, Andreas; Nanni, Paolo

    2008-06-04

    Hollow particles of barium titanate were obtained by a two-step process combining colloidal chemistry and solid-state reaction. BaCO(3) crystals (size ≈1 µm) suspended in a peroxy-Ti(IV) aqueous solution were coated with an amorphous TiO(2) shell using a precipitation process. Calcination of the BaCO(3)@TiO(2) core-shell particles at 700 °C resulted in the formation of BaTiO(3) hollow particles (shell thickness of ≈70 nm) which retain the morphology of the BaCO(3) crystals. Formation of the cavity occurs because out-diffusion of the core phase is much faster than in-diffusion of the shell material. X-ray diffraction (XRD) and Raman spectroscopy indicate that the hollow particles possess a tetragonal ferroelectric structure with axial ratio c/a = 1.005. Piezoresponse force microscopy has shown strong piezoactivity and 180° ferroelectric domains. The process described provides a general route to fabricate hollow ferroelectric structures of several compounds.

  10. Lanthanide-doped hollow nanomaterials as theranostic agents.

    Science.gov (United States)

    Kang, Xiaojiao; Li, Chunxia; Cheng, Ziyong; Ma, Ping'an; Hou, Zhiyao; Lin, Jun

    2014-01-01

    The field of theranostics has sprung up to achieve personalized medicine. The theranostics fuses diagnostic and therapeutic functions, empowering early diagnosis, targeted drug delivery, and real-time monitoring of treatment effect into one step. One particularly attractive class of nanomaterials for theranostic application is lanthanide-doped hollow nanomaterials (LDHNs). Because of the existence of lanthanide ions, LDHNs show outstanding fluorescent and paramagnetic properties, enabling them to be used as multimodal bioimaging agents. Synchronously, the huge interior cavities of LDHNs are able to be applied as efficacious tools for storage and delivery of therapeutic agents. The LDHNs can be divided into two types based on difference of component: single-phase lanthanide-doped hollow nanomaterials and lanthanide-doped hollow nanocomposites. We describe the synthesis of first kind of nanomaterials by use of hard template, soft template, template-free, and self-sacrificing template method. For lanthanide-doped hollow nanocomposites, we divide the preparation strategies into three kinds (one-step, two-step, and multistep method) according to the synthetic procedures. Furthermore, we also illustrate the potential bioapplications of these LDHNs, including biodetection, imaging (fluorescent imaging and magnetic resonance imaging), drug/gene delivery, and other therapeutic applications. © 2013 Wiley Periodicals, Inc.

  11. Hollow-core photonic band gap fibers for particle acceleration

    Directory of Open Access Journals (Sweden)

    Robert J. Noble

    2011-12-01

    Full Text Available Photonic band gap (PBG dielectric fibers with hollow cores are being studied both theoretically and experimentally for use as laser driven accelerator structures. The hollow core functions as both a longitudinal waveguide for the transverse-magnetic (TM accelerating fields and a channel for the charged particles. The dielectric surrounding the core is permeated by a periodic array of smaller holes to confine the mode, forming a photonic crystal fiber in which modes exist in frequency passbands, separated by band gaps. The hollow core acts as a defect which breaks the crystal symmetry, and so-called defect, or trapped modes having frequencies in the band gap will only propagate near the defect. We describe the design of 2D hollow-core PBG fibers to support TM defect modes with high longitudinal fields and high characteristic impedance. Using as-built dimensions of industrially made fibers, we perform a simulation analysis of prototype PBG fibers with dimensions appropriate for speed-of-light TM modes.

  12. Shear and anchorage behaviour of fire exposed hollow core slabs

    NARCIS (Netherlands)

    Fellinger, J.

    2005-01-01

    The fire resistance of hollow core slabs is currently assessed considering flexural failure only. However, fire tests show that shear or anchorage failure can also govern the load bearing behaviour. This paper is based on the dissertation by the author1 and discusses existing and new fire tests. It

  13. Investigation of torsional vibrations in thick walled hollow poroelastic ...

    Indian Academy of Sciences (India)

    Abstract. This paper deals with the study of torsional vibrations of thick walled hollow poroelastic cylinder using Biot's extension theory. Considering the boundaries to be stress free, the frequency equation is obtained in the presence of dissipation which is transcendental and complex valued in nature. In the special case of ...

  14. Investigation of torsional vibrations in thick walled hollow poroelastic ...

    Indian Academy of Sciences (India)

    This paper deals with the study of torsional vibrations of thick walled hollow poroelastic cylinder using Biot's extension theory. Considering the boundaries to be stress free, the frequency equation is obtained in the presence of dissipation which is transcendental and complex valued in nature. In the special case of ...

  15. The Kirkendall effect and nanoscience: hollow nanospheres and nanotubes

    Directory of Open Access Journals (Sweden)

    Abdel-Aziz El Mel

    2015-06-01

    Full Text Available Hollow nanostructures are ranked among the top materials for applications in various modern technological areas including energy storage devices, catalyst, optics and sensors. The last years have witnessed increasing interest in the Kirkendall effect as a versatile route to fabricate hollow nanostructures with different shapes, compositions and functionalities. Although the conversion chemistry of nanostructures from solid to hollow has reached a very advanced maturity, there is still much to be discovered and learned on this effect. Here, the recent progress on the use of the Kirkendall effect to synthesize hollow nanospheres and nanotubes is reviewed with a special emphasis on the fundamental mechanisms occurring during such a conversion process. The discussion includes the oxidation of metal nanostructures (i.e., nanospheres and nanowires, which is an important process involving the Kirkendall effect. For nanospheres, the symmetrical and the asymmetrical mechanisms are both reviewed and compared on the basis of recent reports in the literature. For nanotubes, in addition to a summary of the conversion processes, the unusual effects observed in some particular cases (e.g., formation of segmented or bamboo-like nanotubes are summarized and discussed. Finally, we conclude with a summary, where the prospective future direction of this research field is discussed.

  16. DLVO interaction energies between hollow spherical particles and collector surfaces

    Science.gov (United States)

    The surface element integration technique was used to systematically study Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energies/forces between hollow spherical particles (HPs) and a planar surface or two intercepting half planes under different ionic strength conditions. The inner and outer ...

  17. A microring multimode laser using hollow polymer optical fibre

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 75; Issue 5. A microring ... Keywords. Dye-doped optical fibre; fibre laser; microcavity; whispering gallery mode. ... Cylindrical microcavities with diameters 155, 340 and 615 m were fabricated from a dye-doped hollow polymer optical fibre preform. An average mode ...

  18. Modeling of equilibrium hollow objects stabilized by electrostatics

    NARCIS (Netherlands)

    Mani, E.; Groenewold, J.|info:eu-repo/dai/nl/161973590; Kegel, W.K.|info:eu-repo/dai/nl/113729464

    2011-01-01

    The equilibrium size of two largely different kinds of hollow objects behave qualitatively differently with respect to certain experimental conditions. Yet, we show that they can be described within the same theoretical framework. The objects we consider are ‘minivesicles’ of ionic and nonionic

  19. Hollow core photonic crystal fiber based viscometer with Raman spectroscopy.

    Science.gov (United States)

    Horan, L E; Ruth, A A; Gunning, F C Garcia

    2012-12-14

    The velocity of a liquid flowing through the core of a hollow core photonic crystal fiber (driven by capillary forces) is used for the determination of a liquid's viscosity, using volumes of less than 10 nl. The simple optical technique used is based on the change in propagation characteristics of the fiber as it fills with the liquid of interest via capillary action, monitored by a laser source. Furthermore, the liquid filled hollow core photonic crystal fiber is then used as a vessel to collect Raman scattering from the sample to determine the molecular fingerprint of the liquid under study. This approach has a wide variety of indicative uses in cases where nano-liter samples are necessary. We use 10-12 cm lengths of hollow core photonic crystal fibers to determine the viscosity and Raman spectra of small volumes of two types of monosaccharides diluted in a phosphate buffer solution to demonstrate the principle. The observed Raman signal is strongest when only the core of the hollow core photonic crystal fiber is filled, and gradually decays as the rest of the fiber fills with the sample.

  20. Hollow Nanospheres Array Fabrication via Nano-Conglutination Technology.

    Science.gov (United States)

    Zhang, Man; Deng, Qiling; Xia, Liangping; Shi, Lifang; Cao, Axiu; Pang, Hui; Hu, Song

    2015-09-01

    Hollow nanospheres array is a special nanostructure with great applications in photonics, electronics and biochemistry. The nanofabrication technique with high resolution is crucial to nanosciences and nano-technology. This paper presents a novel nonconventional nano-conglutination technology combining polystyrenes spheres (PSs) self-assembly, conglutination and a lift-off process to fabricate the hollow nanospheres array with nanoholes. A self-assembly monolayer of PSs was stuck off from the quartz wafer by the thiol-ene adhesive material, and then the PSs was removed via a lift-off process and the hollow nanospheres embedded into the thiol-ene substrate was obtained. Thiolene polymer is a UV-curable material via "click chemistry" reaction at ambient conditions without the oxygen inhibition, which has excellent chemical and physical properties to be attractive as the adhesive material in nano-conglutination technology. Using the technique, a hollow nanospheres array with the nanoholes at the diameter of 200 nm embedded into the rigid thiol-ene substrate was fabricated, which has great potential to serve as a reaction container, catalyst and surface enhanced Raman scattering substrate.

  1. Development of Optimized Strength Model of Lateritic Hollow Block ...

    African Journals Online (AJOL)

    The work is an investigation to develop and optimize a model of the compressive strength of lateritic hollow sandcrete block with mound soil inclusion. The study applies the Scheffe's optimization approach to obtain a mathematical model of the form f(xi1,xi2,xi3,,xi4), where xi are proportions of the concrete components, viz: ...

  2. An Experiment in Heat Conduction Using Hollow Cylinders

    Science.gov (United States)

    Ortuno, M.; Marquez, A.; Gallego, S.; Neipp, C.; Belendez, A.

    2011-01-01

    An experimental apparatus was designed and built to allow students to carry out heat conduction experiments in hollow cylinders made of different materials, as well as to determine the thermal conductivity of these materials. The evolution of the temperature difference between the inner and outer walls of the cylinder as a function of time is…

  3. Silicon micromachined hollow microneedles for transdermal liquid transport

    NARCIS (Netherlands)

    Gardeniers, Johannes G.E.; Lüttge, Regina; Berenschot, Johan W.; de Boer, Meint J.; Yeshurun, Shuki Y.; Hefetz, Meir; van 't Oever, Ronny; van den Berg, Albert

    2003-01-01

    This paper presents a novel process for the fabrication of out-of-plane hollow microneedles in silicon. The fabrication method consists of a sequence of deep-reactive ion etching (DRIE), anisotropic wet etching and conformal thin film deposition, and allows needle shapes with different,

  4. Compressive Strength of Hollow Sandcrete Blocks Made with Rice ...

    African Journals Online (AJOL)

    Waste such as rice husk, which is seen polluting the environment are collected and burnt at 600̊C to produce rice husk ash (RHA), which in turn was used as pozzolana in sandcrete block production. Hollow sandcrete blocks were produced at 0, 10, 20, 30, 40 and 50 percent ash to cement replacement. A total of 120 ...

  5. Few photon switching with slow light in hollow fiber

    DEFF Research Database (Denmark)

    Bajcsy, Michal; Hofferberth, S.; Balic, Vlatko

    2009-01-01

    Cold atoms confined inside a hollow-core photonic-crystal fiber with core diameters of a few photon wavelengths are a promising medium for studying nonlinear optical interactions at extremely low light levels. The high electric field intensity per photon and interaction lengths not limited by dif...

  6. Pinhole Viewing Strengthens the Hollow-Face Illusion.

    Science.gov (United States)

    Koessler, Trent; Hill, Harold

    2015-08-01

    A hollow (concave) mask appears convex when viewed from beyond a certain distance even when viewed stereoscopically-this is the hollow-face illusion. At close viewing distances, the same mask is seen as hollow even when disparity information is eliminated by monocular viewing. A potential source of nonpictorial, monocular information that favors a veridical percept at close distances is accommodation in conjunction with focus blur. In this article, we used pinhole viewing to minimize this potential source of information and test whether it affects whether a hollow mask is seen as veridical (concave) or illusory (convex). Since monocular viewing also facilitates the illusory (convex) percept, it was included in the design both as a comparison and to test whether any effect of accommodation depends on vergence. Pinhole viewing was found favor the illusory percept, and its effect was at least as large as, and added to, that of monocular viewing. A control experiment using tinted glasses that attenuate illumination at least as much as the pinholes did not strengthen the illusion ruling out explanations in terms of reduced luminance. For pinhole viewing, there was no difference between monocular and binocular conditions. The results are interpreted as evidence that focus driven depth information affects perceived three-dimensional shape at close distances even when other sources of depth information are available. The lack of a difference between monocular and binocular pinhole viewing suggests that, by disrupting accommodation, pinholes may also interfere with linked vergence cues to depth.

  7. Pinhole Viewing Strengthens the Hollow-Face Illusion

    Directory of Open Access Journals (Sweden)

    Trent Koessler

    2015-08-01

    Full Text Available A hollow (concave mask appears convex when viewed from beyond a certain distance even when viewed stereoscopically—this is the hollow-face illusion. At close viewing distances, the same mask is seen as hollow even when disparity information is eliminated by monocular viewing. A potential source of nonpictorial, monocular information that favors a veridical percept at close distances is accommodation in conjunction with focus blur. In this article, we used pinhole viewing to minimize this potential source of information and test whether it affects whether a hollow mask is seen as veridical (concave or illusory (convex. Since monocular viewing also facilitates the illusory (convex percept, it was included in the design both as a comparison and to test whether any effect of accommodation depends on vergence. Pinhole viewing was found favor the illusory percept, and its effect was at least as large as, and added to, that of monocular viewing. A control experiment using tinted glasses that attenuate illumination at least as much as the pinholes did not strengthen the illusion ruling out explanations in terms of reduced luminance. For pinhole viewing, there was no difference between monocular and binocular conditions. The results are interpreted as evidence that focus driven depth information affects perceived three-dimensional shape at close distances even when other sources of depth information are available. The lack of a difference between monocular and binocular pinhole viewing suggests that, by disrupting accommodation, pinholes may also interfere with linked vergence cues to depth.

  8. Spinning of hollow fiber ultrafiltration membranes from a polymer blend

    NARCIS (Netherlands)

    Wienk, I.M.; Wienk, I.M.; Olde scholtenhuis, F.H.A.; van den Boomgaard, Anthonie; Smolders, C.A.; Smolders, C.A.

    1995-01-01

    In this study the dry-wet spinning technique is used for the preparation of hollow fiber membranes. In the polymer solution a blend of two polymers, poly(ether sulfone) and poly(vinyl pyrrolidone), is used. The morphology of the membranes obtained is related to rheological characteristics and phase

  9. Hollow-Core Photonic Band Gap Fibers for Particle Acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Noble, Robert J.; Spencer, James E.; /SLAC; Kuhlmey, Boris T.; /Sydney U.

    2011-08-19

    Photonic band gap (PBG) dielectric fibers with hollow cores are being studied both theoretically and experimentally for use as laser driven accelerator structures. The hollow core functions as both a longitudinal waveguide for the transverse-magnetic (TM) accelerating fields and a channel for the charged particles. The dielectric surrounding the core is permeated by a periodic array of smaller holes to confine the mode, forming a photonic crystal fiber in which modes exist in frequency pass-bands, separated by band gaps. The hollow core acts as a defect which breaks the crystal symmetry, and so-called defect, or trapped modes having frequencies in the band gap will only propagate near the defect. We describe the design of 2-D hollow-core PBG fibers to support TM defect modes with high longitudinal fields and high characteristic impedance. Using as-built dimensions of industrially-made fibers, we perform a simulation analysis of the first prototype PBG fibers specifically designed to support speed-of-light TM modes.

  10. Hollow Anode Cascading Plasma Focus | Alabraba | Journal of the ...

    African Journals Online (AJOL)

    Journal of the Nigerian Association of Mathematical Physics ... Using the 3-phase model for each focus event, the 9-phase, two solid disc auxiliary anode cascading plasma focus has been extended to include holes at the center of each cascade anode (hereafter referred to as hollow anode cascading focus) with a view of ...

  11. Formation of hollow atoms at metal- and insulator surfaces

    NARCIS (Netherlands)

    Morgenstern, R; Khemliche, H; Hoekstra, R

    1998-01-01

    The interaction of multiply charged ions with various surfaces gives rise to the formation of so-called hollow atoms via multiple electron capture into excited orbitals. The potential energy of the ions is partly converted into photons and kinetic energy of emitted electrons during subsequent decay

  12. Synthesis and simulation of efficient divided wall column sequences for bioethanol recovery and purification from an actual lignocellulosic fermentation broth

    DEFF Research Database (Denmark)

    Torres-Ortega, Carlo Edgar; Rong, Ben-Guang

    2016-01-01

    of column sections as novel synthesis approaches to formulate hybrid units and divided wall columns. Rigorous simulation in Aspen Plus V8.0 was used to simulate the intensified separation systems. The new intensified alternatives achieved relevant savings, ranging from 17 to 23% in TAC (total annual costs...

  13. Fabrication process for tall, sharp, hollow, high aspect ratio polymer microneedles on a platform

    Science.gov (United States)

    Ceyssens, Frederik; Chaudhri, Buddhadev Paul; Van Hoof, Chris; Puers, Robert

    2013-07-01

    This paper reports on a new lithographic process for fabricating arrays of tall, high aspect ratio (defined as height/wall thickness), hollow, polymer microneedles on a platform. The microneedles feature a high sharpness (down to 3 µm tip radius) and aspect ratio (>65) which is a factor 2 and 4 better than the state of the art, respectively. The maximum achievable needle shaft length is over 1 mm. The improved performance was obtained by using an anisotropically patterned silicon substrate covered with an antireflective layer as mold for the needle tip and an optimized SU-8 lithographic process. Furthermore, a platform containing liquid feedthroughs holding an arbitrary number of needles out of plane can be manufactured with only one additional process step. The high aspect ratio microneedles undergo failure at the critical load of around 230 mN in the case of 1 mm long hollow needles with triangular cross section and a base of 175 µm. Penetration into human skin is demonstrated as well.

  14. Microwave-Assisted Solvothermal Synthesis of VO2 Hollow Spheres and Their Conversion into V2O5 Hollow Spheres with Improved Lithium Storage Capability.

    Science.gov (United States)

    Pan, Jing; Zhong, Li; Li, Ming; Luo, Yuanyuan; Li, Guanghai

    2016-01-22

    Monodispersed hierarchically structured V2O5 hollow spheres were successfully obtained from orthorhombic VO2 hollow spheres, which are in turn synthesized by a simple template-free microwave-assisted solvothermal method. The structural evolution of VO2 hollow spheres has been studied and explained by a chemically induced self-transformation process. The reaction time and water content in the reaction solution have a great influence on the morphology and phase structure of the resulting products in the solvothermal reaction. The diameter of the VO2 hollow spheres can be regulated simply by changing vanadium ion content in the reaction solution. The VO2 hollow spheres can be transformed into V2O5 hollow spheres with nearly no morphological change by annealing in air. The nanorods composed of V2O5 hollow spheres have an average length of about 70 nm and width of about 19 nm. When used as a cathode material for lithium-ion batteries, the V2O5 hollow spheres display a diameter-dependent electrochemical performance, and the 440 nm hollow spheres show the highest specific discharge capacity of 377.5 mAhg(-1) at a current density of 50 mAg(-1) , and are better than the corresponding solid spheres and nanorod assemblies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Column-like structures following the course of tubules in human dentin.

    Science.gov (United States)

    Hals, E

    1990-10-01

    Sections, 60-180 microns thick, of permanent teeth, intact or with minor fillings, were cut parallel or transversal to the course of the dentinal tubules. Some teeth were demineralized, embedded in paraffin wax, cut in series, and stained with toluidine blue pH 5.6, hematoxylin-eosin, or PAS. Altogether, sections of 90 teeth were examined by ordinary and polarized light microscopy and contact microradiography. Alternating light and dark bands, usually 8-30 microns wide, extended from the pulpal border along the course of the tubules, gradually increasing in width, fading in the mantle dentin. Cross-sectioned bands appeared as dark and light "discs". This was the background for the term "columns". In the dark columns, usually exhibiting crowding of tubules, the intertubular dentin was dark and radiolucent; in the light columns, light and radiopaque. Dark columns contained a high amount of GAGs, assumed to have exerted an inhibitory effect on their mineralization. The columns probably represent structural elements in the architecture of dentin, possibly offering resistance against mechanical stress. It was suggested that the columns might depict functional differences in the matrix secretion and mineralization capacities of odontoblasts.

  16. Hollow fiber apparatus and use thereof for fluids separations and heat and mass transfers

    Science.gov (United States)

    Bikson, Benjamin; Etter, Stephen; Ching, Nathaniel

    2014-06-10

    A hollow fiber device includes a hollow fiber bundle, comprising a plurality of hollow fibers, a first tubesheet and a second tubesheet encapsulating respective distal ends of the hollow fiber bundle. The tubesheets have boreholes in fluid communication with bores of the hollow fibers. In at least one of the tubesheets, the boreholes are formed radially. The hollow fiber device can be utilized in heat exchange, in gas/gas, liquid/liquid and gas/liquid heat transfer, in combined heat and mass transfer and in fluid separation assemblies and processes. The design disclosed herein is light weight and compact and is particularly advantageous when the pressure of a first fluid introduced into the bores of hollow fibers is higher than the pressure on the shell side of the device.

  17. Hollow fiber apparatus and use thereof for fluids separations and heat and mass transfers

    Science.gov (United States)

    Bikson, Benjamin; Etter, Stephen; Ching, Nathaniel

    2017-04-18

    A hollow fiber fluid separation device includes a hollow fiber cartridge, comprising a plurality of hollow fiber membranes arranged around a central tubular core, a first tubesheet and a second tubesheet encapsulating respective distal ends of the hollow fiber bundle. The tubesheets have boreholes in fluid communication with bores of the hollow fiber membrane. In at least one of the tubesheets, the boreholes are formed radially and are in communication with the central tubular core. The hollow fiber fluid separation device can be utilized in liquid separation applications such as ultrafiltration and in gas separation processes such as air separation. The design disclosed herein is light weight and compact and is particularly advantageous at high operating temperatures when the pressure of the feed fluid introduced into the bores of hollow fibers is higher than the pressure on the shell side of the device.

  18. Templated and template-free fabrication strategies for zero-dimensional hollow MOF superstructures.

    Science.gov (United States)

    Kim, Hyehyun; Lah, Myoung Soo

    2017-05-16

    Various fabrication strategies for hollow metal-organic framework (MOF) superstructures are reviewed and classified using various types of external templates and their properties. Hollow MOF superstructures have also been prepared without external templates, wherein unstable intermediates obtained during reactions convert to the final hollow MOF superstructures. Many hollow MOF superstructures have been fabricated using hard templates. After the core-shell core@MOF structure was prepared using a hard template, the core was selectively etched to generate a hollow MOF superstructure. Another approach for generating hollow superstructures is to use a solid reactant as a sacrificial template; this method requires no additional etching process. Soft templates such as discontinuous liquid/emulsion droplets and gas bubbles in a continuous soft phase have also been employed to prepare hollow MOF superstructures.

  19. Compact Rare Earth Emitter Hollow Cathode

    Science.gov (United States)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

    A compact, high-current, hollow cathode utilizing a lanthanum hexaboride (LaB6) thermionic electron emitter has been developed for use with high-power Hall thrusters and ion thrusters. LaB6 cathodes are being investigated due to their long life, high current capabilities, and less stringent xenon purity and handling requirements compared to conventional barium oxide (BaO) dispenser cathodes. The new cathode features a much smaller diameter than previously developed versions that permit it to be mounted on axis of a Hall thruster ( internally mounted ), as opposed to the conventional side-mount position external to the outer magnetic circuit ("externally mounted"). The cathode has also been reconfigured to be capable of surviving vibrational loads during launch and is designed to solve the significant heater and materials compatibility problems associated with the use of this emitter material. This has been accomplished in a compact design with the capability of high-emission current (10 to 60 A). The compact, high-current design has a keeper diameter that allows the cathode to be mounted on the centerline of a 6- kW Hall thruster, inside the iron core of the inner electromagnetic coil. Although designed for electric propulsion thrusters in spacecraft station- keeping, orbit transfer, and interplanetary applications, the LaB6 cathodes are applicable to the plasma processing industry in applications such as optical coatings and semiconductor processing where reactive gases are used. Where current electrical propulsion thrusters with BaO emitters have limited life and need extremely clean propellant feed systems at a significant cost, these LaB6 cathodes can run on the crudest-grade xenon propellant available without impact. Moreover, in a laboratory environment, LaB6 cathodes reduce testing costs because they do not require extended conditioning periods under hard vacuum. Alternative rare earth emitters, such as cerium hexaboride (CeB6) can be used in this

  20. Behaviour of wrapped cold-formed steel columns under different loading conditions

    Science.gov (United States)

    Baabu, B. Hari; Sreenath, S.

    2017-07-01

    The use of Cold Formed Steel (CFS) sections as structural members is widely accepted because of its light nature. However, the load carrying capacity of these sections will be less compared to hot rolled sections. This study is meant to analyze the possibility of strengthening cold formed members by wrapping it with Glass Fiber Reinforced Polymer (GFRP) laminates. Light gauge steel columns of cross sectional dimensions 100mm x 50mm x 3.15mm were taken for this study. The effective length of the section is about 750mm. A total of 8 specimens including the control specimen is tested under axial and eccentric loading. The columns were tested keeping both ends hinged. For both loading cases the buckling behaviour, ultimate load carrying capacity and load-deflection characteristics of the CFS columns were analyzed. The GFRP laminates were wrapped on columns in three different ways such that wrapping the outer surface of web and flange throughout the length of specimen, wrapping the outer surface of web alone throughout the length of specimen and wrapping the outer surface of web and flange for the upper half length of the specimen where the buckling is expected. For both loading cases, the results indicated that the column with wrapping at the outer surface of web and flange throughout the length of specimen provides better strength for it.

  1. The Sports Column on National Daily Newspapers

    Directory of Open Access Journals (Sweden)

    Alp Çelik

    2015-10-01

    Full Text Available National daily newspapers aim to report detailed daily news. Sport pages of the newspapers contain sport columns and news about sport activities. The aim of this research was to investigate the sport columns appearing on sport pages of national daily newspapers published in Turkey. During the research process, nine national daily newspapers published in Turkey were reviewed for one year. The number of sport columns, publishing page, publishing space in cm. and accessibility of newspapers are ascertained. Newspaper field measurement, statistical and percentage calculations are made by Microsoft Excel. The study was completed with the transfer of the data obtained from Excel to Word as a document. According to the obtained data, regarding the news density on sport columns; Milliyet has the most news published, Cumhuriyet has the most news on front page, Haber Turk has the most space allocated and Zaman has been the most accessible newspaper.

  2. Unbonded Prestressed Columns for Earthquake Resistance

    Science.gov (United States)

    2012-05-01

    Modern structures are able to survive significant shaking caused by earthquakes. By implementing unbonded post-tensioned tendons in bridge columns, the damage caused by an earthquake can be significantly lower than that of a standard reinforced concr...

  3. Nonlinear control of high purity distillation columns

    OpenAIRE

    Groebel, Markus; Allgöwer, Frank; Storz, Markus; Gilles, Ernst Dieter

    1994-01-01

    Two simple models of distillation columns are studied to investigate their suitability for the practical use with exact I/O-linearization. An extension of exact I/O-linearization, the asymptotically exact I/O-linearization is applied to the control of a high purity distillation column, using one of these models to derive the static state feedback law. Simulation studies demonstrate the advantage of asymptotically exact I/O-linearization versus classical exact I/O-linearization techniques. Exp...

  4. Behavior of reinforced concrete short columns exposed to fire

    National Research Council Canada - National Science Library

    Mohamed Bikhiet, M; El-Shafey, Nasser F; El-Hashimy, Hany M

    2014-01-01

    Fire could dramatically reduce strength of reinforced concrete columns. The objective of this work is to study columns exposed to fire under axial load and to evaluate reduction in column compressive capacity after fire...

  5. Gas Chromatograph Method Optimization Trade Study for RESOLVE: 20-meter Column v. 8-meter Column

    Science.gov (United States)

    Huz, Kateryna

    2014-01-01

    RESOLVE is the payload on a Class D mission, Resource Prospector, which will prospect for water and other volatile resources at a lunar pole. The RESOLVE payload's primary scientific purpose includes determining the presence of water on the moon in the lunar regolith. In order to detect the water, a gas chromatograph (GC) will be used in conjunction with a mass spectrometer (MS). The goal of the experiment was to compare two GC column lengths and recommend which would be best for RESOLVE's purposes. Throughout the experiment, an Inficon Fusion GC and an Inficon Micro GC 3000 were used. The Fusion had a 20m long column with 0.25mm internal diameter (Id). The Micro GC 3000 had an 8m long column with a 0.32mm Id. By varying the column temperature and column pressure while holding all other parameters constant, the ideal conditions for testing with each column length in their individual instrument configurations were determined. The criteria used for determining the optimal method parameters included (in no particular order) (1) quickest run time, (2) peak sharpness, and (3) peak separation. After testing numerous combinations of temperature and pressure, the parameters for each column length that resulted in the most optimal data given my three criteria were selected. The ideal temperature and pressure for the 20m column were 95 C and 50psig. At this temperature and pressure, the peaks were separated and the retention times were shorter compared to other combinations. The Inficon Micro GC 3000 operated better at lower temperature mainly due to the shorter 8m column. The optimal column temperature and pressure were 70 C and 30psig. The Inficon Micro GC 3000 8m column had worse separation than the Inficon Fusion 20m column, but was able to separate water within a shorter run time. Therefore, the most significant tradeoff between the two column lengths was peak separation of the sample versus run time. After performing several tests, it was concluded that better

  6. Quality improvements of cell membrane chromatographic column.

    Science.gov (United States)

    Ding, Xuan; Chen, Xiaofei; Cao, Yan; Jia, Dan; Wang, Dongyao; Zhu, Zhenyu; Zhang, Juping; Hong, Zhanying; Chai, Yifeng

    2014-09-12

    Cell Membrane Chromatography (CMC) is a biological affinity chromatographic method using a silica stationary phase covered with specific cell membrane. However, its short life span and poor quality control was highlighted in a lot of research articles. In this study, special attention has been paid to the disruption, cell load and packing procedure in order to improve the quality of the CMC columns. Hereto, two newly established CMC models, HSC-T6/CMC and SMMC-7721/CMC have been developed and used in this research project. The optimization of the abovementioned parameters resulted in a better reproducibility of the retention time of the compound GFT (RSDCMC columns. 3.5×10(7)cells were the optimal cell load for the preparation of the CMC columns, the disruption condition was optimized to 5 cycles (400W and 20s interval per cycle) by an ultrasonic processor reducing the total time of cell disruption to 1.5min and the packing flow rate was optimized by applying a linear gradient program. Additionally, 4% paraformaldehyde (PFA) was employed to improve the column quality and prolong the column life span. The results showed that the retention time was longer with PFA treated columns than the ones obtained with the control groups. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Hollow porous ionic liquids composite polymers based solid phase extraction coupled online with high performance liquid chromatography for selective analysis of hydrophilic hydroxybenzoic acids from complex samples.

    Science.gov (United States)

    Dai, Xingping; Wang, Dongsheng; Li, Hui; Chen, Yanyi; Gong, Zhicheng; Xiang, Haiyan; Shi, Shuyun; Chen, Xiaoqing

    2017-02-10

    Polar and hydrophilic properties of hydroxybenzoic acids usually made them coelute with interferences in high performance liquid chromatography (HPLC) analysis. Then selective analysis of them was necessary. Herein, hollow porous ionic liquids composite polymers (PILs) based solid phase extraction (SPE) was firstly fabricated and coupled online with HPLC for selective analysis of hydroxybenzoic acids from complex matrices. Hollow porous PILs were firstly synthesized using Mobil Composition of Matter No. 48 (MCM-48) spheres as sacrificial support, 1-vinyl-3-methylimidazolium chloride (VMIM(+)Cl(-)) as monomer, and ethylene glycol dimethacrylate (EGDMA) as cross-linker. Various parameters affecting synthesis, adsorption and desorption behaviors were investigated and optimized. Steady-state adsorption studies showed the resulting hollow porous PILs exhibited high adsorption capacity, fast adsorption kinetics, and excellent specific adsorption. Subsequently, the application of online SPE system was studied by selective analysis of protocatechuic acid (PCA), 4-hydroxybenzoic acid (4-HBA), and vanillic acid (VA) from Pollen Typha angustifolia. The obtained limit of detection (LOD) varied from 0.002 to 0.01μg/mL, the linear range (0.05-5.0μg/mL) was wide with correlation coefficient (R) from 0.9982 to 0.9994, and the average recoveries at three spiking levels ranged from 82.7 to 102.4%, with column-to-column relative standard deviation (RSD) below 8.1%. The proposed online method showed good accuracy, precision, specificity and convenience, which opened up a universal and efficient route for selective analysis of hydroxybenzoic acids from complex samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. The crazy hollow formation (Eocene) of central Utah

    Science.gov (United States)

    Weiss, M.P.; Warner, K.N.

    2001-01-01

    The Late Eocene Crazy Hollow Formation is a fluviatile and lacustrine unit that was deposited locally in the southwest arm of Lake Uinta during and after the last stages of the lake the deposited the Green River Formation. Most exposures of the Crazy Hollow are located in Sanpete and Sevier Counties. The unit is characterized by a large variety of rock types, rapid facies changes within fairly short distances, and different lithofacies in the several areas where outcrops of the remnants of the formation are concentrated. Mudstone is dominant, volumetrically, but siltstone, shale, sandstone, conglomerate and several varieties of limestone are also present. The fine-grained rocks are mostly highly colored, especially in shades of yellow, orange and red. Sand grains, pebbles and small cobbles of well-rounded black chert are widespread, and "salt-and-pepper sandstone" is the conspicuous characteristic of the Crazy Hollow. The salt-and-pepper sandstone consists of grains of black chert, white chert, quartz and minor feldspar. The limestone beds and lenses are paludal and lacustrine in origin; some are fossiliferous, and contain the same fauna found in the Green River Formation. With trivial exceptions, the Crazy Hollow Formation lies on the upper, limestone member of the Green River Formation, and the beds of the two units are always accordant in attitude. The nature of the contact differs locally: at some sites there is gradation from the Green River to the Crazy Hollow; at others, rocks typical of the two units intertongue; elsewhere there is a disconformity between the two. A variety of bedrock units overlie the Crazy Hollow at different sites. In the southeasternmost districts it is overlain by the late Eocene formation of Aurora; in western Sevier County it is overlain by the Miocene-Pliocene Sevier River Formation; in northernmost Sanpete County it is overlain by the Oligocene volcanics of the Moroni Formation. At many sites bordering Sanpete and Sevier Valleys

  9. Structural Decoupling and Disturbance Rejection in a Distillation Column

    DEFF Research Database (Denmark)

    Bahar, Mehrdad; Jantzen, Jan; Commault, C.

    1996-01-01

    Introduction, distillation column model, input-output decoupling, disturbance rejection, concluding remarks, references.......Introduction, distillation column model, input-output decoupling, disturbance rejection, concluding remarks, references....

  10. The Fire Resistance Performance of Recycled Aggregate Concrete Columns with Different Concrete Compressive Strengths

    Directory of Open Access Journals (Sweden)

    Hongying Dong

    2014-12-01

    Full Text Available In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA concrete of C30 and C40, respectively. Identical constant axial forces were applied to specimens while being subjected to simulated building fire conditions in a laboratory furnace. Several parameters from the experimental results were comparatively analyzed, including the temperature change, vertical displacement, lateral deflection, fire endurance, and failure characteristics of specimens. The temperature field of specimens was simulated with ABAQUS Software (ABAQUS Inc., Provindence, RI, USA and the results agreed quite well with those from the experiments. Results show that the rate of heat transfer from the surface to the interior of the column increases with the increase of the concrete’s compressive strength for both RAC columns and normal concrete columns. Under the same initial axial force ratio, for columns with the same cross section, those with lower concrete compressive strengths demonstrate better fire resistance performance. The fire resistance performance of RAC columns is better than that of normal concrete columns, with the same concrete compressive strength.

  11. The Fire Resistance Performance of Recycled Aggregate Concrete Columns with Different Concrete Compressive Strengths.

    Science.gov (United States)

    Dong, Hongying; Cao, Wanlin; Bian, Jianhui; Zhang, Jianwei

    2014-12-08

    In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC) components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA) concrete of C30 and C40, respectively. Identical constant axial forces were applied to specimens while being subjected to simulated building fire conditions in a laboratory furnace. Several parameters from the experimental results were comparatively analyzed, including the temperature change, vertical displacement, lateral deflection, fire endurance, and failure characteristics of specimens. The temperature field of specimens was simulated with ABAQUS Software (ABAQUS Inc., Provindence, RI, USA) and the results agreed quite well with those from the experiments. Results show that the rate of heat transfer from the surface to the interior of the column increases with the increase of the concrete's compressive strength for both RAC columns and normal concrete columns. Under the same initial axial force ratio, for columns with the same cross section, those with lower concrete compressive strengths demonstrate better fire resistance performance. The fire resistance performance of RAC columns is better than that of normal concrete columns, with the same concrete compressive strength.

  12. Behaviour of FRP confined concrete in square columns

    Directory of Open Access Journals (Sweden)

    de Diego, A.

    2015-12-01

    Full Text Available A significant amount of research has been conducted on FRP-confined circular columns, but much less is known about rectangular/square columns in which the effectiveness of confinement is much reduced. This paper presents the results of experimental investigations on low strength square concrete columns confined with FRP. Axial compression tests were performed on ten intermediate size columns. The tests results indicate that FRP composites can significantly improve the bearing capacity and ductility of square section reinforced concrete columns with rounded corners. The strength enhancement ratio is greater the lower the concrete strength and also increases with the stiffness of the jacket. The confined concrete behaviour was predicted according to the more accepted theoretical models and compared with experimental results. There are two key parameters which critically influence the fitting of the models: the strain efficiency factor and the effect of confinement in non-circular sections.La mayoría de las investigaciones sobre hormigón confinado con FRP se han realizado sobre pilares de sección circular, pero el comportamiento en secciones cuadradas/rectangulares, donde el confinamiento es menos eficaz, es mucho menos conocido. Este trabajo presenta los resultados de un estudio experimental sobre probetas de hormigón de baja resistencia y sección cuadrada. Se han ensayado a compresión centrada diez probetas de tamaño intermedio. Los resultados indican que el confinamiento mejora significativamente la resistencia y ductilidad del hormigón en columnas de sección cuadrada con las esquinas redondeadas. El incremento de resistencia es mayor cuanto menor es la resistencia del hormigón sin confinar y también aumenta con la rigidez del encamisado. Los resultados se compararon con los obtenidos según los modelos teóricos más aceptados. Hay dos parámetros críticos en el ajuste de los modelos: el factor de eficiencia de la deformación y el

  13. Interface Capacity of Repaired Concrete Columns Strengthened with RC Jackets

    Directory of Open Access Journals (Sweden)

    Achillopoulou Dimitra

    2014-12-01

    Full Text Available The study describes the retrofit of repaired elements by reinforced concrete (RC jacketing conducted to quantify the influence of initial construction deficiencies and of different type of anchors to the ability of the interface to transfer loads. Sixteen specimens (section scale 1:2 were designed with variables the initial deficiencies and the confinement ratio. The results indicate that: a the maximum resistance load and dissipated energy of initially damaged specimens are decreased; b surpassing a specific amount of damage, columns even suitably repaired present lower strain capacity, c welded bars lead to buckling of longitudinal bars.

  14. Synthesis and upconversion luminescence properties of YF3:Yb3+/Er3+ hollow nanofibers derived from Y2O3:Yb3+/Er3+ hollow nanofibers

    Science.gov (United States)

    Li, Dan; Dong, Xiangting; Yu, Wensheng; Wang, Jinxian; Liu, Guixia

    2013-06-01

    YF3:Yb3+/Er3+ hollow nanofibers were successfully fabricated via fluorination of the relevant Y2O3:Yb3+/Er3+ hollow nanofibers which were obtained by calcining the electrospun PVP/[Y(NO3)3 + Yb(NO3)3 + Er(NO3)3] composite nanofibers. The morphology and properties of the products were investigated in detail by X-ray diffraction, scanning electron microscope, transmission electron microscope, and fluorescence spectrometer. YF3:Yb3+/Er3+ hollow nanofibers were pure orthorhombic phase with space group Pnma and were hollow-centered structure with mean diameter of 174 ± 22 nm, and YF3:Yb3+/Er3+ hollow nanofibers are composed of nanoparticles with size in the range of 30-60 nm. Upconversion emission spectrum analysis manifested that YF3:Yb3+/Er3+ hollow nanofibers emitted strong green and weak red upconversion emissions centering at 523, 545, and 654 nm, respectively. The green and red emissions were, respectively, originated from 2H11/2/4S3/2 → 4I15/2 and 4F9/2 → 4Il5/2 energy levels transitions of the Er3+ ions. Moreover, the emitting colors of YF3:Yb3+/Er3+ hollow nanofibers were located in the green region in CIE chromaticity coordinates diagram. This preparation technique could be applied to prepare other rare earth fluoride upconversion luminescence hollow nanofibers.

  15. On the Origin of the High Column Density Turnover in the H I Column Density Distribution

    Science.gov (United States)

    Erkal, Denis; Gnedin, Nickolay Y.; Kravtsov, Andrey V.

    2012-12-01

    We study the high column density regime of the H I column density distribution function and argue that there are two distinct features: a turnover at N H I ≈ 1021 cm-2, which is present at both z = 0 and z ≈ 3, and a lack of systems above N H I ≈ 1022 cm-2 at z = 0. Using observations of the column density distribution, we argue that the H I-H2 transition does not cause the turnover at N H I ≈ 1021 cm-2 but can plausibly explain the turnover at N H I >~ 1022 cm-2. We compute the H I column density distribution of individual galaxies in the THINGS sample and show that the turnover column density depends only weakly on metallicity. Furthermore, we show that the column density distribution of galaxies, corrected for inclination, is insensitive to the resolution of the H I map or to averaging in radial shells. Our results indicate that the similarity of H I column density distributions at z = 3 and 0 is due to the similarity of the maximum H I surface densities of high-z and low-z disks, set presumably by universal processes that shape properties of the gaseous disks of galaxies. Using fully cosmological simulations, we explore other candidate physical mechanisms that could produce a turnover in the column density distribution. We show that while turbulence within giant molecular clouds cannot affect the damped Lyα column density distribution, stellar feedback can affect it significantly if the feedback is sufficiently effective in removing gas from the central 2-3 kpc of high-redshift galaxies. Finally, we argue that it is meaningful to compare column densities averaged over ~ kpc scales with those estimated from quasar spectra that probe sub-pc scales due to the steep power spectrum of H I column density fluctuations observed in nearby galaxies.

  16. Contributions to reversed-phase column selectivity: III. Column hydrogen-bond basicity.

    Science.gov (United States)

    Carr, P W; Dolan, J W; Dorsey, J G; Snyder, L R; Kirkland, J J

    2015-05-22

    Column selectivity in reversed-phase chromatography (RPC) can be described in terms of the hydrophobic-subtraction model, which recognizes five solute-column interactions that together determine solute retention and column selectivity: hydrophobic, steric, hydrogen bonding of an acceptor solute (i.e., a hydrogen-bond base) by a stationary-phase donor group (i.e., a silanol), hydrogen bonding of a donor solute (e.g., a carboxylic acid) by a stationary-phase acceptor group, and ionic. Of these five interactions, hydrogen bonding between donor solutes (acids) and stationary-phase acceptor groups is the least well understood; the present study aims at resolving this uncertainty, so far as possible. Previous work suggests that there are three distinct stationary-phase sites for hydrogen-bond interaction with carboxylic acids, which we will refer to as column basicity I, II, and III. All RPC columns exhibit a selective retention of carboxylic acids (column basicity I) in varying degree. This now appears to involve an interaction of the solute with a pair of vicinal silanols in the stationary phase. For some type-A columns, an additional basic site (column basicity II) is similar to that for column basicity I in primarily affecting the retention of carboxylic acids. The latter site appears to be associated with metal contamination of the silica. Finally, for embedded-polar-group (EPG) columns, the polar group can serve as a proton acceptor (column basicity III) for acids, phenols, and other donor solutes. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Increase the Visibility of Microbial Growth in a Winogradsky Column by Substituting Diatomaceous Earth for Sediment

    Directory of Open Access Journals (Sweden)

    Thomas G. Benoit

    2015-02-01

    Full Text Available The difficulty students have seeing the color associated with microbial growth in a traditional Winogradsky column can be overcome by substituting diatomaceous earth (DE for sediment. Microbial growth in a DE column is visible from the early stages of ecological succession and the colors produced appear more vibrant. A flat-sided tissue culture flask can be used as a column container to provide a large surface area for observation. The enhanced visual experience provided by a DE column increases student engagement and learning. Editor's Note:The ASM advocates that students must successfully demonstrate the ability to explain and practice safe laboratory techniques. For more information, read the laboratory safety section of the ASM Curriculum Recommendations: Introductory Course in Microbiology and the Guidelines for Biosafety in Teaching Laboratories, available at www.asm.org. The Editors of JMBE recommend that adopters of the protocols included in this article follow a minimum of Biosafety Level 1 practices.

  18. Characterization of the NEXT Hollow Cathode Inserts After Long-Duration Testing

    Science.gov (United States)

    Mackey, J.; Shastry, R.; Soulas, G.

    2017-01-01

    Hollow dispenser cathode inserts are a critical element of electric propulsion systems, and should therefore be well understood during long term operation to ensure reliable system performance. This work destructively investigated cathode inserts from the NEXT long-duration test which demonstrated 51,184 hours of high-voltage operation, 918 kg of propellant throughput, and 35.5 MN-s of total impulse. The characterization methods used include scanning electron microscopy with energy dispersive spectroscopy and X-ray diffraction. Microscopy analysis has been performed on fractured surfaces, emission surfaces, and metallographically polished cross-sections of post-test inserts and unused inserts. Impregnate distribution, etch region thickness, impregnate chemical content, emission surface topography, and emission surface phase identification are the primary factors investigated.

  19. Modeling of rotating disc contactor (RDC) column

    Science.gov (United States)

    Ismail, Wan Nurul Aiffah; Zakaria, Siti Aisyah; Noor, Nor Fashihah Mohd; Sulong, Ibrahim; Arshad, Khairil Anuar

    2014-12-01

    Liquid-liquid extraction is one of the most important separation processes. Different kinds of liquid-liquid extractor such as Rotating Disc Contactor (RDC) Column being used in industries. The study of liquid-liquid extraction in an RDC column has become a very important subject to be discussed not just among chemical engineers but mathematician as well. In this research, the modeling of small diameter RDC column using the chemical system involving cumene/isobutryric asid/water are analyzed by the method of Artificial Neural Network (ANN). In the previous research, we begin the process of analyzed the data using methods of design of the experiments (DOE) to identify which factor and their interaction factor are significant and to determine the percentage of contribution of the variance for each factor. From the result obtained, we continue the research by discussed the development and validation of an artificial neural network model in estimating the concentration of continuous and concentration of dispersed outlet for an RDC column. It is expected that an efficient and reliable model will be formed to predict RDC column performance as an alternative to speed up the simulation process.

  20. Vertebral Column Resection for Rigid Spinal Deformity.

    Science.gov (United States)

    Saifi, Comron; Laratta, Joseph L; Petridis, Petros; Shillingford, Jamal N; Lehman, Ronald A; Lenke, Lawrence G

    2017-05-01

    Broad narrative review. To review the evolution, operative technique, outcomes, and complications associated with posterior vertebral column resection. A literature review of posterior vertebral column resection was performed. The authors' surgical technique is outlined in detail. The authors' experience and the literature regarding vertebral column resection are discussed at length. Treatment of severe, rigid coronal and/or sagittal malalignment with posterior vertebral column resection results in approximately 50-70% correction depending on the type of deformity. Surgical site infection rates range from 2.9% to 9.7%. Transient and permanent neurologic injury rates range from 0% to 13.8% and 0% to 6.3%, respectively. Although there are significant variations in EBL throughout the literature, it can be minimized by utilizing tranexamic acid intraoperatively. The ability to correct a rigid deformity in the spine relies on osteotomies. Each osteotomy is associated with a particular magnitude of correction at a single level. Posterior vertebral column resection is the most powerful posterior osteotomy method providing a successful correction of fixed complex deformities. Despite meticulous surgical technique and precision, this robust osteotomy technique can be associated with significant morbidity even in the most experienced hands.

  1. Bioremediation of PAH polluted soils: column studies

    Energy Technology Data Exchange (ETDEWEB)

    Hallberg, R.O. [Dept. of Geology and Geochemistry, Stockholm Univ., Stockholm (Sweden); Trepte, B.S. [Angpannefoereningen AB, Stockholm (Sweden)

    2003-07-01

    Background. Due to spills, discharges and leakage, the gaswork site at Husarviken in Stockholm is today the largest (36 ha) creosote-contaminated site in Sweden. The main pollutants are creosote, lead and mercury. The remediation costs are estimated to be as high as US $125 million. It is thus of great interest to find more cost effective remediation methods. Objectives. The aim of this study was to investigate i) if the addition of NTA, EDTA, nitrate, iron and dry yeast would enhance the bioremediation rate of a complex organic pollutant like PAH and, if so, at what concentrations they would be most efficient, ii) the effect on PAH reduction when larger dimensions of the column is used to diminish the effect of water passing along the sides of the column, iii) long-term effects on the reduction of PAH in field-contaminated soil with high concentrations. Materials and Methods. Creosote-contaminated soil from the Husarviken gaswork site was treated with aerated water in column experiments at room temperature. Three column experiments were performed in 2 and 100 L of homogenised soil samples percolated by recirculating flushing water. Fluoranthene was analysed as a representative of the overall degradation of PAH in the columns. (orig.)

  2. Effect of backmixing on pulse column performance

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Y.W.

    1979-05-01

    A critical survey of the published literature concerning dispersed phase holdup and longitudinal mixing in pulsed sieve-plate extraction columns has been made to assess the present state-of-the-art in predicting these two parameters, both of which are of critical importance in the development of an accurate mathematical model of the pulse column. Although there are many conflicting correlations of these variables as a function of column geometry, operating conditions, and physical properties of the liquid systems involved it has been possible to develop new correlations which appear to be useful and which are consistent with much of the available data over the limited range of variables most likely to be encountered in plant sized equipment. The correlations developed were used in a stagewise model of the pulse column to predict product concentrations, solute inventory, and concentration profiles in a column for which limited experimental data were available. Reasonable agreement was obtained between the mathematical model and the experimental data. Complete agreement, however, can only be obtained after a correlation for the extraction efficiency has been developed. The correlation of extraction efficiency was beyond the scope of this work.

  3. Low cost membrane contactors based on hollow fibres

    Science.gov (United States)

    Dohnal, Mirko; Vesely, Tomas; Raudensky, Miroslav

    2012-04-01

    Membrane contactors are used to solve different chemical engineering tasks (e.g. water saturation with gases). Such elements are traditionally used for bubble less oxidation of blood. However, their industrial applications are rather limited by their high investment costs. This is probably the main reason why membrane contactors are not used so widely, e.g. classical absorbers, etc. If potted bundles of hollow fibres are available, then it is a relatively simple task to design an ad hoc membrane contactor. However, it must be emphasised that to achieve the highest mass transfer efficiency requires a rather time-consuming tuning of each ad hoc designed contactor. To check the differences by water evaporation were aligned two modes, the water inside the hollow fibre membrane and fan air outside, next with the water outsides and flowing pressure air inside the membrane.

  4. Low cost membrane contactors based on hollow fibres

    Directory of Open Access Journals (Sweden)

    Raudensky Miroslav

    2012-04-01

    Full Text Available Membrane contactors are used to solve different chemical engineering tasks (e.g. water saturation with gases. Such elements are traditionally used for bubble less oxidation of blood. However, their industrial applications are rather limited by their high investment costs. This is probably the main reason why membrane contactors are not used so widely, e.g. classical absorbers, etc. If potted bundles of hollow fibres are available, then it is a relatively simple task to design an ad hoc membrane contactor. However, it must be emphasised that to achieve the highest mass transfer efficiency requires a rather time-consuming tuning of each ad hoc designed contactor. To check the differences by water evaporation were aligned two modes, the water inside the hollow fibre membrane and fan air outside, next with the water outsides and flowing pressure air inside the membrane.

  5. Synthesis of porous inorganic hollow fibers without harmful solvents.

    Science.gov (United States)

    Shukla, Sushumna; de Wit, Patrick; Luiten-Olieman, Mieke W J; Kappert, Emiel J; Nijmeijer, Arian; Benes, Nieck E

    2015-01-01

    A route for the fabrication of porous inorganic hollow fibers with high surface-area-to-volume ratio that avoids harmful solvents is presented. The approach is based on bio-ionic gelation of an aqueous mixture of inorganic particles and sodium alginate during wet spinning. In a subsequent thermal treatment, the bio-organic material is removed and the inorganic particles are sintered. The method is applicable to the fabrication of various inorganic fibers, including metals and ceramics. The route completely avoids the use of organic solvents, such as N-methyl-2-pyrrolidone, and additives associated with the currently used fiber fabrication methods. In addition, it inherently avoids the manifestation of so-called macro voids and allows the facile incorporation of additional metal oxides in the inorganic hollow fibers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Silica needle template fabrication of metal hollow microneedle arrays

    Science.gov (United States)

    Zhu, M. W.; Li, H. W.; Chen, X. L.; Tang, Y. F.; Lu, M. H.; Chen, Y. F.

    2009-11-01

    Drug delivery through hollow microneedle (HMN) arrays has now been recognized as one of the most promising techniques because it minimizes the shortcomings of the traditional drug delivery methods and has many exciting advantages—pain free and tunable release rates, for example. However, this drug delivery method has been hindered greatly from mass clinical application because of the high fabrication cost of HMN arrays. Hence, we developed a simple and cost-effective procedure using silica needles as templates to massively fabricate HMN arrays by using popular materials and industrially applicable processes of micro- imprint, hot embossing, electroplating and polishing. Metal HMN arrays with high quality are prepared with great flexibility with tunable parameters of area, length of needle, size of hollow and array dimension. This efficient and cost-effective fabrication method can also be applied to other applications after minor alterations, such as preparation of optic, acoustic and solar harvesting materials and devices.

  7. Spinning Induced Compression Strength of Precast Hollow Concrete Piles

    Directory of Open Access Journals (Sweden)

    Gogot Setyo Budi

    2017-09-01

    Full Text Available Prefabricated precast-hollow concrete pile is widely used as deep foundations due to its several benefits such as the uniformity in concrete quality and its durability. It is also called spun pile since the spinning method is utilized to compact the fresh concrete. During spinning, the fresh concrete is propelled outward due to centrifugal force, which generates a compaction process and develops a hollow in the center of the pile. Several factors, such as the rate of spinning, frequency, and duration of spinning, are affecting the quality of the pile. This paper presents the study of density and compressive strength of spun piles. The specimens were cored from the spun piles with diameter of 800 mm. The results show that the density and the compressive strength of the concrete at outer region of the spun pile are bigger than those at the inner side.

  8. Dual hollow-core anti-resonant fibres

    Science.gov (United States)

    Wheeler, N. V.; Bradley, T. D.; Hayes, J. R.; Jasion, G. T.; Chen, Y.; Sandoghchi, S. R.; Horak, P.; Poletti, F.; Petrovich, M. N.; Richardson, D. J.

    2016-04-01

    While hollow core-photonic crystal fibres are now a well-established fibre technology, the majority of work on these speciality fibres has been on designs with a single core for optical guidance. In this paper we present the first dual hollow-core anti-resonant fibres (DHC-ARFs). The fibres have high structural uniformity and low loss (minimum loss of 0.5 dB/m in the low loss guidance window) and demonstrate regimes of both inter-core coupling and zero coupling, dependent on the wavelength of operation, input polarisation, core separation and bend radius. In a DHC-ARF with a core separation of 4.3 μm, we find that with an optimised input polarisation up to 65% of the light guided in the launch core can be coupled into the second core, opening up applications in power delivery, gas sensing and quantum optics.

  9. Block copolymer/homopolymer dual-layer hollow fiber membranes

    KAUST Repository

    Hilke, Roland

    2014-12-01

    We manufactured the first time block copolymer dual-layer hollow fiber membranes and dual layer flat sheet membranes manufactured by double solution casting and phase inversion in water. The support porous layer was based on polystyrene and the selective layer with isopores was formed by micelle assembly of polystyrene-. b-poly-4-vinyl pyridine. The dual layers had an excellent interfacial adhesion and pore interconnectivity. The dual membranes showed pH response behavior like single layer block copolymer membranes with a low flux for pH values less than 3, a fast increase between pH4 and pH6 and a constant high flux level for pH values above 7. The dry/wet spinning process was optimized to produce dual layer hollow fiber membranes with polystyrene internal support layer and a shell block copolymer selective layer.

  10. MD210 Note: Creation of Hollow Bunches in the PSB

    CERN Document Server

    Oeftiger, Adrian; Findlay, Alan James; Hancock, Steven; Rumolo, Giovanni; CERN. Geneva. ATS Department

    2016-01-01

    MD210 aims for the creation of longitudinally hollow bunches in the CERN PS Booster. The first three sessions have been carried out using the radial loop feedback system in order to drive the beam on a dipolar parametric resonance (instead of the phase loop). It has been found that the damping by the phase loop inhibits the excitation of the resonance to a major extent. The hollow distributions generated under these circumstances fail to reach a satisfying bunching factor. Nonetheless, proving the principally successful application of this technique to the PS Booster promises good results once the phase loop system supports trim functions. The approach, actions and detailed results of the first three MD sessions are presented in this paper.

  11. Thermomechanical Assessment of the Collector for the Hollow Electron Lens

    CERN Document Server

    Anderson, George Bowers

    2017-01-01

    The hollow electron lens (HEL) is a system proposed for the High Luminosity upgrade of the Large Hadron Collider LHC (HL-LHC) [1]. Being considered for installation at LHC point 4, the HEL improves halo control and collimation of proton beams in the collider [2]. This is achieved by creating a hollow tube of electrons using an electron gun. This axisymmetric electron cloud travels around the proton beam for a few meters, overlapping with the proton beam halo, until the electron cloud is dissipated in a collector, which is the focus of this project. A 3D image of the HEL system is found in Figure 1 and a further technical description of such electron lenses is available in [3].

  12. Research on polyvinylidene fluoride (PVDF) hollow-fiber hemodialyzer.

    Science.gov (United States)

    Zhang, Qinglei; Lu, Xiaolong; Zhao, Lihua; Liu, Juanjuan; Wu, Chunfeng

    2016-06-01

    In this study, polyvinylidene fluoride (PVDF) hollow-fiber hemodialysis membranes were prepared by non-solvent-induced phase separation. The PVDF hollow-fiber hemodialyzers were prepared by centrifugal casting. The results showed that the PVDF membrane had better mechanical and separation properties when the membrane wall thickness was 40 μm and the N,N-dimethylacetamide in the core was 70 Vol%. Compared with commercial polysulfone hemodialysis membrane (Fresenius F60S membrane), the PVDF membrane had better mechanical property and ultrafiltration (UF) flux of pure water. The PVDF dialyzer's removal efficiency for middle molecules was proven to be much higher than that of the F60S dialyzer. The UF coefficient of a high-flux PVDF dialyzer is 62.6 ml/h/mm Hg, whereas F60S is 42.5 ml/h/mm Hg, which can promote clearance for middle molecules.

  13. Holographic entanglement entropy for hollow cones and banana shaped regions

    Energy Technology Data Exchange (ETDEWEB)

    Dorn, Harald [Institut für Physik und IRIS Adlershof, Humboldt-Universität zu Berlin,Zum Großen Windkanal 6, D-12489 Berlin (Germany)

    2016-06-09

    We consider banana shaped regions as examples of compact regions, whose boundary has two conical singularities. Their regularised holographic entropy is calculated with all divergent as well as finite terms. The coefficient of the squared logarithmic divergence, also in such a case with internally curved boundary, agrees with that calculated in the literature for infinite circular cones with their internally flat boundary. For the otherwise conformally invariant coefficient of the ordinary logarithmic divergence an anomaly under exceptional conformal transformations is observed. The construction of minimal submanifolds, needed for the entanglement entropy of cones, requires fine-tuning of Cauchy data. Perturbations of such fine-tuning leads to solutions relevant for hollow cones. The divergent parts for the entanglement entropy of hollow cones are calculated. Increasing the difference between the opening angles of their outer and inner boundary, one finds a transition between connected solutions for small differences to disconnected solutions for larger ones.

  14. The Numerical Simulation Analysis of Hydro Forming of Hollow Crankshaft

    Directory of Open Access Journals (Sweden)

    Wang Shi Gang

    2016-01-01

    Full Text Available The hydro forming process of hollow crankshaft was numerically analyzed and simulated based on Dynaform. Then the influence to hydro forming process in different loading paths was studied and the match relations between optimum forming pressure and axial feeding were obtained. The forming result was ideal and the forming parts were qualified. Finally, to the same material, the change trend of pipe billet wall thickness under the same forming pressure and axial feeding was discussed.

  15. Shielding of an oscillating electric field by a hollow conductor

    Science.gov (United States)

    Aguirregabiria, J. M.; Hernández, A.; Rivas, M.

    1996-08-01

    The electric and magnetic fields for a hollow conducting sphere located in a slowly varying uniform electric field background are computed to first-order in a power series expansion in the field frequency. These results are used to define an equivalent RC circuit and to test the circuit approach which is often used in electromagnetic compatibility (EMC). The case of an infinite cylindrical conducting tube under the influence of the same external field is also analyzed.

  16. Hollow glass fibers in reinforcing glass ionomer cements.

    Science.gov (United States)

    Garoushi, Sufyan; Vallittu, Pekka; Lassila, Lippo

    2017-02-01

    This study investigated the reinforcing effect of hollow and solid discontinuous glass fiber fillers with two different loading fractions on select mechanical properties of conventional and resin modified glass ionomer cements (GICs). Experimental fiber reinforced GIC was prepared by adding discontinuous glass fiber (hollow/solid) of 0.5mm in length to the powder of commercial GICs (GC Fuji IX and II LC) with two different weight ratios (5 and 10wt%) using a high speed mixing machine. Fracture toughness, work of fracture, flexural strength, flexural modulus, compressive strength and diametral tensile strength were determined for each experimental and control material. The specimens (n=7) were wet stored (37°C for one day) before testing. Scanning electron microscopy was used to evaluate the microstructure of the experimental fiber reinforced GICs. Fiber length analysis was carried out to investigate the fiber length distribution of experimental GICs. The results were analyzed statistically using ANOVA followed by Tukey's post hoc test. Level of significance was set at 0.05. An increase in fracture toughness (280 and 200%) and flexural strength (170 and 140%) of hollow discontinuous glass fiber reinforced (10wt%) conventional and resin modified GICs respectively, were achieved compared to unreinforced materials (p0.05) between the fiber reinforced and unreinforced GICs. The use of hollow discontinuous glass fiber fillers with conventional and resin modified GIC matrix is a novel reinforcement. It yielded superior toughening and flexural performance compared to the particulate GICs used. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  17. Preparation, Modification, and Application of Hollow Gold Nanospheres

    Directory of Open Access Journals (Sweden)

    Qiong-Qiong Ren

    2015-01-01

    Full Text Available Hollow gold nanospheres (HGNs have great potential applications in biological sensing, biomedical imaging, photothermal therapy, and drug delivery due to their unique localized surface plasmon resonance (LSPR feature, easy modification, good biocompatibility, and excellent photothermal conversion properties. In this review, the latest developments of HGNs in biosensing, bioimaging, photothermal therapy, and drug delivery are summarized, the synthesis methods, surface modification and bioconjugation of HGNs are also covered in this summary.

  18. Mathematical modeling of alcohol distillation columns

    Directory of Open Access Journals (Sweden)

    Ones Osney Pérez

    2011-04-01

    Full Text Available New evaluation modules are proposed to extend the scope of a modular simulator oriented to the sugar cane industry, called STA 4.0, in a way that it can be used to carry out x calculation and analysis in ethanol distilleries. Calculation modules were developed for the simulation of the columns that are combined in the distillation area. Mathematical models were supported on materials and energy balances, equilibrium relations and thermodynamic properties of the ethanol-water system. Ponchon-Savarit method was used for the evaluation of the theoretical stages in the columns. A comparison between the results using Ponchon- Savarit method and those obtained applying McCabe-Thiele method was done for a distillation column. These calculation modules for ethanol distilleries were applied to a real case for validation.

  19. Neutron camera employing row and column summations

    Science.gov (United States)

    Clonts, Lloyd G.; Diawara, Yacouba; Donahue, Jr, Cornelius; Montcalm, Christopher A.; Riedel, Richard A.; Visscher, Theodore

    2016-06-14

    For each photomultiplier tube in an Anger camera, an R.times.S array of preamplifiers is provided to detect electrons generated within the photomultiplier tube. The outputs of the preamplifiers are digitized to measure the magnitude of the signals from each preamplifier. For each photomultiplier tube, a corresponding summation circuitry including R row summation circuits and S column summation circuits numerically add the magnitudes of the signals from preamplifiers for each row and for each column to generate histograms. For a P.times.Q array of photomultiplier tubes, P.times.Q summation circuitries generate P.times.Q row histograms including R entries and P.times.Q column histograms including S entries. The total set of histograms include P.times.Q.times.(R+S) entries, which can be analyzed by a position calculation circuit to determine the locations of events (detection of a neutron).

  20. Modification of W surfaces by exposure to hollow cathode plasmas

    Science.gov (United States)

    Stancu, C.; Stokker-Cheregi, F.; Moldovan, A.; Dinescu, M.; Grisolia, C.; Dinescu, G.

    2017-10-01

    In this work, we assess the surface modifications induced on W samples following exposure to He and He/H2 radiofrequency plasmas in hollow cathode discharge configuration. Our study addresses issues that relate to the use of W in next-generation fusion reactors and, therefore, the investigation of W surface degradation following exposure and heating by plasmas to temperatures above 1000 °C is of practical importance. For these experiments, we used commercially available tungsten samples having areas of 30 × 15 mm and 0.1 mm thickness. The hollow cathode plasma was produced using a radiofrequency (RF) generator (13.56 MHz) between parallel plate electrodes. The W samples were mounted as one of the electrodes. The He and He/H2 plasma discharges had a combined effect of heating and bombardment of the W surfaces. The surface modifications were studied for discharge powers between 200 and 300 W, which resulted in the heating of the samples to temperatures between 950 and 1230 °C, respectively. The samples were weighed prior and after plasma exposure, and loss of mass was measured following plasma exposure times up to 90 min. The analysis of changes in surface morphology was carried out by optical microscopy, scanning electron microscopy and atomic force microscopy. Additionally, optical emission spectra of the respective plasmas were recorded from the region localized inside the hollow cathode gap. We discuss the influence of experimental parameters on the changes in surface morphology.

  1. Development of hollow anode penning ion source for laboratory application

    Science.gov (United States)

    Das, B. K.; Shyam, A.; Das, R.; Rao, A. D. P.

    2012-03-01

    The research work presented here focuses for the development of miniature penning type ion source. One hollow anode penning type ion source was developed in our laboratory. The size of the ion source is 38 mm diameter and 55 mm length. The ion source consists of two cathodes, a hollow anode and one piece of rare earth permanent magnet. The plasma was created in the plasma region between cathodes and the hollow anode. The J × B force in the region helps for efficient ionization of the gas even in the high vacuum region˜1×10 -5 Torr. The ions were extracted in the axial direction with help of the potential difference between the electrodes and the geometry of the extraction angle. The effect of the extraction electrode geometry for efficient extraction of the ions from the plasma region was examined. This ion source is a self extracted ion source. The self extracted phenomena reduce the cost and the size of the ion source. The extracted ion current was measured by a graphite probe. An ion current of more than 200 μA was observed at the probe placed 70 mm apart from the extraction electrode. In this paper, the structure of the ion source, effect of operating pressure, potential difference and the magnetic field on the extracted ion current is reported.

  2. Sandwich-structured hollow fiber membranes for osmotic power generation

    KAUST Repository

    Fu, Feng Jiang

    2015-11-01

    In this work, a novel sandwich-structured hollow fiber membrane has been developed via a specially designed spinneret and optimized spinning conditions. With this specially designed spinneret, the outer layer, which is the most crucial part of the sandwich-structured membrane, is maintained the same as the traditional dual-layer membrane. The inner substrate layer is separated into two layers: (1) an ultra-thin middle layer comprising a high molecular weight polyvinylpyrrolidone (PVP) additive to enhance integration with the outer polybenzimidazole (PBI) selective layer, and (2) an inner-layer to provide strong mechanical strength for the membrane. Experimental results show that a high water permeability and good mechanical strength could be achieved without the expensive post treatment process to remove PVP which was necessary for the dual-layer pressure retarded osmosis (PRO) membranes. By optimizing the composition, the membrane shows a maximum power density of 6.23W/m2 at a hydraulic pressure of 22.0bar when 1M NaCl and 10mM NaCl are used as the draw and feed solutions, respectively. To our best knowledge, this is the best phase inversion hollow fiber membrane with an outer selective PBI layer for osmotic power generation. In addition, this is the first work that shows how to fabricate sandwich-structured hollow fiber membranes for various applications. © 2015 Elsevier B.V.

  3. Creation of Hollow Bunches using a Double Harmonic RF system

    CERN Document Server

    Carli, Christian

    2001-01-01

    The main motivation for the creation of hollow bunches in the PSB is to increase the bunching factor at transfer to the PS. Due to the reduction of the peak current and direct transverse space charge forces, one expects less blow up and losses at low energy in the PS. Thus, it does not matter when the hollow distribution in longitudinal phase space is created in the PSB cycle. We propose methods involving the h=1 and h=2 RF systems available in the PSB. The first method is based on controlled blow up by recombination of the bunch in one bucket, with another empty bucket. By appropriate adjustment of the phase between the two RF systems, more empty phase space can be inserted close to the centre creating a hollow distribution. The second method is based on a redistribution of phase space. The beam is transferred from one h=2 sub-bucket to the other and, during that process, regions from the centre with high density and from the periphery are exchanged. Simulations of both methods, based on tracking of particle...

  4. Detritiation of water using microporous hollow-fiber membranes

    Energy Technology Data Exchange (ETDEWEB)

    Kelso, R.C. [Nevada Division of Environmental Protection, Carson City, NV (United States); Ahmed, T.; Middlebrooks, E.J. [Univ. of Nevada, Reno, NV (United States)

    1997-03-01

    A novel concept of tritium (HTO) removal with microporous hollow fiber membranes was evaluated in this study. Small-scale laboratory modules were constructed and tested to determine the mass transfer characteristics of the hollow fibers under varying system parameters. Tritiated water is pumped through the fiber lumen and air, saturated with water vapor, is pumped over the exterior of the fibers in a countercurrent mode. The high HTO concentration gradient encourages the HTO to diffuse across the porous membrane wall, and to transfer directly into the saturated air stream. A dimensionless mathematical correlation that predicts the tritium transfer coefficient across the membranes is presented for parallel flow modules. The measured overall mass transfer coefficients in the membrane module are two to three orders of magnitude greater than those of conventional bubble stripping. In additions, factors that influence the mass transfer performance of the membrane modules in practical applications are evaluated. The results indicate that very low concentrations of HTO can be separated from water using microporous hollow fiber membranes. 33 refs., 8 figs., 3 tabs.

  5. Hollow fiber adsorbents for CO2 capture: Kinetic sorption performance

    KAUST Repository

    Lively, Ryan P.

    2011-07-01

    We describe a CO 2 capture platform based on hollow polymeric fibers with sorbent particles embedded in the porous fiber wall for post-combustion CO 2 capture. These fibers are intended for use in a rapid temperature swing adsorption (RTSA) process. The RTSA system utilizes the hollow fiber morphology by flowing cooling water on the bore-side of the fibers during sorption to prevent temperature rise associated with the sorption enthalpy. Steam or hot water is flowed through the bores during desorption to desorb CO 2 rapidly. To minimize material transfer between the bore and the fiber wall, a dense Neoprene ® lumen layer is cast on the bore-side of the fiber wall. In this paper, the key sorption step and associated kinetic resistances for the uncooled fibers are examined and evaluated for this portion of the RTSA process. Chopped fibers in a packed bed, as well as fibers assembled into a parallel flow module, have been tested in a simulated flue gas stream. Kinetic limitations in the hollow fiber modules are largely overcome by increasing the superficial gas velocity and the fiber packing in the module-indicating that film diffusion is the controlling mass transfer limitation in the fiber system. The un-cooled fiber modules lose apparent capacity as superficial velocities are increased, likely indicating non-isothermal operation, whereas the actively-cooled fibers in the packed bed maintain apparent capacity at all flowrates studied. © 2011 Elsevier B.V.

  6. Vapor chamber with hollow condenser tube heat sink

    Science.gov (United States)

    Ong, K. S.; Haw, P. L.; Lai, K. C.; Tan, K. H.

    2017-04-01

    Heat pipes are heat transfer devices capable of transferring large quantities of heat effectively and efficiently. A vapor chamber (VC) is a flat heat pipe. A novel VC with hollow condenser tubes embedded on the top of it is proposed. This paper reports on the experimental thermal performance of three VC devices embedded with hollow tubes and employed as heat sinks. The first device consisted of a VC with a single hollow tube while the other two VCs had an array of multi-tubes with different tube lengths. All three devices were tested under natural and force air convection cooling. An electrical resistance heater was employed to provide power inputs of 10 and 40 W. Surface temperatures were measured with thermocouple probes at different locations around the devices. The results show that temperatures increased with heater input while total device thermal resistances decreased. Force convection results in lower temperatures and lower resistance. Dry-out occurs at high input power and with too much condensing area. There appears to be an optimum fill ratio which depended upon dimensions of the VC and also heating power.

  7. Retention Models on Core-Shell Columns.

    Science.gov (United States)

    Jandera, Pavel; Hájek, Tomáš; Růžičková, Marie

    2017-07-13

    A thin, active shell layer on core-shell columns provides high efficiency in HPLC at moderately high pressures. We revisited three models of mobile phase effects on retention for core-shell columns in mixed aqueous-organic mobile phases: linear solvent strength and Snyder-Soczewiński two-parameter models and a three-parameter model. For some compounds, two-parameter models show minor deviations from linearity due to neglect of possible minor retention in pure weak solvent, which is compensated for in the three-parameter model, which does not explicitly assume either the adsorption or the partition retention mechanism in normal- or reversed-phase systems. The model retention equation can be formulated as a function of solute retention factors of nonionic compounds in pure organic solvent and in pure water (or aqueous buffer) and of the volume fraction of an either aqueous or organic solvent component in a two-component mobile phase. With core-shell columns, the impervious solid core does not participate in the retention process. Hence, the thermodynamic retention factors, defined as the ratio of the mass of the analyte mass contained in the stationary phase to its mass in the mobile phase in the column, should not include the particle core volume. The values of the thermodynamic factors are lower than the retention factors determined using a convention including the inert core in the stationary phase. However, both conventions produce correct results if consistently used to predict the effects of changing mobile phase composition on retention. We compared three types of core-shell columns with C18-, phenyl-hexyl-, and biphenyl-bonded phases. The core-shell columns with phenyl-hexyl- and biphenyl-bonded ligands provided lower errors in two-parameter model predictions for alkylbenzenes, phenolic acids, and flavonoid compounds in comparison with C18-bonded ligands.

  8. Continuing life test of a xenon hollow cathode for a space plasma contactor

    Science.gov (United States)

    Sarver-Verhey, Timothy R.

    1994-01-01

    Implementation of a hollow cathode plasma contactor for charge control on the Space Station has required validation of long-life hollow cathodes. A test series of hollow cathodes and hollow cathode plasma contactors was initiated as part of the plasma contactor development program. An on-going wear-test of a hollow cathode has demonstrated cathode operation in excess of 10,000 hours with small changes in operating parameters. The discharge has experienced 10 shutdowns during the test, all of which were due to test facility failures or expellant replenishment. In all cases, the cathode was re-ignited at approximately 42 volts and resumed typical operation. This test represents the longest demonstrated stable operation of a high current (greater than 1 A) xenon hollow cathode reported to date.

  9. Extended test of a xenon hollow cathode for a space plasma contactor

    Science.gov (United States)

    Sarver-Verhey, Timothy R.

    1994-01-01

    Implementation of a hollow cathode plasma contactor for charge control on the Space Station has required validation of long-life hollow cathodes. A test series of hollow cathodes and hollow cathode plasma contactors was initiated as part of the plasma contactor development program. An on-going wear-test of a hollow cathode has demonstrated cathode operation in excess of 4700 hours with small changes in operating parameters. The discharge experienced 4 shutdowns during the test, all of which were due to test facility failures or expellant replenishment. In all cases, the cathode was reignited at approximately 42 volts and resumed typical operation. This test represents the longest demonstrated stable operation of a high current (greater than 1A) xenon hollow cathode reported to date.

  10. Preparation of SnO 2 /Carbon Composite Hollow Spheres and Their Lithium Storage Properties

    KAUST Repository

    Lou, Xiong Wen

    2008-10-28

    In this work, we present a novel concept of structural design for preparing functional composite hollow spheres and derived double-shelled hollow spheres. The approach involves two main steps: preparation of porous hollow spheres of one component and deposition of the other component onto both the interior and exterior surfaces of the shell as well as in the pores. We demonstrate the concept by preparing SnO2/carbon composite hollow spheres and evaluate them as potential anode materials for lithium-ion batteries. These SnO2/carbon hollow spheres are able to deliver a reversible Li storage capacity of 473 mA h g-1 after 50 cycles. Unusual double-shelled carbon hollow spheres are obtained by selective removal of the sandwiched porous SnO2 shells. © 2008 American Chemical Society.

  11. Preparation and surface encapsulation of hollow TiO nanoparticles for electrophoretic displays

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Qian [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Tan Tingfeng, E-mail: tantingfeng@sina.com [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Department of Materials Science and Engineering, Tianjin Institute of Urban Construction, Tianjin 300384 (China); Qi Peng [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Wang Shirong, E-mail: wangshirong@tju.edu.cn [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Bian Shuguang [High Technology Research and Development Center, Ministry of Science and Technology, Beijing 100044 (China); Li Xianggao; An Yong; Liu Zhaojun [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

    2011-02-01

    Hollow black TiO nanosparticles were obtained via deposition of inorganic coating on the surface of hollow core-shell polymer latex with Ti(OBu){sub 4} as precursor and subsequent calcination in ammonia gas. Hollow TiO particles were characterized by scanning electron microscope, transmission electronic microscopy, X-ray diffraction, and thermogravimetric analysis. Encapsulation of TiO via dispersion polymerization was promoved by pretreating the pigments with 3-(trimethoxysilyl) propyl methacrylate, making it possible to prepare hollow TiO-polymer particles. When St and DVB were used as polymerization monomer, hollow TiO-polymer core-shell particles came into being via dispersion polymerization, and the lipophilic degree is 28.57%. Glutin-arabic gum microcapsules containing TiO-polymer particles electrophoretic liquid were prepared using via complex coacervation. It was founded that hollow TiO-polymer particles had enough electrophoretic mobility after coating with polymer.

  12. Preparation and surface encapsulation of hollow TiO nanoparticles for electrophoretic displays

    Science.gov (United States)

    Zhao, Qian; Tan, Tingfeng; Qi, Peng; Wang, Shirong; Bian, Shuguang; Li, Xianggao; An, Yong; Liu, Zhaojun

    2011-02-01

    Hollow black TiO nanosparticles were obtained via deposition of inorganic coating on the surface of hollow core-shell polymer latex with Ti(OBu)4 as precursor and subsequent calcination in ammonia gas. Hollow TiO particles were characterized by scanning electron microscope, transmission electronic microscopy, X-ray diffraction, and thermogravimetric analysis. Encapsulation of TiO via dispersion polymerization was promoved by pretreating the pigments with 3-(trimethoxysilyl) propyl methacrylate, making it possible to prepare hollow TiO-polymer particles. When St and DVB were used as polymerization monomer, hollow TiO-polymer core-shell particles came into being via dispersion polymerization, and the lipophilic degree is 28.57%. Glutin-arabic gum microcapsules containing TiO-polymer particles electrophoretic liquid were prepared using via complex coacervation. It was founded that hollow TiO-polymer particles had enough electrophoretic mobility after coating with polymer.

  13. Synthesis of barium-strontium titanate hollow tubes using Kirkendall effect

    Science.gov (United States)

    Chen, Xuncai; Im, SangHyuk; Kim, Jinsoo; Kim, Woo-Sik

    2018-02-01

    (BaSr)TiO3 hexagonal hollow tubes was fabricated by a solid-state interfacial reaction including a Kirkendall diffusion. Using a co-precipitation and sol-gel process, a core@shell structure of (BaSr)CO3@TiO2 rods were prepared, and then converted to (BaSr)TiO3 hollow tubes at 750 °C. This was a first achievement of single-phase crystal hollow tube. Here, the inner diameter and wall thickness of hollow tube were about 700 nm and 130 nm, respectively. The fabrication of (BaSr)TiO3 hollow tubes was monitored with scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), transmission electron microscopy (TEM), and X-ray diffraction (XRD) to investigate their formation mechanism. The present synthetic approach would provide a new insight into the design and fabrication of hollow architectures of many perovskite oxides.

  14. WHEELSET AXLE WITH THE CAVITY OF UNIFORM CROSS SECTION

    Directory of Open Access Journals (Sweden)

    S. R. Kolesnykov

    2014-10-01

    Full Text Available Purpose. Due to operation in complex loading conditions, the rolling stock wheelsets should provide high reliability, since the train traffic safety largely depends on them. Design and technical condition of wheelsets affect the smoothness, intensity of forces generated by the interaction between the car and track, and the motion resistance. Specificity of the axle operation consists in the fact that it undergoes the bending stresses under loading. These stresses are unevenly distributed along the cross-sectional area, reaching the highest values in the outer fibers and the minimal values in the internal ones. This aspect sets the problem of replacement of the uniform cross section with the hollow cross section. The disadvantages of hollow axle design, which are used at the present time, should include a significant manufacturing complexity of the variable section cavity. The purpose is to develop a modernized design of the wheelset axle. Methodology. A construction of the hollow axle having an inner longitudinal cylindrical through hole of the constant diameter throughout its length was proposed. The item is made of steel seamless tube. The inner surface of the tube is treated by mechanical means to remove the voltage concentrations in the internal longitudinal cylindrical through hole, which has a constant diameter along the entire length of the axle. Findings. Application of this design will facilitate manufacturing of the hollow axle and the machining of the inner longitudinal through hole, while retaining all the use advantages of the hollow axle in the rolling stock wheel pairs. Another use advantage of the hollow axle of this design is the absence of partial heterogeneity of the metal, which is inevitably, occurs during the solid axles blanking. Originality. A new design of the wheelset hollow axle of railway rolling stock was proposed. Practical value. Introduction of the new design simplifying the manufacture and mechanical treatment of

  15. Rasch models with exchangeable rows and columns

    DEFF Research Database (Denmark)

    Lauritzen, Steffen Lilholt

    The article studies distributions of doubly infinite binary matrices with exchangeable rows and columns which satify the further property that the probability of any $m \\times n$ submatrix is a function of the row- and column sums of that matrix. We show that any such distribution is a (unique......) mixture of random Rasch distributions. The non-degenerate elements of these distributions were introduced by Rasch (1960). We investigate the relationship between these random Rasch distributions and a problem in visual perception, the characters of a certain Abelian semigroup, and the problem...

  16. Facile preparation method for rare earth phosphate hollow spheres and their photoluminescence properties.

    Science.gov (United States)

    Guan, Mingyun; Tao, Feifei; Sun, Jianhua; Xu, Zheng

    2008-08-05

    We have developed a template-free hydrothermal method of constructing rare earth phosphate hollow spheres using H(6)P(4)O(13) as the PO(4) (3-) source. The mechanism of hollow spheres formation was proposed on the basis of Ostwald ripening. The resulting hollow spheres, especially with the aid of doping of other lanthanide cations, exhibit emission spanning the whole UV-visible wavelength range.

  17. Stress Analysis of Adhesive Lap Joint of Hollow Shafts Subjected to Torsional Moments

    OpenAIRE

    仲野, 雄一; 高城, 有希久

    2001-01-01

    The stress and strain distributions in adhesively bonded lap joints of dissimilar hollow shafts are examined using the axisymmetric theory of elasticity. In the analysis, the joint is modeled as an elastic three-body contact problem where the hollow shafts and the adhesive are replaced by finite hollow cylinders. The effects of the ratio of Young's modulus of the adhesive to that of the shaft, the overlap length and the thickness of the adhesive on the stress distributions at the interfaces i...

  18. Compact and Robust Refilling and Connectorization of Hollow Core Photonic Crystal Fiber Gas Reference Cells

    Science.gov (United States)

    Poberezhskiy, Ilya Y.; Meras, Patrick; Chang, Daniel H.; Spiers, Gary D.

    2007-01-01

    This slide presentation reviews a method for refilling and connectorization of hollow core photonic crystal fiber gas reference cells. Thees hollow-core photonic crystal fiber allow optical propagation in air or vacuum and are for use as gas reference cell is proposed and demonstrated. It relies on torch-sealing a quartz filling tube connected to a mechanical splice between regular and hollow-core fibers.

  19. Titania coated hollow glass microspheres for environmental applications

    Science.gov (United States)

    Koopman, Mark C.

    The potential applicability of titania coated hollow glass microspheres (HGMs) to the photocatalytic degradation of microbiological and organic chemical water pollutants could have dramatic positive effects on improving the quality of industrial wastewaters that empty into rivers and streams, as well as potential use in economically improving the quality of drinking water. Heterogeneous photocatalysis using titania has been extensively studied since the 1990's because of its non-toxic nature, its high quantum yield of electrons and photo-holes, and its ability to use ambient solar radiation as a power source. Although titania embodies extraordinarily attractive properties for a range of environmental applications, a viable substrate or method of using the material effectively has not been recognized. HGMs are particularly attractive as a support for titania because of their low density and high surface area to volume ratio, but details of how they react to imposed loading, wear, and impact have not been addressed, nor have materials engineering analyses that could maximize their utility been made. In this study we have examined the microstructure, morphology and micro-compression properties of two types of titania coated hollow microspheres, a commercially produced HGM and cenospheres, a derivative of fly ash. Comparisons of uncoated and titania coated hollow microspheres showed improved failure loads and facture energies for the titania coated materials over the uncoated hollow microspheres. Also, the relationship between failure load and hollow microsphere diameter was characterized and the function employed to explain part of the gain in average failure load for the HGMs. Microscopic examination of titania coated HGMs that were subjected to various turbulent conditions, as well as intentional fracture, indicated good interfacial integrity, which supports the viability of both types of HGMs for potential applications. The photocatalytic reactivity of the titania

  20. The use of real-time ultrasound feedback in teaching abdominal hollowing exercises to healthy subjects

    National Research Council Canada - National Science Library

    Henry, Sharon M; Westervelt, Karen C

    2005-01-01

    Randomized controlled trial. To determine if supplementing typical clinical instruction with real-time ultrasound feedback facilitates performance and retention of the abdominal hollowing exercise (AHE...

  1. A simple approach to hollow maxillary complete denture fabrication: An innovative technique

    Directory of Open Access Journals (Sweden)

    Kathleen Manuela D'souza

    2017-01-01

    Full Text Available A severely atrophic maxillary arch exhibits reduced denture bearing area and increased inter-ridge distance, thus, affecting retention of the complete denture. Such clinical situations necessitate the fabrication of a hollow complete denture to reduce the weight of the prosthesis and increase retention. This article describes a simple technique to fabricate a hollow maxillary complete denture using salt and thermoplastic poly (methyl methacrylate sheet. The vacuum-formed thermoplastic matrix regulates the quantity of salt and determines its placement in the unpolymerized denture base material during the denture packing stage. The matrix lining the hollow cavity also aids to reinforce the hollow denture base.

  2. Hollow polymer microneedle array fabricated by photolithography process combined with micromolding technique.

    Science.gov (United States)

    Wang, Po-Chun; Wester, Brock A; Rajaraman, Swaminathan; Paik, Seung-Joon; Kim, Seong-Hyok; Allen, Mark G

    2009-01-01

    Transdermal drug delivery through microneedles is a minimally invasive procedure causing little or no pain, and is a potentially attractive alternative to intramuscular and subdermal drug delivery methods. This paper demonstrates the fabrication of a hollow microneedle array using a polymer-based process combining UV photolithography and replica molding techniques. The key characteristic of the proposed fabrication process is to define a hollow lumen for microfluidic access via photopatterning, allowing a batch process as well as high throughput. A hollow SU-8 microneedle array, consisting of 825mum tall and 400 mum wide microneedles with 15-25 mum tip diameters and 120 mum diameter hollow lumens was designed, fabricated and characterized.

  3. Mesoscale cavities in hollow-core waveguides for quantum optics with atomic ensembles

    Directory of Open Access Journals (Sweden)

    Haapamaki C.M.

    2016-08-01

    Full Text Available Single-mode hollow-core waveguides loaded with atomic ensembles offer an excellent platform for light–matter interactions and nonlinear optics at low photon levels. We review and discuss possible approaches for incorporating mirrors, cavities, and Bragg gratings into these waveguides without obstructing their hollow cores. With these additional features controlling the light propagation in the hollow-core waveguides, one could potentially achieve optical nonlinearities controllable by single photons in systems with small footprints that can be integrated on a chip. We propose possible applications such as single-photon transistors and superradiant lasers that could be implemented in these enhanced hollow-core waveguides.

  4. Calculation of shear strength of prestressed hollow core slabs by use of plastic theory

    DEFF Research Database (Denmark)

    Hoang, Linh Cao; Jørgensen, Henrik Brøner; Nielsen, Mogens Peter

    2014-01-01

    This paper deals with calculations of the shear capacity of precast, prestressed hollow core slabs. Such slabs are often used as floor systems in Building structures. A common way to produce hollow core slabs is to use the extrusion technique where long strips of slabs are extruded and thereafter...... saw-cut into units with the desirable length. For this reason, hollow core slabs are usually not shear reinforced and anchorage of the prestressing strands has to be established by bond. Hollow core slabs may therefore be more critical to shear and Anchorage failure than ordinary two-way spanning...... reinforced concrete slabs....

  5. Calculation of shear strength of prestressed hollow core slabs by use of plastic theory

    DEFF Research Database (Denmark)

    Hoang, Linh Cao; Jørgensen, H.G.; Nielsen, Mogens Peter

    2014-01-01

    Th is paper deals with calculations of the shear capacity of precast, prestressed hollow core slabs. Such slabs are often used as floor systems in building structures. A common way to produce hollow core slabs is to use the extrusion technique where long strips of slabs are extruded and thereafter...... saw-cut into units with the desirable length. For this reason, hollow core slabs are usually not shear reinforced and anchorage of the prestressing strands has to be established by bond. Hollow core slabs may therefore be more critical to shear and anchorage failure than ordinary two-way spanning...... reinforced concrete slabs....

  6. Metal oxide hollow nanoparticles formation by a single nanosecond pulsed laser ablation in liquid

    Science.gov (United States)

    Zhang, Tao; Wang, Zhen; Hwang, David J.

    2017-10-01

    In this study, the trend of metal oxide hollow nanoparticles formation is experimentally inspected by a single nanosecond pulsed laser ablation of a bulk metal material in water and/or ethanol. Analysis results by transmission electron microscope indicate that the hollow formation can be completed or initiated by a single nanosecond laser pulse, dictated by the diffusive thermo-chemical and/or bubble-assisted assembly mechanisms, depending on the surrounding liquid medium and laser parameters. The results not only provide experimental clues to unveiling complex mechanisms involved with the hollow formation by the multiple laser shots but also will contribute to improving the hollow particle production efficiency.

  7. Self-Templated Formation of Hollow Structures for Electrochemical Energy Applications.

    Science.gov (United States)

    Yu, Le; Wu, Hao Bin; Lou, Xiong Wen David

    2017-02-21

    The rational design and synthesis of hollow structured functional materials are of great significance as both fundamental challenges in materials science and practical solutions for efficient energy utilization in modern society. The unique structural features of hollow functional materials bring outstanding electrochemical properties for both energy storage and electrocatalysis. However, conventional templating methods are normally less efficient in constructing hollow structures with desirable compositions and architectures. In the past decade, many novel synthetic approaches directly converting templates into hollow structures have been developed. Collectively termed as the "self-templated" strategy, it makes use of various physical/chemical processes to transform solid templates into hollow structures of target materials. Of particular note is the outstanding capability to construct complex hollow architectures of a wide variety of inorganic or hybrid functional materials, thus providing effective solutions for various electrochemical energy applications. In this Account, we present the recent progress in self-templated formation of hollow structures especially with complex architectures, and their remarkable performance in electrochemical energy-related technologies. These advanced self-templated methods are summarized as three categories. "Selective etching" creates hollow structures from solid templates of same materials by removing some of the internal parts, forming multishelled or unusual hollow architectures. "Outward diffusion" utilizes the relocation of mass in templates from inner region to outer region driven by various mechanisms, to construct hollow structures with multiple or hierarchical shells. "Heterogeneous contraction" typically applies to thermally decomposable templates and generates various hollow structures under nonequilibrium heating conditions. We further demonstrate some remarkable electrochemical properties of such hollow structures

  8. Enhanced catalytic activity of solid and hollow platinum-cobalt nanoparticles towards reduction of 4-nitrophenol

    Science.gov (United States)

    Krajczewski, Jan; Kołątaj, Karol; Kudelski, Andrzej

    2016-12-01

    Previous investigations of hollow platinum nanoparticles have shown that such nanostructures are more active catalysts than their solid counterparts towards the following electrochemical reactions: reduction of oxygen, evolution of hydrogen, and oxidation of borohydride, methanol and formic acid. In this work we show that synthesised using standard galvanic replacement reaction (with Co templates) hollow platinum nanoparticles exhibit enhanced catalytic activity also towards reduction of 4-nitrophenol by sodium borohydride in water. Unlike in the case of procedures involving hollow platinum catalysts employed so far to carry out this reaction it is not necessary to couple analysed platinum nanoparticles to the surface of an electrode. Simplification of the analyzed reaction may eliminate same experimental errors. We found that the enhanced catalytic activity of hollow Pt nanoparticles is not only connected with generally observed larger surface area of hollow nanostructures, but is also due to the contamination of formed hollow nanostructures with cobalt, from which sacrificial templates used in the synthesis of hollow Pt nanostrustures have been formed. Because using sacrificial templates is a typical method of synthesis of hollow metal nanostructures, formed hollow nanoparticles are probably often contaminated, which may significantly influence their catalytic activity.

  9. Pilot scale benzene stripping column testing: Review of test data and application to the ITP columns

    Energy Technology Data Exchange (ETDEWEB)

    Georgeton, G.K.; Gaughan, T.P.; Taylor, G.A.

    1993-09-10

    Radioactive cesium will be removed from aqueous high level waste (HLW) solutions by precipitation with sodium tetraphenyl borate (TPB) in the In-Tank Precipitation (ITP) process. Benzene is generated due to the radiolysis of TPB, and dissolves into the decontaminated salt solution (DSS) and into the water used to wash (WW) the precipitate. These solutions will be processed through stripping columns to reduce the benzene concentration to satisfy limits for disposal of the DSS and for temporary storage of the WW. A pilot scale testing program to evaluate the stripping column operation in support of ITP startup activities has been completed. Equipment and test plans were developed so that data obtained from the pilot scale testing would be directly applicable to full scale column operation and could be used to project hydraulic performance and stripping efficiency of both columns. A review of the test data indicate that the ITP stripping columns will be capable of reducing benzene concentrations in salt solutions to satisfy Saltstone and Tank 22 acceptance limits. An antifoam (AF) will be required to maintain the column differential pressure below the vendor recommendation of 40 inches wc so that design feed rates can be achieved. Additionally, the testing program indicated that the nitrogen rate can be decreased from the ITP column design rates and still satisfy benzene concentration requirements in the product.

  10. Seismic Behaviour of Synthetic-Frc Columns

    Science.gov (United States)

    Paultre, P.; Eid, R.

    2017-09-01

    Inclusion of short discrete fibres into the concrete mixture can increase the compressive strength and ductility of normal-strength concrete (NSC) and high-strength concrete (HSC) column specimens under compressive loading as already has been shown by several studies. Concrete design codes ensure ductile behaviour of columns by setting a requirement for a minimum amount of transverse steel reinforcement. Therefore, the inclusion of discrete short fibres into the concrete mixture combined with a reduced amount of lateral reinforcement can be an alternative to the latter full amount required by the codes. This paper presents tests that were performed on large-scale fibre-reinforced NSC circular columns under cyclic flexure and constant axial load simulating earthquake loading. The aim of this test program is to examine the combined confinement effect of steel or synthetic fibres and the transverse steel reinforcement type (spirals or hoops) on the structural performance of RC columns. The results show that in terms of ductility and energy dissipation, the behaviour of the fibre-reinforced concrete (FRC) specimens is improved compared to the nonfibrous ones. This behaviour is also predicted by the proposed confinement model which takes into account the mechanical and the geometrical properties of the concrete and the reinforcement as well as those of the fibres.

  11. Robust Geometric Control of a Distillation Column

    DEFF Research Database (Denmark)

    Kymmel, Mogens; Andersen, Henrik Weisberg

    1987-01-01

    A frequency domain method, which makes it possible to adjust multivariable controllers with respect to both nominal performance and robustness, is presented. The basic idea in the approach is that the designer assigns objectives such as steady-state tracking, maximum resonance peaks, bandwidth, m...... is used to examine and improve geometric control of a binary distillation column....

  12. Superior dislocation hip with anterior column acetabular

    African Journals Online (AJOL)

    abp

    2012-06-21

    Jun 21, 2012 ... Abstract. Superior variety of anterior dislocation of the hip is a rare injury. Its occurrence with acetabular fractures has been documented infrequently. We report a case of superior dislocation of the hip with anterior column acetabular fracture. Open reduction of the hip and internal fixation of the fracture was ...

  13. Thermal Analysis of LANL Ion Exchange Column

    Energy Technology Data Exchange (ETDEWEB)

    Laurinat, J.E.

    1999-06-16

    This document reports results from an ion exchange column heat transfer analysis requested by Los Alamos National Laboratory (LANL). The object of the analysis is to demonstrate that the decay heat from the Pu-238 will not cause resin bed temperatures to increase to a level where the resin significantly degrades.

  14. Density Gradient Columns for Chemical Displays.

    Science.gov (United States)

    Guenther, William B.

    1986-01-01

    Procedures for preparing density gradient columns for chemical displays are presented. They include displays illustrating acid-base reactions, metal ion equilibria, and liquid density. The lifetime of these metastable displays is surprising, some lasting for months in display cabinets. (JN)

  15. Synthesis and applications of monolithic HPLC columns

    Science.gov (United States)

    Liang, Chengdu

    Silica and carbon monolithic columns were synthesized and modified for liquid chromatography applications. Column configurations and cladding techniques were investigated in detail. Three novel approaches have been developed for the synthesis of bimodal porous rods. Out of these three methods, gel-casting was adopted for the synthesis of silica monoliths with ordered mesopores and uniform macropores; the use of colloidal templates and dual phase separation has been successfully implemented for the synthesis of carbon monoliths with well-controlled meso- and macro- porosities. The formation of mesopores in carbon materials has been further studied in the microphase separation of block copolymers. Electrochemical modification of carbon monoliths was discovered to be an efficient method for converting covalently bonded functionalities to carbon monoliths. N,N'-diethylaminobenzene has been attached to carbon surface for the separation of proteins and protein digests. The performances of carbon-based monolithic columns were studied intensely through frontal analysis and Van Deemter plot. Temperature and pressure effects were also investigated in carbon-based columns. The density of bonding on the modified carbon monoliths was characterized by thermogravimetric analysis.

  16. Chief Editor's column/Science Smiles

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 4. Chief Editor's column / Science Smiles. R K Laxman. Science Smiles Volume 1 Issue 4 April 1996 pp 4-4. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/001/04/0004-0004. Author Affiliations.

  17. [Spondylosis: diseases of the vertebral column].

    Science.gov (United States)

    Pérez, Amador Schüller

    2008-01-01

    Frequent and transcendent diseases for the difficulties of his diagnosis and treatment. The components of the vertebral column, vertebral bodies, discs and unvertebral joints, spondylosis ligaments must be considered to be a functional Unit. The Patology of each one of their parts concerns or reverberates in others.

  18. Rationally fabricating hollow particles of complex oxides by a templateless hydrothermal route: the case of single-crystalline SrHfO3 hollow cuboidal nanoshells.

    Science.gov (United States)

    Ye, Tiannan; Dong, Zhenghong; Zhao, Yongnan; Yu, Jianguo; Wang, Fengqin; Zhang, Lingling; Zou, Yongcun

    2011-03-21

    Based on the theory of sol-gel science, perovskite SrHfO(3) hollow cuboidal particles with tunable sizes were rationally synthesized by templateless hydrothermal reactions in KOH solutions. The concentrated KOH solution not only elevated the supersaturation of the reactants to promote the grain growth of SrHfO(3) but also controlled the aggregated particle sizes by compressing the electrical double layers of the primary particulates. The following Ostwald ripening process produced hollow particles with sizes ranging from submicrometer to hundred nanometre. The HRTEM image and SAED pattern revealed the single crystal nature of each hollow cuboidal nanoshell. The KOH concentration and reaction time related experiments confirmed that the formation of SrHfO(3) hollow cuboidal nanoshell was driven by the Ostwald ripening process and followed our assumption. The particles experienced solid, core-shell and hollow morphologies as the reaction proceeded. Also, the formation of SrHfO(3) hollow cuboidal nanoshells favored high reaction temperature which initiated and accelerated the ripening process. The as-prepared hollow cuboidal nanoshells displayed blue light emission under UV laser excitation at room temperature. After calcination, the photoluminescence intensity declined due to the improvement of crystallinity.

  19. [Study on Hollow Brick Wall's Surface Temperature with Infrared Thermal Imaging Method].

    Science.gov (United States)

    Tang, Ming-fang; Yin, Yi-hua

    2015-05-01

    To address the characteristic of uneven surface temperature of hollow brick wall, the present research adopts soft wares of both ThermaCAM P20 and ThermaCAM Reporter to test the application of infrared thermal image technique in measuring surface temperature of hollow brick wall, and further analyzes the thermal characteristics of hollow brick wall, and building material's impact on surface temperature distribution including hollow brick, masonry mortar, and so on. The research selects the construction site of a three-story-high residential, carries out the heat transfer experiment, and further examines the exterior wall constructed by 3 different hollow bricks including sintering shale hollow brick, masonry mortar and brick masonry. Infrared thermal image maps are collected, including 3 kinds of sintering shale hollow brick walls under indoor heating in winter; and temperature data of wall surface, and uniformity and frequency distribution are also collected for comparative analysis between 2 hollow bricks and 2 kinds of mortar masonry. The results show that improving heat preservation of hollow brick aid masonry mortar can effectively improve inner wall surface temperature and indoor thermal environment; non-uniformity of surface temperature decreases from 0. 6 to 0. 4 °C , and surface temperature frequency distribution changes from the asymmetric distribution into a normal distribution under the condition that energy-saving sintering shale hollow brick wall is constructed by thermal mortar replacing cement mortar masonry; frequency of average temperature increases as uniformity of surface temperature increases. This research provides a certain basis for promotion and optimization of hollow brick wall's thermal function.

  20. Numerical Study of Stability of Cold Formed Built-Up Columns

    OpenAIRE

    Zaharia, Raul; Dubina, Dan

    2005-01-01

    By means of numerical simulations using ANSYS program, the stability behavior of built-up columns made of back-to-back cold formed C sections, bolted together by C stitches, is analyzed. Comparison of the numerical analysis with the results obtained using two different design methods and experimental results are provided.

  1. Numerical Study of Stability of Cold Formed Built-Up Columns

    Directory of Open Access Journals (Sweden)

    Raul Zaharia

    2005-01-01

    Full Text Available By means of numerical simulations using ANSYS program, the stability behavior of built-up columns made of back-to-back cold formed C sections, bolted together by C stitches, is analyzed. Comparison of the numerical analysis with the results obtained using two different design methods and experimental results are provided.

  2. 40 CFR 799.6784 - TSCA water solubility: Column elution method; shake flask method.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 31 2010-07-01 2010-07-01 true TSCA water solubility: Column elution method; shake flask method. 799.6784 Section 799.6784 Protection of Environment ENVIRONMENTAL PROTECTION... and analyzed by the chosen method. (ii) Fractions from the middle eluate range where the...

  3. Behaviour of Steel Tubular Stub and Slender Columns in-filled with ...

    African Journals Online (AJOL)

    In this paper, an attempt was made with steel tubular columns in-filled with recycled aggregate concrete instead of normal conventional concrete so as to utilize the construction and demolition debris for effective recycling in construction works. The behaviour of circular and square concrete-filled steel tubular sections ...

  4. Pt monolayer shell on hollow Pd core electrocatalysts: Scale up synthesis, structure, and activity for the oxygen reduction reaction

    Directory of Open Access Journals (Sweden)

    Vukmirovic Miomir B.

    2013-01-01

    Full Text Available We report on synthesis, characterization and the oxygen reduction reaction (ORR kinetics of Pt monolayer shell on Pd(hollow, or Pd-Au(hollow core electrocatalysts. Comparison between the ORR catalytic activity of the electrocatalysts with hollow cores and those of Pt solid and Pt hollow nanoparticles has been obtained using the rotating disk electrode technique. Hollow nanoparticles were made using Ni or Cu nanoparticles as sacrificial templates. The Pt ORR specific and mass activities of the electrocatalysts with hollow cores were found considerably higher than those of the electrocatalysts with the solid cores. We attribute this enhanced Pt activity to the smooth surface morphology and hollow-induced lattice contraction, in addition to the mass-saving geometry of hollow particles.

  5. Hollow fiber membrane lumen modified by polyzwitterionic grafting

    KAUST Repository

    Le, Ngoc Lieu

    2016-08-24

    In this study, we demonstrate an effective way to modify the lumen of polyetherimide hollow fibers by grafting zwitterionic poly(sulfobetaine) to increase the membrane resistance to fouling. Surface-selective grafting of the protective hydrogel layers has been achieved in a facile two-step process. The first step is the adsorption of a macromolecular redox co-initiator on the lumen-side surface of the membrane, which in the second step, after flushing the lumen of the membrane with a solution comprising monomers and a complementary redox initiator, triggers the in situ cross-linking copolymerization at room temperature. The success of grafting reaction has been verified by the surface elemental analyses using X-ray photoelectron spectroscopy (XPS) and the surface charge evaluation using zeta potential measurements. The hydrophilicity of the grafted porous substrate is improved as indicated by the change of contact angle value from 44° to 30°, due to the hydration layer on the surface produced by the zwitterionic poly(sulfobetaine). Compared to the pristine polyetherimide (PEI) substrate, the poly(sulfobetaine) grafted substrates exhibit high fouling resistance against bovine serum albumin (BSA) adsorption, E. coli attachment and cell growth on the surface. Fouling minimization in the lumen is important for the use of hollow fibers in different processes. For instance, it is needed to preserve power density of pressure-retarded osmosis (PRO). In high-pressure PRO tests, a control membrane based on PEI with an external polyamide selective layer was seriously fouled by BSA, leading to a high water flux drop of 37%. In comparison, the analogous membrane, whose lumen was modified with poly(sulfobetaine), not only had a less water flux decline but also had better flux recovery, up to 87% after cleaning and hydraulic pressure impulsion. Clearly, grafting PRO hollow fiber membranes with zwitterionic polymeric hydrogels as a protective layer potentially sustains PRO

  6. Spray Modeling for Outwardly-Opening Hollow-Cone Injector

    KAUST Repository

    Sim, Jaeheon

    2016-04-05

    The outwardly-opening piezoelectric injector is gaining popularity as a high efficient spray injector due to its precise control of the spray. However, few modeling studies have been reported on these promising injectors. Furthermore, traditional linear instability sheet atomization (LISA) model was originally developed for pressure swirl hollow-cone injectors with moderate spray angle and toroidal ligament breakups. Therefore, it is not appropriate for the outwardly-opening injectors having wide spray angles and string-like film structures. In this study, a new spray injection modeling was proposed for outwardly-opening hollow-cone injector. The injection velocities are computed from the given mass flow rate and injection pressure instead of ambiguous annular nozzle geometry. The modified Kelvin-Helmholtz and Rayleigh-Taylor (KH-RT) breakup model is used with adjusted initial Sauter mean diameter (SMD) for modeling breakup of string-like structure. Spray injection was modeled using a Lagrangian discrete parcel method within the framework of commercial CFD software CONVERGE, and the new model was implemented through the user-defined functions. A Siemens outwardly-opening hollow-cone spray injector was characterized and validated with existing experimental data at the injection pressure of 100 bar. It was found that the collision modeling becomes important in the current injector because of dense spray near nozzle. The injection distribution model showed insignificant effects on spray due to small initial droplets. It was demonstrated that the new model can predict the liquid penetration length and local SMD with improved accuracy for the injector under study.

  7. Towards implementation of hollow core fibres for surgical applications

    Science.gov (United States)

    Urich, Artur; Delmonte, Tiina; Maier, Robert R. J.; Hand, Duncan P.; Shephard, Jonathan D.

    2011-03-01

    Presently, there is no truly flexible delivery system for light from Er:Yag medical lasers (λ = 2.94 μm) which allows surgeons to work unrestricted. Instead, either a relatively inflexible articulated arm or multi-mode fibre, limited to large bend radii, must be used. One proposed solution is the use of novel types of hollow core - band gap optical fibre rather than more traditional large area solid core fibres. In these silica based fibres, material absorption and damage limitations are overcome by using a photonic band gap structure. This confines radiation to lower order modes, that are guided in a small diameter air core. The overall fibre diameter is also smaller, which allows a smaller mechanical bend radius. Together with the guidance in air, this improves the laser power damage threshold. However, there are many practical hurdles that must be overcome to achieve a robust system for use in surgery. One of the main problems is that the fibre structure is hollow and ingress of dust, vapour, fluids and other contaminants need to be prevented to ensure safe in-vivo usage. Additionally, any infibre contamination will degrade the laser damage resistance of the fibre leading to potential catastrophic failure. The development of a robust and hermetically sealed end cap for the fibre, without adversely affecting beam quality or damage threshold is an essential prerequisite for the safe and efficient use of such fibres in surgery. In this paper we report on the progress on implementing end caps and describe novel methods of sealing off these hollow fibres in particular for surgical applications. This work will demonstrate that the use of these superior fibres with low loss guidance at 2.94 μm in surgery is feasible.

  8. Hollow Fiber Membrane Contactors for CO2 Capture: Modeling and Up-Scaling to CO2 Capture for an 800 MWe Coal Power Station

    Directory of Open Access Journals (Sweden)

    Kimball Erin

    2014-11-01

    Full Text Available A techno-economic analysis was completed to compare the use of Hollow Fiber Membrane Modules (HFMM with the more conventional structured packing columns as the absorber in amine-based CO2 capture systems for power plants. In order to simulate the operation of industrial scale HFMM systems, a two-dimensional model was developed and validated based on results of a laboratory scale HFMM. After successful experiments and validation of the model, a pilot scale HFMM was constructed and simulated with the same model. The results of the simulations, from both sizes of HFMM, were used to assess the feasibility of further up-scaling to a HFMM system to capture the CO2 from an 800 MWe power plant. The system requirements – membrane fiber length, total contact surface area, and module volume – were determined from simulations and used for an economic comparison with structured packing columns. Results showed that a significant cost reduction of at least 50% is required to make HFMM competitive with structured packing columns. Several factors for the design of industrial scale HFMM require further investigation, such as the optimal aspect ratio (module length/diameter, membrane lifetime, and casing material and shape, in addition to the need to reduce the overall cost. However, HFMM were also shown to have the advantages of having a higher contact surface area per unit volume and modular scale-up, key factors for applications requiring limited footprints or flexibility in configuration.

  9. Hollow-core infrared fiber incorporating metal-wire metamaterial

    DEFF Research Database (Denmark)

    Yan, Min; Mortensen, Asger

    2009-01-01

    waveguides usually use a layer of metallic coating on the inner wall of the waveguide. Such a metallic layer, though reflective, still absorbs guided light significantly due to its finite Ohmic loss, especially for transverse-magnetic (TM) light. In this paper, we show that metal-wire based metamaterials may......Infrared (IR) light is considered important for short-range wireless communication, thermal sensing, spectroscopy, material processing, medical surgery, astronomy etc. However, IR light is in general much harder to transport than optical light or microwave radiation. Existing hollow-core IR...

  10. The magnetic properties of the hollow cylindrical ideal remanence magnet

    DEFF Research Database (Denmark)

    Bjørk, Rasmus

    2016-01-01

    We consider the magnetic properties of the hollow cylindrical ideal remanence magnet. This magnet is the cylindrical permanent magnet that generates a uniform field in the cylinder bore, using the least amount of magnetic energy to do so. The remanence distribution of this magnet is derived...... and the generated field is compared to that of a Halbach cylinder of equal dimensions. The ideal remanence magnet is shown in most cases to generate a significantly lower field than the equivalent Halbach cylinder, although the field is generated with higher efficiency. The most efficient Halbach cylinder is shown...... to generate a field exactly twice as large as the equivalent ideal remanence magnet....

  11. Mathematical modelling of dextran filtration through hollow fibre membranes

    DEFF Research Database (Denmark)

    Vinther, Frank; Pinelo, Manuel; Brøns, Morten

    2014-01-01

    In this paper we present a mathematical model of an ultrafiltration process. The results of the model are produced using standard numerical techniques with Comsol Multiphysics. The model describes the fluid flow and separation in hollow fibre membranes. The flow of solute and solvent within...... either increase or decrease as a function of pressure. The influence of a concentration dependent viscosity is to increase the concentration on the membrane surface. This leads to a decrease in both the observed and the intrinsic rejection, when compared to a constant viscosity. For small values...

  12. Modeling of equilibrium hollow objects stabilized by electrostatics.

    Science.gov (United States)

    Mani, Ethayaraja; Groenewold, Jan; Kegel, Willem K

    2011-05-18

    The equilibrium size of two largely different kinds of hollow objects behave qualitatively differently with respect to certain experimental conditions. Yet, we show that they can be described within the same theoretical framework. The objects we consider are 'minivesicles' of ionic and nonionic surfactant mixtures, and shells of Keplerate-type polyoxometalates. The finite-size of the objects in both systems is manifested by electrostatic interactions. We emphasize the importance of constant charge and constant potential boundary conditions. Taking these conditions into account, indeed, leads to the experimentally observed qualitatively different behavior of the equilibrium size of the objects.

  13. Modeling of equilibrium hollow objects stabilized by electrostatics

    Energy Technology Data Exchange (ETDEWEB)

    Mani, Ethayaraja; Groenewold, Jan; Kegel, Willem K, E-mail: w.k.kegel@uu.nl [Van' t Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute, Utrecht University, Padualaan 8, 3584 CH Utrecht (Netherlands)

    2011-05-18

    The equilibrium size of two largely different kinds of hollow objects behave qualitatively differently with respect to certain experimental conditions. Yet, we show that they can be described within the same theoretical framework. The objects we consider are 'minivesicles' of ionic and nonionic surfactant mixtures, and shells of Keplerate-type polyoxometalates. The finite-size of the objects in both systems is manifested by electrostatic interactions. We emphasize the importance of constant charge and constant potential boundary conditions. Taking these conditions into account, indeed, leads to the experimentally observed qualitatively different behavior of the equilibrium size of the objects.

  14. Nonlinear modes in the hollow-cores of liquid vortices

    KAUST Repository

    Amaouche, Mustapha

    2013-09-01

    In this paper we show that the wave patterns observed on the interfacial contours of hollow-core vortices, produced within a shallow layer of fluid contained in stationary cylinder and driven by a rotating disk at the bottom [G.H. Vatistas, H.A. Abderrahmane, M.H. Kamran Siddiqui, Experimental confirmation of Kelvin\\'s equilibria, Phys. Rev. Lett. 100 (2008) 174503-174504], can be described as travelling cnoidal waves. These rotating stationary waves are obtained as solutions of a Korteweg-de Vries type equation, in accordance with the geometrical and kinematic characteristics of the observed polygonal patterns. © 2013 Elsevier Masson SAS. All rights reserved.

  15. Fractional Fourier transform for an anomalous hollow beam.

    Science.gov (United States)

    Wang, Kuilong; Zhao, Chengliang

    2009-12-01

    Based on the definition of fractional Fourier transform (FRT), the propagation properties of an anomalous hollow beam (AHB) through the FRT have been investigated in detail. An analytical formula is derived for the FRT of an AHB. By using the derived formula, the properties of an AHB in the FRT plane are illustrated numerically. The results show that the properties of an AHB in the FRT plane are closely related to the parameters of the beam and the fractional order p. The derived formula provides an effective and convenient way for analyzing and calculating the FRT of an AHB.

  16. An experiment in heat conduction using hollow cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Ortuno, M; Marquez, A; Gallego, S; Neipp, C; Belendez, A, E-mail: a.belendez@ua.es [Departamento de Fisica, IngenierIa de Sistemas y TeorIa de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)

    2011-07-15

    An experimental apparatus was designed and built to allow students to carry out heat conduction experiments in hollow cylinders made of different materials, as well as to determine the thermal conductivity of these materials. The evolution of the temperature difference between the inner and outer walls of the cylinder as a function of time is analysed, and when the process reaches the steady state regime the thermal conductivity can be easily calculated. Several materials such as wood, plastic and metals are considered and the values of their thermal conductivities, obtained experimentally, are compared with those given in the reference list.

  17. Polarization spectroscopy of atomic erbium in a hollow cathode lamp

    Science.gov (United States)

    Ang’ong’a, Jackson; Gadway, Bryce

    2018-02-01

    In this work we perform polarization spectroscopy of erbium atoms in a hollow cathode lamp (HCL). We review the theory behind Doppler-free polarization spectroscopy, theoretically model the expected erbium polarization spectra, and compare the numerically calculated spectra to our experimental data. We further analyze the dependence of the measured spectra on the HCL current and the peak intensities of our pump and probe lasers to determine conditions. Applications include wavelength stabilization of diode laser radiation to the 400.91 nm erbium transition.

  18. Optical frequency standard using acetylene-filled hollow-core photonic crystal fibers

    DEFF Research Database (Denmark)

    Triches, Marco; Michieletto, Mattia; Hald, Jan

    2015-01-01

    Gas-filled hollow-core photonic crystal fibers are used to stabilize a fiber laser to the 13C2H2 P(16) (ν1+ν3) transition at 1542 nm using saturated absorption. Four hollow-core fibers with different crystal structure are compared in terms of long term lock-point repeatability and fractional freq...

  19. Sweep gas membrane distillation in a membrane contactor with metallic hollow fibers

    NARCIS (Netherlands)

    Shukla, Sushumna; Benes, Nieck Edwin; Vankelecom, I.F.J.; Mericq, J.P.; Belleville, M.P.; Hengl, N.; Sanchez Marcano, Jose

    2015-01-01

    This work revolves around the use of porous metal hollow fibers in membrane distillation. Various stages are covered, starting from membrane synthesis up to the testing of a pilot scale membrane module. Mechanically stable metal hollow fibers have been synthesized by phase inversion of a stainless

  20. Hollow fibre membrane contactor as a gas-liquid model contactor

    NARCIS (Netherlands)

    Dindore, V.Y.; Brilman, Derk Willem Frederik; Versteeg, Geert

    2005-01-01

    Microporous hollow fiber gas–liquid membrane contactors have a fixed and well-defined gas–liquid interfacial area. The liquid flow through the hollow fiber is laminar, thus the liquid side hydrodynamics are well known. This allows the accurate calculation of the fiber side physical mass transfer

  1. Hollow fiber membrane contactor as a gas-liquid model contactor

    NARCIS (Netherlands)

    Dindore, V. Y.; Brilman, D. W. F.; Versteeg, G. F.

    2005-01-01

    Microporous hollow fiber gas-liquid membrane contactors have a fixed and well-defined gas-liquid interfacial area. The liquid flow through the hollow fiber is laminar, thus the liquid side hydrodynamics are well known. This allows the accurate calculation of the fiber side physical mass transfer

  2. Solvent-free synthesis of nanosized hierarchical sodalite zeolite with a multi-hollow polycrystalline structure

    KAUST Repository

    Zeng, Shangjing

    2016-08-03

    A solvent-free route is developed for preparing nanoscale sodalite zeolite with a multi-hollow structure. Furthermore, the synthesis of nanosized hollow sodalite polycrystalline aggregates with a mesoporous structure and high crystallinity is investigated by adding an organosilane surfactant as a mesopore-generating agent.

  3. Synthesis of hollow asymmetrical silica dumbbells with a movable inner core

    NARCIS (Netherlands)

    Nagao, D.; van Kats, C.M.; Hayasaka, K.; Sugimoto, M.; Konno, M.; Imhof, A.; van Blaaderen, A.

    2010-01-01

    Hollow asymmetrical silica dumbbells containing a movable inner core were fabricated by a template-assisted method. Three different templates were employed for the fabrication of the hollow asymmetrical dumbbells. For the preparation of the first template, silica particles were uniformly covered

  4. Investigation of the Rolling Motion of a Hollow Cylinder Using a Smartphone's Digital Compass

    Science.gov (United States)

    Wattanayotin, Phattara; Puttharugsa, Chokchai; Khemmani, Supitch

    2017-01-01

    This study used a smartphone's digital compass to observe the rolling motion of a hollow cylinder on an inclined plane. The smartphone (an iPhone 4s) was attached to the end of one side of a hollow cylinder to record the experimental data using the SensorLog application. In the experiment, the change of angular position was measured by the…

  5. Multimode laser emission from dye-doped hollow polymer optical fibre

    Indian Academy of Sciences (India)

    2014-02-09

    Feb 9, 2014 ... Home; Journals; Pramana – Journal of Physics; Volume 82; Issue 2. Multimode laser emission from dye-doped hollow polymer optical fibre ... Well-resolved multimode laser emission was observed for the first time from a freestanding microring cavity based on Rhodamine B dye-doped hollow polymer ...

  6. Charged micropollutant removal with hollow fiber nanofiltration membranes based on polycation/polyzwitterion/polyanion multilayers

    NARCIS (Netherlands)

    de Grooth, Joris; Reurink, Dennis Maik; Ploegmakers, J.; de Vos, Wiebe Matthijs; Nijmeijer, Dorothea C.

    2014-01-01

    Hollow fiber nanofiltration membranes can withstand much higher foulant concentrations than their spiral wound counterparts and can be used in water purification without pretreatment. Still, the preparation of hollow fiber nanofiltration membranes is much less established. In this work, we demonstrate

  7. Southern Appalachian hillslope erosion rates measured by soil and detrital radiocarbon in hollows

    Science.gov (United States)

    T.C. Hales; K.M. Scharer; R.M. Wooten

    2012-01-01

    Understanding the dynamics of sediment generation and transport on hillslopes provides important constraints on the rate of sediment output from orogenic systems. Hillslope sediment fluxes are recorded by organic material found in the deposits infilling unchanneled convergent topographic features called hollows. This study describes the first hollow infilling rates...

  8. High-power picosecond pulse delivery through hollow core photonic band gap fibers

    DEFF Research Database (Denmark)

    Michieletto, Mattia; Johansen, Mette Marie; Lyngsø, Jens Kristian

    2015-01-01

    We demonstrated robust and bend insensitive fiber delivery of high power pulsed laser with diffraction limited beam quality for two different kind of hollow core photonic band gap fibers......We demonstrated robust and bend insensitive fiber delivery of high power pulsed laser with diffraction limited beam quality for two different kind of hollow core photonic band gap fibers...

  9. Facile synthesis of magnetic hierarchical copper silicate hollow nanotubes for efficient adsorption and removal of hemoglobin.

    Science.gov (United States)

    Zhang, Min; Wang, Baoyu; Zhang, Yanwei; Li, Weizhen; Gan, Wenjun; Xu, Jingli

    2016-01-21

    This study reports the fabrication of magnetic copper silicate hierarchical hollow nanotubes, which are featured by a tailored complex wall structure and high surface area. Moreover, they exhibit excellent performance as an easily recycled adsorbent for protein separation. Particularly, this strategy can be extended as a general method to prepare other magnetic metal silicate hollow nanotubes.

  10. Preliminary Design of Reactive Distillation Columns

    OpenAIRE

    Thery, Raphaële; Meyer, Xuân-Mi; Joulia, Xavier; Meyer, Michel

    2005-01-01

    A procedure that combines feasibility analysis, synthesis and design of reactive distillation columns is introduced. The main interest of this methodology lies on a progressive introduction of the process complexity. From minimal information concerning the physicochemical properties of the system, three steps lead to the design of the unit and the specification of its operating conditions. Most of the methodology exploits and enriches approaches found in the literature. Each step is des...

  11. A comparison of the low frequency electrical signatures of iron oxide versus calcite precipitation in granular zero valent iron columns.

    Science.gov (United States)

    Wu, Yuxin; Slater, Lee; Versteeg, Roelof; LaBrecque, Douglas

    2008-01-28

    Geophysical methods have been proposed as technologies for non-invasively monitoring geochemical alteration in permeable reactive barriers (PRBs). We conducted column experiments to investigate the effect of mineralogy on the electrical signatures resulting from iron corrosion and mineral precipitation in Fe0 columns using (a) Na2SO4, and (b) NaHCO3 plus CaCl2 mixture, solutions. At the influent interface where the reactions were most severe, a contrasting time-lapse electrical response was observed between the two columns. Solid phase analysis confirmed the formation of corrosion halos and increased mineralogical complexity in the corroded sections of the columns compared to the minimal/non-corroded sections. We attribute the contrasting time-lapse signatures to the differences in the electrical properties of the mineral phases formed within the two columns. While newly precipitated/transformed polarizable and semi-conductive iron oxides (mostly magnetite and green rust) increase the polarization and conductivity of the sulfate column, the decrease of both parameters in the bicarbonate column is attributed to the precipitation of non-polarizable and non-conductive calcite. Our results show that precipitate mineralogy is an important factor influencing the electrical properties of the corroded iron cores and must be considered if electrical geophysical methods are to be developed to monitor PRB barrier corrosion processes in situ.

  12. Comparison of monolithic silica and polymethacrylate capillary columns for LC.

    Science.gov (United States)

    Moravcová, Dana; Jandera, Pavel; Urban, Jiri; Planeta, Josef

    2004-07-01

    Organic polymer monolithic capillary columns were prepared in fused-silica capillaries by radical co-polymerization of ethylene dimethacrylate and butyl methacrylate monomers with azobisisobutyronitrile as initiator of the polymerization reaction in the presence of various amounts of porogenic solvent mixtures and different concentration ratios of monomers and 1-propanol, 1,4-butanediol, and water. The chromatographic properties of the organic polymer monolithic columns were compared with those of commercial silica-based particulate and monolithic capillary and analytical HPLC columns. The tests included the determination of H-u curves, column permeabilities, pore distribution by inversed-SEC measurements, methylene and polar selectivities, and polar interactions with naphthalenesulphonic acid test samples. Organic polymer monolithic capillary columns show similar retention behaviour to chemically bonded alkyl silica columns for compounds with different polarities characterized by interaction indices, Ix, but have lower methylene selectivities and do not show polar interactions with sulphonic acids. The commercial capillary and analytical silica gel-based monolithic columns showed similar selectivities and provided symmetrical peaks, indicating no significant surface heterogeneities. To allow accurate characterization of the properties of capillary monolithic columns, the experimental data should be corrected for extra-column contributions. With 0.3 mm ID capillary columns, corrections for extra-column volume contributions are sufficient, but to obtain true information on the efficiency of 0.1 mm ID capillary columns, the experimental bandwidths should be corrected for extra-column contributions to peak broadening.

  13. Modular evolution of the Cetacean vertebral column.

    Science.gov (United States)

    Buchholtz, Emily A

    2007-01-01

    Modular theory predicts that hierarchical developmental processes generate hierarchical phenotypic units that are capable of independent modification. The vertebral column is an overtly modular structure, and its rapid phenotypic transformation in cetacean evolution provides a case study for modularity. Terrestrial mammals have five morphologically discrete vertebral series that are now known to be coincident with Hox gene expression patterns. Here, I present the hypothesis that in living Carnivora and Artiodactyla, and by inference in the terrestrial ancestors of whales, the series are themselves components of larger precaudal and caudal modular units. Column morphology in a series of fossil and living whales is used to predict the type and sequence of developmental changes responsible for modification of that ancestral pattern. Developmental innovations inferred include independent meristic additions to the precaudal column in basal archaeocetes and basilosaurids, stepwise homeotic reduction of the sacral series in protocetids, and dissociation of the caudal series into anterior tail and fluke subunits in basilosaurids. The most dramatic change was the novel association of lumbar and anterior caudal vertebrae in a module that crosses the precaudal/caudal boundary. This large unit is defined by shared patterns of vertebral morphology, count, and size in all living whales (Neoceti).

  14. Observations and Measurements of Anomalous Hollow Electron Beams in a Storage Ring

    CERN Document Server

    Wu, Y K; Wu, Juhao

    2005-01-01

    This paper reports first observations and measurements of anomalous hollow electron beams in a storage ring. In a lattice with a negative chromaticity, hollow electron beams consisting of a solid core beam inside and a large ring beam outside have been created and studied in the Duke storage ring. We report the detailed measurements of the hollow beam phenomenon, including its distinct image pattern, spectrum signature, and its evolution with time. By capturing the post-instability bursting beam, the hollow beam is a unique model system for studying the transverse instabilities, in particular, the interplay of the wake field and the lattice nonlinearity. In addition, the hollow beam can be used as a powerful tool to study the linear and nonlinear particle dynamics in the storage ring.

  15. Facile synthesis of hollow nano-spheres and hemispheres of cobalt by polyol reduction

    Energy Technology Data Exchange (ETDEWEB)

    Yang Haitao; Shen Chengmin; Song Ningning; Wang Yumei; Yang Tianzhong; Gao Hongjun; Cheng Zhaohua, E-mail: htyang@aphy.iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2010-09-17

    The hydrophilic hollow nano-spheres and hemispheres of Co are synthesized via ethylene glycol reduction of cobalt acetate in the presence of PVP and Pd nano-particle seeds. The dimensions of the hollow core can be tuned from 100 to 300 nm by controlling the amount of Pd nano-particle seeds. The morphology of the hollow materials strongly depends on the molar ratio of the amide unit in PVP over Co and the M{sub w} of PVP. The hollow structure is formed when the ratio falls in the range 1-1.5 and the M{sub w} is over 40 000. Based on the experimental data, a possible formation mechanism of Co hollow spheres is proposed.

  16. Dual layer hollow fiber sorbents for trace H2S removal from gas streams

    KAUST Repository

    Bhandari, Dhaval A.

    2013-05-01

    Hollow fiber sorbents are pseudo monolithic materials with potential use in various adsorption based applications. Dual layer hollow fiber sorbents have the potential to allow thermal regeneration without direct contact of the regeneration fluid with the sorbent particles. This paper considers the application of dual layer hollow fiber sorbents for a case involving trace amounts of H2S removal from a simulated gas stream and offers a comparison with single layer hollow fiber sorbents. The effect of spin dope composition and core layer zeolite loading on the gas flux, H2S transient sorption capacity and pore structure are also studied. This work can be used as a guide to develop and optimize dual layer hollow fiber sorbent properties beyond the specific example considered here. © 2013 Elsevier Ltd.

  17. Effect of wall thickness and material on flexural fatigue of hollow rolling elements

    Science.gov (United States)

    Bamberger, E. N.; Parker, R. J.

    1978-01-01

    Hollow cylindrical bars were tested in a rolling-contact fatigue tester to determine the effects of material and outside diameter to inside diameter (OD/ID) ratios on fatigue failure mode and subsequent failure propagation. The range of applied loads with OD/ID ratios of 2.0, 1.6, 1.4, and 1.2 resulted in maximum tangential tensile stresses ranging from 165 to 655 MPa at the bore surface. Flexural failures of the hollow test bars occurred when this bore stress was 490 MPa or greater with AISI 52100 hollow bars and 338 MPa or greater with AISI M-50 hollow bars. Good correlation was obtained in relating the failures of these hollow bars with flexural failures of drilled balls from full-scale bearing test published previously.

  18. Advanced postbuckling and imperfection sensitivity of the elastic-plastic Shanley-Hutchinson model column

    DEFF Research Database (Denmark)

    Christensen, Claus Dencker; Byskov, Esben

    2008-01-01

    The postbuckling behavior and imperfection sensitivity of the Shanley-Hutchinson plastic model column introduced by Hutchinson in 1973 are examined. The study covers the initial, buckled state and the advanced postbuckling regime of the geometrically perfect realization as well as its sensitivity...... postbuckling state. Finally, it is shown that the maximum load is often considerably larger than the bifurcation load. Section 2 presents a new asymptotic expansion which is utilized to study the imperfection sensitivity of the Shanley-Hutchinson elastic-plastic model column. The method is mainly characterized...

  19. A simple way to establish a dual-core hollow fiber for laser surgery applications

    Science.gov (United States)

    Jing, Chengbin; Kendall, Wesley; Harrington, James A.

    2016-03-01

    A dual-core hollow fiber has two separate cores for propagation of light. Such a fiber can have some good applications in laser surgery. The dual-core guide can transmit an infrared laser beam for cutting or ablation while a visible laser beam is simultaneously transmitted as a pilot or aiming beam. The traditional fabrication procedure for a dual-core hollow fiber involves chemical vapor deposition (CVD) growth on silica tubing of an inner cladding layer followed by the deposition of a low index polymer on the outside of the tubing. This will provide a hollow structure that has a clad-core-clad tube. This work provides an alternative approach which involves nesting of two hollow waveguides to establish a dual-core hollow fiber. An Ag/AgI hollow glass fiber is fabricated for transmitting CO2 laser. Another silica glass tube is selected carefully so that its inner diameter is just slightly larger than the outer diameter of the Ag/AgI hollow fiber. The outer surface of the as-selected glass tubing is coated with a low refractive index polymer. The Ag/AgI hollow fiber was inserted into the polymer coated silica glass tubing to establish an air or silicone oil gap between the two tubes. A visible laser beam is transmitted through the outer tube's core. The CO2 laser beam is transmitted through the inner Ag/AgI hollow fiber. The dual-core hollow fibers show good transmission for both the red aiming beam and the CO2 laser. Therefore this structure can be a good candidate for laser surgery applications.

  20. EX0904 Water Column Summary Report and Profile Data Collection

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX0904: Water Column Exploration Field...

  1. Multiple Steady-States in a Heat Integrated Distillation Column (HIDiC)

    OpenAIRE

    Kano, Manabu; Fukushima, Tomohiro; Makita, Hiroshi; Hasebe, Shinji

    2007-01-01

    A heat integrated distillation column (HIDiC) is a new and highly energy-efficient distillation process. In the present work, multiple steady-states in HIDiC are analyzed. In HIDiC, the pressure in the rectifying section is kept higher than that in the stripping section by using a compressor to enhance heat transfer from the rectifying section to the stripping section through the wall. Therefore, an energy balance, particularly the influence of the compressor, must be taken into account for t...

  2. Feasibility of hollow core fiber based optical lattice clock

    Science.gov (United States)

    Ilinova, Ekaterina; Babb, James F.; Derevianko, Andrei; Theoretical atomic; molecular physics group Team; Atomic; Molecular Physics Division Team

    2017-04-01

    The possibility of building the optical lattice clock based on the narrow 1S0 -3P0 transition in Hg and other alkaline-earth like atoms optically trapped inside the hollow core fiber has been studied. The general form of the long range atom-surface interaction potential at non-zero temperatures has been calculated for the hollow capillary geometry. The resulting 1S0 -3P0 transition frequency shift has been calculated for Sr and Hg atoms as a function of their position inside the capillary. Its dependence on the geometric parameters and optical properties of the capillary material has been analyzed. The resonant enhancement of the atom-surface interaction potential and radiative decay rate of the 3P0 state at certain parameters of the waveguide has been studied. For the silica capillary with inner radius Rin > 15 μm and thickness d 1 μm the atom surface interaction induced 1S0 -3P0 transition frequency shift on the capillary axis can be suppressed down to the level δν / ν <10-18 . The additional frequency shifts and atom loss from the optical trap due to the residual birefringence of the waveguide and collisions with the buffer gas molecules have been evaluated. University of Nevada, Reno.

  3. Hollow laser plasma self-confined microjet generation

    Science.gov (United States)

    Sizyuk, Valeryi; Hassanein, Ahmed; Center for Materials under Extreme Environment Team

    2017-10-01

    Hollow laser beam produced plasma (LPP) devices are being used for the generation of the self-confined cumulative microjet. Most important place by this LPP device construction is achieving of an annular distribution of the laser beam intensity by spot. An integrated model is being developed to detailed simulation of the plasma generation and evolution inside the laser beam channel. The model describes in two temperature approximation hydrodynamic processes in plasma, laser absorption processes, heat conduction, and radiation energy transport. The total variation diminishing scheme in the Lax-Friedrich formulation for the description of plasma hydrodynamic is used. Laser absorption and radiation transport models on the base of Monte Carlo method are being developed. Heat conduction part on the implicit scheme with sparse matrixes using is realized. The developed models are being integrated into HEIGHTS-LPP computer simulation package. The integrated modeling of the hollow beam laser plasma generation showed the self-confinement and acceleration of the plasma microjet inside the laser channel. It was found dependence of the microjet parameters including radiation emission on the hole and beam radiuses ratio. This work is supported by the National Science Foundation, PIRE project.

  4. Properties of dry masonry mixtures based on hollow aluminosilicate microspheres

    Directory of Open Access Journals (Sweden)

    Semenov Vyacheslav

    2017-01-01

    Full Text Available At present, there is a steady increase in the volume of housing construction in the Russian Federation. The modern trends in the field of energy and resource saving determine the need of the use of efficient building materials that ensure the safety, comfort and minimum cost of housing construction. Among the materials, often used for erecting of fencing structures, it is possible to note effective small-piece elements (ceramic and light-weight concrete units, etc.. To ensure the solidity of such structures, it is necessary to use the masonry mortars whose properties correspond to those of the main wall material. The existing dry mixes for obtaining of such mortars are expensive and often do not meet the minimum physical-and-mechanical and exploitation requirements. The solution of this problem is the usage of the hollow ceramics (aluminosilicate microspheres as a filler for such mixes. The article presents the results of studies of the main physical-and-mechanical and exploitation characteristics of dry masonry mixes with hollow ceramics microspheres modified with various chemical additives. The effect of the compounding factors on the average density and strength of dry masonry mixes was studied. The compositions have been optimized by the methods of mathematical planning.

  5. Hollow ZIF-8 Nanoworms from Block Copolymer Templates

    KAUST Repository

    Yu, Haizhou

    2015-10-16

    Recently two quite different types of “nano-containers” have been recognized as attractive potential drug carriers; these are wormlike filamenteous micelles (“filomicelles”) on the one hand and metal organic frameworks on the other hand. In this work we combine these two concepts. We report for the first time the manufacturing of metal organic framework nanotubes with a hollow core. These worm-like tubes are about 200 nm thick and several μm long. The preparation is simple: we first produce long and flexible filament-shaped micelles by block copolymer self-assembly. These filomicelles serve as templates to grow a very thin layer of interconnected ZIF-8 crystals on their surface. Finally the block copolymer is removed by solvent extraction and the hollow ZIF-8 nanotubes remain. These ZIF-NTs are surprisingly stable and withstand purification by centrifugation. The synthesis method is straightforward and can easily be applied for other metal organic framework materials. The ZIF-8 NTs exhibit high loading capacity for the model anti cancer drug doxorubicin (DOX) with a pH-triggered release. Hence, a prolonged circulation in the blood stream and a targeted drug release behavior can be expected.

  6. Light weight hollow maxillary complete denture: A case series

    Directory of Open Access Journals (Sweden)

    Laxman Singh Kaira

    2012-01-01

    Full Text Available Retention, stability and support are the basic principles on which the success of a complete denture relies on. The skill lies in applying these principles efficiently in critical situations. Residual ridge resorption occurs at a three times faster rate in mandibular arch than in the maxillary arch. The severely resorbed maxillary and mandibular edentulous arches that are narrow and constricted with increased interarch space provide decreased support, retention and stability. The consequent weight of the processed complete denture only compromises them further. The severely resorbed jaw can have various treatment options. Extreme resorption of the maxillary denture-bearing area may lead to problems with prosthetic rehabilitation. The advantage of a hollow maxillary or mandibular denture is the reduction of excessive weight of acrylic resin, which normally replaces lost alveolar ridge in the interridge space of the denture wearer. This clinical report describes two case reports of edentulous patients with resorbed ridges where a simplified technique of fabricating a light weight hollow maxillary complete denture was used for the preservation of denture bearing areas.

  7. An optimized hollow microneedle for minimally invasive blood extraction.

    Science.gov (United States)

    Li, Cheng Guo; Lee, Chang Yeol; Lee, Kwang; Jung, Hyungil

    2013-02-01

    The healthcare system relies widely on biochemical information obtained from blood sample extracted via hypodermic needles, despite the invasiveness and pain associated with this procedure. Therefore, an alternative micro-scale needle for minimally invasive blood sampling is highly desirable. Traditional fabrication techniques to create microneedles do not generate needles with the combined features of a sharp tip, long length, and hollow structure concurrently. Here, we report the fabrication of a microneedle long enough to reach blood vessels and sharp enough to minimize nerve contact for minimally invasive blood extraction. The microneedle structure was precisely controlled using a drawing lithography technique, and a sharp tip angle was introduced using a laser-cutting system. We investigated the characteristics of a microneedle with a length of 1,800 μm length, an inner diameter of 60 μm, a tip diameter of 120 μm, and a 15° bevel angle through in-vitro liquid extraction and mechanical strength analysis. We demonstrated that the proposed structure results in blood extraction at a reasonable rate, and that a microneedle with this geometry can reliably penetrate skin without breaking. We integrated this microneedle into a blood extraction device to extract a 20 μl volume of mouse blood in-vivo. Our optimized, hollow microneedle can potentially be incorporated with other cutting-edge technologies such as microactuators, biosensors, and microfluidic chips to create blood analysis systems for point-of-care diagnostics.

  8. Hollow-Cone Spray Modeling for Outwardly Opening Piezoelectric Injector

    KAUST Repository

    Sim, Jaeheon

    2016-01-04

    Linear instability sheet atomization (LISA) breakup model has been widely used for modeling hollow-cone spray. However, the model was originally developed for inwardlyopening pressure-swirl injectors by assuming toroidal ligament breakups. Therefore, LISA model is not suitable for simulating outwardly opening injectors having string-like structures at wide spray angles. Furthermore, the varying area and shape of the annular nozzle exit makes the modeling difficult. In this study, a new spray modeling was proposed for outwardly opening hollow-cone injector. The injection velocities are computed from the given mas flow rate and injection pressure regardless of ambiguous nozzle exit geometries. The modified Kelvin-Helmholtz and Rayleigh-Taylor (KH-RT) breakup model is used with adjusted initial Sauter mean diameter (SMD) for modeling breakup of string-like liquid film spray. Liquid spray injection was modeled using Lagrangian discrete parcel method within the framework of commercial CFD software CONVERGE, and the detailed model was implemented by user defined functions. It was found that the new model predicted the liquid penetration length and local SMD accurately for various fuels and chamber conditions.

  9. Identification of a Binary Distillation Column Using Pulse Testing

    OpenAIRE

    KIRBAŞLAR, Ş. İsmail; AYDIN, Ahmet; DRAMUR, Umur

    1998-01-01

    The binary system of methanol-tert-buthanol was studied at atmospheric pressure in a 53-tray, 35 mm inside diameter sieve tray distillation column. The column had a vertical thermosiphon reboiler and an overhead condenser. During the continuous distillation, the effect of the reflux flow rate and vapour flow rate to the column as rectangular pulse input variables were investigated in the frequency domain. The experimental rectangular pulse input x(t) and output y(t) of the column we...

  10. Cross flow flotation column for coal and minerals beneficiation

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Ralph W.; Patton, Robert A.

    1997-12-01

    An apparatus and process are disclosed for the separation of coal from pyritic impurities using a modified froth flotation system. The froth flotation column incorporates a helical track about the inner wall of the column in a region intermediate between the top and base of the column. A standard impeller located about the central axis of the column is used to generate a centrifugal force thereby increasing the separation efficiency of coal from the pyritic particles and hydrophilic tailings.

  11. Numerical Simulations of Settlement of Jet Grouting Columns

    Directory of Open Access Journals (Sweden)

    Juzwa Anna

    2016-03-01

    Full Text Available The paper presents the comparison of results of numerical analyses of interaction between group of jet grouting columns and subsoil. The analyses were conducted for single column and groups of three, seven and nine columns. The simulations are based on experimental research in real scale which were carried out by authors. The final goal for the research is an estimation of an influence of interaction between columns working in a group.

  12. Estimations of gas flow maldistribution in packed-bed columns

    Energy Technology Data Exchange (ETDEWEB)

    Petrova, T.; Darakchiev, R.; Semkov, K.; Darakchiev, S. [Institute of Chemical Engineering, Bulgarian Academy of Sciences, Sofia (Bulgaria)

    2008-12-15

    A review of research articles dealing with estimation of the rate of gas flow maldistribution in packed-bed columns is presented. The proposed relations for determination of the maldistribution factor are given along with the conditions at which they are obtained. It is shown that the indices of maldistribution are usually based on particular terms, i.e., variation coefficient, dispersion or standard deviation. However, they cannot be regarded as a single indicator of gas maldistribution if the gas flow irregularities are not homogeneously distributed over the cross-section. There is no unified methodology for measuring the gas flow velocity profile. Schemes for measuring the velocity profiles, as well as equations for calculating the maldistribution factor are recommended. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  13. Simulators of tray distillation columns as tools for interpreting ...

    African Journals Online (AJOL)

    Simulators of tray distillation columns were used to provide technical guidelines for interpreting signals from gamma ray scans used for analysing malfunctions in distillation columns. The transmitted radiation intensities at 0.05 m intervals were determined from top to the bottom of simulators of tray distillation columns ...

  14. Mechanistic model for dispersion coefficients in bubble column

    CSIR Research Space (South Africa)

    Skosana, PJ

    2015-05-01

    Full Text Available A mechanistic model describing the mass and momentum exchange in bubble columns is proposed that is based on the observations that the gas distribution in a bubble column is not uniform across the column and that as a consequence large liquid...

  15. Partial Path Column Generation for the Vehicle Routing Problem

    DEFF Research Database (Denmark)

    Jepsen, Mads Kehlet; Petersen, Bjørn

    This paper presents a column generation algorithm for the Capacitated Vehicle Routing Problem (CVRP) and the Vehicle Routing Problem with Time Windows (VRPTW). Traditionally, column generation models of the CVRP and VRPTW have consisted of a Set Partitioning master problem with each column...

  16. Life-cycle impacts assessment of steel, composite, concrete and wooden columns

    DEFF Research Database (Denmark)

    Rossi, Barbara; Lukic, Ivan; Du, Guangli

    2011-01-01

    This paper presents a comparative study showing the environmental profile of structural members used in the construction domain. The functional unit is a column that is realistic in terms of dimensions and load bearing capacity, made of steel or high strength steel sections, steel and concrete...... (composite), reinforced concrete, solid wood and glue-laminated wood. The design of the columns is made following the Eurocodes. Several environmental impacts are assessed, such as the global warming potential and energy consumption while also focusing on the acidification potential. The results...... are presented in the forms of bar charts for each considered column. For steel and concrete, depending on the source of information, the inventory can vary substantially e.g. the CO and CH4 emissions. Several sources of information are provided and used to perform a brief sensitivity analysis. The influence...

  17. Application of a probabilistic model of rainfall-induced shallow landslides to complex hollows

    Directory of Open Access Journals (Sweden)

    A. Talebi

    2008-07-01

    Full Text Available Recently, D'Odorico and Fagherazzi (2003 proposed "A probabilistic model of rainfall-triggered shallow landslides in hollows" (Water Resour. Res., 39, 2003. Their model describes the long-term evolution of colluvial deposits through a probabilistic soil mass balance at a point. Further building blocks of the model are: an infinite-slope stability analysis; a steady-state kinematic wave model (KW of hollow groundwater hydrology; and a statistical model relating intensity, duration, and frequency of extreme precipitation. Here we extend the work of D'Odorico and Fagherazzi (2003 by incorporating a more realistic description of hollow hydrology (hillslope storage Boussinesq model, HSB such that this model can also be applied to more gentle slopes and hollows with different plan shapes. We show that results obtained using the KW and HSB models are significantly different as in the KW model the diffusion term is ignored. We generalize our results by examining the stability of several hollow types with different plan shapes (different convergence degree. For each hollow type, the minimum value of the landslide-triggering saturated depth corresponding to the triggering precipitation (critical recharge rate is computed for steep and gentle hollows. Long term analysis of shallow landslides by the presented model illustrates that all hollows show a quite different behavior from the stability view point. In hollows with more convergence, landslide occurrence is limited by the supply of deposits (supply limited regime or rainfall events (event limited regime while hollows with low convergence degree are unconditionally stable regardless of the soil thickness or rainfall intensity. Overall, our results show that in addition to the effect of slope angle, plan shape (convergence degree also controls the subsurface flow and this process affects the probability distribution of landslide occurrence in different hollows. Finally, we conclude that

  18. Modèle de confinement pour les colonnes de section circulaire en béton armé confiné avec des enveloppes en polymère renforcé de fibres de carbone Confinement model for circular RC columns wrapped with CFRP composite

    Directory of Open Access Journals (Sweden)

    Benzaid R.

    2012-09-01

    concrete cylinders, significantly. A simple model is presented to predict the compressive strength and axial strain of FRP-confined RC columns.

  19. Conventional and enantioselective gas chromatography with microfabricated planar columns for analysis of real-world samples of plant volatile fraction.

    Science.gov (United States)

    Cagliero, C; Galli, S; Galli, M; Elmi, I; Belluce, M; Zampolli, S; Sgorbini, B; Rubiolo, P; Bicchi, C

    2016-01-15

    Within a project exploring the application of lab-on-chip GC to in-field analysis of the plant volatile fraction, this study evaluated the performance of a set of planar columns (also known as microchannels, MEMS columns, or microfabricated columns) of different dimensions installed in a conventional GC unit. Circular double-spiral-shaped-channel planar columns with different square/rectangular sections up to 2m long were applied to the analysis of both essential oils and headspace samples of a group of medicinal and aromatic plants (chamomile, peppermint, sage, rosemary, lavender and bergamot) and of standard mixtures of related compounds; the results were compared to those obtained with reference narrow-bore columns (l:5m, dc:0.1mm, df:0.1 μm). The above essential oils and headspaces were first analyzed quali-and quantitatively with planar columns statically coated with conventional stationary phases (5%-phenyl-polymethylsiloxane and auto-bondable nitroterephthalic-acid-modified polyethylene glycol), and then submitted to chiral recognition of their diagnostic markers, by enantioselective GC with a planar columns coated with a cyclodextrin derivative (30% 6(I-VII)-O-TBDMS-3(I-VII)-O-ethyl-2(I-VII)-O-ethyl-β-cyclodextrin in PS-086). Column characteristics and analysis conditions were first optimized to obtain suitable retention and efficiency for the samples investigated. The planar columns tested showed performances close to the reference conventional narrow-bore columns, with theoretical plate numbers per meter (N/m) ranging from 6100 to 7200 for those coated with the conventional stationary phases, and above 5600 for those with the chiral selector. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Investigation of Axial Strengthened Reinforced Concrete Columns under Lateral Blast Loading

    Directory of Open Access Journals (Sweden)

    Mohammad Esmaeilnia Omran

    2017-01-01

    Full Text Available Different factors can affect blast response of structural components. Hence, experimental tests could be the best method for evaluating structures under blast loading. Therefore, an experimental explosion loading has been done on RC members by the authors. Four RC components, with identical geometry and material, with and without axial load were imposed to air blast. Observed data of the members’ response under blast loading was used for validation of finite element modeling process using ABAQUS software. With respect to complexity, limitations, and high costs of experimental tests, analytical studies and software modeling can be good alternatives. Accordingly, in this paper, the behavior of 6 different models of normal and strengthened RC columns under blast loading was evaluated using ABAQUS. Strengthening configurations considered here were designed for enhancing axial capacity of RC columns. Therefore, we can investigate the effectiveness of axial strengthening of column on its blast resistance capacity and residual axial strength. The considered strengthening methods were different steel jacket configurations including steel angle, channel, and plate sections. The results showed that retrofitting significantly improves blast performance of the columns. Moreover, residual strength capacity of the columns strengthened with steel channel is higher than the other models.

  1. Research on seismic behavior and shear strength of SRHC frame columns

    Science.gov (United States)

    Zheng, Shansuo; Qin, Qing; Zhang, Yixin; Zhang, Liang; Yang, Wei

    2017-04-01

    The seismic behavior of steel reinforced high strength and high performance concrete (SRHC) frame columns was investigated through pseudo-static experiments of 16 frame columns with various shear span ratios, axial compression ratios, concrete strengths, steel ratios and stirrup ratios. Three kinds of failure mechanisms are presented and the characteristics of experimental hysteretic curves and skeleton curves with different design parameters are discussed. The columns' ductility and energy dissipation were quantitatively evaluated based on seismic resistance. The research results indicate that SRHC frame columns can withstand extreme bearing capacity, but the abilities of ductility and energy dissipation are inferior because of SRHC's natural brittleness. As a result, the axial load ratio should be restricted and some construction measures adopted, such as increasing the stirrup ratio. This research established effect factors on the bearing capacity of SPHC columns. Finally, an algorithm for obtaining ultimate bearing capacity using the flexural failure mode is established based on a modified plane-section assumption. The authors also established equations to determine shearing baroclinic failure and shear bond failure based on the accumulation of the axial load force distribution ratio. The calculated results of shear bearing capacity for different failure modes were in good agreement with the experimental results.

  2. Effect of Eccentricity of Load on Critical Force of Thin-Walled Columns CFRP

    Directory of Open Access Journals (Sweden)

    Pawel Wysmulski

    2017-09-01

    Full Text Available The subject of study was a thin-walled C-section made of carbon fiber reinforced polymer (CFRP. Column was subjected to eccentric compression in the established direction. In the computer simulation, the boundary conditions were assumed in the form of articulated support of the sections of the column. Particular studies included an analysis of the effects of eccentricity on the critical force value. The research was conducted using two independent research methods: numerical and experimental. Numerical simulations were done using the finite element method using the advanced system Abaqus®. The high sensitivity of the critical force value corresponding to the local buckling of the channel section to the load eccentricity was demonstrated.

  3. Electrochemically-modulated liquid chromatography (EMLC): Column design, retention processes, and applications

    Energy Technology Data Exchange (ETDEWEB)

    Ting, En -Yi [Iowa State Univ., Ames, IA (United States)

    1997-10-08

    This work describes the continued development of a new separation technique, electrochemically-modulated liquid chromatography (EMLC), from column design, retention mechanisms to pharmaceutical applications. The introduction section provides a literature review of the technique as well as a brief overview of the research in each of the chapters. This section is followed by four chapters which investigate the issues of EMLC column design, the retention mechanism of monosubstituted aromatic compounds, and the EMLC-based applications to two important classes of pharmaceutical compounds (i.e., corticosteroids and benzodiazepines). These four sections have been removed to process separately for inclusion on the database. The dissertation concludes with a general summary, a prospectus, and a list of references cited in the General Introduction. 32 refs.

  4. Column subset selection is NP-complete

    OpenAIRE

    Shitov, Yaroslav

    2017-01-01

    Let $M$ be a real $r\\times c$ matrix and let $k$ be a positive integer. In the column subset selection problem (CSSP), we need to minimize the quantity $\\|M-SA\\|$, where $A$ can be an arbitrary $k\\times c$ matrix, and $S$ runs over all $r\\times k$ submatrices of $M$. This problem and its applications in numerical linear algebra are being discussed for several decades, but its algorithmic complexity remained an open issue. We show that CSSP is NP-complete.

  5. Hydrodynamic Study Of Column Bioleaching Processes

    Directory of Open Access Journals (Sweden)

    Sadowski Zygmunt

    2015-06-01

    Full Text Available The modelling of flow leaching solution through the porous media has been considered. The heap bioleaching process can be tested using the column experimental equipment. This equipment was employed to the hydrodynamic studies of copper ore bioleaching. The copper ore (black shale ore with the support, inertial materials (glass small balls and polyethylene beads was used to the bioleaching tests. The packed beds were various composition, the ore/support ratio was changed. The correlation between the bed porosity and bioleaching kinetics, and copper recovery was investigated.

  6. Preinjector for Linac 1, accelerating column

    CERN Multimedia

    1974-01-01

    For a description of the Linac 1 preinjector, please see first 7403070X. High up on the wall of the Faraday cage (7403073X) is this drum-shaped container of the ion source (7403083X). It is mounted at the HV end of the accelerating column through which the ions (usually protons; many other types of ions in the course of its long history) proceed through the Faraday cage wall to the low-energy end (at ground potential) of Linac 1. The 520 kV accelerating voltage was supplied by a SAMES generator (7403074X).

  7. A general route to hollow mesoporous rare-earth silicate nanospheres as a catalyst support.

    Science.gov (United States)

    Jin, Renxi; Yang, Yang; Zou, Yongcun; Liu, Xianchun; Xing, Yan

    2014-02-17

    Hollow mesoporous structures have recently aroused intense research interest owing to their unique structural features. Herein, an effective and precisely controlled synthesis of hollow rare-earth silicate spheres with mesoporous shells is reported for the first time, produced by a simple hydrothermal method, using silica spheres as the silica precursors. The as-prepared hollow rare-earth silicate spheres have large specific surface area, high pore volume, and controllable structure parameters. The results demonstrate that the selection of the chelating reagent plays critical roles in forming the hollow mesoporous structures. In addition, a simple and low-energy-consuming approach to synthesize highly stable and dispersive gold nanoparticle-yttrium silicate (AuNPs/YSiO) hollow nanocomposites has also been developed. The reduction of 4-nitrophenol with AuNPs/YSiO hollow nanocomposites as the catalyst has clearly demonstrated that the hollow rare-earth silicate spheres are good carriers for Au nanoparticles. This strategy can be extended as a general approach to prepare multifunctional yolk-shell structures with diverse compositions and morphologies simply by replacing silica spheres with silica-coated nanocomposites. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Synthesis and characterization of hollow magnetic nanospheres modified with Au nanoparticles for bio-encapsulation

    Energy Technology Data Exchange (ETDEWEB)

    Seisno, Satoshi, E-mail: seino@mit.eng.osaka-u.ac.jp; Suga, Kent; Nakagawa, Takashi; Yamamoto, Takao A.

    2017-04-01

    Hollow magnetic nanospheres modified with Au nanoparticles were successfully synthesized. Au/SiO{sub 2} nanospheres fabricated by a radiochemical process were used as templates for ferrite templating. After the ferrite plating process, Au/SiO{sub 2} templates were fully coated with magnetite nanoparticles. Dissolution of the SiO{sub 2} core lead to the formation of hollow magnetic nanospheres with Au nanoparticles inside. The hollow magnetic nanospheres consisted of Fe{sub 3}O{sub 4} grains, with an average diameter of 60 nm, connected to form the sphere wall, inside which Au grains with an average diameter of 7.2 nm were encapsulated. The Au nanoparticles immobilized on the SiO{sub 2} templates contributed to the adsorption of the Fe ion precursor and/or Fe{sub 3}O{sub 4} seeds. These hollow magnetic nanospheres are proposed as a new type of nanocarrier, as the Au grains could specifically immobilize biomolecules inside the hollow sphere. - Highlights: • A procedure to synthesize hollow magnetic nanospheres with Au inside was reported. • The Au nanoparticles inside the hollow showed high Au-S binding affinity. • The nanospheres are expected to be suitable as a new magnetic carrier for DDS.

  9. Production and modification of hollow powders in plasma under controlled pressure

    Science.gov (United States)

    Gulyaev, Igor P.

    2013-06-01

    Conducting plasma processes under high or low pressure is an efficient way to affect the heat, mass and momentum exchange in a two-phase flow and this technique is widely used in such well-developed technologies as low-pressure plasma spraying (LPPS) and high pressure plasma-chemical processes. In addition operating pressure is a key parameter in novel plasma process for modification of hollow powders properties. Plasma processing of porous ceramic powders is an effective method of producing hollow spheres (HOSP) with predefined properties. Regardless the method hollow powders were produced their geometric and structural properties can be adjusted by re-melting in plasma of certain pressure: low pressure processing will expand hollow spheres and high pressure - contract it. Regulating the outer diameter of hollow sphere allows adjusting its shell thickness, apparent density, gas pressure in the cavity etc. Preliminary experiments with zirconia hollow powders demonstrated good agreement with theoretical estimations of HOSP properties. The same technique can be used for adjusting properties of ceramic hollow powders produced by different methods, including cost effective fly-ash particles (cenospheres).

  10. Sustained-releasing hollow microparticles with dual-anticancer drugs elicit greater shrinkage of tumor spheroids.

    Science.gov (United States)

    Baek, Jong-Suep; Choo, Chee Chong; Tan, Nguan Soon; Loo, Say Chye Joachim

    2017-10-06

    Polymeric particulate delivery systems are vastly explored for the delivery of chemotherapeutic agents. However, the preparation of polymeric particulate systems with the capability of providing sustained release of two or more drugs is still a challenge. Herein, poly (D, L-lactic-co-glycolic acid, 50:50) hollow microparticles co-loaded with doxorubicin and paclitaxel were developed through double-emulsion solvent evaporation technique. Hollow microparticles were formed through the addition of an osmolyte into the fabrication process. The benefits of hollow over solid microparticles were found to be higher encapsulation efficiency and a more rapid drug release rate. Further modification of the hollow microparticles was accomplished through the introduction of methyl-β-cyclodextrin. With this, a higher encapsulation efficiency of both drugs and an enhanced cumulative release were achieved. Spheroid study further demonstrated that the controlled release of the drugs from the methyl-β-cyclodextrin -loaded hollow microparticles exhibited enhanced tumor regressions of MCF-7 tumor spheroids. Such hollow dual-drug-loaded hollow microparticles with sustained releasing capabilities may have a potential for future applications in cancer therapy.

  11. Performance of different hollow fiber membranes for seawater desalination using membrane distillation

    KAUST Repository

    Francis, Lijo

    2014-08-11

    Membrane distillation requires a highly porous hydrophobic membrane with low surface energy. In this paper, we compare the direct contact membrane distillation (DCMD) performances of four different types of in-house fabricated hollow fiber membranes and two different commercially available hollow fiber membranes. Hollow fiber membranes are fabricated using wet-jet phase inversion technique and the polymeric matrices used for the fabrication are polyvinylidine fluoride (PVDF) and polyvinyl chloride (PVC). Commercial hollow fiber membrane materials are made of polytetrafluoroethylene (PTFE) and polypropylene (PP). PVDF hollow fibers showed a superior performance among all the hollow fibers tested in the DCMD process and gave a water vapor flux of 31 kg m-2h-1 at a feed and coolant inlet temperatures of 80 and 20°C, respectively. Under the same conditions, the water vapor flux observed for PP, PTFE, and PVC hollow fiber membranes are 13, 11, and 6 kg m-2h-1, respectively, with 99.99% salt rejection observed for all membranes used.

  12. Testing and performance analysis of a hollow fiber-based core for evaporative cooling and liquid desiccant dehumidification

    DEFF Research Database (Denmark)

    Jradi, Muhyiddine; Riffat, Saffa

    2016-01-01

    In this study, an innovative heat and mass transfer core is proposed to provide thermal comfort and humidity control using a hollow fiber contactor with multiple bundles of micro-porous hollow fibers. The hollow fiberbased core utilizes 12 bundles aligned vertically, each with 1,000 packed polypr...... of 47%. Being cheap and simple to design with their attractive heat and mass transfer characteristics and the corresponding large surface area-to-volume ratio, hollow fiber membrane contactors provide a promising alternative for cooling and dehumidification applications.......In this study, an innovative heat and mass transfer core is proposed to provide thermal comfort and humidity control using a hollow fiber contactor with multiple bundles of micro-porous hollow fibers. The hollow fiberbased core utilizes 12 bundles aligned vertically, each with 1,000 packed...

  13. Axial and Flexural Strength of Square RC Columns with No-rounded Corners Wrapped with CFRP under Eccentric Loading

    Directory of Open Access Journals (Sweden)

    Ade Lisantono

    2018-01-01

    Full Text Available This paper presents the results of a study on the axial and flexural strength of reinforced concrete (RC columns with no-rounded corners wrapped with Carbon Fiber Reinforced Polymer (CFRP under eccentric loading based on an experimental program. The main parameters under investigation are the number of layers of CFRP wrap. Thirty-six concrete cylinders with a standard size of (150×300 mm were cast and tested in this study to get the modulus of elasticity and compressive strength of concrete. Of these 36 concrete cylinders were divided into four groups, unwrapped, wrapped with one layer of CFRP, wrapped with two layers of CFRP, and wrapped with three layers of CFRP. Twelve rectangular reinforced concrete columns were also cast and tested in this study.  The column specimens had dimensions (75×75×750 mm with no-rounded corners of the column section.  The column specimens were also divided into four groups, unwrapped, wrapped with one layer of CFRP, wrapped with two layers of CFRP, and wrapped with three layers of CFRP. The experiment results show that the load-carrying capacity of the wrapped column increased by the increasing number of CFRP layers. Comparing the experimental results with the compressive strength concrete and the maximum load-carrying capacity of wrapped RC Column predicted by the theories proposed by several researchers with the concern of no-rounded corners were also presented.

  14. Observations of iodine monoxide columns from satellite

    Directory of Open Access Journals (Sweden)

    A. Schönhardt

    2008-02-01

    Full Text Available Iodine species in the troposphere are linked to ozone depletion and new particle formation. In this study, a full year of iodine monoxide (IO columns retrieved from measurements of the SCIAMACHY satellite instrument is presented, coupled with a discussion of their uncertainties and the detection limits. The largest amounts of IO are found near springtime in the Antarctic. A seasonal variation of iodine monoxide in Antarctica is revealed with high values in springtime, slightly less IO in the summer period and again larger amounts in autumn. In winter, no elevated IO levels are found in the areas accessible to satellite measurements. This seasonal cycle is in good agreement with recent ground-based measurements in Antarctica. In the Arctic region, no elevated IO levels were found in the period analysed. This implies that different conditions with respect to iodine release exist in the two Polar Regions. To investigate possible release mechanisms, comparisons of IO columns with those of tropospheric BrO, and ice coverage are described and discussed. Some parallels and interesting differences between IO and BrO temporal and spatial distributions are identified. Overall, the large spatial coverage of satellite retrieved IO data and the availability of a long-term dataset provide new insight about the abundances and distributions of iodine compounds in the troposphere.

  15. Apparatus and process to enhance the uniform formation of hollow glass microspheres

    Science.gov (United States)

    Schumacher, Ray F

    2013-10-01

    A process and apparatus is provided for enhancing the formation of a uniform population of hollow glass microspheres. A burner head is used which directs incoming glass particles away from the cooler perimeter of the flame cone of the gas burner and distributes the glass particles in a uniform manner throughout the more evenly heated portions of the flame zone. As a result, as the glass particles are softened and expand by a released nucleating gas so as to form a hollow glass microsphere, the resulting hollow glass microspheres have a more uniform size and property distribution as a result of experiencing a more homogenous heat treatment process.

  16. Integrated carbon fiber electrodes within hollow polymer microneedles for transdermal electrochemical sensing.

    Science.gov (United States)

    Miller, Philip R; Gittard, Shaun D; Edwards, Thayne L; Lopez, Deanna M; Xiao, Xiaoyin; Wheeler, David R; Monteiro-Riviere, Nancy A; Brozik, Susan M; Polsky, Ronen; Narayan, Roger J

    2011-03-30

    In this study, carbon fiber electrodes were incorporated within a hollow microneedle array, which was fabricated using a digital micromirror device-based stereolithography instrument. Cell proliferation on the acrylate-based polymer used in microneedle fabrication was examined with human dermal fibroblasts and neonatal human epidermal keratinocytes. Studies involving full-thickness cadaveric porcine skin and trypan blue dye demonstrated that the hollow microneedles remained intact after puncturing the outermost layer of cadaveric porcine skin. The carbon fibers underwent chemical modification in order to enable detection of hydrogen peroxide and ascorbic acid; electrochemical measurements were demonstrated using integrated electrode-hollow microneedle devices.

  17. Hollow Electron Beam Collimation for HL-LHC - Effects on the Beam Core

    CERN Document Server

    Fitterer, M; Valishev, A; Bruce, R; Papotti, G; Redaelli, S; Valentino, G; Valentino, G; Valuch, D; Xu, C

    2017-01-01

    Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the High Luminosity Large Hadron Collider (HL-LHC). To ensure the successful operation of the hollow beam collimator the unwanted effects on the beam core, which might arise from the operation with a pulsed electron beam, must be minimized. This paper gives a summary of the effect of hollow electron lenses on the beam core in terms of sources, provides estimates for HL-LHC and discusses the possible mitigation methods.

  18. Hollow Electron Beam Collimation for HL-LHC - Effects on the Beam Core

    Energy Technology Data Exchange (ETDEWEB)

    Fitterer, M. [Fermilab; Stancari, G. [Fermilab; Valishev, A. [Fermilab; Bruce, R. [CERN; Papotti, G [CERN; Redaelli, S. [CERN; Valentino, G. [Malta U.; Valentino, G. [CERN; Valuch, D. [CERN; Xu, C. [CERN

    2017-06-13

    Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the High Luminosity Large Hadron Collider (HL-LHC). To ensure the successful operation of the hollow beam collimator the unwanted effects on the beam core, which might arise from the operation with a pulsed electron beam, must be minimized. This paper gives a summary of the effect of hollow electron lenses on the beam core in terms of sources, provides estimates for HL-LHC and discusses the possible mitigation methods.

  19. Studies on poly (vinyl chloride/silica dioxide composite hollow fiber membrane

    Directory of Open Access Journals (Sweden)

    Mei Shuo

    2016-01-01

    Full Text Available Poly (vinyl chloride/silica dioxide composite hollow fiber membranes were prepared by using the method of immersion-precipitation process. The influences of stretching ratio on the formation of the interfacial microporous of poly (vinyl chloride/silica dioxide composite hollow fiber membranes were specifically investigated by scanning electron microscope, dynamic mechanical analysis, and finite element method. Results show that with the stretching ratio increasing, numerous IFM appear on the surface of membranes. Finite element method actually reflects the dynamic change of microporous structure of poly (vinyl chloride/silica dioxide composite hollow fiber membranes.

  20. Monitoring of N-methyl carbamate pesticide residues in water using hollow fibre supported liquid membrane and solid phase extraction

    Science.gov (United States)

    Msagati, Titus A. M.; Mamba, Bhekie B.

    The aim of this work was to develop a method for the determination of N-methyl carbamates in water involving hollow fibre supported liquid membrane (HFSLM) and solid phase extraction (SPE) as sample preparation methods. Four N-methyl carbamate pesticides, aldicarb, carbaryl, carbofuran and methiocarb sulfoxide, were simultaneously extracted and analysed by a liquid chromatograph with a diode array detector (LC-UV/DAD) and a liquid chromatograph coupled to a ion trap quadrupole mass spectrometer (LC-ESI-MS). The high performance liquid chromatography (HPLC) separation of carabamate extracts was performed on a C18 column with water-acetonitrile as the mobile phase. The mass spectrometry analyses were carried out in the positive mode, operating under both the selected ion monitoring (SIM) and full scan modes. The solid phase recoveries of the extracts ranged between 8% and 98%, with aldicarb having the highest recoveries, followed by carbaryl, carbofuran and methiocarb had the lowest recovery. The HFSLM recovery ranged between 8% and 58% and the order of recovery was similar to the SPE trend. Factors controlling the efficiency of the HFSLM extraction such as sample pH, stripping phase pH, enrichment time, stirring speed as well as organic solvent used for entrapment of analytes, were optimised to achieve the highest enrichment factors.

  1. Reassessing the Plastic Hinge Model for Energy Dissipation of Axially Loaded Columns

    Directory of Open Access Journals (Sweden)

    R. M. Korol

    2014-01-01

    Full Text Available This paper investigates the energy dissipation potential of axially loaded columns and evaluates the use of a plastic hinge model for analysis of hi-rise building column collapse under extreme loading conditions. The experimental program considered seven axially loaded H-shaped extruded aluminum structural section columns having slenderness ratios that would be typical of floor-to-ceiling heights in buildings. All seven test specimens initially experienced minor-axis overall buckling followed by formation of a plastic hinge at the mid-height region, leading to local buckling of the flanges on the compression side of the plastic hinge, and eventual folding of the compression flanges. The experimental energy absorption, based on load-displacement relations, was compared to the energy estimates based on section plastic moment resistance based on measured yield stress and based on measured hinge rotations. It was found that the theoretical plastic hinge model underestimates a column’s actual ability to absorb energy by a factor in the range of 3 to 4 below that obtained from tests. It was also noted that the realizable hinge rotation is less than 180°. The above observations are based, of course, on actual columns being able to sustain high tensile strains at hinge locations without fracturing.

  2. Automatic Detection and Segmentation of Columns in As-Built Buildings from Point Clouds

    Directory of Open Access Journals (Sweden)

    Lucía Díaz-Vilariño

    2015-11-01

    Full Text Available Over the past few years, there has been an increasing need for tools that automate the processing of as-built 3D laser scanner data. Given that a fast and active dimensional analysis of constructive components is essential for construction monitoring, this paper is particularly focused on the detection and segmentation of columns in building interiors from incomplete point clouds acquired with a Terrestrial Laser Scanner. The methodology addresses two types of columns: round cross-section and rectangular cross-section. Considering columns as vertical elements, the global strategy for segmentation involves the rasterization of a point cloud onto the XY plane and the implementation of a model-driven approach based on the Hough Transform. The methodology is tested in two real case studies, and experiments are carried out under different levels of data completeness. The results show the robustness of the methodology to the presence of clutter and partial occlusion, typical in building indoors, even though false positives can be obtained if other elements with the same shape and size as columns are present in the raster.

  3. A 13000-hour test of a mercury hollow cathode

    Science.gov (United States)

    Rawlin, V. K.

    1973-01-01

    A mercury-fed hollow cathode was tested for 12,979 hours in a bell jar at SERT 2 neutralizer operating conditions. The net electron current drawn to a collector was 0.25 ampere at average collector voltages between 21.8 and 36.7 volts. The mercury flow rate was varied from 5.6 to 30.8 equivalent milliamperes to give stable operation at the desired electrode voltages and currents. Variations with time in the neutralizer discharge characteristics were observed and hypothesized to be related to changes in the cathode orifice dimensions and the availability of electron emissive material. A facility failure caused abnormal test conditions for the last 876 hours and led to the cathode heater failure which concluded the test.

  4. The physics of light distribution in hollow structures

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, L.A. [Univ. of British Columbia, Vancouver (Canada)

    1994-12-31

    The purpose of this paper is to serve as an introduction, for non-physicists, to the subject of light distribution in hollow structures. The motivation for light distribution is the importance of getting the maximum value from available light. We all recognize that photons cost money (one photon costs about $10{sup -25} to make) so we obviously want to try to make the maximum number of photons for a given cost. What is often overlooked, however, is that these photons have the highest value only if they are delivered to the right place in the correct quantity. This means that there is often substantial economic value in the high quality distribution of light. This problem is discussed from a very general perspective, in order to show the role of general optical films for manipulating light. The underlying physics at work in such films is described, and examples of common optical light deistribution films are provided.

  5. Atlas of uranium emission intensities in a hollow cathode discharge

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, B.A.; Keller, R.A.; Engleman, R. Jr.

    1980-07-01

    The uranium emission spectrum from a hollow cathode discharge is displayed from 11,000 to 26,000 cm/sup -1/. This atlas lists 4928 spectral lines of uranium; 3949 are classified to the neutral spectrum and 431 are classified to the singly ionized spectrum. Listed wavenumbers are accurate to +-0.003 cm/sup -1/ and the listed relative intensities to +-8%. The richness of the spectrum makes this atlas useful for wavenumber calibration of lasers, spectrographs, and monochromators to an accuracy of 1 part in 10/sup 7/. This atlas is also useful as a guide to the uranium spectrum, and relative oscillator strengths (gf values) can be calculated from the intensities to a precision of +-20%.

  6. Mode Division Multiplexing Exploring Hollow-Core Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Xu, Jing; Lyngso, Jens Kristian; Leick, Lasse

    2013-01-01

    We review our recent exploratory investigations on mode division multiplexing using hollow-core photonic bandgap fibers (HC-PBGFs). Compared with traditional multimode fibers, HC-PBGFs have several attractive features such as ultra-low nonlinearities, low-loss transmission window around 2 µm etc....... After having discussed the potential and challenges of using HC-PBGFs as transmission fibers for mode multiplexing applications, we will report a number of recent proof-of-concept results obtained in our group using direct detection receivers. The first one is the transmission of two 10.7 Gbit/s non......-return to zero (NRZ) data signals over a 30 m 7-cell HC-PBGF using the offset mode launching method. In another experiment, a short piece of 19-cell HC-PBGF was used to transmit two 20 Gbit/s NRZ channels using a spatial light modulator for precise mode excitation. Bit-error-ratio (BER) performances below...

  7. Core–Shell Electrospun Hollow Aluminum Oxide Ceramic Fibers

    Directory of Open Access Journals (Sweden)

    Jonathan W. Rajala

    2015-10-01

    Full Text Available In this work, core–shell electrospinning was employed as a simple method for the fabrication of composite coaxial polymer fibers that became hollow ceramic tubes when calcined at high temperature. The shell polymer solution consisted of polyvinyl pyrollidone (PVP in ethanol mixed with an aluminum acetate solution to act as a ceramic precursor. The core polymer was recycled polystyrene to act as a sacrificial polymer that burned off during calcination. The resulting fibers were analyzed with X-ray diffraction (XRD and energy dispersive spectroscopy (EDS to confirm the presence of gamma-phase aluminum oxide when heated at temperatures above 700 °C. The fiber diameter decreased from 987 ± 19 nm to 382 ± 152 nm after the calcination process due to the polymer material being burned off. The wall thickness of these fibers is estimated to be 100 nm.

  8. Hollow platinum alloy tailored counter electrodes for photovoltaic applications

    Science.gov (United States)

    Li, Pinjiang; Zhang, Yange; Fa, Wenjun; Yang, Xiaogang; Wang, Liang

    2017-08-01

    Without sacrifice of photovoltaic performances, low-platinum alloy counter electrodes (CEs) are promising in bringing down the fabrication cost of dye-sensitized solar cells (DSSCs). We present here the realization of ZnO nanostructure assisted hollow platinum-nickel (PtNi) alloy microstructure CEs with a simple hydrothermal methods and maximization of electrocatalytic behaviors by tuning Zn precursors. The maximal power conversion efficiency is up to 8.74% for the liquid-junction dye-sensitized solar cells with alloyed PtNi0.41 electrode, yielding a 37.6% cell efficiency enhancement in comparison with pristine solar cell from planar Pt electrode. Moreover, the dissolution-resistant and charge-transfer abilities toward I-/I3- redox electrolyte have also been markedly enhanced due to competitive dissolution reactions and alloying effects.

  9. Sensing Features of Long Period Gratings in Hollow Core Fibers

    Directory of Open Access Journals (Sweden)

    Agostino Iadicicco

    2015-04-01

    Full Text Available We report on the investigation of the sensing features of the Long-Period fiber Gratings (LPGs fabricated in hollow core photonic crystal fibers (HC-PCFs by the pressure assisted Electric Arc Discharge (EAD technique. In particular, the characterization of the LPG in terms of shift in resonant wavelengths and changes in attenuation band depth to the environmental parameters: strain, temperature, curvature, refractive index and pressure is presented. The achieved results show that LPGs in HC-PCFs represent a novel high performance sensing platform for measurements of different physical parameters including strain, temperature and, especially, for measurements of environmental pressure. The pressure sensitivity enhancement is about four times greater if we compare LPGs in HC and standard fibers. Moreover, differently from LPGs in standard fibers, these LPGs realized in innovative fibers, i.e., the HC-PCFs, are not sensitive to surrounding refractive index.

  10. Design and fabrication of Ni nanowires having periodically hollow nanostructures

    Science.gov (United States)

    Sada, Takao; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

    2014-09-01

    We propose a concept for the design and fabrication of metal nanowires having periodically hollow nanostructures inside the pores of an anodic aluminum oxide (AAO) membrane using a sacrificial metal. In this study, nickel (Ni) and silver (Ag) were used as the base metal and the sacrificial metal, respectively. Alternating an applied potential between -0.4 and -1.0 V provided alternatively deposited Ni and Ag segments in a Ni-Ag `barcode' nanowire with a diameter of 18 or 35 nm. After etching away the Ag segments, we fabricated Ni nanowires with nanopores of 12 +/- 5.3 nm. Such nanostructure formation is explained by the formation of a Ni shell layer over the surface of the Ag segments due to the strong affinity of Ni2+ for the interior surfaces of AAO. The Ni shell layer allows the Ni segments to remain even after dissolution of the Ag segments. Because the electroplating conditions can be easily controlled, we could carefully adjust the size and pitch of the periodically hollow nanospaces. We also describe a method for the fabrication of Ni nanorods by forming an Ag shell instead of a Ni shell on the Ni-Ag barcode nanowire, in which the interior of the AAO surfaces was modified with a compound bearing a thiol group prior to electroplating.We propose a concept for the design and fabrication of metal nanowires having periodically hollow nanostructures inside the pores of an anodic aluminum oxide (AAO) membrane using a sacrificial metal. In this study, nickel (Ni) and silver (Ag) were used as the base metal and the sacrificial metal, respectively. Alternating an applied potential between -0.4 and -1.0 V provided alternatively deposited Ni and Ag segments in a Ni-Ag `barcode' nanowire with a diameter of 18 or 35 nm. After etching away the Ag segments, we fabricated Ni nanowires with nanopores of 12 +/- 5.3 nm. Such nanostructure formation is explained by the formation of a Ni shell layer over the surface of the Ag segments due to the strong affinity of Ni2+ for the

  11. The role of the diaphragm during abdominal hollowing exercises.

    Science.gov (United States)

    Allison, Garry T; Kendle, Kym; Roll, Suzanne; Schupelius, Jason; Scott, Quentin; Panizza, Janine

    1998-01-01

    This study investigated the surface electromyographical (EMG) profiles of the diaphragm, anterolateral abdominals and rectus abdominis during abdominal hollowing exercises (AHE) in 20 healthy subjects. Muscle activity was assessed at 1000Hz over two seconds in crook lying at three incremental loads above a baseline of 40mmHg monitored by a pressure biofeedback unit. EMG amplitude increased significantly above resting for all muscles during correct performance of AHE at 5mmHg. At 15mmHg, all subjects were deemed to have performed AHE incorrectly and both the diaphragm and rectus abdominis activity were significantly elevated (p < 0.05). This supports the concept that the diaphragm plays a significant role in motor control strategies used by subjects performing different forms of AHE.

  12. Interference Cancellation for Hollow-Core Fiber Reference Cells

    DEFF Research Database (Denmark)

    Seppä, Jeremias; Merimaa, Mikko; Merimaa, Mikko

    2015-01-01

    Doppler-free saturated absorption spectroscopy of gases in hollow-core fiber (HCF)-based cells can be used for realizing new compact, robust, and portable frequency standards. In this paper, methods for cancelling interferences resulting from the optical connections between standard fiber and HCF...... and other factors such as varying coupling to HCF modes are investigated. Laser power modulation with simultaneous detection of ac and dc signal is used to separate saturated absorption from interferences. In addition, a technique of two piezoelectric stack actuators stretching the fiber at different...... locations is described. The presented experimental results demonstrate that 99% interference attenuation is readily attainable with the techniques. Frequency comb-referenced measurement of saturated acetylene absorption features near 1.54 μm, with fiber length and power modulation, is presented...

  13. Sharpening of hollow silicon microneedles to reduce skin penetration force

    Science.gov (United States)

    Khanna, Puneet; Luongo, Kevin; Strom, Joel A.; Bhansali, Shekhar

    2010-04-01

    In this research, hollow silicon microneedles with sharpened tips have been fabricated without any reduction to the needle shaft diameter. By sharpening the needles only at the tip and not over the entire length of the needle, their mechanical strength is maintained, while reducing the insertion force into skin. The process achieves this geometry by novel use photoresist depletion during DRIE. Microneedles of varying levels of tip sharpness were tested on human cadaver skin to measure their force of penetration. The results show a marked decrease of insertion force with progressive sharpening of microneedle tips, reducing more than 75 times in magnitude for extremely sharp tips. The toughness of human skin was derived to be approximately 24.28 kJ m-2.

  14. Measuring Beam Quality of Hollow Core Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Shephard, J.D.; Roberts, John; Jones, J.D.C.

    2006-01-01

    In this paper, the authors measure the quality of the delivered beam from hollow core photonic crystal fibers (HC-PCFs). The$M^2$parameter is determined, and the near- to far-field transition is examined. The influence on these properties due to the presence of a core surround mode is evaluated.......17 for the same output beam. This highlights the need for careful consideration when measuring and describing the beam quality delivered by these novel photonic fibers........ The applicability of the International Standards Organization 11146 : 1999 standard for$M^2$measurement of the beam quality of HC-PCFs is discussed. Because they are dependent on the measurement parameters, such as choice of aperturing scheme and the axis of measurement,$M^2$values could vary from 1.32 to 3...

  15. Human hepatocyte functions in a crossed hollow fiber membrane bioreactor.

    Science.gov (United States)

    De Bartolo, Loredana; Salerno, Simona; Curcio, Efrem; Piscioneri, Antonella; Rende, Maria; Morelli, Sabrina; Tasselli, Franco; Bader, Augustinus; Drioli, Enrico

    2009-05-01

    An important challenge in liver tissue engineering is the development of bioartificial systems that are able to favour the liver reconstruction and to modulate liver cell behaviour. A crossed hollow fiber membrane bioreactor was developed to support the long-term maintenance and differentiation of human hepatocytes. The bioreactor consists of two types of hollow fiber (HF) membranes with different molecular weight cut-off (MWCO) and physico-chemical properties cross-assembled in alternating manner: modified polyetheretherketone (PEEK-WC) and polyethersulfone (PES), used for the medium inflow and outflow, respectively. The combination of these two fiber set produces an extracapillary network for the adhesion of cells and a high mass exchange through the cross-flow of culture medium. The transport of liver specific products such as albumin and urea together with the transport of drug such as diazepam was modelled and compared with the experimental metabolic data. The theoretical metabolite concentration differed 7.5% for albumin and 5% for urea with respect to experimental data. The optimised perfusion conditions of the bioreactor allowed the maintenance of liver functions in terms of urea synthesis, albumin secretion and diazepam biotransformation up to 18 days of culture. In particular the good performance of the bioreactor was confirmed by the high rate of urea synthesis (28.7 microg/h 10(6) cells) and diazepam biotransformation. In the bioreactor human hepatocytes expressed at high levels the individual cytochrome P450 isoenzymes involved in the diazepam metabolism. The results demonstrated that crossed HF membrane bioreactor is able to support the maintenance of primary human hepatocytes preserving their liver specific functions for all investigated period. This device may be a potential tool in the liver tissue engineering for drug metabolism/toxicity testing and study of disease pathogenesis alternatively to animal experimentation.

  16. Process for manufacturing hollow fused-silica insulator cylinder

    Science.gov (United States)

    Sampayan, Stephen E.; Krogh, Michael L.; Davis, Steven C.; Decker, Derek E.; Rosenblum, Ben Z.; Sanders, David M.; Elizondo-Decanini, Juan M.

    2001-01-01

    A method for building hollow insulator cylinders that can have each end closed off with a high voltage electrode to contain a vacuum. A series of fused-silica round flat plates are fabricated with a large central hole and equal inside and outside diameters. The thickness of each is related to the electron orbit diameter of electrons that escape the material surface, loop, and return back. Electrons in such electron orbits can support avalanche mechanisms that result in surface flashover. For example, the thickness of each of the fused-silica round flat plates is about 0.5 millimeter. In general, the thinner the better. Metal, such as gold, is deposited onto each top and bottom surface of the fused-silica round flat plates using chemical vapor deposition (CVD). Eutectic metals can also be used with one alloy constituent on the top and the other on the bottom. The CVD, or a separate diffusion step, can be used to defuse the deposited metal deep into each fused-silica round flat plate. The conductive layer may also be applied by ion implantation or gas diffusion into the surface. The resulting structure may then be fused together into an insulator stack. The coated plates are aligned and then stacked, head-to-toe. Such stack is heated and pressed together enough to cause the metal interfaces to fuse, e.g., by welding, brazing or eutectic bonding. Such fusing is preferably complete enough to maintain a vacuum within the inner core of the assembled structure. A hollow cylinder structure results that can be used as a core liner in a dielectric wall accelerator and as a vacuum envelope for a vacuum tube device where the voltage gradients exceed 150 kV/cm.

  17. Supported graphene oxide hollow fibre membrane for oily wastewater treatment

    Science.gov (United States)

    Othman, Nur Hidayati; Alias, Nur Hashimah; Shahruddin, Munawar Zaman; Hussein, Siti Nurliyana Che Mohamed; Dollah, Aqilah

    2017-12-01

    Oil and gas industry deals with a large amount of undesirable discharges of liquid, solid, and gaseous wastes and the amounts can considerably change during the production phases. Oilfield wastewater or produced water is known to constitute various organic and inorganic components. Discharging the produced water can pollute surface and underground water and therefore the necessity to treat this oily wastewater is an inevitable challenge. The current technologies for the treatment of this metastable oil-in-water are not really effective and very pricey. As a result, there is a great interest from many parties around the world in finding cost-effective technologies. In recent years, membrane processes have been utilized for oily wastewater treatment. In these work, a graphene oxide membrane supported on a highly porous Al2O3 hollow fibre was prepared using vacuum assisted technique and its performance in treating oily wastewater was investigated. Graphene oxide (GO) was prepared using a modified Hummer's method and further characterized using XRD, FTIR, TGA and SEM. The results showed that the GO was successfully synthesized. The GO membrane was deposited on alumina hollow fibre substrates. The membrane performance was then investigated using dead-end filtration setup with synthetic oily wastewater as a feed. The effects of operating times on rejection rate and permeate flux were investigated. The experimental results showed that the oil rejections were over 90%. It was concluded that the supported GO membrane developed in this study may be considered feasible in treating oily wastewater. Detail study on the effects of transmembrane pressure, oil concentration, pH and fouling should be carried out in the future

  18. Study of clean up procedures using Charcoal-Alumina-Celite column, immunoaffinity column and strata x column to determine deoxynivalenol by high performance liquid chromatography in wheat

    Directory of Open Access Journals (Sweden)

    Jacqueline Cea

    2011-04-01

    Full Text Available Fusarium graminearum is the most common toxic fungal species affecting grains in Uruguay. Since 1977, due to favorable climate conditions, there have been harvests with prominent Fusarium Head Blight in wheat. This were in 1984, 1990, 1993, 1996 and 2001.Natural Toxin Department of Technological Laboratory of Uruguay as National Reference Laboratory, is continuously improving the analytical methods in order to have a good response to the industry requirements and to the monitoring programs for import and exports commodities. The objective of this work was to compare different clean up methods in order to select the best one for routine determination of deoxynivalenol (DON in wheat (grain and flour.  Charcoal-alumina-celite (7+5+3,  immunoaffinity columns DONPREP R-Biopharm Rhone and Strata X 33 m polymeric sorbent  Phenomenex columns were used to perform the study. Considering as reference analytical method the internal protocol  PEC.TOX.063 accredited by United Kingdom Accreditation Service (UKAS  following the ISO 17025 requirements, and  based on AOAC method 986.17( chapter 49, 2002 for extraction and clean-up  and on J.AOAC 70(3, 1987:479-483 for the high performance liquid chromatography (HPLC detection, two more clean up methods were evaluated. In all of them PEC.TOX.063 detection procedure was carried out. PEC.TOX.063 used for the clean up an in house column chromatography prepared with charcoal-alumina-celite (7+5+3 . Extraction was performed using acetonitrile- water (84+16 and an aliquot of the extract was passed through the column. Extract was dryed under vacuum and DON detected by HPLC using photodiode array detector. For the method that used immunoaffinity columns, water was the extraction solvent, and manufacture protocol was followed up. An aliquot of the extract was passed through the column. Column was washed using water and DON eluated using methanol 100%. For the method that used Strata X column for the clean up, the

  19. Screening and quantification of anticancer compounds in traditional Chinese medicine by hollow fiber cell fishing and hollow fiber liquid/solid-phase microextraction.

    Science.gov (United States)

    Wang, Caiyun; Hu, Shuang; Chen, Xuan; Bai, Xiaohong

    2016-05-01

    Hollow fiber cell fishing, based on HepG-2, SKOV-3, and ACHN cancer cells, and hollow fiber liquid/solid microextraction with HPLC were developed and introduced for researching the anticancer activity of Rhizoma Curcumae Longae, Radix Curcumae, and Rhizoma Curcumae. The structures of curcumin, demethoxycurcumin, and bisdemethoxycurcumin screened were identified and their contents were determined. The compound target fishing factors and cell apoptosis rates under the effect of the three medicines were determined. The binding sites (cell membrane and cell organelle) and binding target (phospholipase C) on the cell were researched. Hollow fiber liquid/solid-phase microextraction mechanism was analyzed and expounded. Before the application, cell seeding time, growth state and survival rate, compound nonspecific binding, positive and negative controls, repeatability in hollow fiber cell fishing with high-performance liquid chromatography; extraction solvent, sample pH, salt concentration, agitation speed, extraction time, temperature and sample volume in hollow fiber liquid/solid-phase microextraction with high-performance liquid chromatography were investigated. The results demonstrated that the proposed strategy is a simple and quick method to identify bioactive compounds at the cellular level as well as determine their contents (particularly trace levels of the bioactive compounds), analyze multicompound and multitarget entirety effects, and elucidate the efficacious material base in traditional medicine. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Comparison of two column characterisation systems based on pharmaceutical applications.

    Science.gov (United States)

    Haghedooren, Erik; Németh, Tamás; Dragovic, Sanja; Noszál, Béla; Hoogmartens, Jos; Adams, Erwin

    2008-05-02

    A useful column characterisation system should help chromatographers to select the most appropriate column to use, e.g. when a particular chromatographic column is not available or when facing the dilemma of selecting a suitable column for analysis according to an official monograph. Official monographs of the European Pharmacopoeia and the United States Pharmacopeia are not allowed to mention the brand name of the stationary phase used for the method development. Also given the overwhelming offer of several hundreds of commercially available reversed-phase liquid chromatographic columns, the choice of a suitable column could be difficult sometimes. To support rational column selection, a column characterisation study was started in our laboratory in 2000. In the same period, Euerby et al. also developed a column characterisation system, which is now released as Column Selector by ACD/Labs. The aim of this project was to compare the two existing column characterisation systems, i.e. the KUL system and the Euerby system. Other research groups active in this field will not be discussed here. Euerby et al. developed a column characterisation system based on 6 test parameters, while the KUL system is based on 4 chromatographic parameters. Comparison was done using a set of 63 columns. For 7 different pharmaceutical separations (fluoxetine, gemcitabine, erythromycin, tetracycline, tetracaine, amlodipine and bisacodyl), a ranking was built based on an F-value (KUL method) or Column Difference Factor value (Euerby method) versus a (virtual) reference column. Both methods showed a similar ranking. The KUL and Euerby methods do not perfectly match, but they yield very similar results, allowing with a relatively high certainty, the selection of similar or dissimilar columns as compared to a reference column. An analyst that uses either of the two methods, will end up with a similar ranking. From a practical point of view, it must be noted that the KUL method only includes 4

  1. Refreshment topics II: Design of distillation columns

    Directory of Open Access Journals (Sweden)

    Milojević Svetomir

    2006-01-01

    Full Text Available For distillation column design it is necessary to define all the variable parameters such as component concentrations in different streams temperatures, pressures, mass and energy flow, which are used to represent the separation process of some specific system. They are related to each other according to specific laws, and if the number of such parameters exceeds the number of their relationships, in order to solve a problem some of them must be specified in advance or some constraints assumed for the mass balance, the balance of energy, phase equilibria or chemical equilibria. Knowledge of specific elements which are the constituents of a distillation unit must be known to define the number of design parameters as well as some additional apparati also necessary to realize the distilation. Each separate apparatus might be designed and constructed only if all the necessary and variable parameters for such a unit are defined. This is the right route to solve a distilation unit in many different cases. The construction of some distillation unit requires very good knowledge of mass, heat and momentum transfer phenomena. Moreover, the designer needs to know which kind of apparatus will be used in the distillation unit to realize a specific production process. The most complicated apparatus in a rectification unit is the distillation column. Depending on the complexity of the separation process one, two or more columns are often used. Additional equipment are heat exchangers (reboilers, condensers, cooling systems, heaters, separators, tanks for reflux distribution, tanks and pumps for feed transportation, etc. Such equipment is connected by pipes and valves, and for the normal operation of a distillation unit other instruments for measuring the flow rate, temperature and pressure are also required. Problems which might arise during the determination and selection of such apparati and their number requires knowledge of the specific systems which must

  2. Enhanced reductive dechlorination in columns treated with edible oil emulsion

    Science.gov (United States)

    Long, Cameron M.; Borden, Robert C.

    2006-09-01

    The effect of edible oil emulsion treatment on enhanced reductive dechlorination was evaluated in a 14 month laboratory column study. Experimental treatments included: (1) emulsified soybean oil and dilute HCl to inhibit biological activity; (2) emulsified oil only; (3) emulsified oil and anaerobic digester sludge; and (4) continuously feeding soluble substrate. A single application of emulsified oil was effective in generating strongly reducing, anaerobic conditions for over 14 months. PCE was rapidly reduced to cis-DCE in all three live columns. Bioaugmentation with a halorespiring enrichment culture resulted in complete dechlorination of PCE to ethene in the soluble substrate column (yeast extract and lactate). However, an additional treatment with a pulse of yeast extract and bioaugmentation culture was required to stimulate complete dechlorination in the emulsion treated columns. Once the dechlorinating population was established, the emulsion only column degraded PCE from 90-120 μM to below detection with concurrent ethene production in a 33 day contact time. The lower biodegradation rates in the emulsion treated columns compared to the soluble substrate column suggest that emulsified oil barriers may require a somewhat longer contact time for effective treatment. In the HCl inhibited column, partitioning of PCE to the retained oil substantially delayed PCE breakthrough. However, reduction of PCE to more soluble degradation products ( cis-DCE, VC and ethene) greatly reduced the impact of oil-water partitioning in live columns. There was only a small decline in the hydraulic conductivity ( K) of column #1 (low pH + emulsion, Kfinal/ Kinitial = 0.57) and column #2 (live + emulsion, Kfinal/ Kinitial = 0.73) indicating emulsion injection did not result in appreciable clogging of the clayey sand. However, K loss was greater in column #3 (sludge +emulsion, Kfinal/ Kinitial = 0.12) and column #4 (soluble substrate, Kfinal/ Kinitial = 0.03) indicating clogging due

  3. Replication of human tracheobronchial hollow airway models using a selective laser sintering rapid prototyping technique.

    Science.gov (United States)

    Clinkenbeard, Rodney E; Johnson, David L; Parthasarathy, Ramkumar; Altan, M Cengiz; Tan, Kah-Hoe; Park, Seok-Min; Crawford, Richard H

    2002-01-01

    Exposures to toxic or pathogenic aerosols are known to produce adverse health effects. The nature and severity of these effects often are governed in large part by the location and amount of aerosol deposition within the respiratory tract. Morphologically detailed replica hollow lung airway casts are widely used in aerosol deposition research; however, techniques are not currently available that allow replicate deposition studies in identical morphologically detailed casts produced from a common reference anatomy. This project developed a technique for the precision manufacture of morphologically detailed human tracheobronchial airway models based on high-resolution anatomical imaging data. Detailed physical models were produced using the selective laser sintering (SLS) rapid prototyping process. Input to the SLS process was a three-dimensional computer model developed by boundary-based two-dimension to three-dimension conversion of anatomical images from the original National Institutes of Health/National Library of Medicine Visible Human male data set. The SLS process produced identical replicate models that corresponded exactly to the anatomical section images, within the limits of the measurement. At least five airway generations were achievable, corresponding to airways less than 2 mm in diameter. It is anticipated that rapid prototyping manufacture of respiratory tract structures based on reference anatomies such as the Visible Male and Visible Female may provide "gold standard" models for inhaled aerosol deposition studies. Adaptations of the models to represent various disease states may be readily achieved, thereby promoting exploration of pharmaceutical research on targeted drug delivery via inhaled aerosols.

  4. Numerical Investigation on Primary Atomization Mechanism of Hollow Cone Swirling Sprays

    Directory of Open Access Journals (Sweden)

    Jia-Wei Ding

    2016-01-01

    Full Text Available The atomization process of swirling sprays in gas turbine engines has been investigated using a LES-VOF model. With fine grid resolution, the ligament and droplet formation processes are captured in detail. The spray structure of fully developed sprays and the flow field are observed firstly. A central recirculation zone is generated inside the hollow cone section due to the entrainment of air by the liquid sheet and strong turbulent structures promote the breakup of ligaments. At the exit of injector nozzle, surface instability occurs due to disturbance factors. Axial and transverse mode instabilities produce a net-like structure ligament zone. Finally, the generation mechanism of the droplet is analyzed. It is found that the breakup mechanism of ligaments is located at the Raleigh capillary region. Axial symmetry oscillation occurs due to the surface tension force and the capillary waves pinch off from the neck of the ligaments. Secondary breakup and coalescence occur at the “droplet zone,” resulting in a wider distribution curve at the downstream area.

  5. Fabrication of a hollow obturator as a single unit for management of bilateral subtotal maxillectomy.

    Science.gov (United States)

    Patil, Pravinkumar G; Patil, Smita P

    2012-04-01

    Prosthetic rehabilitation with an obturator for a total or subtotal maxillectomy patient is a challenging task, as there are little or no residual maxillary structures to depend on for support, retention, and stability of the prosthesis. This clinical report describes the prosthodontic management of a patient operated on for a bilateral subtotal maxillectomy secondary to ameloblastoma of the palate with a closed hollow obturator. The processing technique described in this article to fabricate the hollow obturator is a variation of other well-known techniques. The variation comprises the use of a wax bolus to maintain a predictable internal dimension for a hollow obturator. This technique allows fabrication of a complete hollow obturator prosthesis as a single unit in heat-polymerized acrylic resin using a single-step flasking procedure. © 2012 by the American College of Prosthodontists.

  6. General synthesis route to fabricate uniform upconversion luminescent gadolinium oxide hollow spheres.

    Science.gov (United States)

    Jia, Guang; Zhang, Cuimiao; Ding, Shiwen; Wang, Liyong

    2011-08-01

    Uniform upconversion luminescent gadolinium oxide hollow spheres were successfully synthesized via a homogeneous precipitation method with carbon spheres as template followed by a calcination process. During the annealing process, the carbon spheres template can be effectively removed and the amorphous precursor has converted to crystalline Gd2O3, which can be confirmed by the XRD and TG-DSC analysis. SEM and TEM images indicate that the Gd2O3 hollow spheres with diameters of 300-400 nm are uniform in size and distribution. The rare earth activator ions Ln3+-doped Gd2O3 hollow spheres exhibit intense upconversion luminescence with different colors under 980 nm light excitation, which may find potential applications in the fields such as drug delivery or biological labeling. Moreover, the upconversion luminescent mechanisms of the hollow spherical phosphors were investigated in detail.

  7. Seismic assessment of WSDOT bridges with prestressed hollow core piles : part II.

    Science.gov (United States)

    2009-12-01

    This report investigates the seismic performance of a reinforced concrete : bridge with prestressed hollow core piles. Both nonlinear static and nonlinear dynamic : analyses were carried out. A three-dimensional spine model of the bridge was : ...

  8. Method and apparatus for producing gas-filled hollow spheres. [target pellets for inertial confinement fusion

    Science.gov (United States)

    Wang, T. G.; Elleman, D. D. (Inventor)

    1982-01-01

    A system for forming hollow spheres containing pressured gas is described which includes a cylinder device containing a molten solid material with a nozzle at its end. A second gas nozzle, lying slightly upstream from the tip of the first nozzle, is connected to a source that applies pressured filler gas that is to fill the hollow spheres. High pressure is applied to the molten metal, as by moving a piston within the cylinder device, to force the molten material out of the first nozzle. At the same time, pressured gas fills the center of the extruded hollow liquid pipe that breaks into hollow spheres. The environment outside the nozzles contains gas at a high pressure such as 100 atmospheres. Gas is supplied to the gas nozzle at a slightly higher pressure such as 101 atmospheres. The pressure applied to the molten material is at a still higher pressure such as 110 atmospheres.

  9. A General Synthesis Strategy for Hierarchical Porous Metal Oxide Hollow Spheres

    Directory of Open Access Journals (Sweden)

    Huadong Fu

    2015-01-01

    Full Text Available The hierarchical porous TiO2 hollow spheres were successfully prepared by using the hydrothermally synthesized colloidal carbon spheres as templates and tetrabutyl titanate as inorganic precursors. The diameter and wall thickness of hollow TiO2 spheres were determined by the hard templates and concentration of tetrabutyl titanate. The particle size, dispersity, homogeneity, and surface state of the carbon spheres can be easily controlled by adjusting the hydrothermal conditions and adding certain amount of the surfactants. The prepared hollow spheres possessed the perfect spherical shape, monodispersity, and hierarchically pore structures, and the further experiment verified that the present approach can be used to prepare other metal oxide hollow spheres, which could be used as catalysis, fuel cells, lithium-air battery, gas sensor, and so on.

  10. Template-mediated Synthesis of Hollow Microporous Organic Nanorods with Tunable Aspect Ratio

    Science.gov (United States)

    Li, Qingyin; Jin, Shangbin; Tan, Bien

    2016-01-01

    Hollow microporous organic nanorods (HMORs) with hypercrosslinked polymer (HCPs) shells were synthesized through emulsion polymerization followed by hypercrosslinking. The HMORs have tunable aspect ratios, high BET surface areas and monodispersed morphologies, showing good performance in gas adsorpion. PMID:27506370

  11. Synthesis and characterization of hollow spherical copper phosphide (Cu 3P) nanopowders

    Science.gov (United States)

    Liu, Shuling; Qian, Yitai; Xu, Liqiang

    2009-03-01

    In this paper, hollow spherical Cu 3P nanopowders were synthesized by using copper sulfate pentahydrate (CuSO 4ṡ5H 2O) and yellow phosphorus in a mixed solvent of glycol, ethanol and water at 140-180 ∘C for 12 h. X-ray powder diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), electron diffraction pattern (ED) and transmission electronic microscopy (TEM) studies show that the as-synthesized nanocrystal is pure hexagonal phase Cu 3P with a hollow spherical morphology. Based on the TEM observations, a possible aggregation growth mechanism was proposed for the formation of Cu 3P hollow structures. Meanwhile, the effects of some key factors such as solvents, reaction temperature and reaction time on the final formation of the Cu 3P hollow structure were also discussed.

  12. Electrophoresis assisted time-of-flow mass spectrometry using hollow nanomechanical resonators

    National Research Council Canada - National Science Library

    Swathi Chaudhari; Kamalesh Chaudhari; Seokbeom Kim; Faheem Khan; Jungchul Lee; Thomas Thundat

    2017-01-01

    ...’ shaped hollow nanomechanical resonators (HNR). Capillary electrophoresis was coupled with the HNR based mass detection to overcome low ionic conductivity of channels embedded in the HNR preventing direct in-situ electrophoretic separation...

  13. Slurry Bubble Column Reactor Optimization (book chapter)

    Energy Technology Data Exchange (ETDEWEB)

    Gamwo, I.K.; Gidaspow, D. (Illinois Inst. of Technology, Chicago, IL); Jung, J. (ANL)

    2007-03-01

    Slurry bubble column reactors (SBCR) are the preferred contactors for the conversion of syngas to fules and chemicals partially due to their superior heat and mass transfer characteristics. The multiphase fluid dynamics in these systems greatly affect the reactor volumetric productivity. Here, we have developed a computational fluid dynamics (CFD) assisted design methodology for searching the optimum particle size for maximum production in a SBCR. Reactor optimization due to heat exchanger configuration was also investigated. We have rearranged the heat exchangers in a SBCR and constructed a CFD model for a baffled reactor. The novel arrangement of the exchangers prevents the unfavorable high catalysts concentration at the lower stage of the reactor. Thus an optimum catalyst concentration is maintained during the course of the production of liquid fuels.

  14. Near shore floating oscillating wave column

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    Three different types of floating buoys, using oscillating wave columns, have been considered for generating electric power in an Atlantic environment. The study considered the situation close to the shore, but in the ultimate it was hoped to deploy units offshore. Although other designs would have greater power capture efficiency, the Spar Buoy was studied in greatest depth as it was expected to have the edge in terms of building cost and operating economics. A risk assessment was carried out for both concrete and steel buoys. The report covers (1) history of the project development; (2) project definition; (3) power generation and sensitivities and (4) lessons learned. The study was sponsored by Great Britain's DTI.

  15. Maximum Variance Hashing via Column Generation

    Directory of Open Access Journals (Sweden)

    Lei Luo

    2013-01-01

    item search. Recently, a number of data-dependent methods have been developed, reflecting the great potential of learning for hashing. Inspired by the classic nonlinear dimensionality reduction algorithm—maximum variance unfolding, we propose a novel unsupervised hashing method, named maximum variance hashing, in this work. The idea is to maximize the total variance of the hash codes while preserving the local structure of the training data. To solve the derived optimization problem, we propose a column generation algorithm, which directly learns the binary-valued hash functions. We then extend it using anchor graphs to reduce the computational cost. Experiments on large-scale image datasets demonstrate that the proposed method outperforms state-of-the-art hashing methods in many cases.

  16. Education and training column: the learning collaborative.

    Science.gov (United States)

    MacDonald-Wilson, Kim L; Nemec, Patricia B

    2015-03-01

    This column describes the key components of a learning collaborative, with examples from the experience of 1 organization. A learning collaborative is a method for management, learning, and improvement of products or processes, and is a useful approach to implementation of a new service design or approach. This description draws from published material on learning collaboratives and the authors' experiences. The learning collaborative approach offers an effective method to improve service provider skills, provide support, and structure environments to result in lasting change for people using behavioral health services. This approach is consistent with psychiatric rehabilitation principles and practices, and serves to increase the overall capacity of the mental health system by structuring a process for discovering and sharing knowledge and expertise across provider agencies. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

  17. Anionic ligand assisted synthesis of 3-D hollow TiO2 architecture with enhanced photoelectrochemical performance.

    Science.gov (United States)

    Shin, Seong Sik; Kim, Dong Wook; Park, Jong Hoon; Kim, Dong Hoe; Kim, Ju Seong; Hong, Kug Sun; Cho, In Sun

    2014-12-30

    Hollow structured materials have shown great advantages for use in photoelectrochemical devices. However, their poor charge transport limits overall device performance. Here, we report a unique 3-D hollow architecture of TiO2 that greatly improves charge transport properties. We found that citric acid (CA) plays crucial roles in the formation of the 3-D hollow architecture. First, CA controls the hydrolysis rate of Ti ions and facilitates surface hydrolysis on templates during hydrothermal synthesis. Second, CA suppresses the growth of the carbon template at the initial reaction stage, resulting in the formation of comparatively small hollow fibers. More importantly, a prolonged hydrothermal reaction with CA enables a hollow sphere to grow into entangled hollow fibers via biomimetic swallowing growth. To demonstrate advantages of the 3-D hollow architecture for photoelectrochemical devices, we evaluated its photoelectrochemical performance, specifically the electrolyte diffusion and electron dynamics, by employing dye-sensitized solar cells as a model device. A systemic analysis reveals that the 3-D hollow architecture greatly improves both the electrolyte diffusion and electron transport compared to those of the nanoparticle and hollow sphere due to the elongated porous hollow morphology as well as the densely interconnected nanoparticles at the wall layer.

  18. Novel electrostatic column for ion projection lithography

    Energy Technology Data Exchange (ETDEWEB)

    Chalupka, A.; Stengl, G.; Buschbeck, H.; Lammer, G.; Vonach, H.; Fischer, R.; Hammel, E.; Loeschner, H.; Nowak, R.; Wolf, P. (IMS - Ion Microfabrication Systems GmbH, A-1020 Vienna (Austria)); Finkelstein, W.; Hill, R.W. (Advanced Lithography Group, Columbia, Maryland 21045 (United States)); Berry, I.L. (Department of Defense, Microelectronics Research Laboratory, Columbia, Maryland 21045 (United States)); Harriott, L.R. (AT T Bell Laboratories, Murray Hill, New Jersey 07974 (United States)); Melngailis, J. (University of Maryland, College Park, Maryland 20742 (United States)); Randall, J.N. (Texas Instruments, Dallas, Texas 75243 (United States)); Wolfe, J.C. (University of Houston, Houston, Texas 77204 (United States)); Stroh, H.; Wollnik, H. (University of Giessen, D-35392 Giessen (Germany)); Mondelli, A.A.; Petillo, J.J. (Science Applications International Corporation, McLean, Virginia 22102 (United States)); Leung, K. (Lawrence Berkeley Laboratory, University of Californi

    1994-11-01

    Ion projection lithography (IPL) is being considered for high volume sub-0.25-[mu]m lithography. A novel ion-optical column has been designed for exposing 20[times]20 mm[sup 2] fields at 3[times] reduction from stencil mask to wafer substrates. A diverging lens is realized by using the stencil mask as the first electrode of the ion-optical column. The second and third electrode form an accelerating field lens. The aberrations of the first two lenses (diverging lens and field lens) are compensated by an asymmetric Einzel lens projecting an ion image of the stencil mask openings onto the wafer substrate with better than 2 mrad telecentricity. Less than 30 nm intrafield distortion was calculated within 20[times]20 mm[sup 2] exposure fields. The calculation uncertainty is estimated to be about 10 nm. The calculation holds for helium ions with [approx]10 keV ion energy at the stencil mask and 150 keV ion energy at the wafer plane. A virtual ion source size of 10 [mu]m has been assumed. The calculated chromatic aberrations are less than 60 nm, assuming 6 eV energy spread of the ions extracted from a duoplasmatron source. Recently a multicusp ion source has been developed for which preliminary results indicate an energy spread of less than 2 eV. Thus, with a multicusp source chromatic aberrations of less than 20 nm are to be expected. The ion energy at the crossover between the field lens and the asymmetric Einzel lens is 200 keV. Therefore, stochastic space charge induced degradations in resolution can be kept sufficiently low. The divergence of the ion image projected to the wafer plane is less than 2 mrad. Thus, the usable'' depth of focus for the novel ion optics is in the order of 10 [mu]m.

  19. La2O3 hollow nanospheres for high performance lithium-ion rechargeable batteries.

    Science.gov (United States)

    Sasidharan, Manickam; Gunawardhana, Nanda; Inoue, Masamichi; Yusa, Shin-ichi; Yoshio, Masaki; Nakashima, Kenichi

    2012-03-28

    An efficient and simple protocol for synthesis of novel La(2)O(3) hollow nanospheres of size about 30 ± 2 nm using polymeric micelles is reported. The La(2)O(3) hollow nanospheres exhibit high charge capacity and cycling performance in lithium-ion rechargeable batteries (LIBs), which was scrutinized for the first time among the rare-earth oxides. This journal is © The Royal Society of Chemistry 2012

  20. Hollow fiber membrane contactor as a gas-liquid model contactor

    OpenAIRE

    Dindore, V. Y.; Brilman, D. W. F.; Versteeg, G. F.

    2005-01-01

    Microporous hollow fiber gas-liquid membrane contactors have a fixed and well-defined gas-liquid interfacial area. The liquid flow through the hollow fiber is laminar, thus the liquid side hydrodynamics are well known. This allows the accurate calculation of the fiber side physical mass transfer coefficient from first principles. Moreover, in the case of gas-liquid membrane contactor, the gas-liquid exposure time can be varied easily and independently without disturbing the gas-liquid interfa...

  1. Low Loss and Highly Birefringent Hollow-Core Photonic Crystal Fiber

    DEFF Research Database (Denmark)

    Roberts, P. John; Williams, D.P.; Mangan, Brian J.

    2006-01-01

    A hollow-core photonic crystal fiber design is proposed which enables both low-loss and polarization-maintained signal propagation. The design relies on an arrangement of antiresonant features positioned on the glass ring that surrounds the air core.......A hollow-core photonic crystal fiber design is proposed which enables both low-loss and polarization-maintained signal propagation. The design relies on an arrangement of antiresonant features positioned on the glass ring that surrounds the air core....

  2. Facile and green fabrication of organic single-crystal hollow micro/nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jun; Chen Yingzhi; Ou Xuemei; Zhang Xiaohong [Nano-organic Photoelectronic Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Zhang Xiujuan, E-mail: xjzhang@suda.edu.cn, E-mail: xhzhang@mail.ipc.ac.cn [Functional Nano and Soft Materials Laboratory (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China)

    2011-07-15

    Under high humidity and appropriate temperature, tris (8-hydroxyquinoline) aluminum (Alq3) solid micro/nanostructures may be etched into hollow structures and still retain their crystalline structures and surface morphologies. The shapes and sizes of the hollow structures are easily adjusted by varying the experimental parameters. Throughout the entire process, water is introduced into the system instead of organic or corrosive solvents, making this method convenient and environmentally friendly; it can also be extended to application in other materials such as TCNQ.

  3. Measurement of blood glucose by infrared spectroscopy using hollow-optical fiber probe

    Science.gov (United States)

    Tanaka, Y.; Kino, S.; Matsuura, Y.

    2013-03-01

    An infrared spectroscopy system based on a hollow-optical fiber probe for measurement of blood glucose concentration is developed. The probe consists of a flexible hollow-optical fiber and an ATR prism attached at the distal end of the fiber. This flexible probe enables measurement of oral mucosa and ear lobes that have blood capillaries near the skin surface. Experimental results show that absorption peaks of blood glucose are detected by the system.

  4. Mesoporous Single-crystal CoSn(OH)6 Hollow Structures with Multilevel Interiors

    OpenAIRE

    Wang, Zhiyu; Wang, Zichen; Wu, Haobin; Lou, Xiong Wen (David)

    2013-01-01

    Hollow nanostructures represent a unique class of functional nanomaterials with many applications. In this work, a one-pot and unusual ?pumpkin-carving? protocol is demonstrated for engineering mesoporous single-crystal hollow structures with multilevel interiors. Single-crystal CoSn(OH)6 nanoboxes with uniform size and porous shell are synthesized by fast growth of CoSn(OH)6 nanocubes and kinetically-controlled etching in alkaline medium. Detailed investigation on reaction course suggests th...

  5. Simulation study of Hollow Electron Beam Collimation in HL-LHC.

    Energy Technology Data Exchange (ETDEWEB)

    Fitterer, M. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Stancari, G. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Valishev, A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Redaelli, S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2016-10-05

    Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the HL-LHC. In this note we evaluate the performance of a hollow electron lens for different HL-LHC scenarios in terms of halo removal rates and the effect of profile imperfections of the electron beam on the proton beam core in case of a pulsed operation of the e-lens.

  6. Efficient frequency generation in phoXonic cavities based on hollow whispering gallery mode resonators.

    Science.gov (United States)

    Farnesi, Daniele; Righini, Giancarlo; Nunzi Conti, Gualtiero; Soria, Silvia

    2017-03-07

    We report on nonlinear optical effects on phoxonic cavities based on hollow whispering gallery mode resonators pumped with a continuous wave laser. We observed stimulated scattering effects such as Brillouin and Raman, Kerr effects such as degenerated and non-degenerated four wave mixing, and dispersive wave generation. These effects happened concomitantly. Hollow resonators give rise to a very rich nonlinear scenario due to the coexistence of several family modes.

  7. Centimeter to decimeter hollow concretions and voids in Gale Crater sediments, Mars

    OpenAIRE

    Wiens, Roger C.; Rubin, David M.; Goetz, Walter; Fairén, Alberto G.; Schwenzer, Susanne P.; Johnson, Jeffrey R.; Milliken, Ralph; Clark, Ben; Mangold, Nicolas; Stack, Kathryn M.; Oehler, Dorothy; Rowland, Scott; Chan, Marjorie; Vaniman, David; Maurice, Sylvestre

    2017-01-01

    Voids and hollow spheroids between ∼1 and 23 cm in diameter occur at several locations along the traverse of the Curiosity rover in Gale crater, Mars. These hollow spherical features are significantly different from anything observed in previous landed missions. The voids appear in dark-toned, rough-textured outcrops, most notably at Point Lake (sols 302-305) and Twin Cairns Island (sol 343). Point Lake displays both voids and cemented spheroids in close proximity; other locations show one or...

  8. Integrated carbon fiber electrodes within hollow polymer microneedles for transdermal electrochemical sensing

    OpenAIRE

    Miller, Philip R; Gittard, Shaun D.; Edwards, Thayne L.; Lopez, DeAnna M.; Xiao, Xiaoyin; Wheeler,David R.; Monteiro-Riviere, Nancy A.; Brozik, Susan M.; Polsky, Ronen; Narayan, Roger J

    2011-01-01

    In this study, carbon fiber electrodes were incorporated within a hollow microneedle array, which was fabricated using a digital micromirror device-based stereolithography instrument. Cell proliferation on the acrylate-based polymer used in microneedle fabrication was examined with human dermal fibroblasts and neonatal human epidermal keratinocytes. Studies involving full-thickness cadaveric porcine skin and trypan blue dye demonstrated that the hollow microneedles remained intact after punct...

  9. UV-enhanced sacrificial layer stabilised graphene oxide hollow fibre membranes for nanofiltration

    OpenAIRE

    J. Y. Chong; Aba, N. F. D.; Wang, B.; Mattevi, C.; K. Li

    2015-01-01

    Graphene oxide (GO) membranes have demonstrated great potential in gas separation and liquid filtration. For upscale applications, GO membranes in a hollow fibre geometry are of particular interest due to the high-efficiency and easy-assembly features at module level. However, GO membranes were found unstable in dry state on ceramic hollow fibre substrates, mainly due to the drying-related shrinkage, which has limited the applications and post-treatments of GO membranes. We demonstrate here t...

  10. Emission characteristics of laser ablation-hollow cathode glow discharge spectral source

    Directory of Open Access Journals (Sweden)

    Karatodorov Stefan

    2014-11-01

    Full Text Available The emission characteristics of a scheme combining laser ablation as sample introduction source and hollow cathode discharge as excitation source are presented. The spatial separation of the sample material introduction by laser ablation and hollow cathode excitation is achieved by optimizing the gas pressure and the sample-cathode gap length. At these conditions the discharge current is maximized to enhance the analytical lines intensity.

  11. Micro-Displacement Sensor Based on a Hollow-Core Photonic Crystal Fiber

    Directory of Open Access Journals (Sweden)

    Orlando Frazão

    2012-12-01

    Full Text Available A sensing head based on a hollow-core photonic crystal fiber for in-reflection measurement of micro-displacements is presented. The sensing structure takes advantage of the multimodal behavior of a short segment of hollow-core photonic crystal fiber in-reflection, being spliced to a single mode fiber at its other end. A modal interferometer is obtained when the sensing head is close to a mirror, through which displacement is measured.

  12. Optical phase response to temperature in a hollow-core photonic crystal fiber.

    Science.gov (United States)

    Meiselman, Seth; Cranch, Geoffrey A

    2017-10-30

    Analysis of previous measurements of thermal phase sensitivity in hollow core photonic crystal fibers is presented with additional new corroborating measurements, resolving a discrepancy in previously reported results. We extend an existing derivation of thermo-mechanical phase sensitivity in solid- and hollow-core photonic crystal fiber to also include kagome lattice photonic crystal fibers. Measured thermal phase response is shown to agree with theoretical prediction to within a few percent.

  13. Strength assessment of a cryostat used by the hollow electron test station.

    CERN Document Server

    Efremov, Filip

    2015-01-01

    The following report explains the work I have done on my summer student work project and the experience I have gained during the process. The work consisted of a strength assessment of a cryogenic vacuum insulated vessel according to European regulations. The cryogenic vacuum insulated vessel is used for the cooling of the solenoids. The solenoids are used in the hollow electron test station and create the magnetic fields used for testing electron guns and validating the concept of a hollow electron lens.

  14. Uniform hollow magnetite spheres: Facile synthesis, growth mechanism, and their magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xing, E-mail: xzhou@mail.usts.edu.cn [School of Chemistry, Biology and Material Engineering, Suzhou University of Science and Technology, Suzhou 215009 (China); Research Center for Engineering Technology of Polymeric Composites of Shanxi Province, North University of China, Taiyuan 030051 (China); Zhao, Guizhe [Research Center for Engineering Technology of Polymeric Composites of Shanxi Province, North University of China, Taiyuan 030051 (China); Liu, Yaqing, E-mail: zfflyq98@163.com [Research Center for Engineering Technology of Polymeric Composites of Shanxi Province, North University of China, Taiyuan 030051 (China)

    2014-11-15

    Highlights: • Uniform Fe{sub 3}O{sub 4} hollow spheres with high saturation magnetization were synthesized through a simple solvothermal process. • Without using any hard templates or external magnetic field. • The as-prepared magnetite hollow spheres exhibit a ferromagnetic behavior with high Ms of ca. 85.9 emu/g at room temperature. • The morphology of Fe{sub 3}O{sub 4} with nanoparticles, hollow, and irregular structures could be adjusted by changing the reactive conditions. - Abstract: Hierarchical porous Fe{sub 3}O{sub 4} hollow spheres with high saturation magnetization were synthesized through a simple solvothermal process in ethylene glycol (EG) in the presence of Tetrabutylammonium chloride (TBAC) and urea. By investigating the effect of reaction temperature, time, the amount of urea, and concentration of iron ion on the formation of hollow spheres, it was proposed that the main formation mechanism of hollow spheres is Ostwald ripening process combined with assembly-then-inside-out evacuation process. Additionally, it is found that the morphology of Fe{sub 3}O{sub 4} with nanoparticles, hollow, and irregular structures could be adjusted by changing the above factors. The resulting products were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometer (VSM). The hierarchical porous Fe{sub 3}O{sub 4} hollow spheres exhibited enhanced saturation magnetization as compared with Fe{sub 3}O{sub 4} nanoparticles.

  15. Distortional buckling modes of semi-discretized thin-walled columns

    DEFF Research Database (Denmark)

    Andreassen, Michael Joachim; Jönsson, Jeppe

    2012-01-01

    stress equations for simply supported columns with constrained transverse displacements at the end sections and a constant axial initial stress. Based on the known boundary conditions the reduced order differential equations are solved by using the trigonometric solution functions and solving the related......This paper presents distorting buckling solutions for semi-discretized thin-walled columns using the coupled differential equations of a generalized beam theory (GBT). In two related papers recently published by the authors a novel semi-discretization approach to GBT has been presented. The cross...... section is discretized and analytical solutions are sought for the variation along the beam. With this new approach the general GBT equations for identification of a full set of deformation modes corresponding to both homogeneous and non-homogenous equations are formulated and solved. Thereby giving...

  16. Temperature-compensated 8-bit column driver for AMLCD

    Science.gov (United States)

    Dingwall, Andrew G. F.; Lin, Mark L.

    1995-06-01

    An all-digital, 5 V input, 50 Mhz bandwidth, 10-bit resolution, 128- column, AMLCD column driver IC has been designed and tested. The 10-bit design can enhance display definition over 6-bit nd 8-bit column drivers. Precision is realized with on-chip, switched-capacitor DACs plus transparently auto-offset-calibrated, opamp outputs. Increased resolution permits multiple 10-bit digital gamma remappings in EPROMs over temperature. Driver IC features include externally programmable number of output column, bi-directional digital data shifting, user- defined row/column/pixel/frame inversion, power management, timing control for daisy-chained column drivers, and digital bit inversion. The architecture uses fewer reference power supplies.

  17. Effect of axial mixing on RDC and PSE columns performance

    CERN Document Server

    Bastani, D

    2001-01-01

    Using the experimental data obtained from two RDC columns at two different sizes (7.62 and 21.9 cm) and one PSE column with 21.5 cm size, the effect of axial mixing on the performance of these columns was studied. Comparison between the experimental and theoretical (neglecting the axial mixing) number of transfer units indicates that, this effect in PSE columns is more than RDC columns (400% and 200% respectively). These results show that this effect can increase the height of the PSE column up to 4 times for a specific efficiency. Also the results show that this effect is more in law interfacial tension systems, which shows no need of application of agitation facilities when these systems are used.

  18. Laser metal deposition with spatial variable orientation based on hollow-laser beam with internal powder feeding technology

    Science.gov (United States)

    Shi, Tuo; Lu, Bingheng; Shi, Shihong; Meng, Weidong; Fu, Geyan

    2017-02-01

    In this study, a hollow-laser beam with internal powder feeding (HLB-IPF) head is applied to achieve non-horizontal cladding and deposition of overhanging structure. With the features of this head such as uniform scan energy distribution, thin and straight spraying of the powder beam, the deposition in spatial variable orientation is conducted using a 6-axis robot. During the deposition process the head keeps tangential to the growth direction of the part. In the experiment, a ;vase; shaped metal part with overhanging structure is successfully deposited, and the largest overhanging angle achieves 80° to the vertical direction. The ;step effect; between cladding layers is completely eliminated with the best surface roughness of Ra=3.864 μm. Cross section of cladding layers with unequal height are deposited for angle change. Test results indicate that the formed part has uniform wall thickness, fine microstructure and high microhardness.

  19. Mesoporous single-crystal CoSn(OH)6 hollow structures with multilevel interiors.

    Science.gov (United States)

    Wang, Zhiyu; Wang, Zichen; Wu, Haobin; Lou, Xiong Wen David

    2013-01-01

    Hollow nanostructures represent a unique class of functional nanomaterials with many applications. In this work, a one-pot and unusual "pumpkin-carving" protocol is demonstrated for engineering mesoporous single-crystal hollow structures with multilevel interiors. Single-crystal CoSn(OH)6 nanoboxes with uniform size and porous shell are synthesized by fast growth of CoSn(OH)6 nanocubes and kinetically-controlled etching in alkaline medium. Detailed investigation on reaction course suggests that the formation of a passivation layer of Co(III) species around the liquid-solid interface is critical for the unusual hollowing process. With reasonable understanding on the mechanism involved, this approach shows high versatility for the synthesis of CoSn(OH)6 hollow architectures with a higher order of interior complexity, such as yolk-shell particles and multishelled nanoboxes. The obtained CoSn(OH)6 hollow nanostructures can be easily converted to hollow nanostructures of tin-based ternary metal oxides with excellent photocatalytic and electrochemical properties.

  20. Low-temperature template-free synthesis of Cu 2O hollow spheres

    Science.gov (United States)

    Sui, Yongming; Zhang, Yanyan; Fu, Wuyou; Yang, Haibin; Zhao, Qiang; Sun, Peng; Ma, Dong; Yuan, Mingxia; Li, Yixing; Zou, Guangtian

    2009-04-01

    Cuprous oxide (Cu 2O) hollow spheres have been successfully prepared via a template-free hydrothermal method with the assistance of poly(vinylprrolidone) (PVP) at 90 °C. The structure and morphology of the Cu 2O hollow spheres were characterized by X-ray diffraction, field-emission scanning electron microscope, and transmission electron microscope. The as-prepared hollow spheres are cubic phase Cu 2O. The as-prepared products have a hollow sphere structure with outer diameters of 400-700 nm and the thickness of shells is about 40-70 nm. Poly(vinylprrolidone) is employed for the first time to improve the stabilization of crystalline phase occurred at a rate commensurate with localized Ostwald ripening and self-transformation for producing Cu 2O hollow spheres. A possible PVP-assisted Ostwald ripening process is proposed for the formation of Cu 2O hollow spheres on the basis of intermediate products at different growth stages.