Automated measurement of stent strut coverage in intravascular optical coherence tomography

Science.gov (United States)

Ahn, Chi Young; Kim, Byeong-Keuk; Hong, Myeong-Ki; Jang, Yangsoo; Heo, Jung; Joo, Chulmin; Seo, Jin Keun

2015-02-01

Optical coherence tomography (OCT) is a non-invasive, cross-sectional imaging modality that has become a prominent imaging method in percutaneous intracoronary intervention. We present an automated detection algorithm for stent strut coordinates and coverage in OCT images. The algorithm for stent strut detection is composed of a coordinate transformation from the polar to the Cartesian domains and application of second derivative operators in the radial and the circumferential directions. Local region-based active contouring was employed to detect lumen boundaries. We applied the method to the OCT pullback images acquired from human patients in vivo to quantitatively measure stent strut coverage. The validation studies against manual expert assessments demonstrated high Pearson's coefficients ( R = 0.99) in terms of the stent strut coordinates, with no significant bias. An averaged Hausdorff distance of < 120 μm was obtained for vessel border detection. Quantitative comparison in stent strut to vessel wall distance found a bias of < 12.3 μm and a 95% confidence of < 110 μm.

Variable volume combustor with aerodynamic support struts

Science.gov (United States)

Ostebee, Heath Michael; Johnson, Thomas Edward; Stewart, Jason Thurman; Keener, Christopher Paul

2017-03-07

The present application provides a combustor for use with a gas turbine engine. The combustor may include a number of micro-mixer fuel nozzles and a fuel injection system for providing a flow of fuel to the micro-mixer fuel nozzles. The fuel injection system may include a number of support struts supporting the fuel nozzles and providing the flow of fuel therethrough. The support struts may include an aerodynamic contoured shape so as to distribute evenly a flow of air to the micro-mixer fuel nozzles.

Nonlinear process in the mode transition in typical strut-based and cavity-strut based scramjet combustors

Science.gov (United States)

Yan, Li; Liao, Lei; Huang, Wei; Li, Lang-quan

2018-04-01

The analysis of nonlinear characteristics and control of mode transition process is the crucial issue to enhance the stability and reliability of the dual-mode scramjet engine. In the current study, the mode transition processes in both strut-based combustor and cavity-strut based combustor are numerically studied, and the influence of the cavity on the transition process is analyzed in detail. The simulations are conducted by means of the Reynolds averaged Navier-Stokes (RANS) equations coupled with the renormalization group (RNG) k-ε turbulence model and the single-step chemical reaction mechanism, and this numerical approach is proved to be valid by comparing the predicted results with the available experimental shadowgraphs in the open literature. During the mode transition process, an obvious nonlinear property is observed, namely the unevenly variations of pressure along the combustor. The hysteresis phenomenon is more obvious upstream of the flow field. For the cavity-strut configuration, the whole flow field is more inclined to the supersonic state during the transition process, and it is uneasy to convert to the ramjet mode. In the scram-to-ram transition process, the process would be more stable, and the hysteresis effect would be reduced in the ram-to-scram transition process.

Analytical prediction of the unsteady lift on a rotor caused by downstream struts

Science.gov (United States)

Taylor, A. C., III; Ng, W. F.

1987-01-01

A two-dimensional, inviscid, incompressible procedure is presented for predicting the unsteady lift on turbomachinery blades caused by the upstream potential disturbance of downstream flow obstructions. Using the Douglas-Neumann singularity superposition potential flow computer program to model the downstream flow obstructions, classical equations of thin airfoil theory are then employed, to compute the unsteady lift on the upstream rotor blades. The method is applied to a particular geometry which consists of a rotor, a downstream stator, and downstream struts which support the engine casing. Very good agreement between the Douglas-Neumann program and experimental measurements was obtained for the downstream stator-strut flow field. The calculations for the unsteady lift due to the struts were in good agreement with the experiments in showing that the unsteady lift due to the struts decays exponentially with increased axial separation of the rotor and the struts. An application of the method showed that for a given axial spacing between the rotor and the strut, strut-induced unsteady lift is a very weak function of the axial or circumferential position of the stator.

Irradiated strut allografts for reconstructing tumour defects: how effective?

International Nuclear Information System (INIS)

Astrid Lobo Gajiwala; Manish Agarwal; Ajay Puri; Cynthia D Lima

2008-01-01

Full text: Allografts are biological options for reconstructing large bone defects. We report our experience with 87 irradiated (25 kGy of gamma radiation) strut allografts used in various defects following tumour surgery. Reconstruction in 35 full segment defects involved 22 full segment allografts used alone, 4 allograft prosthetic composites (APC) and 9 allografts combined with a vascularized fibula. Twelve partial segment defects were reconstructed with allograft struts (including 2 APC). Full segment allograft struts (mainly fibulae) were used in 40 contained post-curettage defects. The cases were studied for time to incorporation and complications. The follow-up ranged from 12 to 72 months. Of the 26 full segment defects where allograft alone or APC was used, 2 were lost to follow-up, 5 died before incorporation and 3 grafts were removed (2 infection and 1 local recurrence). Six united primarily at 2-4 years. Seven patients with non union were autografted at both junctions resulting in 6 unions. One patient had early plate breakage and refused further treatment. One allograft fractured after union after autografting. Two of 4 APC also united. In contrast, the 9 allograft-vascularized fibula combinations showed unambiguous incorporation between 5-9 months with only one junction requiring bone grafting. Of the 12 partial segment struts, barring one removed for infection, 11 have completely incorporated. Thirty one out of 40 struts placed within contained post curettage defects have incorporated (2 removed for infection and seven lost to follow-up). There were total 6 infections (7%) 4 of which occurred 1-2 years after surgery. Irradiated full segment struts alone incorporate poorly and are best used combined with a live fibula. Irradiated full and partial segment allografts used inside contained defects give consistently good results. Frozen grafts seem to incorporate faster and better than lyophilised grafts. (Author)

Experimental investigation on combustion performance of cavity-strut injection of supercritical kerosene in supersonic model combustor

Science.gov (United States)

Sun, Ming-bo; Zhong, Zhan; Liang, Jian-han; Wang, Hong-bo

2016-10-01

Supersonic combustion with cavity-strut injection of supercritical kerosene in a model scramjet engine was experimentally investigated in Mach 2.92 facility with the stagnation temperatures of approximately 1430 K. Static pressure distribution in the axial direction was determined using pressure transducers installed along the centerline of the model combustor top walls. High speed imaging camera was used to capture flame luminosity and combustion region distribution. Multi-cavities were used to and stabilize the combustion in the supersonic combustor. Intrusive injection by thin struts was used to enhance the fuel-air mixing. Supercritical kerosene at temperatures of approximately 780 K and various pressures was prepared using a heat exchanger driven by the hot gas from a pre-burner and injected at equivalence ratios of approximately 1.0. In the experiments, combustor performances with different strut injection schemes were investigated and compared to direct wall injection scheme based on the measured static pressure distributions, the specific thrust increments and the images obtained by high-speed imaging camera. The experimental results showed that the injection by thin struts could obtain an enhanced mixing in the field but could not acquire a steady flame when mixing field cannot well match cavity separation region. There is no significant difference on performance between different schemes since the unsteady intermittent and oscillating flame leads to no actual combustion efficiency improvement.

Vena Cava Filter Retrieval with Aorto-Iliac Arterial Strut Penetration.

Science.gov (United States)

Holly, Brian P; Gaba, Ron C; Lessne, Mark L; Lewandowski, Robert J; Ryu, Robert K; Desai, Kush R; Sing, Ronald F

2018-05-03

To evaluate the safety and technical success of inferior vena cava (IVC) filter retrieval in the setting of aorto-iliac arterial strut penetration. IVC filter registries from six large United States IVC filter retrieval practices were retrospectively reviewed to identify patients who underwent IVC filter retrieval in the setting of filter strut penetration into the adjacent aorta or iliac artery. Patient demographics, implant duration, indication for placement, IVC filter type, retrieval technique and technical success, adverse events, and post procedural clinical outcomes were identified. Arterial penetration was determined based on pre-procedure CT imaging in all cases. The IVC filter retrieval technique used was at the discretion of the operating physician. Seventeen patients from six US centers who underwent retrieval of an IVC filter with at least one strut penetrating either the aorta or iliac artery were identified. Retrieval technical success rate was 100% (17/17), without any major adverse events. Post-retrieval follow-up ranging from 10 days to 2 years (mean 4.6 months) was available in 12/17 (71%) patients; no delayed adverse events were encountered. Findings from this series suggest that chronically indwelling IVC filters with aorto-iliac arterial strut penetration may be safely retrieved.

Insidious strut fractures in a DeBakey-Surgitool aortic valve prosthesis.

Science.gov (United States)

Scott, S M; Sethi, G K; Paulson, D M; Takaro, T

1978-04-01

Recent reports of cage wear occurring in DeBakey-Surgitool aortic valve prostheses prompted us to examine with image intensification all our patients who have had this type of prosthesis implanted. One patient, who was asymptomatic, was discovered to have a prosthesis with two fractured struts. This patient's prosthetic valve was replaced successfully with a stented porcine heterograft prosthesis. Including the valve removed from this patient, 8 DeBakey-Surgitool aortic valves with structural defects have been reported to the manufacturer. In the absence of a catastrophic event, patients with valves having fractured or worn struts may be totally asymptomatic, and routine periodic roentgenographic examination may be the only way of detecting strut wear or fracture.

Strut fracture in a Bjork-Shiley aortic valve prosthesis.

Science.gov (United States)

Lifschultz, B D; Donoghue, E R

1985-10-01

Strut fracture can be a life-threatening adverse effect of mechanical prosthetic heart valves. This complication has occurred in the DeBakey, the Beall, the Cooley-Cutter and, most recently, the Bjork-Shiley valves. We report the case of a 35-year-old man who died suddenly 16 months after a 60 degree Bjork-Shiley Convexo-Concave heart valve prosthesis was inserted in the aortic position. At autopsy, the two welded attachments of the valve's outlet strut had fractured. The valve's tilting disc was found in his abdominal aorta.

Efficient tungsten oxide/bismuth oxyiodide core/shell photoanode for photoelectrochemical water splitting

Science.gov (United States)

Ma, Haipeng; Zhang, Jing; Liu, Zhifeng

2017-11-01

The novel WO3 nanorods (NRs)/BiOI core/shell structure composite is used as an efficient photoanode applied in photoelectrochemical (PEC) water splitting for the first time. It is synthesized via facile hydrothermal method and, successive ionic layer adsorption and reaction (SILAR) process. This facile synthesis route can achieve uniform WO3/BiOI core/shell composite nanostructures and obtain varied BiOI morphologies simultaneously. The WO3 NRs/BiOI-20 composite exhibits enhanced PEC activity compared to pristine WO3 with a photocurrent density of 0.79 mA cm-2 measured at 0.8 V vs. RHE under AM 1.5G. This excellent performance benefits from the broader absorption spectrum and suppressed electron-hole recombination. This novel core/shell composite may provide insight in developing more efficient solar driven photoelectrodes.

[Strut fracture of a convex-concave 60 degree Björk-Shiley mitral valve prosthesis 5 years after implantation--metallurgic analysis of the prosthesis strut].

Science.gov (United States)

Lemke, B; Rathmann, J; Wiebe, V; Witzel, U

1991-08-01

Acute mechanical failure of prosthetic heart valves is rare, but associated with high mortality when occurring. For convexo-concave Björk-Shiley prostheses only fractures of the outlet strut are reported. We present a case of lethal mechanical complication 5 years after implantation. By additional metallurgic analysis we were able to identify a sequential course of the outlet strut fracture. This could lead to new approaches for early detection of this complication.

Significant efficiency enhancement of hybrid solar cells using core-shell nanowire geometry for energy harvesting.

Science.gov (United States)

Tsai, Shin-Hung; Chang, Hung-Chih; Wang, Hsin-Hua; Chen, Szu-Ying; Lin, Chin-An; Chen, Show-An; Chueh, Yu-Lun; He, Jr-Hau

2011-12-27

A novel strategy employing core-shell nanowire arrays (NWAs) consisting of Si/regioregular poly(3-hexylthiophene) (P3HT) was demonstrated to facilitate efficient light harvesting and exciton dissociation/charge collection for hybrid solar cells (HSCs). We experimentally demonstrate broadband and omnidirectional light-harvesting characteristics of core-shell NWA HSCs due to their subwavelength features, further supported by the simulation based on finite-difference time domain analysis. Meanwhile, core-shell geometry of NWA HSCs guarantees efficient charge separation since the thickness of the P3HT shells is comparable to the exciton diffusion length. Consequently, core-shell HSCs exhibit a 61% improvement of short-circuit current for a conversion efficiency (η) enhancement of 31.1% as compared to the P3HT-infiltrated Si NWA HSCs with layers forming a flat air/polymer cell interface. The improvement of crystal quality of P3HT shells due to the formation of ordering structure at Si interfaces after air mass 1.5 global (AM 1.5G) illumination was confirmed by transmission electron microscopy and Raman spectroscopy. The core-shell geometry with the interfacial improvement by AM 1.5G illumination promotes more efficient exciton dissociation and charge separation, leading to η improvement (∼140.6%) due to the considerable increase in V(oc) from 257 to 346 mV, J(sc) from 11.7 to 18.9 mA/cm(2), and FF from 32.2 to 35.2%, which is not observed in conventional P3HT-infiltrated Si NWA HSCs. The stability of the Si/P3HT core-shell NWA HSCs in air ambient was carefully examined. The core-shell geometry should be applicable to many other material systems of solar cells and thus holds high potential in third-generation solar cells.

Characterization of a hydro-pneumatic suspension strut with gas-oil emulsion

Science.gov (United States)

Yin, Yuming; Rakheja, Subhash; Yang, Jue; Boileau, Paul-Emile

2018-06-01

The nonlinear stiffness and damping properties of a simple and low-cost design of a hydro-pneumatic suspension (HPS) strut that permits entrapment of gas into the hydraulic oil are characterized experimentally and analytically. The formulation of gas-oil emulsion is studied in the laboratory, and the variations in the bulk modulus and mass density of the emulsion are formulated as a function of the gas volume fraction. An analytical model of the HPS is formulated considering polytropic change in the gas state, seal friction, and the gas-oil emulsion flows through orifices and valves. The model is formulated considering one and two bleed orifices configurations of the strut. The measured data acquired under a nearly constant temperature are used to identify gas volume fraction of the emulsion, and friction and flow discharge coefficients as functions of the strut velocity and fluid pressure. The results suggested that single orifice configuration, owing to high fluid pressure, causes greater gas entrapment within the oil and thus significantly higher compressibility of the gas-oil emulsion. The model results obtained under different excitations in the 0.1-8 Hz frequency range showed reasonably good agreements with the measured stiffness and damping properties of the HPS strut. The results show that the variations in fluid compressibility and free gas volume cause increase in effective stiffness but considerable reduction in the damping in a highly nonlinear manner. Increasing the gas volume fraction resulted in substantial hysteresis in the force-deflection and force-velocity characteristics of the strut.

Investigation of mixing characteristics in strut injectors using modal decomposition

Science.gov (United States)

Soni, Rahul Kumar; De, Ashoke

2018-01-01

Effect of a large-scale vortical structure on mixing and spreading of a shear layer is numerically investigated. Two strut configurations, namely, straight and tapered struts at two convective Mach numbers (Mc = 1.4 and 0.37) for two jet heights (0.6 and 1 mm) are investigated. The hydrogen jet is injected through a two-dimensional slot in oncoming coflow at Mach 2. An excellent agreement between simulated and experimental data is witnessed, whereas the instantaneous data reveal the presence of various large-scale structures in the flow field. From the instantaneous field, it becomes apparent that both the geometries have different vortical breakdown locations. It is also noticed that an early onset of vortex breakdown manifests itself into the mixing layer thickness enhancement, the effect of which is reflected in overall mixing characteristics. It becomes evident that the shear strength plays an important role in the near field mixing. The higher shear strength promotes the generation of large vortices. The analysis shows that the SS-0.6 case offers highest mixing efficiency being dominated by relatively large-scale structures. Eigenmodes obtained through Proper Orthogonal Decomposition (POD) confirm the presence of dominating structures and shed light into the series of events involved in vortex pairing/merging and breakdown. Dynamic modal decomposition also strengthens the observation made through the POD.

An effective simplified model of composite compression struts for partially-restrained steel frame with reinforced concrete infill walls

Science.gov (United States)

Sun, Guohua; Chuang-Sheng, Walter Yang; Gu, Qiang; DesRoches, Reginald

2018-04-01

To resolve the issue regarding inaccurate prediction of the hysteretic behavior by micro-based numerical analysis for partially-restrained (PR) steel frames with solid reinforced concrete (RC) infill walls, an innovative simplified model of composite compression struts is proposed on the basis of experimental observation on the cracking distribution, load transferring mechanism, and failure modes of RC infill walls filled in PR steel frame. The proposed composite compression struts model for the solid RC infill walls is composed of α inclined struts and main diagonal struts. The α inclined struts are used to reflect the part of the lateral force resisted by shear connectors along the frame-wall interface, while the main diagonal struts are introduced to take into account the rest of the lateral force transferred along the diagonal direction due to the complicated interaction between the steel frame and RC infill walls. This study derives appropriate formulas for the effective widths of the α inclined strut and main diagonal strut, respectively. An example of PR steel frame with RC infill walls simulating simulated by the composite inclined compression struts model is illustrated. The maximum lateral strength and the hysteresis curve shape obtained from the proposed composite strut model are in good agreement with those from the test results, and the backbone curve of a PR steel frame with RC infill walls can be predicted precisely when the inter-story drift is within 1%. This simplified model can also predict the structural stiffness and the equivalent viscous damping ratio well when the inter-story drift ratio exceeds 0.5%.

Impact of stent strut design in metallic stents and biodegradable scaffolds.

Science.gov (United States)

Foin, Nicolas; Lee, Renick D; Torii, Ryo; Guitierrez-Chico, Juan Luis; Mattesini, Alessio; Nijjer, Sukhjinder; Sen, Sayan; Petraco, Ricardo; Davies, Justin E; Di Mario, Carlo; Joner, Michael; Virmani, Renu; Wong, Philip

2014-12-20

Advances in the understanding of healing mechanisms after stent implantation have led to the recognition of stent strut thickness as an essential factor affecting re-endothelialization and overall long term vessel healing response after Percutaneous Coronary Interventions (PCI). Emergence of Drug-eluting stents (DESs) with anti-proliferative coating has contributed to reducing the incidence of restenosis and Target Lesion Revascularization (TVR), while progress and innovations in stent materials have in the meantime facilitated the design of newer platforms with more conformability and thinner struts, producing lesser injury and improving integration into the vessel wall. Recent advances in biodegradable metal and polymer materials now also allow for the design of fully biodegradable platforms, which are aimed at scaffolding the vessel only temporarily to prevent recoil and constrictive remodeling of the vessel during the initial period required, and are then progressively resorbed thereby avoiding the drawback of leaving an unnecessary implant permanently in the vessel. The aim of this article is to review recent evolution in stent material and stent strut design while understanding their impact on PCI outcomes. The article describes the different metallic alloys and biodegradable material properties and how these have impacted the evolution of stent strut thickness and ultimately outcomes in patients. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Beam Shear Design According to Eurocode 2 - Limitations for the Concrete Strut Inclinations

DEFF Research Database (Denmark)

Hagsten, Lars German; Hestbech, Lars; Fisker, Jakob

2011-01-01

and are presented. These beams are all designed to fail in shear and the shear reinforcement is designed for different values of the concrete strut inclinations (cot θ varies from 1.5 to 3.4). These tests indicate a clear connection between the values of the concrete strut inclinations and crack width in the SLS......The beam shear design method adopted in Eurocode 2 is based on a lower bound plastic solution. This method is combined with limitations on the concrete strut inclination, θ. These limitations are introduced to ensure acceptable crack width in the SLS. 7 full scale beams have been tested....... In cases where larger crack widths (w > 0.4 mm) can be accepted, larger values of the concrete strut inclinations can be chosen. This will lead to less shear reinforcements. The results are also compared with analytical analysis based on energy methods. At the SLS the beams are expected to be cracked...

Outlet strut fracture and leaflet escape of Bjork-Shiley convexo-concave valve.

Science.gov (United States)

Uchino, Gaku; Yoshida, Hideo; Sakoda, Naoya; Hattori, Shigeru; Kawabata, Takuya; Saiki, Munehiro; Fujita, Yasufumi; Yunoki, Keiji; Hisamochi, Kunikazu; Mine, Yoshinari

2017-06-01

Prosthetic valve fracture is a serious complication and may arise in patient post-valve replacement. We experienced an outlet strut fracture and leaflet escape of a Bjork-Shiley convexo-concave valve. We performed an emergency redo mitral valve replacement and successfully retrieved the fractured strut and escaped leaflet from superficial femoral artery and the abdominal aorta. The patient showed an uneventful postoperative recovery.

Asymptomatic strut fracture in DeBakey-Surgitool aortic valves: incidence, management, and metallurgic aspects.

Science.gov (United States)

Von Der Emde J, J; Eberlein, U; Breme J, J

1990-01-01

From August 1971 through November 1972, we implanted 62 Model 2 DeBakey-Surgitool aortic valve prostheses in 62 patients, 4 of whom later had clinically asymptomatic strut fractures. In 1 case, the patient died suddenly, and autopsy revealed detachment of the ball-cage; in each of the other 3 cases, fractures of 2 struts close to the base of the prosthesis were diagnosed fluoroscopically, and the patients underwent successful reoperation. The interval between implantation and reoperation ranged from 11 months to 16 years, 9 months. In 1 patient, retrospective study of chest radiographs revealed that the fracture had been present for 2(1/2) years. Larger valves (>/= A6) were affected significantly more often than smaller ones. We performed metallurgic analysis of 1 prosthesis: results revealed strut wear from fatigue cracking and secondary abrasion. Strut fracture was also promoted by suspension of the cage at right angles to the prosthetic ring and by use of a pyrolytic carbon ball in a titanium cage (i.e., an occluder harder than its holder). Patients with DeBakey-Surgitool aortic valve prostheses should undergo annual radiologic examinations to enable early detection of strut fractures. Prophylactic valve replacement is not indicated.

Solution-processed core-shell nanowires for efficient photovoltaic cells.

Science.gov (United States)

Tang, Jinyao; Huo, Ziyang; Brittman, Sarah; Gao, Hanwei; Yang, Peidong

2011-08-21

Semiconductor nanowires are promising for photovoltaic applications, but, so far, nanowire-based solar cells have had lower efficiencies than planar cells made from the same materials, even allowing for the generally lower light absorption of nanowires. It is not clear, therefore, if the benefits of the nanowire structure, including better charge collection and transport and the possibility of enhanced absorption through light trapping, can outweigh the reductions in performance caused by recombination at the surface of the nanowires and at p-n junctions. Here, we fabricate core-shell nanowire solar cells with open-circuit voltage and fill factor values superior to those reported for equivalent planar cells, and an energy conversion efficiency of ∼5.4%, which is comparable to that of equivalent planar cells despite low light absorption levels. The device is made using a low-temperature solution-based cation exchange reaction that creates a heteroepitaxial junction between a single-crystalline CdS core and single-crystalline Cu2S shell. We integrate multiple cells on single nanowires in both series and parallel configurations for high output voltages and currents, respectively. The ability to produce efficient nanowire-based solar cells with a solution-based process and Earth-abundant elements could significantly reduce fabrication costs relative to existing high-temperature bulk material approaches.

Core-shell nanophosphor architecture: toward efficient energy transport in inorganic/organic hybrid solar cells.

Science.gov (United States)

Li, Qinghua; Yuan, Yongbiao; Chen, Zihan; Jin, Xiao; Wei, Tai-huei; Li, Yue; Qin, Yuancheng; Sun, Weifu

2014-08-13

In this work, a core-shell nanostructure of samarium phosphates encapsulated into a Eu(3+)-doped silica shell has been successfully fabricated, which has been confirmed by X-ray diffraction, transmission electron microscopy (TEM), and high-resolution TEM. Moreover, we report the energy transfer process from the Sm(3+) to emitters Eu(3+) that widens the light absorption range of the hybrid solar cells (HSCs) and the strong enhancement of the electron-transport of TiO2/poly(3-hexylthiophene) (P3HT) bulk heterojunction (BHJ) HSCs by introducing the unique core-shell nanoarchitecture. Furthermore, by applying femtosecond transient absorption spectroscopy, we successfully obtain the electron transport lifetimes of BHJ systems with or without incorporating the core-shell nanophosphors (NPs). Concrete evidence has been provided that the doping of core-shell NPs improves the efficiency of electron transfers from donor to acceptor, but the hole transport almost remains unchanged. In particular, the hot electron transfer lifetime was shortened from 30.2 to 16.7 ps, i.e., more than 44% faster than pure TiO2 acceptor. Consequently, a notable power conversion efficiency of 3.30% for SmPO4@Eu(3+):SiO2 blended TiO2/P3HT HSCs is achieved at 5 wt % as compared to 1.98% of pure TiO2/P3HT HSCs. This work indicates that the core-shell NPs can efficiently broaden the absorption region, facilitate electron-transport of BHJ, and enhance photovoltaic performance of inorganic/organic HSCs.

Strut fracture of Björk-Shiley convexo-concave valve in Japan--risk of small valve size--.

Science.gov (United States)

Watarida, S; Shiraishi, S; Nishi, T; Imura, M; Yamamoto, Y; Hirokawa, R; Fujita, M

2001-08-01

The Björk-Shiley convexo-concave (BSCC) prosthetic valve was introduced in 1979. Between 1979 and 1986, approximately 86,000 BSCC valves were implanted. By December 31, 1994, 564 complete strut fractures had been reported to the manufacture. We experienced a case of an outlet strut fracture and investigated the risk of BSCC prosthetic valve fractures in Japan. To investigate the risk factor of a strut fracture in Japan, we investigated published cases of strut fractures. Between 1979 and 1986, 2021 BSCC valves were implanted in Japan. By January 31, 2000, 11 complete strut fractures of 60-degree BSCC valves including our case had occurred. The patients were eight males and three females. The average age at valve replacement was 42.4+/-8.1 years, and nine of eleven (81.8%) were patients valve fractured was 47.7+/-6.4 years, and eight of eleven (72.7%) were patients valve were 27 mm (n=5) (45.5%), 29 mm (n=3) (27.2%), and 31 mm (n=3) (27.2%). Four patients died and seven patients survived. Although only 11 BSCC valve struts fractured and statistical analysis could not be performed, our findings suggest that the high risk group for a strut fracture in Japan is young male patients with a mitral valve, >= 27 mm in size with BSCC models manufactured before March 1982. When following-up patients with BSCC models manufactured before March 1982, the possibility of a strut fracture in all BSCC valve sizes should be kept in mind.

基于 Struts 框架的软件实训系统%Software Training System Based on Struts Architecture

Institute of Scientific and Technical Information of China (English)

龚雄兴; 宁彬; 袁磊

2012-01-01

　　基于Struts框架的软件实训系统主要是利用Web技术实现软件实训实践过程的网络化、信息化。文章分析了以 Struts 框架为技术基础的软件实训系统的设计与实现，改进了该系统应用及维护中的安全控制和中文请求响应设计，以更符合建设软件实训系统的现实需求。%　　Software training system mainly uses Web technique to realize cyberization and informatization of teaching process on software training. Based on Struts architecture, it analyzes the design and realization of the software training system. Then safety control and response to Chinese language during the application are improved.

Study on durability and reliability of strut type suspension noise based on experimental methods

International Nuclear Information System (INIS)

Kim, Gu Gyong; Kang, Sung Su; Lee, Yong Jun; Park, Soon Cheol; Jung, Won Wook

2012-01-01

When cars are released from the factory, strut noises are very small and therefore it is difficult to perceive them. As the use time and travel distance increase, however, strut noises get larger so as to cause users much uneasiness. The noises generated at the field include engine noises and flow noises and therefore it is difficult to clearly discern the noises generated from struts. This study developed a test method which can reproduce field strut noises in the lab. Using the newly developed noise evaluation test, this study analyzed the effects that insulator performance degradation and failure can have on car noises. The study also confirmed that the insulator durability test by the simple back-and-forth motion cannot completely reflect the state of the parts failure in the field. Based on this, the study also confirmed that field noises can be reproduced through a durability test that considers heat aging

Super-paramagnetic core-shell material with tunable magnetic behavior by regulating electron transfer efficiency and structure stability of the shell

Directory of Open Access Journals (Sweden)

Wenyan Zhang

Full Text Available In this work, a spherical nano core-shell material was constructed by encapsulating Fe3O4 microsphere into conductive polymer-metal composite shell. The Fe3O4 microspheres were fabricated by assembling large amounts of Fe3O4 nano-crystals, which endowed the microspheres with super-paramagnetic property and high saturation magnetization. The polymer-metal composite shell was constructed by inserting Pt nano-particles (NPs into the conductive polymer polypyrrole (PPy. As size and dispersion of the Pt NPs has an important influence on their surface area and surface energy, it was effective to enlarge the interface area between PPy and Pt NPs, enhance the electron transfer efficiency of PPy/Pt composite shell, and reinforced the shell’s structural stability just by tuning the size and dispersion of Pt NPs. Moreover, core-shell structure of the materials made it convenient to investigate the PPy/Pt shell’s shielding effect on the Fe3O4 core’s magnetic response to external magnetic fields. It was found that the saturation magnetization of Fe3O4/PPy/Pt core-shell material could be reduced by 20.5% by regulating the conductivity of the PPy/Pt shell. Keywords: Super-paramagnetic, Conductivity, Magnetic shielding, Structural stability

Amphiphilic core shell nanoparticles containing dense polyethyleneimine shells for efficient delivery of microRNA to Kupffer cells

Directory of Open Access Journals (Sweden)

Liu Z

2016-06-01

Full Text Available Zuojin Liu,1,* Dechao Niu,2,3,* Junyong Zhang,1 Wenfeng Zhang,1 Yuan Yao,2 Pei Li,2 Jianping Gong1 1Department of Hepatobiliary Surgery, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, 2Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, 3Lab of Low-Dimensional Materials Chemistry, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai, People’s Republic of China *These authors contributed equally to this work Abstract: Efficient and targeted delivery approach to transfer exogenous genes into macrophages is still a great challenge. Current gene delivery methods often result in low cellular uptake efficiency in vivo in some types of cells, especially for the Kupffer cells (KCs. In this article, we demonstrate that amphiphilic core–shell nanoparticles (NPs consisting of well-defined hydrophobic poly(methyl methacrylate (PMMA cores and branched polyethyleneimine (PEI shells (denoted as PEI@PMMA NPs are efficient nanocarriers to deliver microRNA (miRNA-loaded plasmid to the KCs. Average hydrodynamic diameter of PEI@PMMA NPs was 279 nm with a narrow size distribution. The NPs also possessed positive surface charges up to +30 mV in water, thus enabling effective condensation of negatively charged plasmid DNA. Gel electrophoresis assay showed that the resultant PEI@PMMA NPs were able to completely condense miRNA plasmid at a weight ratio of 25:1 (N/P ratio equal to 45:1. The Cell Counting Kit-8 assay and flow cytometry results showed that the PEI@PMMA/miRNA NPs displayed low cytotoxicity and cell apoptosis activity against the KCs. The maximum cell transfection efficiency reached 34.7% after 48 hours, which is much higher than that obtained by using the commercial Lipofectamine™ 2000 (1.7%. Bio-transmission electron microscope observation revealed that the PEI@PMMA NPs were mainly distributed in

Role of jet spacing and strut geometry on the formation of large scale structures and mixing characteristics

Science.gov (United States)

Soni, Rahul Kumar; De, Ashoke

2018-05-01

The present study primarily focuses on the effect of the jet spacing and strut geometry on the evolution and structure of the large-scale vortices which play a key role in mixing characteristics in turbulent supersonic flows. Numerically simulated results corresponding to varying parameters such as strut geometry and jet spacing (Xn = nDj such that n = 2, 3, and 5) for a square jet of height Dj = 0.6 mm are presented in the current study, while the work also investigates the presence of the local quasi-two-dimensionality for the X2(2Dj) jet spacing; however, the same is not true for higher jet spacing. Further, the tapered strut (TS) section is modified into the straight strut (SS) for investigation, where the remarkable difference in flow physics is unfolded between the two configurations for similar jet spacing (X2: 2Dj). The instantaneous density and vorticity contours reveal the structures of varying scales undergoing different evolution for the different configurations. The effect of local spanwise rollers is clearly manifested in the mixing efficiency and the jet spreading rate. The SS configuration exhibits excellent near field mixing behavior amongst all the arrangements. However, in the case of TS cases, only the X2(2Dj) configuration performs better due to the presence of local spanwise rollers. The qualitative and quantitative analysis reveals that near-field mixing is strongly affected by the two-dimensional rollers, while the early onset of the wake mode is another crucial parameter to have improved mixing. Modal decomposition performed for the SS arrangement sheds light onto the spatial and temporal coherence of the structures, where the most dominant structures are found to be the von Kármán street vortices in the wake region.

Metal oxide core shell nanostructures as building blocks for efficient light emission (SISGR)

Energy Technology Data Exchange (ETDEWEB)

Chang, Jane P [Univ. of California, Los Angeles, CA (United States); Dorman, James [Univ. of California, Los Angeles, CA (United States); Cheung, Cyrus [Univ. of California, Los Angeles, CA (United States)

2016-01-12

The objective of this research is to synthesize core-shell nano-structured metal oxide materials and investigate their structural, electronic and optical properties to understand the microscopic pathways governing the energy conversion process, thereby controlling and improving their efficiency. Specifically, the goal is to use a single metal oxide core-shell nanostructure and a single excitation source to generate photons with long emission lifetime over the entire visible spectrum and when controlled at the right ratio, generating white light. In order to achieve this goal, we need to control the energy transfer between light emitting elements, which dictates the control of their interatomic spacing and spatial distribution. We developed an economical wet chemical process to form the nanostructured core and to control the thickness and composition of the shell layers. With the help from using DOE funded synchrotron radiation facility, we delineated the growth mechanism of the nano-structured core and the shell layers, thereby enhancing our understanding of structure-property relation in these materials. Using the upconversion luminescence and the lifetime measurements as effective feedback to materials sysnthes is and integration, we demonstrated improved luminescence lifetimes of the core-shell nano-structures and quantified the optimal core-multi-shell structure with optimum shell thickness and composition. We developed a rare-earths co-doped LaPO₄ core-multishell structure in order to produce a single white light source. It was decided that the mutli-shell method would produce the largest increase in luminescence efficiency while limiting any energy transfer that may occur between the dopant ions. All samples resulted in emission spectra within the accepted range of white light generation based on the converted CIE color coordinates. The white light obtained varied between warm and cool white depending on the layering architecture, allowing for the

Improved Hypersonic Inlet Performance Using Validated Strut Compression Designs

Science.gov (United States)

Bulman, M. J.; Stout, P. W.; Fernandez, R.

1997-01-01

Aerojet is currently executing two Strutjet propulsion contracts: one a Rocket Based Combined Cycle (RBCC) engine for a NASA-Marshall Space Flight Center (MSFC) Advanced Reusable Transportation Technology (ARTT) program, the second a Dual Mode Ram/Scramjet engine for a USAF Wright Laboratories Storable Fuel Scramjet Flow Path Concepts program. The engines employed in both programs operate at supersonic and low hypersonic speeds and use inlets employing forebody external and sidewall compression. Aerojet has developed and validated a successful design methodology applicable to these inlet types. Design features include an integrated vehicle forebody, external side compression struts, strut sidewall and throat bleed, a throat shock trap, and variable geometry internal contraction. Computation Fluid Dynamic (CFD) predictions and test data show these inlets allow substantially increased flow turning angles over other designs. These increased flow turning angles allow shorter and lighter engines than current designs, which in turn enables higher performing vehicles with broad operating characteristics. This paper describes the designs of two different inlets evaluated by the NASA-MSFC and USAF programs, discusses the results of wind tunnel tests performed by NASA-Lewis Research Center, and provides correlations of test data with CFD predictions. Parameters of interest include low Mach number starting capability, start sensitivity as a function of back pressure at various contraction ratios, flow turning angles, strut and throat bleed effects, and pressure recovery at various Mach numbers.

Optical coherence tomography at follow-up after percutaneous coronary intervention: relationship between procedural dissections, stent strut malapposition and stent healing

DEFF Research Database (Denmark)

Radu, Maria; Jørgensen, Erik; Kelbæk, Henning

2011-01-01

To analyse the relationship between strut apposition as visualised with optical coherence tomography (OCT) at follow-up and clinical and procedural characteristics at stent implantation, and to examine the relationship between strut apposition and stent healing.......To analyse the relationship between strut apposition as visualised with optical coherence tomography (OCT) at follow-up and clinical and procedural characteristics at stent implantation, and to examine the relationship between strut apposition and stent healing....

Survival following fracture of strut from mitral prosthesis with disc translocation.

Science.gov (United States)

McEnany, M T; Wheeler, E O; Austen, W G

1979-07-01

Mechanical complications of prosthetic valves are increasingly rare. The acute, catastrophic nature of the symptoms associated with massive transvalvular regurgitation preclude survival except with immediate operation. In the patient described herein, two weld fractures of a Björk-Shiley mitral prosthetic strut led to displacement of the valve occluder into the left atrium. The patient survived reoperation, following which the strut was detected radiologically in the left ventricular free wall. A slow, limited recovery resulted from his 5 preoperative hours of deep shock and coma. No complication attributable to the retained ventricular foreign body has been identified.

Outlet strut fracture of Björk-Shiley convexo-concave valves: can valve-manufacturing characteristics explain the risk?

Science.gov (United States)

Omar, R Z; Morton, L S; Beirne, M; Blot, W J; Lawford, P V; Hose, R; Taylor, K M

2001-06-01

Björk-Shiley 60 degrees convexo-concave prosthetic heart valves (Shiley, Inc, Irvine, Calif, a subsidiary of Pfizer, Inc) continue to be a concern for approximately 35,000 nonexplanted patients worldwide, with approximately 600 events reported to the manufacturer to date. Fractures of the outlet struts of the valves began to appear in the early 1980s and have continued to the present, but their causes are only partially understood. A matched case-control study was conducted evaluating manufacturing records for 52 valves with outlet strut fractures and 248 control subjects matched for age at implantation, valve size, and valve position. In addition to the risk factors recognized as determinants of outlet strut fracture, the United Kingdom case-control study has observed 7- to 9-fold increased risk with performance of multiple hook deflection tests. This test was performed more than once, usually after rework on the valve. Six valves in this study underwent multiple hook deflection tests, of which 4 experienced an outlet strut fracture. Cracks and further rework were noted for these valves. Significant associations were also observed between outlet strut fracture and disc-to-strut gap measurements taken before the attachment of the sewing ring. It is our view that a combination of factors related to valve design, manufacturing process, and patient characteristics are responsible for outlet strut fractures of Björk-Shiley convexo-concave valves. Multiple hook deflection tests have emerged as a potential new risk factor for outlet strut fracture in both The Netherlands and the United Kingdom. This factor appears to be correlated with the presence of other abnormalities. A further study is needed to investigate the factors correlated with multiple hook deflection tests. On confirmation of risk, the presence of multiple hook deflection tests may be added to equations, quantifying the risk of outlet strut fracture for comparison against risk of mortality and serious

Investigations on the Influence of the In-Stream Pylon and Strut on the Performance of a Scramjet Combustor

Directory of Open Access Journals (Sweden)

Hao Ouyang

2014-01-01

Full Text Available The influence of the in-stream pylon and strut on the performance of scramjet combustor was experimentally and numerically investigated. The experiments were conducted with a direct-connect supersonic model combustor equipped with multiple cavities. The entrance parameter of combustor corresponds to scramjet flight Mach number 4.0 with a total temperature of 947 K. The research results show that, compared with the scramjet combustor without pylon and strut, the wall pressure and the thrust of the scramjet increase due to the improvement of mixing and combustion effect due to the pylon and strut. The total pressure loss caused by the strut is considerable whereas pylon influence is slight.

Anatomical variations and morphometric study of the optic strut and the anterior clinoid process

Directory of Open Access Journals (Sweden)

Eldan Kapur

2012-05-01

Full Text Available The optic strut and the anterior clinoid process represent bony structures that are closely related to anatomically and clinically significant elements such as the cavernous sinus, the internal carotid artery, the optic nerve and the pituitary gland. The objective of our study was to quantify dimensions of the optic strut and anterior clinoid process, and to determine variations in positions and forms of these structures. A descriptive anatomical study was performed on 200 dry human skulls. We analyzed dimensions and variations in position of the optic strut, dimensions of the anterior clinoid process as well as the incidence and forms of the caroticoclinoid foramen. The average thickness of the optic strut on skulls belonging to males was 3 mm and 2.8 mm on those belonging to females. The optic strut was most commonly attached to the anterior two fifths on the lower side of the anterior clinoid process. On the male skulls the average width of the anterior clinoid process was 9.4 mm (right and 9.1 mm (left. Its length was 9.9 and 9.3 mm. On female skulls the average width of the process was 8.7 mm (right and 8.3 mm (left, while the length measured 9.3 mm on the right and 8.9 mm on the opposite side. In our sample, a complete caroticoclinoid foramen appeared in 4.25%, a contact form in 2.75%. At last, an incomplete form of the foramen was observed in 9.75%. The anatomic variations of the investigated structures must be considered during the approaches to the cavernous sinus and neurovascular elements of the sellar region.

Excessive strut wear allowing ball-poppet embolization in a DeBakey-Surgitool aortic valve prosthesis.

Science.gov (United States)

Sutherland, R D; Guynes, W A; Nichols, C T; Martinez, H E

1982-01-01

Excessive cage strut wear allowing ball-poppet embolization caused the sudden death of a 47 year old lady in whom a DeBakey-Surgitool aortic prosthesis had been implanted nine years earlier. Patients with this type of prosthesis should have periodic valvular cine fluoroscopy with image intensification to allow visualization of significant strut wear or fracture, and appropriate prosthetic valve replacement.

Long range node-strut analysis of trabecular bone microarchitecture

DEFF Research Database (Denmark)

Schmah, Tanya; Marwan, Norbert; Thomsen, Jesper Skovhus

2011-01-01

PURPOSE: We present a new morphometric measure of trabecular bone microarchitecture, called mean node strength (NdStr), which is part of a newly developed approach called long range node-strut analysis. Our general aim is to describe and quantify the apparent "latticelike" microarchitecture of th...

Asymptomatic Strut Fracture in DeBakey-Surgitool Aortic Valves: Incidence, Management, and Metallurgic Aspects

OpenAIRE

Von Der Emde, Jürgen; Eberlein, Ulrich; Breme, Jürgen

1990-01-01

From August 1971 through November 1972, we implanted 62 Model 2 DeBakey-Surgitool aortic valve prostheses in 62 patients, 4 of whom later had clinically asymptomatic strut fractures. In 1 case, the patient died suddenly, and autopsy revealed detachment of the ball-cage; in each of the other 3 cases, fractures of 2 struts close to the base of the prosthesis were diagnosed fluoroscopically, and the patients underwent successful reoperation. The interval between implantation and reoperation rang...

Effect of compressive force on aeroelastic stability of a strut-braced wing

Science.gov (United States)

Sulaeman, Erwin

2002-01-01

Recent investigations of a strut-braced wing (SBW) aircraft show that, at high positive load factors, a large tensile force in the strut leads to a considerable compressive axial force in the inner wing, resulting in a reduced bending stiffness and even buckling of the wing. Studying the influence of this compressive force on the structural response of SBW is thus of paramount importance in the early stage of SBW design. The purpose of the this research is to investigate the effect of compressive force on aeroelastic stability of the SBW using efficient structural finite element and aerodynamic lifting surface methods. A procedure is developed to generate wing stiffness distribution for detailed and simplified wing models and to include the compressive force effect in the SBW aeroelastic analysis. A sensitivity study is performed to generate response surface equations for the wing flutter speed as functions of several design variables. These aeroelastic procedures and response surface equations provide a valuable tool and trend data to study the unconventional nature of SBW. In order to estimate the effect of the compressive force, the inner part of the wing structure is modeled as a beam-column. A structural finite element method is developed based on an analytical stiffness matrix formulation of a non-uniform beam element with arbitrary polynomial variations in the cross section. By using this formulation, the number of elements to model the wing structure can be reduced without degrading the accuracy. The unsteady aerodynamic prediction is based on a discrete element lifting surface method. The present formulation improves the accuracy of existing lifting surface methods by implementing a more rigorous treatment on the aerodynamic kernel integration. The singularity of the kernel function is isolated by implementing an exact expansion series to solve an incomplete cylindrical function problem. A hybrid doublet lattice/doublet point scheme is devised to reduce

Anterior debridement and fusion followed by posterior pedicle screw fixation in pyogenic spondylodiscitis: autologous iliac bone strut versus cage.

Science.gov (United States)

Pee, Yong Hun; Park, Jong Dae; Choi, Young-Geun; Lee, Sang-Ho

2008-05-01

An anterior approach for debridement and fusion with autologous bone graft has been recommended as the gold standard for surgical treatment of pyogenic spondylodiscitis. The use of anterior foreign body implants at the site of active infection is still a challenging procedure for spine surgeons. Several authors have recently introduced anterior grafting with titanium mesh cages instead of autologous bone strut in the treatment of spondylodiscitis. The authors present their experience of anterior fusion with 3 types of cages followed by posterior pedicle screw fixation. They also compare their results with the use of autologous iliac bone strut. The authors retrospectively reviewed the cases of 60 patients with pyogenic spondylodiscitis treated by anterior debridement between January 2003 and April 2005. Fusion using either cages or iliac bone struts was performed during the same course of anesthesia followed by posterior fixation. Twenty-three patients underwent fusion with autologous iliac bone strut, and 37 patients underwent fusion with 1 of the 3 types of cages. The infections resolved in all patients, as noted by normalization of their erythrocyte sedimentation rates and C-reactive protein levels. Patients in both groups were evaluated in terms of their preoperative and postoperative clinical and imaging findings. Single-stage anterior debridement and cage fusion followed by posterior pedicle screw fixation can be effective in the treatment of pyogenic spondylodiscitis. There was no difference in clinical and imaging outcomes between the strut group and cage group except for the subsidence rate. The subsidence rate was higher in the strut group than in the cage group. The duration until subsidence was also shorter in the strut group than in the cage group.

Delayed coverage in malapposed and side-branch struts with respect to well-apposed struts in drug-eluting stents: In vivo assessment with optical coherence tomography

NARCIS (Netherlands)

J.L. Gutiérrez-Chico; E.S. Regar (Eveline); E. NüesC.H. (Eveline); T. Okamura (Takayuki); J.J. Wykrzykowska (Joanna); C. di Mario (Carlo); S.W. Windecker (Stephan); G.A. van Es (Gerrit Anne); P. Gobbens (Pierre); P. Jüni (Peter); P.W.J.C. Serruys (Patrick)

2011-01-01

textabstractBackground-Pathology studies on fatal cases of very late stent thrombosis have described incomplete neointimal coverage as common substrate, in some cases appearing at side-branch struts. Intravascular ultrasound studies have described the association between incomplete stent apposition

A Preliminary Investigation of Wastewater Treatment Efficiency and Economic Cost of Subsurface Flow Oyster-Shell-Bedded Constructed Wetland Systems

Directory of Open Access Journals (Sweden)

Chia-Chuan Hsu

2013-06-01

Full Text Available We conducted a preliminary investigation of wastewater treatment efficiency and economic cost of the oyster-shell-bedded constructed wetlands (CWs compared to the conventional gravel-bedded CW based on field monitoring data of water quality and numerical modeling. Four study subsurface (SSF CWs were built to receive wastewater from Taipei, Taiwan. Among these sites, two are vertical wetlands, filled with bagged- (VA and scattered- (VB oyster shells, and the other two horizontal wetlands were filled with scattered-oyster shells (HA and gravels (HB. The BOD, NO3−, DO and SS treatment efficiency of VA and VB were higher than HA and HB. However, VA was determined as the best option of CW design due to its highest cost-effectiveness in term of BOD removal (only 6.56 US$/kg as compared to VB, HA and HB (10.88–25.01 US$/kg. The results confirmed that oyster shells were an effective adsorption medium in CWs. Hydraulic design and arrangement of oyster shells could be important in determining their treatment efficiency and cost-effectiveness. A dynamic model was developed to simulate substance transmissions in different treatment processes in the CWS using AQUASIM 2.1 based on the water quality data. Feasible ranges of biomedical parameters involved were determined for characterizing the importance of different biochemical treatment processes in SSF CWs. Future work will involve extending the experimental period to confirm the treatment efficiency of the oyster-shell-bedded CW systems in long-term operation and provide more field data for the simulated model instead of the literature values.

Four shells atomic model to computer the counting efficiency of electron-capture nuclides

International Nuclear Information System (INIS)

Grau Malonda, A.; Fernandez Martinez, A.

1985-01-01

The present paper develops a four-shells atomic model in order to obtain the efficiency of detection in liquid scintillation courting, Mathematical expressions are given to calculate the probabilities of the 229 different atomic rearrangements so as the corresponding effective energies. This new model will permit the study of the influence of the different parameters upon the counting efficiency for nuclides of high atomic number. (Author) 7 refs

A fractured inferior vena cava filter strut migrating to the left pulmonary artery

Directory of Open Access Journals (Sweden)

Tamer Hudali

2015-01-01

Full Text Available Inferior vena cava filters are increasingly used in patients with recurrent venous thromboembolism who are contraindicated to anticoagulation. Migration of a broken strut to the pulmonary artery is a very rare complication of these filters. We report the case of an 83-year-old female who experienced this complication with the migratory strut remaining in the same position for years. This case provides evidence that such filters probably have higher rates of complications than what has been thought that remain asymptomatic. The indications and the management of complications of such devices need to be studied further.

Performance analysis of nanodisk and core/shell/shell-nanowire type III-Nitride heterojunction solar cell for efficient energy harvesting

Science.gov (United States)

Routray, S. R.; Lenka, T. R.

2017-11-01

Now-a-days III-Nitride nanowires with axial (nanodisk) and radial (core/shell/shell-nanowire) junctions are two unique and potential methods for solar energy harvesting adopted by worldwide researchers. In this paper, polarization behavior of GaN/InGaN/GaN junction and its effect on carrier dynamics of nanodisk and CSS-nanowire type solar cells are intensively studied and compared with its planar counterpart by numerical simulations using commercially available Victory TCAD. It is observed that CSS-NW with hexagonal geometrical shapes are robust to detrimental impact of polarization charges and could be good enough to accelerate carrier collection efficiency as compared to nanodisk and planar solar cells. This numerical study provides an innovative aspect of fundamental device physics with respect to polarization charges in CSS-NW and nanodisk type junction towards photovoltaic applications. The internal quantum efficiencies (IQE) are also discussed to evaluate carrier collection mechanisms and recombination losses in each type of junctions of solar cell. Finally, it is interesting to observe a maximum conversion efficiency of 6.46% with 91.6% fill factor from n-GaN/i-In0.1Ga0.9N/p-GaN CSS-nanowire solar cell with an optimized thickness of 180 nm InGaN layer under one Sun AM1.5 illumination.

Controllable synthesis of mesoporous multi-shelled ZnO microspheres as efficient photocatalysts for NO oxidation

Science.gov (United States)

Chen, Xiaolang; Zhang, Huiqiang; Zhang, Dieqing; Miao, Yingchun; Li, Guisheng

2018-03-01

The successful application of hierarchically porous structure in environmental treatment has provided new insights for solving environmental problems. Hierarchically structured semiconductor materials were considered as promising photocatalysts for NO oxidation in gas phase. Multi-shelled ZnO microspheres (MMSZ) were controllably shaped with hierarchically porous structures via a facile hydrothermal route using amino acid (N-Acetyl-D-Proline) as template and post-calcination treatment. Symmetric Ostwald ripening was used to explain the morphological evolution of hierarchical nanostructure. MMSZ was proved highly efficient for oxidizing NO (400 ppb) in gas phase under UV light irradiation with a much higher photocatalytic removal rate (77.3%) than that of the as-obtained ZnO crystals with other hierachically porous structures, owing to its higher photocurrent intensity. Such greatly enhanced photocatalytic activity can be assigned to the enhanced crystallinity of ZnO, mesopores and unique multi-shelled structure. Enhanced crystallinity promotes photogenerated charges under light irradiation. Mesoporous porosity can ensure enough light scattering between the shells. Multi-shelled structure endows ZnO with higher specific surface area and high frequency of multiple light reflection, resulting in more exposed active sites, higher light utilization efficiency, and fast separation efficiency of photogenerated charge carriers. The experimental results demonstrated that the photogenerated holes (h+) are the main active species. Hierarchically structured ZnO is not only contributed to directly use solar energy to solving various problems caused by atmospheric pollution, but also has potential applications in energy converse and storage including solar cells, lithium batteries, water-splitting, etc.

Biological effect of microengineered grooved stents on strut healing: a randomised OCT-based comparative study in humans

Science.gov (United States)

Vesga, Boris; Hernandez, Hector; Higuera, Sergio; Gasior, Pawel; Echeveri, Dario; Delgado, Juan A; Dager, Antonio; Arana, Camilo; Simonton, Charles; Maehara, Akiko; Palmaz, Julio; Granada, Juan F

2017-01-01

Objective To evaluate the biological effect of microengineered stent grooves (MSG) on early strut healing in humans by performing optical coherence tomography (OCT) analysis 3 weeks following the implantation. Background In the experimental setting, MSG accelerate endothelial cell migration and reduce neointimal proliferation compared with bare metal stent (BMS). Methods A total of 37 patients undergoing percutaneous coronary intervention with de novo coronary lesions were randomly assigned to either MSG (n=19) or an identical BMS controls (n=18). All patients underwent OCT imaging at 3 weeks. A total of 7959 struts were included in the final analysis. Results At 3 weeks following stent implantation, almost all struts analysed (~97%) had evidence of tissue coverage. The percentage of partially covered struts was comparable between both groups. However, the percentage of fully embedded struts was higher in the BMS group (81.22%, 49.75–95.52) compared with the MSG group (74.21%, 58.85–86.38). The stent-level analysis demonstrated reduction in neointimal formation (neointimal hyperplasia area and volume reduction of ~14% and ~19%, respectively) in the MSG versus the BMS group. In the strut-level analysis, an even greater reduction (~22% in neointimal thickness) was seen in the MSG group. Layered neointimal was present in ~6% of the OCT frames in the BMS group while it was not present in the MSG group. Conclusions MSG induced a more homogeneous and predictable pattern of surface healing in the early stages following stent implantation. The biological effect of MSG on stent healing has the potential to improve the safety profile of current generation drug-eluting stents. Classifications BMS, OCT, clinical trials. PMID:28674616

STRESS-DEFORMED STATE OF A STRUT-FRAMED CRANE GIRDER

Directory of Open Access Journals (Sweden)

Kh. M. Muselemov

2017-01-01

Full Text Available Objectives. The aim of the present work is to study the influence of design parameters on the stress-deformed state of a sprengel crane girder; to compile the tables and corresponding graphs illustrating changes in internal force factors in the characteristic cross-sections of the system elements under consideration. The article describes the study of the stress-deformed state (SDS of a metal strut-framed crane girder.Methods. Numerical methods of analysis based on the use of the Green's function are used during solving this problem. A dimensionless parameter is introduced, depending on which the tables and graphs are constructed. According to the known algorithm, the calculations of internal force factors in the sections of the considered construction are performed.Results. Depending on the dimensionless parameter characterising the geometry and physical features of the system, tables of bending moments and transverse forces are compiled. According to these tables, the appropriate graphs are plotted in order to choose easily the optimal design parameters.Conclusion. The dependence of the moments and transverse forces on the dimensionless parameter k was found, the corresponding graphs were plotted and the metal costs for the girders were calculated. The minimum values of the moments and transverse forces are established to take place when the dimensionless parameter k values are close to zero. The most economical was a strut-framed crane girder having k = 0.0001. The most uneconomical had k = 0.05 and k =∞. Eventually, the sprengel girders were found to be more profitable as compared to conventional crane girders. In the examples considered in the article, the metal savings amounted up to 14%. The presented methodology allows the calculation and designing of strut-framed crane girders with two racks to be carried out. 

Suggesting alternatives for reinforced concrete deep beams by reinforcing struts and ties

Directory of Open Access Journals (Sweden)

Saleem Abdul-Razzaq Khattab

2017-01-01

Full Text Available This paper studied reinforcing struts and ties in deep beams based on the Strut-and-Tie Model (STM of ACI 318M-14. The study contained testing 9 simply supported specimens, divided into 3 groups. The difference between the groups was the loading type which was 2-concentrated forces, 1-concentrated force and uniformly distributed load. Each group contained three specimens; the first specimens in each group were conventional deep beams as references which had a length of 1400 mm, a height of 400 mm and a width of 150 mm. The second specimens were the same as references in dimensions, but with removing shoulders. In addition, only the paths of struts & ties of STM were reinforced in the second specimens as compression and tension members, respectively. The third specimens were the frames that took their dimensions from STM of ACI 318M-14. From the experimental work, it is found that the proposed frames were good alternatives for the references despite the small loss in ultimate capacity. However, these proposed frames already carried loads greater than the factored design loads of STM. In comparison with the references, these proposed frames provided 41-51% reduction in weight, 4-27% reduction in cost besides providing front side area about 46-55%.

A few insights into the nature of classical and quantum gravity via null-strut calculus

International Nuclear Information System (INIS)

Kheyfets, Arkady

1989-01-01

Null-strut calculus is a 3 + 1 formulation of standard Regge calculus, wherein the dynamics of 3-geometry is propagated in time along light rays, or 'null struts'. However, just as Regge calculus is a discrete and geometric tool for the description of Einstein's theory of gravitation, so too NSC offers itself as a discrete and geometric tool for the description of Einstein's spacetime as the dynamics of discrete spacelike 3-geometries in time, or discrete geometrodynamics. It has for its objectives to provide a discrete model of a 3 + 1 split of spacetime into space plus time, while in so doing to preserve and illuminate the geometric content of Einstein's theory of gravity. The feature of 'light-cone-produced duality' is central to null-strut calculus. This paper will capitalise on this feature, and will attempt to provide some insights into the nature of classical and quantum gravity. (Author)

Dossier Shell Eco-Marathon; Dossier Shell Eco-Marathon

Energy Technology Data Exchange (ETDEWEB)

Matla, P.

2012-05-15

Three articles address subjects concerning the annual race with highly energy efficient cars: the Shell Eco-Marathon. [Dutch] In 3 artikelen wordt aandacht besteed aan de ontwerpen voor de jaarlijkse race met superzuinige auto's, de Shell Eco-Marathon.

Synthesis of core-shell heterostructured Cu/Cu2O nanowires monitored by in situ XRD as efficient visible-light photocatalysts

KAUST Repository

Chen, Wei

2013-01-01

Core-shell heterostructured Cu/Cu2O nanowires with a high aspect ratio were synthesized from Cu foam using a novel oxidation/reduction process. In situ XRD was used as an efficient tool to acquire phase transformation details during the temperature-programmed oxidation of Cu foam and the subsequent reduction process. Based on knowledge of the crucial phase transformation, optimal synthesis conditions for producing high-quality CuO and core-shell Cu/Cu2O nanowires were determined. In favor of efficient charge separation induced by the special core-shell heterostructure and the advanced three-dimensional spatial configuration, Cu/Cu2O nanowires exhibited superior visible-light activity in the degradation of methylene blue. The present study illustrates a novel strategy for fabricating efficiently core-shell heterostructured nanowires and provides the potential for developing their applications in electronic devices, for environmental remediation and in solar energy utilization fields. This journal is © The Royal Society of Chemistry.

Flexible 3D Fe@VO2 core-shell mesh: A highly efficient and easy-recycling catalyst for the removal of organic dyes.

Science.gov (United States)

Li, Jing; Wang, Ruoqi; Su, Zhen; Zhang, Dandan; Li, Heping; Yan, Youwei

2018-10-01

Nowadays, it is extremely urgent to search for efficient and effective catalysts for water purification due to the severe worldwide water-contamination crises. Here, 3D Fe@VO 2 core-shell mesh, a highly efficient catalyst toward removal of organic dyes with excellent recycling ability in the dark is designed and developed for the first time. This novel core-shell structure is actually 304 stainless steel mesh coated by VO 2 , fabricated by an electrophoretic deposition method. In such a core-shell structure, Fe as the core allows much easier separation from the water, endowing the catalyst with a flexible property for easy recycling, while VO 2 as the shell is highly efficient in degradation of organic dyes with the addition of H 2 O 2 . More intriguingly, the 3D Fe@VO 2 core-shell mesh exhibits favorable performance across a wide pH range. The 3D Fe@VO 2 core-shell mesh can decompose organic dyes both in a light-free condition and under visible irradiation. The possible catalytic oxidation mechanism of Fe@VO 2 /H 2 O 2 system is also proposed in this work. Considering its facile fabrication, remarkable catalytic efficiency across a wide pH range, and easy recycling characteristic, the 3D Fe@VO 2 core-shell mesh is a newly developed high-performance catalyst for addressing the universal water crises. Copyright © 2018 Elsevier B.V. All rights reserved.

Flow Characteristics Near to Stent Strut Configurations on Femoropopliteal Artery

Science.gov (United States)

Paisal, Muhammad Sufyan Amir; Fadhil Syed Adnan, Syed; Taib, Ishkrizat; Ismail, Al Emran; Kamil Abdullah, Mohammad; Nordin, Normayati; Seri, Suzairin Md; Darlis, Nofrizalidris

2017-08-01

Femoropopiteal artery stenting is a common procedure suggested by medical expert especially for patient who is diagnosed with severe stenosis. Many researchers reported that the growth of stenosis is significantly related to the geometry of stent strut configuration. The different shapes of stent geometry are presenting the different flow pattern and re-circulation in stented femoropopliteal artery. The blood flow characteristics near to the stent geometry are predicted for the possibility of thrombosis and atherosclerosis to be formed as well as increase the growth of stenosis. Thus, this study aims to determine the flow characteristic near to stent strut configuration based on different hemodynamic parameters. Three dimensional models of stent and simplified femoropopliteal artery are modelled using computer aided design (CAD) software. Three different models of stent shapes; hexagon, circle and rectangle are simulated using computational fluid dynamic (CFD) method. Then, parametric study is implemented to predict the performance of stent due to hemodynamic differences. The hemodynamic parameters considered are pressure, velocity, low wall shear stress (WSSlow) and wall shear stress (WSS). From the observation, flow re-circulation has been formed for all simulated stent models which the proximal region shown the severe vortices. However, rectangular shape of stent strut (Type P3) shows the lowest WSSlow and the highest WSS between the range of 4 dyne/cm2 and 70 dyne/cm2. Stent Type P3 also shows the best hemodynamic stent performance as compare to others. In conclusion, Type P3 has a favourable result in hemodynamic stent performance that predicted less probability of thrombosis and atherosclerosis to be formed as well as reduces the growth of restenosis.

Luminescence and efficiency optimization of InGaN/GaN core-shell nanowire LEDs by numerical modelling

Science.gov (United States)

Römer, Friedhard; Deppner, Marcus; Andreev, Zhelio; Kölper, Christopher; Sabathil, Matthias; Strassburg, Martin; Ledig, Johannes; Li, Shunfeng; Waag, Andreas; Witzigmann, Bernd

2012-02-01

We present a computational study on the anisotropic luminescence and the efficiency of a core-shell type nanowire LED based on GaN with InGaN active quantum wells. The physical simulator used for analyzing this device integrates a multidimensional drift-diffusion transport solver and a k . p Schrödinger problem solver for quantization effects and luminescence. The solution of both problems is coupled to achieve self-consistency. Using this solver we investigate the effect of dimensions, design of quantum wells, and current injection on the efficiency and luminescence of the core-shell nanowire LED. The anisotropy of the luminescence and re-absorption is analyzed with respect to the external efficiency of the LED. From the results we derive strategies for design optimization.

Mesoporous multi-shelled ZnO microspheres for the scattering layer of dye sensitized solar cell with a high efficiency

Energy Technology Data Exchange (ETDEWEB)

Xia, Weiwei; Mei, Chao; Zeng, Xianghua, E-mail: xhzeng@yzu.edu.cn; Wu, Guoqing; Shen, Xiaoshuang [College of Physics Science and Technology and Institute of Optoelectronic Technology, Yangzhou University, Yangzhou 225002 (China); Chang, Shuai [Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)

2016-03-14

Both light scattering and dye adsorbing are important for the power conversion efficiency PCE performance of dye sensitized solar cell (DSSC). Nanostructured scattering layers with a large specific surface area are regarded as an efficient way to improve the PCE by increasing dye adsorbing, but excess adsorbed dye will hinder light scattering and light penetration. Thus, how to balance the dye adsorbing and light penetration is a key problem to improve the PCE performance. Here, multiple-shelled ZnO microspheres with a mesoporous surface are fabricated by a hydrothermal method and are used as scattering layers on the TiO{sub 2} photoanode of the DSSC in the presence of N719 dye and iodine–based electrolyte, and the results reveal that the DSSCs based on triple shelled ZnO microsphere with a mesoporous surface exhibit an enhanced PCE of 7.66%, which is 13.0% higher than those without the scattering layers (6.78%), indicating that multiple-shelled microspheres with a mesoporous surface can ensure enough light scattering between the shells, and a favorable concentration of the adsorbed dye can improve the light penetration. These results may provide a promising pathway to obtain the high efficient DSSCs.

Topologically Micropatterned Collagen and Poly(ε-caprolactone) Struts Fabricated Using the Poly(vinyl alcohol) Fibrillation/Leaching Process To Develop Efficiently Engineered Skeletal Muscle Tissue.

Science.gov (United States)

Kim, Minseong; Kim, WonJin; Kim, GeunHyung

2017-12-20

Optimally designed three-dimensional (3D) biomedical scaffolds for skeletal muscle tissue regeneration pose significant research challenges. Currently, most studies on scaffolds focus on the two-dimensional (2D) surface structures that are patterned in the micro-/nanoscales with various repeating sizes and shapes to induce the alignment of myoblasts and myotube formation. The 2D patterned surface clearly provides effective analytical results of pattern size and shape of the myoblast alignment and differentiation. However, it is inconvenient in terms of the direct application for clinical usage due to the limited thickness and 3D shapeability. Hence, the present study suggests an innovative hydrogel or synthetic structure that consists of uniaxially surface-patterned cylindrical struts for skeleton muscle regeneration. The alignment of the pattern on the hydrogel (collagen) and poly(ε-caprolactone) struts was attained with the fibrillation of poly(vinyl alcohol) and the leaching process. Various cell culture results indicate that the C2C12 cells on the micropatterned collagen structure were fully aligned, and that a significantly high level of myotube formation was achieved when compared to the collagen structures that were not treated with the micropatterning process.

Production Efficiency of Cocoon Shell of Silkworm, Bombyx mori L. (Bombycidae: Lepidoptera, as an Index for Evaluating the Nutritive Value of Mulberry, Morus sp. (Moraceae, Varieties

Directory of Open Access Journals (Sweden)

Jalaja Suresh Kumar

2011-01-01

Full Text Available The nutritional efficiency of mulberry leaves consumed by silkworms, Bombyx mori L., is usually evaluated in terms of the proportion of cocoon shell weight to the amount of food ingested. The production efficiency of cocoon shell is generally used to identify the superiority of a mulberry variety for silkworm rearing. In this study the production efficiency of cocoon shell was used as an index for evaluating the nutritive value of different mulberry varieties of India. Among the varieties, V-1, having highest production efficiency of cocoon shell with less amount of food ingested and highest digestibility, is regarded as the best suitable variety with nutritive values ideal for silkworm rearing.

A Stewart isolator with high-static-low-dynamic stiffness struts based on negative stiffness magnetic springs

Science.gov (United States)

Zheng, Yisheng; Li, Qingpin; Yan, Bo; Luo, Yajun; Zhang, Xinong

2018-05-01

In order to improve the isolation performance of passive Stewart platforms, the negative stiffness magnetic spring (NSMS) is employed to construct high static low dynamic stiffness (HSLDS) struts. With the NSMS, the resonance frequencies of the platform can be reduced effectively without deteriorating its load bearing capacity. The model of the Stewart isolation platform with HSLDS struts is presented and the stiffness characteristic of its struts is studied firstly. Then the nonlinear dynamic model of the platform including both geometry nonlinearity and stiffness nonlinearity is established; and its simplified dynamic model is derived under the condition of small vibration. The effect of nonlinearity on the isolation performance is also evaluated. Finally, a prototype is built and the isolation performance is tested. Both simulated and experimental results demonstrate that, by using the NSMS, the resonance frequencies of the Stewart isolator are reduced and the isolation performance in all six directions is improved: the isolation frequency band is increased and extended to a lower-frequency level.

Core-Shell Structuring of Pure Metallic Aerogels towards Highly Efficient Platinum Utilization for the Oxygen Reduction Reaction.

Science.gov (United States)

Cai, Bin; Hübner, René; Sasaki, Kotaro; Zhang, Yuanzhe; Su, Dong; Ziegler, Christoph; Vukmirovic, Miomir B; Rellinghaus, Bernd; Adzic, Radoslav R; Eychmüller, Alexander

2018-03-05

The development of core-shell structures remains a fundamental challenge for pure metallic aerogels. Here we report the synthesis of Pd x Au-Pt core-shell aerogels composed of an ultrathin Pt shell and a composition-tunable Pd x Au alloy core. The universality of this strategy ensures the extension of core compositions to Pd transition-metal alloys. The core-shell aerogels exhibited largely improved Pt utilization efficiencies for the oxygen reduction reaction and their activities show a volcano-type relationship as a function of the lattice parameter of the core substrate. The maximum mass and specific activities are 5.25 A mg Pt -1 and 2.53 mA cm -2 , which are 18.7 and 4.1 times higher than those of Pt/C, respectively, demonstrating the superiority of the core-shell metallic aerogels. The proposed core-based activity descriptor provides a new possible strategy for the design of future core-shell electrocatalysts. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Research on shock wave characteristics in the isolator of central strut rocket-based combined cycle engine under Ma5.5

Science.gov (United States)

Wei, Xianggeng; Xue, Rui; Qin, Fei; Hu, Chunbo; He, Guoqiang

2017-11-01

A numerical calculation of shock wave characteristics in the isolator of central strut rocket-based combined cycle (RBCC) engine fueled by kerosene was carried out in this paper. A 3D numerical model was established by the DES method. The kerosene chemical kinetic model used the 9-component and 12-step simplified mechanism model. Effects of fuel equivalence ratio, inflow total temperature and central strut rocket on-off on shock wave characteristics were studied under Ma5.5. Results demonstrated that with the increase of equivalence ratio, the leading shock wave moves toward upstream, accompanied with higher possibility of the inlet unstart. However, the leading shock wave moves toward downstream as the inflow total temperature rises. After the central strut rocket is closed, the leading shock wave moves toward downstream, which can reduce risks of the inlet unstart. State of the shear layer formed by the strut rocket jet flow and inflow can influence the shock train structure significantly.

Efficient photocatalytic degradation of malachite green dye under visible irradiation by water soluble ZnS:Mn/ZnS core/shell nanoparticles

Science.gov (United States)

Khaparde, Rohini A.; Acharya, Smita A.

2018-05-01

ZnS:Mn/ ZnS core/shell nanoparticles was prepared by two step synthesis method. In first step, oleic acid - coated Mn doped ZnS core nanoparticles were prepared which were charged through ligand exchange. Shell of ZnS NPs was finally deposited upon the surface of charged Mn doped ZnS core. Scanning electron microscopy (SEM) image exhibit morphological confirmation of ZnS:Mn/ZnS core/shell. As Nano ZnS are the most suitable candidates for photocatalyst that extensively involved in degradation and complete mineralization of various toxic organic pollutants owing to its high efficiency, strong oxidizing power, non-toxicity, high photochemical and biological stability, corrosive resistance and low cost. Photodegradation of malachite green is systematically investigated by adding different molar proportional of ZnS:Mn/ZnS core/shell in the dye. The rate of de-coloration of dye is detected by UV-VIS absorption spectroscopy. Efficient detoriation in the colour of dye is attributed to the core /shell morphology of the particles.

[Minor strut fracture of the Björk-Shiley mitral valve].

Science.gov (United States)

Sugita, T; Yasuda, R; Watarida, S; Onoe, M; Tabata, R; Mori, A

1990-06-01

In May, 1982, a 49-year-old man underwent mitral valve replacement (MVR) in our hospital with a 31 mm Björk-Shiley prosthesis for mitral regurgitation. He had been doing well until his episode of palpitation and dyspnea of sudden onset, and was transferred to our ICU with severe cardiogenic shock in Aug, 1986. Chest X-ray film revealed pulmonary edema and breakage of the valve with migration of the disc and the minor strut of the prosthesis. He was operated upon 5 hours after the onset of his complaints. The minor strut was removed from the left upper pulmonary vein and mitral valve re-replacement was done with a 29 mm Björk-Shiley Monostrut valve. The disc which had dislocated into the abdominal aorta was also recovered on the twenty-third post operative day. His postoperative course was uneventful. Immediate diagnosis and subsequent re-operation is absolute indication for rescue from acute cardiac failure due to mechanical failure of any prosthetic valve.

Satisfactory arterial repair 1 year after ultrathin strut biodegradable polymer sirolimus-eluting stent implantation: an angioscopic observation.

Science.gov (United States)

Ishihara, Takayuki; Awata, Masaki; Iida, Osamu; Fujita, Masashi; Masuda, Masaharu; Okamoto, Shin; Nanto, Kiyonori; Kanda, Takashi; Tsujimura, Takuya; Uematsu, Masaaki; Mano, Toshiaki

2018-01-15

The ultrathin strut biodegradable polymer sirolimus-eluting stent (Orsiro, O-SES) exhibits satisfactory clinical outcomes. However, no report to date has documented the intravascular status of artery repair after O-SES implantation. We examined 5 O-SES placed in 4 patients (age 65 ± 12 years, male 75%) presenting with stable angina pectoris due to de novo lesions in native coronary arteries. Coronary angioscopy was performed immediately after percutaneous coronary intervention and 1 year later. Angioscopic images were analyzed to determine the following: (1) dominant grade of neointimal coverage (NIC) over the stent; (2) maximum yellow plaque grade; and (3) existence of thrombus. Yellow plaque grade was evaluated both immediately after stent implantation and at the time of follow-up observation. The other parameters were evaluated at the time of follow-up examination. NIC was graded as: grade 0, stent struts exposed; grade 1, struts bulging into the lumen, although covered; grade 2, struts embedded in the neointima, but translucent; grade 3, struts fully embedded and invisible. Yellow plaque severity was graded as: grade 0, white; grade 1, light yellow; grade 2, yellow; and grade 3, intensive yellow. Angioscopic findings at 1 year demonstrated the following: dominant NIC grade 1, grade 2, and grade 3 in 1, 2, and 2 stents, respectively; all stents were covered to some extent; focal thrombus adhesion was observed in only 1 stent. Yellow plaque grade did not change from immediately after stent implantation to follow-up. O-SES demonstrated satisfactory arterial repair 1 year after implantation.

Portal WEB 2.0. utilizando Framework Struts

OpenAIRE

Palacín Mateo, Manuel

2007-01-01

El propósito de este proyecto es la implementación de un portal interactivo de contactos utilizando las tecnologías J2EE mediante Struts y siguiendo la tendencia Web 2.0. Previo a esta implementación se ha hecho una valoración del mercado actual de los portales de contactos y se han evaluado los servicios que ofrecen para posteriormente añadirlos a la demostración tecnológica. Tras esto se ha explicado lo que es la tendencia Web 2.0. Finalmente se han evaluado las diferentes opciones o tec...

Experimental study on combustion modes and thrust performance of a staged-combustor of the scramjet with dual-strut

Science.gov (United States)

Yang, Qingchun; Chetehouna, Khaled; Gascoin, Nicolas; Bao, Wen

2016-05-01

To enable the scramjet operate in a wider flight Mach number, a staged-combustor with dual-strut is introduced to hold more heat release at low flight Mach conditions. The behavior of mode transition was examined using a direct-connect model scramjet experiment along with pressure measurements. The typical operating modes of the staged-combustor are analyzed. Fuel injection scheme has a significant effect on the combustor operating modes, particularly for the supersonic combustion mode. Thrust performances of the combustor with different combustion modes and fuel distributions are reported in this paper. The first-staged strut injection has a better engine performance in the operation of subsonic combustion mode. On the contrast, the second-staged strut injection has a better engine performance in the operation of supersonic combustion mode.

High-efficient production of SiC/SiO2 core-shell nanowires for effective microwave absorption

KAUST Repository

Zhong, Bo; Sai, Tianqi; Xia, Long; Yu, Yuanlie; Wen, Guangwu

2017-01-01

In the current report, we have demonstrated that the high-efficient production of SiC/SiO2 core-shell nanowires can be achieved through the introduction of trace of water vapor during the chemical vapor deposition process. The yield of the SiC/SiO2 core-shell nanowires is dramatically improved due to the introduction of water vapor. The SiC/SiO2 core-shell nanowires exhibit an excellent microwave absorption property in the frequency range of 2.0–18.0GHz with a very low weight percentage of 0.50wt.% in the absorbers. A minimum reflection loss value of −32.72dB (>99.99% attenuation) at 13.84GHz has been observed with the absorber thickness of 3.0mm. Moreover, the SiC/SiO2 core-shell nanowires based absorber can reach an effective absorption bandwidth (<−10dB) of 5.32GHz with the absorber thickness of 3.5mm. Furthermore, a possible absorption mechanism is also proposed in detail for such effective attenuation of microwave which can be attributed to the dielectric loss and magnetic loss of SiC/SiO2 core-shell nanowires.

High-efficient production of SiC/SiO2 core-shell nanowires for effective microwave absorption

KAUST Repository

Zhong, Bo

2017-02-21

In the current report, we have demonstrated that the high-efficient production of SiC/SiO2 core-shell nanowires can be achieved through the introduction of trace of water vapor during the chemical vapor deposition process. The yield of the SiC/SiO2 core-shell nanowires is dramatically improved due to the introduction of water vapor. The SiC/SiO2 core-shell nanowires exhibit an excellent microwave absorption property in the frequency range of 2.0–18.0GHz with a very low weight percentage of 0.50wt.% in the absorbers. A minimum reflection loss value of −32.72dB (>99.99% attenuation) at 13.84GHz has been observed with the absorber thickness of 3.0mm. Moreover, the SiC/SiO2 core-shell nanowires based absorber can reach an effective absorption bandwidth (<−10dB) of 5.32GHz with the absorber thickness of 3.5mm. Furthermore, a possible absorption mechanism is also proposed in detail for such effective attenuation of microwave which can be attributed to the dielectric loss and magnetic loss of SiC/SiO2 core-shell nanowires.

Highly efficient photocatalytic conversion of solar energy to hydrogen by WO3/BiVO4 core-shell heterojunction nanorods

Science.gov (United States)

Kosar, Sonya; Pihosh, Yuriy; Bekarevich, Raman; Mitsuishi, Kazutaka; Mawatari, Kazuma; Kazoe, Yutaka; Kitamori, Takehiko; Tosa, Masahiro; Tarasov, Alexey B.; Goodilin, Eugene A.; Struk, Yaroslav M.; Kondo, Michio; Turkevych, Ivan

2018-04-01

Photocatalytic splitting of water under solar light has proved itself to be a promising approach toward the utilization of solar energy and the generation of environmentally friendly fuel in a form of hydrogen. In this work, we demonstrate highly efficient solar-to-hydrogen conversion efficiency of 7.7% by photovoltaic-photoelectrochemical (PV-PEC) device based on hybrid MAPbI3 perovskite PV cell and WO3/BiVO4 core-shell nanorods PEC cell tandem that utilizes spectral splitting approach. Although BiVO4 is characterized by intrinsically high recombination rate of photogenerated carriers, this is not an issue for WO3/BiVO4 core-shell nanorods, where highly conductive WO3 cores are combined with extremely thin absorber BiVO4 shell layer. Since the BiVO4 layer is thinner than the characteristic carrier diffusion length, the photogenerated charge carriers are separated at the WO3/BiVO4 heterojunction before their recombination. Also, such architecture provides sufficient optical thickness even for extremely thin BiVO4 layer due to efficient light trapping in the core-shell WO3/BiVO4 nanorods with high aspect ratio. We also demonstrate that the concept of fill factor can be used to compare I-V characteristics of different photoanodes regarding their optimization for PV/PEC tandem devices.

Six-strut arrangements for cartesian movements of mirrors

International Nuclear Information System (INIS)

Noll, T.; Zeschke, Th.; Reichardt, G.; Lammert, H.; Gudat, W.

2001-01-01

At BESSY a new six-strut arrangement for general small travel mirror adjustment mechanisms has been developed. This patented (Patent DE 10042802.5) arrangement allows very simple movements in all six linear and rotational degrees of freedom. The movements of the mirror are simply determined by moving either one drive, or up to three drives by the same amount. The first mirror adjustment systems of this design is successfully in operation since the start of BESSY II. Their performance and reliability is very satisfactory. This contribution will present the concepts

Strut fracture with Björk-Shiley 70 degrees convexo-concave valve. An international multi-institutional follow-up study.

Science.gov (United States)

Ericsson, A; Lindblom, D; Semb, G; Huysmans, H A; Thulin, L I; Scully, H E; Bennett, J G; Ostermeyer, J; Grunkemeier, G L

1992-01-01

Between 1980 and 1983, 831 Björk-Shiley 70 degrees convexo-concave prosthetic heart valves were implanted at five institutions in Sweden, Germany. The Netherlands, and Canada. As of January 1991, there were 34 outlet strut fractures occurring from 0.2 to 10.1 years (median = 4.6 years) after implantation. In addition, there were 28 sudden, unexplained deaths. The mortality after strut fracture was 84%. The mortality after emergency valve replacement for strut fracture was 50%. The 10-year actuarial fracture rate (standard error) was 10.5 (2.4)% for large (29-33 mm) valves vs. 3.3 (1.2)% for 21-27 mm valves (P less than 0.001). Within valve size groups, fracture rates for aortic and mitral valves were similar. Cox regression analysis found only valve size to be significantly associated with strut fracture. There is a further subgrouping of the valves according to the manufacturer: group I are the earlier large 29-33 mm) valves; group II are the later large valves; group III are the small size (21-27 mm) valves. The risk of strut fracture was highest in group I (12.3% at 10 years) with an approximatively constant hazard (1.4% per year). A comparison was made with a statistical model incorporating all cases reported to the manufacturer. This model estimates fracture rates approximately 63%-73% of those found in the present study. These findings lead us to recommend that group I patients should be considered for elective reoperation on an individual basis, giving careful attention to risk factors and contraindications.

Strut and tie modeling for RC short beams with corroded stirrups

Directory of Open Access Journals (Sweden)

Ahmed K. El-Sayed

Full Text Available Corrosion of steel reinforcement is one of the major problems that shorten the service life of reinforced concrete (RC structures. Steel stirrups, due to their location as an outer reinforcement, are more susceptible to corrosion problems and damage. However, there is limited research work in the literature on the effects of stirrup corrosion on the shear strength of RC beams. This paper attempts to evaluate analytically the residual shear strength of RC short beams with corrosion-damaged stirrups. The shear strength of short or deep beams are generally determined using the strut and tie model. The corrosion effects were implemented in the model to make it capable of predicting the residual shear capacity of RC beams with corroded stirrups. The effect of corrosion is implemented considering the reduction in geometry of the concrete cross section due to spalling and reduction in effective compressive strength of concrete due to corrosion cracks. The proposed strut and tie model which accounts for the corrosion effects was verified using the experimental data available in the literature, and good agreement was found.

Multiple piece turbine airfoil

Science.gov (United States)

Kimmel, Keith D; Wilson, Jr., Jack W.

2010-11-02

A turbine airfoil, such as a rotor blade or a stator vane, for a gas turbine engine, the airfoil formed as a shell and spar construction with a plurality of dog bone struts each mounted within openings formed within the shell and spar to allow for relative motion between the spar and shell in the airfoil chordwise direction while also forming a seal between adjacent cooling channels. The struts provide the seal as well as prevent bulging of the shell from the spar due to the cooling air pressure.

Test Program for High Efficiency Gas Turbine Exhaust Diffuser

Energy Technology Data Exchange (ETDEWEB)

Norris, Thomas R.

2009-12-31

This research relates to improving the efficiency of flow in a turbine exhaust, and thus, that of the turbine and power plant. The Phase I SBIR project demonstrated the technical viability of “strutlets” to control stalls on a model diffuser strut. Strutlets are a novel flow-improving vane concept intended to improve the efficiency of flow in turbine exhausts. Strutlets can help reduce turbine back pressure, and incrementally improve turbine efficiency, increase power, and reduce greenhouse gas emmission. The long-term goal is a 0.5 percent improvement of each item, averaged over the US gas turbine fleet. The strutlets were tested in a physical scale model of a gas turbine exhaust diffuser. The test flow passage is a straight, annular diffuser with three sets of struts. At the end of Phase 1, the ability of strutlets to keep flow attached to struts was demonstrated, but the strutlet drag was too high for a net efficiency advantage. An independently sponsored followup project did develop a highly-modified low-drag strutlet. In combination with other flow improving vanes, complicance to the stated goals was demonstrated for for simple cycle power plants, and to most of the goals for combined cycle power plants using this particular exhaust geometry. Importantly, low frequency diffuser noise was reduced by 5 dB or more, compared to the baseline. Appolicability to other diffuser geometries is yet to be demonstrated.

Structural FEM analysis of the strut-to-fuselage joint of a two-seat composite aircraft

International Nuclear Information System (INIS)

Vargas-Rojas, Erik; Camarena-Arellano, Diego; Hernández-Moreno, Hilario

2014-01-01

An analysis of a strut-to-fuselage joint is realized in order to evaluate the zones with a high probability of failure by means of a safety factor. The whole section is analyzed using the Finite Element Method (FEM) so as to estimate static resistance behavior, therefore it is necessary a numerical mock-up of the section, the mechanical properties of the Carbon-Epoxy (C-Ep) material, and to evaluate the applied loads. Results of the analysis show that the zones with higher probability of failure are found around the wing strut and the fuselage joint, with a safety factor lower than expected in comparison with the average safety factor used on aircrafts built mostly with metals

About two new efficient nonlinear shell elements

International Nuclear Information System (INIS)

Yin, J.; Suo, X.Z.; Combescure, A.

1989-01-01

The aim of the paper is to present the development of two shell elements for non linear analysis. The first one is an axisymetric curved shell element and it is developed for buckling analysis. The formulation is given, as well as some typical applications. The second one is an extension of the classical DKT element to large strains taking into account all aspects of non linearities. This element is used for the simulation of four point bending of cracked pipes. The whole experiment is simulated by the calculation taking into account very large strains at the crack tip and propagation of the crack

Core-shell microspheres with porous nanostructured shells for liquid chromatography.

Science.gov (United States)

Ahmed, Adham; Skinley, Kevin; Herodotou, Stephanie; Zhang, Haifei

2018-01-01

The development of new stationary phases has been the key aspect for fast and efficient high-performance liquid chromatography separation with relatively low backpressure. Core-shell particles, with a solid core and porous shell, have been extensively investigated and commercially manufactured in the last decade. The excellent performance of core-shell particles columns has been recorded for a wide range of analytes, covering small and large molecules, neutral and ionic (acidic and basic), biomolecules and metabolites. In this review, we first introduce the advance and advantages of core-shell particles (or more widely known as superficially porous particles) against non-porous particles and fully porous particles. This is followed by the detailed description of various methods used to fabricate core-shell particles. We then discuss the applications of common silica core-shell particles (mostly commercially manufactured), spheres-on-sphere particles and core-shell particles with a non-silica shell. This review concludes with a summary and perspective on the development of stationary phase materials for high-performance liquid chromatography applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

78 FR 73997 - Airworthiness Directives; Various Aircraft Equipped with Wing Lift Struts

Science.gov (United States)

2013-12-10

...-0023; Directorate Identifier 96-CE-072-AD; Amendment 39-17688; AD 99-01-05 R1] RIN 2120-AA64... Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are revising Airworthiness Directive (AD) 99-01-05 for certain aircraft equipped with wing lift struts. AD 99-01-05 required repetitively inspecting the wing...

Design of squat shear walls using continuous strut-and-tie resistant models

International Nuclear Information System (INIS)

Santos, S.H. de C; Silva, R.E. da

1993-01-01

A new approach is presented for designing squat shear walls, subjected to seismic loading. In this approach, the strut-and-tie resistant models, proposed by Schlaich et al., are generalized in order to analyze continuous fields of compression and tension stresses. The application of the presented methodology is illustrated through numerical examples. (author)

78 FR 3356 - Airworthiness Directives; Various Aircraft Equipped With Wing Lift Struts

Science.gov (United States)

2013-01-16

...) of this AD, inspect the wing lift strut forks for cracks using magnetic particle procedures, such as... for Non-destructive Testing, or MIL-STD-410. (i) If no external corrosion is found on any wing lift..., the surface should be sanded or polished smooth before testing to assure a consistent and smooth...

Self-oscillations of aircraft landing gear shock-strut at considerable non-linear friction

Directory of Open Access Journals (Sweden)

Б.М. Шифрин

2004-01-01

Full Text Available  The report considers self-oscillations at ε >1. The previous works were dedicated to the elastic frictional L.G. shock strut oscillations, the mathematical model of which is a non-linear differential equation with low ε parameter of its right-hand part.

An efficient, selective collisional ejection mechanism for inner-shell population inversion in laser-driven plasmas

Energy Technology Data Exchange (ETDEWEB)

SCHROEDER,W. ANDREAS; NELSON,THOMAS R.; BORISOV,A.B.; LONGWORTH,J.W.; BOYER,K.; RHODES,C.K.

2000-06-07

A theoretical analysis of laser-driven collisional ejection of inner-shell electrons is presented to explain the previously observed anomalous kilovolt L-shell x-ray emission spectra from atomic Xe cluster targets excited by intense sub-picosecond 248nrn ultraviolet radiation. For incident ponderomotively-driven electrons photoionized by strong above threshold ionization, the collisional ejection mechanism is shown to be highly l-state and significantly n-state (i.e. radially) selective for time periods shorter than the collisional dephasing time of the photoionized electronic wavefunction. The resulting preference for the collisional ejection of 2p electrons by an ionized 4p state produces the measured anomalous Xe(L) emission which contains direct evidence for (i) the generation of Xe{sup 27+}(2p{sup 5}3d{sup 10}) and Xe{sup 28+}(2p{sup 5}3d{sup 9}) ions exhibiting inner-shell population inversion and (ii) a coherent correlated electron state collision responsible for the production of double 2p vacancies. For longer time periods, the selectivity of this coherent impact ionization mechanism is rapidly reduced by the combined effects of intrinsic quantum mechanical spreading and dephasing--in agreement with the experimentally observed and extremely strong {minus}{lambda}{sup {minus}6} pump-laser wavelength dependence of the efficiency of inner-shell (2p) vacancy production in Xe clusters excited in underdense plasmas.

Efficiency Enhanced Colloidal Mn-Doped Type II Core/Shell ZnSe/CdS Quantum Dot Sensitized Hybrid Solar Cells

Directory of Open Access Journals (Sweden)

A. Jamshidi

2015-01-01

Full Text Available Colloidal Mn-doped ZnSe/CdS core/shell quantum dots (QDs are synthesized for the first time and employed as a strategy to boost the power conversion efficiency of quantum dot sensitized solar cells. By using Mn-doping as a band gap engineering tool for core/shell QDs an effective improvement of absorption spectra could be obtained. The mid-states generated by a proper Mn content alleviate carrier separation and enhance the electron injection rate, thus facilitating electron transport to the TiO2 substrate. It is demonstrated that a device constructed with 0.25% Mn-doped ZnSe/CdS leads to an enhancement of the electron injection rate and power conversion efficiency by 4 times and 1.3, respectively.

The Transport of Mass, Energy, and Entropy in Cryogenic Support Struts for Engineering Design

Science.gov (United States)

Elchert, J. P.

2012-01-01

Engineers working to understand and reduce cryogenic boil-off must solve a variety of transport problems. An important class of nonlinear problems involves the thermal and mechanical design of cryogenic struts. These classic problems are scattered about the literature and typically require too many resources to obtain. So, to save time for practicing engineers, the author presents this essay. Herein, a variety of new, old, and revisited analytical and finite difference solutions of the thermal problem are covered in this essay, along with commentary on approach and assumptions. This includes a few thermal radiation and conduction combined mode solutions with a discussion on insulation, optimum emissivity, and geometrical phenomenon. Solutions to cooling and heat interception problems are also presented, including a discussion of the entropy generation. The literature on the combined mechanical and thermal design of cryogenic support struts is reviewed with an introduction to the associated numerical methods.

Simulation study of 3–5 keV x-ray conversion efficiency from Ar K-shell vs. Ag L-shell targets on the National Ignition Facility laser

Energy Technology Data Exchange (ETDEWEB)

Kemp, G. E., E-mail: kemp10@llnl.gov; Colvin, J. D.; Fournier, K. B.; May, M. J.; Barrios, M. A.; Patel, M. V.; Scott, H. A.; Marinak, M. M. [Lawrence Livermore National Laboratory, Livermore, California 94550-9698 (United States)

2015-05-15

Tailored, high-flux, multi-keV x-ray sources are desirable for studying x-ray interactions with matter for various civilian, space and military applications. For this study, we focus on designing an efficient laser-driven non-local thermodynamic equilibrium 3–5 keV x-ray source from photon-energy-matched Ar K-shell and Ag L-shell targets at sub-critical densities (∼n{sub c}/10) to ensure supersonic, volumetric laser heating with minimal losses to kinetic energy, thermal x rays and laser-plasma instabilities. Using HYDRA, a multi-dimensional, arbitrary Lagrangian-Eulerian, radiation-hydrodynamics code, we performed a parameter study by varying initial target density and laser parameters for each material using conditions readily achievable on the National Ignition Facility (NIF) laser. We employ a model, benchmarked against Kr data collected on the NIF, that uses flux-limited Lee-More thermal conductivity and multi-group implicit Monte-Carlo photonics with non-local thermodynamic equilibrium, detailed super-configuration accounting opacities from CRETIN, an atomic-kinetics code. While the highest power laser configurations produced the largest x-ray yields, we report that the peak simulated laser to 3–5 keV x-ray conversion efficiencies of 17.7% and 36.4% for Ar and Ag, respectively, occurred at lower powers between ∼100–150 TW. For identical initial target densities and laser illumination, the Ag L-shell is observed to have ≳10× higher emissivity per ion per deposited laser energy than the Ar K-shell. Although such low-density Ag targets have not yet been demonstrated, simulations of targets fabricated using atomic layer deposition of Ag on silica aerogels (∼20% by atomic fraction) suggest similar performance to atomically pure metal foams and that either fabrication technique may be worth pursuing for an efficient 3–5 keV x-ray source on NIF.

Wireless energy transfer between anisotropic metamaterials shells

Energy Technology Data Exchange (ETDEWEB)

Díaz-Rubio, Ana; Carbonell, Jorge; Sánchez-Dehesa, José, E-mail: jsdehesa@upv.es

2014-06-15

The behavior of strongly coupled Radial Photonic Crystals shells is investigated as a potential alternative to transfer electromagnetic energy wirelessly. These sub-wavelength resonant microstructures, which are based on anisotropic metamaterials, can produce efficient coupling phenomena due to their high quality factor. A configuration of selected constitutive parameters (permittivity and permeability) is analyzed in terms of its resonant characteristics. The coupling to loss ratio between two coupled resonators is calculated as a function of distance, the maximum (in excess of 300) is obtained when the shells are separated by three times their radius. Under practical conditions an 83% of maximum power transfer has been also estimated. -- Highlights: •Anisotropic metamaterial shells exhibit high quality factors and sub-wavelength size. •Exchange of electromagnetic energy between shells with high efficiency is analyzed. •Strong coupling is supported with high wireless transfer efficiency. •End-to-end energy transfer efficiencies higher than 83% can be predicted.

Wireless energy transfer between anisotropic metamaterials shells

International Nuclear Information System (INIS)

Díaz-Rubio, Ana; Carbonell, Jorge; Sánchez-Dehesa, José

2014-01-01

The behavior of strongly coupled Radial Photonic Crystals shells is investigated as a potential alternative to transfer electromagnetic energy wirelessly. These sub-wavelength resonant microstructures, which are based on anisotropic metamaterials, can produce efficient coupling phenomena due to their high quality factor. A configuration of selected constitutive parameters (permittivity and permeability) is analyzed in terms of its resonant characteristics. The coupling to loss ratio between two coupled resonators is calculated as a function of distance, the maximum (in excess of 300) is obtained when the shells are separated by three times their radius. Under practical conditions an 83% of maximum power transfer has been also estimated. -- Highlights: •Anisotropic metamaterial shells exhibit high quality factors and sub-wavelength size. •Exchange of electromagnetic energy between shells with high efficiency is analyzed. •Strong coupling is supported with high wireless transfer efficiency. •End-to-end energy transfer efficiencies higher than 83% can be predicted

Three-Dimensional Printing of Hollow-Struts-Packed Bioceramic Scaffolds for Bone Regeneration.

Science.gov (United States)

Luo, Yongxiang; Zhai, Dong; Huan, Zhiguang; Zhu, Haibo; Xia, Lunguo; Chang, Jiang; Wu, Chengtie

2015-11-04

Three-dimensional printing technologies have shown distinct advantages to create porous scaffolds with designed macropores for application in bone tissue engineering. However, until now, 3D-printed bioceramic scaffolds only possessing a single type of macropore have been reported. Generally, those scaffolds with a single type of macropore have relatively low porosity and pore surfaces, limited delivery of oxygen and nutrition to surviving cells, and new bone tissue formation in the center of the scaffolds. Therefore, in this work, we present a useful and facile method for preparing hollow-struts-packed (HSP) bioceramic scaffolds with designed macropores and multioriented hollow channels via a modified coaxial 3D printing strategy. The prepared HSP scaffolds combined high porosity and surface area with impressive mechanical strength. The unique hollow-struts structures of bioceramic scaffolds significantly improved cell attachment and proliferation and further promoted formation of new bone tissue in the center of the scaffolds, indicating that HSP ceramic scaffolds can be used for regeneration of large bone defects. In addition, the strategy can be used to prepare other HSP ceramic scaffolds, indicating a universal application for tissue engineering, mechanical engineering, catalysis, and environmental materials.

Bioresorbable scaffold -fourth revolution or failed revolution: Is low scaffold strut thickness the wrong target?

Directory of Open Access Journals (Sweden)

Sundeep Mishra

2017-11-01

Full Text Available Bioresorbable scaffold (BRS technology has currently fallen into disrepute because of inordinately high risk of scaffold thrombosis and post-procedure myocardial infarction. Low tensile and radial strengths of polymeric BRS contributing to improper strut embedment have been identified as major correlates of poor outcomes following BRS implantation. Magnesium has a better tensile/radial strength compared with polymeric BRS but it is still far lower than cobalt-chromium. Newers innovations utilizing alteration in polymer composition and orientation or even newer polymers have focused on attempts to reduce strut thickness but may have little effect on tensile/radial strength of finished product and therefore may not impact the BRS outcome on long run. Currently, newer generation BRS usage may be restricted to suitable low risk younger patients with proper vessel preparation and application of technique.

Hierarchical tailoring of strut architecture to control permeability of additive manufactured titanium implants

Energy Technology Data Exchange (ETDEWEB)

Zhang, Z. [Department of Materials, Imperial College London, South Kensington Campus, London, SW7 2AZ (United Kingdom); Jones, D. [School of Engineering, University of Liverpool, Brownlow Hill, Liverpool, L69 3GH (United Kingdom); Yue, S. [Manchester X-ray Imaging Facility, School of Materials, The University of Manchester, Oxford Road, M13 9PL (United Kingdom); Lee, P.D., E-mail: peter.lee@manchester.ac.uk [Manchester X-ray Imaging Facility, School of Materials, The University of Manchester, Oxford Road, M13 9PL (United Kingdom); Jones, J.R. [Department of Materials, Imperial College London, South Kensington Campus, London, SW7 2AZ (United Kingdom); Sutcliffe, C.J. [School of Engineering, University of Liverpool, Brownlow Hill, Liverpool, L69 3GH (United Kingdom); Jones, E. [Department of Advanced Technology, Stryker Orthopaedics, Raheen Business Park, Limerick (Ireland)

2013-10-15

Porous titanium implants are a common choice for bone augmentation. Implants for spinal fusion and repair of non-union fractures must encourage blood flow after implantation so that there is sufficient cell migration, nutrient and growth factor transport to stimulate bone ingrowth. Additive manufacturing techniques allow a large number of pore network designs. This study investigates how the design factors offered by selective laser melting technique can be used to alter the implant architecture on multiple length scales to control and even tailor the flow. Permeability is a convenient parameter that characterises flow, correlating to structure openness (interconnectivity and pore window size), tortuosity and hence flow shear rates. Using experimentally validated computational simulations, we demonstrate how additive manufacturing can be used to tailor implant properties by controlling surface roughness at a microstructual level (microns), and by altering the strut ordering and density at a mesoscopic level (millimetre). Highlights: • Experimentally validated permeability prediction tools for hierarchical implants. • Randomised structures form preferential flow channels with stronger shear flows. • Hierarchical strut structures allow independent tailoring of flow and pore size.

Hierarchical tailoring of strut architecture to control permeability of additive manufactured titanium implants

International Nuclear Information System (INIS)

Zhang, Z.; Jones, D.; Yue, S.; Lee, P.D.; Jones, J.R.; Sutcliffe, C.J.; Jones, E.

2013-01-01

Porous titanium implants are a common choice for bone augmentation. Implants for spinal fusion and repair of non-union fractures must encourage blood flow after implantation so that there is sufficient cell migration, nutrient and growth factor transport to stimulate bone ingrowth. Additive manufacturing techniques allow a large number of pore network designs. This study investigates how the design factors offered by selective laser melting technique can be used to alter the implant architecture on multiple length scales to control and even tailor the flow. Permeability is a convenient parameter that characterises flow, correlating to structure openness (interconnectivity and pore window size), tortuosity and hence flow shear rates. Using experimentally validated computational simulations, we demonstrate how additive manufacturing can be used to tailor implant properties by controlling surface roughness at a microstructual level (microns), and by altering the strut ordering and density at a mesoscopic level (millimetre). Highlights: • Experimentally validated permeability prediction tools for hierarchical implants. • Randomised structures form preferential flow channels with stronger shear flows. • Hierarchical strut structures allow independent tailoring of flow and pore size

Numerical analysis and design optimization of supersonic after-burning with strut fuel injectors for scramjet engines

Science.gov (United States)

Candon, M. J.; Ogawa, H.

2018-06-01

Scramjets are a class of hypersonic airbreathing engine that offer promise for economical, reliable and high-speed access-to-space and atmospheric transport. The expanding flow in the scramjet nozzle comprises of unburned hydrogen. An after-burning scheme can be used to effectively utilize the remaining hydrogen by supplying additional oxygen into the nozzle, aiming to augment the thrust. This paper presents the results of a single-objective design optimization for a strut fuel injection scheme considering four design variables with the objective of maximizing thrust augmentation. Thrust is found to be augmented significantly owing to a combination of contributions from aerodynamic and combustion effects. Further understanding and physical insights have been gained by performing variance-based global sensitivity analysis, scrutinizing the nozzle flowfields, analyzing the distributions and contributions of the forces acting on the nozzle wall, and examining the combustion efficiency.

The effect of struts on the radiation diagram of Cassegrain antennas

International Nuclear Information System (INIS)

Henriques, L.M.D.

1981-09-01

This work presents a study on the effect of subreflector support members of Cassegrain antennas using the theory of scattering by cylinders structures. Expression for the surface current densities and arbitrary cross sections cylinders are developed, and the components for the scattered field are obtained. Using these results we analyse the effect of the struts on the gain reduction, and the rise of maximum side-lobe level. The final results obtained are then compared to other approximate theories. (author)

Comparison of Single Ti6Al4V Struts Made Using Selective Laser Melting and Electron Beam Melting Subject to Part Orientation

Directory of Open Access Journals (Sweden)

Volker Weißmann

2017-03-01

Full Text Available The use of additive manufacturing technologies to produce lightweight or functional structures is widespread. Especially Ti6Al4V plays an important role in this development field and parts are manufactured and analyzed with the aim to characterize the mechanical properties of open-porous structures and to generate scaffolds with properties specific to their intended application. An SLM and an EBM process were used respectively to fabricate the Ti6Al4V single struts. For mechanical characterization, uniaxial compression tests and hardness measurements were conducted. Furthermore, the struts were manufactured in different orientations for the determination of the mechanical properties. Roughness measurements and a microscopic characterization of the struts were also carried out. Some parts were characterized following heat treatment (hot isostatic pressing. A functional correlation was found between the compressive strength and the slenderness ratio (λ as well as the equivalent diameter (d and the height (L of EBM and SLM parts. Hardness investigations revealed considerable differences related to the microstructure. An influence of heat treatment as well as of orientation could be determined. In this work, we demonstrate the influence of the fabrication quality of single struts, the roughness and the microstructure on mechanical properties as a function of orientation.

Bioresorbable scaffold -fourth revolution or failed revolution: Is low scaffold strut thickness the wrong target?

Science.gov (United States)

Mishra, Sundeep

Bioresorbable scaffold (BRS) technology has currently fallen into disrepute because of inordinately high risk of scaffold thrombosis and post-procedure myocardial infarction. Low tensile and radial strengths of polymeric BRS contributing to improper strut embedment have been identified as major correlates of poor outcomes following BRS implantation. Magnesium has a better tensile/radial strength compared with polymeric BRS but it is still far lower than cobalt-chromium. Newers innovations utilizing alteration in polymer composition and orientation or even newer polymers have focused on attempts to reduce strut thickness but may have little effect on tensile/radial strength of finished product and therefore may not impact the BRS outcome on long run. Currently, newer generation BRS usage may be restricted to suitable low risk younger patients with proper vessel preparation and application of technique. Copyright © 2017 Cardiological Society of India. Published by Elsevier B.V. All rights reserved.

Efficiency of Acacia Tortillis Plant Pod Shell as a Low Cost and Available Adsorbent for the Removal of Phenol

Directory of Open Access Journals (Sweden)

Hossien JafariMansoorian

2015-05-01

Full Text Available The presence of nondegradable toxic compounds such as phenol in the environment has nowadays led to many health and environmental problems. The present empirical study was conducted on the lab scale to evaluate the efficiency of Acacia tortillis pod shell as a new alternative and low cost adsorbent for removing phenol from aqueous solutions. The experiment was performed in a batch system and the effects of important operation variables including initial phenol concentrations of 0.5, 1, 2, 4, 8, 16, 32, and 64 mg/l, absorbent doses of 0.1, 0.2, 0.4, 0.8, and 1.6g/l in predetermined mesh sizes (ranging over 30-60 and 60-100, pH levels of 2, 4, 6, 8, 10, and 12, and contact times of 10, 20, 30, 40, 50, and 60 min were evaluated. Finally, the Freundlich and Langmuir adsorption isotherms were determined in order to describe the relationship between the colored solution and the absorbent. Results showed that the highest phenol absorption efficiency achieved was above 95% which was obtained with an optimum pH level of 2, an optimum absorbent dose of 0.2 g/l, and a mesh size of 60-100 for a contact time of 10 minutes and at a low pollutant concentration. Increasing phenol concentration increased its removal efficiency but this removal rate was lower at extreme concentrations. Also, the adsorption process was found to be more compatible with the Freundlich model. Based on the results obtained, the pod shells of Acacia tortillis pod shell may be claimed to be an effective, efficient, and cheap absorbent for the removal of phenol from aqueous solutions.

Synthesis of core-shell heterostructured Cu/Cu2O nanowires monitored by in situ XRD as efficient visible-light photocatalysts

KAUST Repository

Chen, Wei; Fan, Zhongli; Lai, Zhiping

2013-01-01

strategy for fabricating efficiently core-shell heterostructured nanowires and provides the potential for developing their applications in electronic devices, for environmental remediation and in solar energy utilization fields. This journal is © The Royal

Analysis of thin composite structures using an efficient hex-shell finite element

Energy Technology Data Exchange (ETDEWEB)

Shiri, Seddik [Universite Bordeaux, Pessac (France); Naceur, Hakim [Universite de valenciennes, Valenciennes (France)

2013-12-15

In this paper a general methodology for the modeling of material composite multilayered shell structures is proposed using a Hex-shell finite element modeling. The first part of the paper is devoted to the general FE formulation of the present composite 8-node Hex-shell element called SCH8, based only on displacement degrees of freedom. A particular attention is given to alleviate shear, trapezoidal and thickness locking, without resorting to the classical plane-stress assumption. The anisotropic material behavior of layered shells is modeled using a fully three dimensional elastic orthotropic material law in each layer, including the thickness stress component. Applications to laminate thick shell structures are studied to validate the methodology, and good results have been obtained in comparison with ABAQUS commercial code.

Optimised photocatalytic hydrogen production using core–shell AuPd promoters with controlled shell thickness

DEFF Research Database (Denmark)

Jones, Wilm; Su, Ren; Wells, Peter

2014-01-01

of these materials towards the reforming of alcohols for hydrogen production. The core–shell structured Au–Pd bimetallic nanoparticle supported on TiO2 has being of interest as it exhibited extremely high quantum efficiencies for hydrogen production. However, the effect of shell composition and thickness...... of the nanoparticles by a combination of X-ray absorption fine structure and X-ray photoelectron spectroscopy. Photocatalytic ethanol reforming showed that the core–shell structured Au–Pd promoters supported on TiO2 exhibit enhanced activity compared to that of monometallic Au and Pd as promoters, whilst the core......–shell Au–Pd promoters containing one ML equivalent Pd provide the optimum reactivity....

Euler Strut: A Mechanical Analogy for Dynamics in the Vicinity of a Critical Point

Science.gov (United States)

Bobnar, Jaka; Susman, Katarina; Parsegian, V. Adrian; Rand, Peter R.; Cepic, Mojca; Podgornik, Rudolf

2011-01-01

An anchored elastic filament (Euler strut) under an external point load applied to its free end is a simple model for a second-order phase transition. In the static case, a load greater than the critical load causes a Euler buckling instability, leading to a change in the filament's shape. The analysis of filament dynamics with an external point…

Structural Analysis of Shipping Casks, Vol. 9. Energy Absorption Capabilities of Plastically Deformed Struts Under Specified Impact Loading Conditions (Thesis)

International Nuclear Information System (INIS)

Davis, F.C.

2001-01-01

The purpose of this investigation was to determine the energy absorption characteristics of plastically deformed inclined struts under impact loading. This information is needed to provide a usable method by which designers and analysts of shipping casks for radioactive or fissile materials can determine the energy absorption capabilities of external longitudinal fins on cylindrical casks under specified impact conditions. A survey of technical literature related to experimental determination of the dynamic plastic behavior of struts revealed no information directly applicable to the immediate problem, especially in the impact velocity ranges desired, and an experimental program was conducted to obtain the needed data. Mild-steel struts with rectangular cross sections were impacted by free-falling weights dropped from known heights. These struts or fin specimens were inclined at five different angles to simulate different angles of impact that fins on a shipping cask could experience under certain accident conditions. The resisting force of the deforming strut was measured and recorded as a function of time by using load cells instrumented with resistance strain gage bridges, signal conditioning equipment, an oscilloscope, and a Polaroid camera. The acceleration of the impacting weight was measured and recorded as a function of time during the latter portion of the testing program by using an accelerometer attached to the drop hammer, appropriate signal conditioning equipment, the oscilloscope, and the camera. A digital computer program was prepared to numerically integrate the force-time and acceleration-time data recorded during the tests to obtain deformation-time data. The force-displacement relationships were then integrated to obtain values of absorbed energy with respect to deformation or time. The results for various fin specimen geometries and impact angles are presented graphically, and these curves may be used to compute the energy absorption capacity of

Simple and efficient synthesis of copper(II)-modified uniform magnetic Fe3O4@SiO2 core/shell microspheres for immobilization of cellulase

Science.gov (United States)

Li, Shi-Kuo; Hou, Xiao-Cheng; Huang, Fang-Zhi; Li, Chuan-Hao; Kang, Wen-Juan; Xie, An-Jian; Shen, Yu-Hua

2013-11-01

In this paper, we reported a simple and efficient protocol for preparation of Cu2+-modified magnetic Fe3O4@SiO2 core/shell microspheres for immobilization of cellulase. The uniform magnetic Fe3O4@SiO2 core/shell microspheres with a thin shell of 20 nm were synthesized through a solvothermal method followed by a sol-gel process. An amino-terminated silane coupling agent of (3-aminopropyl)triethoxysilane (APTS) was then grafted on them for capturing Cu2+ ions. The reaction process is very simple, efficient, and economical. Noticeably, the content of Cu2+ ions on the magnetic core/shell microspheres can reach 4.6 Wt%, endowing them possess as high immobilization capacity as 225.5 mg/g for cellulase. And the immobilized cellulase can be retained over 90 % on the magnetic microspheres after six cycles. Meanwhile, the magnetic microspheres decorated with Cu2+ ions show a superparamagnetic character with a high magnetic saturation of 58.5 emu/g at room temperature, suggesting conveniently and rapidly recycle the enzyme from solution. This facile, recyclable, high immobilization capacity and activity strategy may find potential applications in enzyme catalytic reactions with low cost.

Simple and efficient synthesis of copper(II)-modified uniform magnetic Fe3O4@SiO2 core/shell microspheres for immobilization of cellulase

International Nuclear Information System (INIS)

Li, Shi-Kuo; Hou, Xiao-Cheng; Huang, Fang-Zhi; Li, Chuan-Hao; Kang, Wen-Juan; Xie, An-Jian; Shen, Yu-Hua

2013-01-01

In this paper, we reported a simple and efficient protocol for preparation of Cu 2+ -modified magnetic Fe 3 O 4 @SiO 2 core/shell microspheres for immobilization of cellulase. The uniform magnetic Fe 3 O 4 @SiO 2 core/shell microspheres with a thin shell of 20 nm were synthesized through a solvothermal method followed by a sol–gel process. An amino-terminated silane coupling agent of (3-aminopropyl)triethoxysilane (APTS) was then grafted on them for capturing Cu 2+ ions. The reaction process is very simple, efficient, and economical. Noticeably, the content of Cu 2+ ions on the magnetic core/shell microspheres can reach 4.6 Wt%, endowing them possess as high immobilization capacity as 225.5 mg/g for cellulase. And the immobilized cellulase can be retained over 90 % on the magnetic microspheres after six cycles. Meanwhile, the magnetic microspheres decorated with Cu 2+ ions show a superparamagnetic character with a high magnetic saturation of 58.5 emu/g at room temperature, suggesting conveniently and rapidly recycle the enzyme from solution. This facile, recyclable, high immobilization capacity and activity strategy may find potential applications in enzyme catalytic reactions with low cost

Effect of shells on photoluminescence of aqueous CdTe quantum dots

International Nuclear Information System (INIS)

Yuan, Zhimin; Yang, Ping

2013-01-01

Graphical abstract: Size-tunable CdTe coated with several shells using an aqueous solution synthesis. CdTe/CdS/ZnS quantum dots exhibited high PL efficiency up to 80% which implies the promising applications for biomedical labeling. - Highlights: • CdTe quantum dots were fabricated using an aqueous synthesis. • CdS, ZnS, and CdS/ZnS shells were subsequently deposited on CdTe cores. • Outer ZnS shells provide an efficient confinement of electron and hole inside the QDs. • Inside CdS shells can reduce the strain on the QDs. • Aqueous CdTe/CdS/ZnS QDs exhibited high stability and photoluminescence efficiency of 80%. - Abstract: CdTe cores with various sizes were fabricated in aqueous solutions. Inorganic shells including CdS, ZnS, and CdS/ZnS were subsequently deposited on the cores through a similar aqueous procedure to investigate the effect of shells on the photoluminescence properties of the cores. In the case of CdTe/CdS/ZnS quantum dots, the outer ZnS shell provides an efficient confinement of electron and hole wavefunctions inside the quantum dots, while the middle CdS shell sandwiched between the CdTe core and ZnS shell can be introduced to obviously reduce the strain on the quantum dots because the lattice parameters of CdS is situated at the intermediate-level between those of CdTe and ZnS. In comparison with CdTe/ZnS core–shell quantum dots, the as-prepared water-soluble CdTe/CdS/ZnS quantum dots in our case can exhibit high photochemical stability and photoluminescence efficiency up to 80% in an aqueous solution, which implies the promising applications in the field of biomedical labeling

Design aids for stiffened composite shells with cutouts

CERN Document Server

Sahoo, Sarmila

2017-01-01

This book focuses on the free vibrations of graphite-epoxy laminated composite stiffened shells with cutout both in terms of the natural frequencies and mode shapes. The dynamic analysis of shell structures, which may have complex geometry and arbitrary loading and boundary conditions, is solved efficiently by the finite element method, even including cutouts in shells. The results may be readily used by practicing engineers dealing with stiffened composite shells with cutouts. Several shell forms viz. cylindrical shell, hypar shell, conoidal shell, spherical shell, saddle shell, hyperbolic paraboloidal shell and elliptic paraboloidal shell are considered in the book. The dynamic characteristics of stiffened composite shells with cutout are described in terms of the natural frequency and mode shapes. The size of the cutouts and their positions with respect to the shell centre are varied for different edge constraints of cross-ply and angle-ply laminated composite shells. The effects of these parametric variat...

Shell energy scenarios to 2050

International Nuclear Information System (INIS)

2008-01-01

Shell developed two scenarios that describe alternative ways the energy future may develop. In the first scenario (Scramble) policymakers pay little attention to more efficient energy use until supplies are tight. Likewise, greenhouse gas emissions are not seriously addressed until there are major climate shocks. In the second scenario (Blueprints) growing local actions begin to address the challenges of economic development, energy security and environmental pollution. A price is applied to a critical mass of emissions giving a huge stimulus to the development of clean energy technologies, such as carbon dioxide capture and storage, and energy efficiency measures. The result is far lower carbon dioxide emissions. Both these scenarios can help Shell to test their strategy against a range of possible developments over the long-term. However, according to Shell, the Blueprints' outcomes offer the best hope for a sustainable future, whether or not they arise exactly in the way described. However, with the right combination of policy, technology and commitment from governments, industry and society globally, Shell believes it can be realized. But achieving the targets will not be easy, and time is short. Clear thinking, huge investment, and effective leadership are required

[Late outlet strut fracture of an aortic Björk-Shiley and embolization of the prosthetic disc].

Science.gov (United States)

Brochet, E; Bougis de Brux, M A; Assayag, P; Benacin, Y; Gamerman, G; Guerot, C; Valère, P E

1988-09-01

A new case of late fracture of an outlet strut in a convexo-concave Björk-Shiley valve is reported. The fracture occurred 6 years after aortic implantation of the valve and was responsible for aorto-iliac embolization by the prosthetic disc and death of the patient from cardiogenic shock. This not uncommon complication of the Björk-Shiley valve prosthesis is usually ascribed to the relative fragility of its outlet strut welded to the metallic ring and subjected to strong pressures. Although most cases were observed within the first two years of prosthetic valve insertion, and mainly with valves manufactured in 1981 and 1982, our case and a few others demonstrate the possibility of late rupture. Cardiologists must be aware of this possible complication, since in some favourable cases it can be diagnosed at an early stage and the patient's life can be saved by an emergency operation.

Yolk-Shelled C@Fe3 O4 Nanoboxes as Efficient Sulfur Hosts for High-Performance Lithium-Sulfur Batteries.

Science.gov (United States)

He, Jiarui; Luo, Liu; Chen, Yuanfu; Manthiram, Arumugam

2017-09-01

Owing to the high theoretical specific capacity (1675 mA h g -1 ) and low cost, lithium-sulfur (Li-S) batteries offer advantages for next-generation energy storage. However, the polysulfide dissolution and low electronic conductivity of sulfur cathodes limit the practical application of Li-S batteries. To address such issues, well-designed yolk-shelled carbon@Fe 3 O 4 (YSC@Fe 3 O 4 ) nanoboxes as highly efficient sulfur hosts for Li-S batteries are reported here. With both physical entrapment by carbon shells and strong chemical interaction with Fe 3 O 4 cores, this unique architecture immobilizes the active material and inhibits diffusion of the polysulfide intermediates. Moreover, due to their high conductivity, the carbon shells and the polar Fe 3 O 4 cores facilitate fast electron/ion transport and promote continuous reactivation of the active material during the charge/discharge process, resulting in improved electrochemical utilization and reversibility. With these merits, the S/YSC@Fe 3 O 4 cathodes support high sulfur content (80 wt%) and loading (5.5 mg cm -2 ) and deliver high specific capacity, excellent rate capacity, and long cycling stability. This work provides a new perspective to design a carbon/metal-oxide-based yolk-shelled framework as a high sulfur-loading host for advanced Li-S batteries with superior electrochemical properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Intra- and interobserver reliability and intra-catheter reproducibility using frequency domain optical coherence tomography for the evaluation of morphometric stent parameters and qualitative assessment of stent strut coverage

DEFF Research Database (Denmark)

Antonsen, Lisbeth; Thayssen, Per; Junker, Anders

2015-01-01

to investigate the intra- and interobserver reliability, as well as the intra-catheter reproducibility of quantitative FD-OCT-assessment of morphometric stent parameters and qualitative FD-OCT-evaluation of strut coverage in 10 randomly selected 6-month follow-up Nobori® biolimus-eluting stents (N-BESs). METHODS...... in another 10 N-BESs (219 CSAs and 1860 struts) were independently assessed by one of the analysts. RESULTS: The intraobserver variability with regard to relative difference of mean luminal area and mean stent area at the CSA-level was very low: 0.1%±1.4% and 0.5%±3.2%. Interobserver variability also proved...... (CI): 0.88-0.93, pstented coronary segments, and for qualitative assessment of strut coverage....

pH-sensitive chitosan/alginate core-shell nanoparticles for efficient and safe oral insulin delivery.

Science.gov (United States)

Mukhopadhyay, Piyasi; Chakraborty, Souma; Bhattacharya, Sourav; Mishra, Roshnara; Kundu, P P

2015-01-01

Chitosan-alginate (CS/ALG) nanoparticles were prepared by formation of an ionotropic pre-gelation of an alginate (ALG) core entrapping insulin, followed by chitosan (CS) polyelectrolyte complexation, for successful oral insulin administration. Mild preparation process without harsh chemicals is aimed at improving insulin bio-efficiency in in vivo model. The nanoparticles showed an average particle size of 100-200 nm in dynamic light scattering (DLS), with almost spherical or sub-spherical shape and ∼ 85% of insulin encapsulation. Again, retention of almost entire amount of encapsulated insulin in simulated gastric buffer followed by its sustained release in simulated intestinal condition proved its pH sensitivity in in vitro release studies. Significant hypoglycemic effects with improved insulin-relative bioavailability (∼ 8.11%) in in vivo model revealed the efficacy of these core-shell nanoparticles of CS/ALG as an oral insulin carrier. No systemic toxicity was found after its peroral treatment, suggesting these core-shell nanoparticles as a promising device for potential oral insulin delivery. Copyright © 2014 Elsevier B.V. All rights reserved.

Highly efficient biosensors by using well-ordered ZnO/ZnS core/shell nanotube arrays

Science.gov (United States)

Tarish, Samar; Xu, Yang; Wang, Zhijie; Mate, Faten; Al-Haddad, Ahmed; Wang, Wenxin; Lei, Yong

2017-10-01

We have studied the fabrication of highly efficient glucose sensors using well-ordered heterogeneous ZnO/ZnS core/shell nanotube arrays (CSNAs). The modified electrodes exhibit a superior electrochemical response towards ferrocyanide/ferricyanide and in glucose sensing. Further, the fabricated glucose biosensor exhibited good performance over an acceptable linear range from 2.39 × 10-5 to 2.66 × 10-4 mM, with a sensitivity of 188.34 mA mM-1 cm-2, which is higher than that of the ZnO nanotube array counterpart. A low limit of detection was realized (24 μM), which is good compared with electrodes based on conventional structures. In addition, the enhanced direct electrochemistry of glucose oxidase indicates the fast electron transfer of ZnO/ZnS CSNA electrodes, with a heterogeneous electron transfer rate constant (K s) of 1.69 s-1. The fast electron transfer is attributed to the high conductivity of the modified electrodes. The presented ZnS shell can facilitate the construction of future sensors and enhance the ZnO surface in a biological environment.

The influence of shell thickness of Au@TiO2 core-shell nanoparticles on the plasmonic enhancement effect in dye-sensitized solar cells.

Science.gov (United States)

Liu, Wei-Liang; Lin, Fan-Cheng; Yang, Yu-Chen; Huang, Chen-Hsien; Gwo, Shangjr; Huang, Michael H; Huang, Jer-Shing

2013-09-07

Plasmonic core-shell nanoparticles (PCSNPs) can function as nanoantennas and improve the efficiency of dye-sensitized solar cells (DSSCs). To achieve maximum enhancement, the morphology of PCSNPs needs to be optimized. Here we precisely control the morphology of Au@TiO2 PCSNPs and systematically study its influence on the plasmonic enhancement effect. The enhancement mechanism was found to vary with the thickness of the TiO2 shell. PCSNPs with a thinner shell mainly enhance the current, whereas particles with a thicker shell improve the voltage. While pronounced plasmonic enhancement was found in the near infrared regime, wavelength-independent enhancement in the visible range was observed and attributed to the plasmonic heating effect. Emission lifetime measurement confirms that N719 molecules neighboring nanoparticles with TiO2 shells exhibit a longer lifetime than those in contact with metal cores. Overall, PCSNPs with a 5 nm shell give the highest efficiency enhancement of 23%. Our work provides a new synthesis route for well-controlled Au@TiO2 core-shell nanoparticles and gains insight into the plasmonic enhancement in DSSCs.

Ununited fracture neck of femur treated with closed reduction and internal fixation with cancellous screw and fibular strut graft

Directory of Open Access Journals (Sweden)

Singh Daria

2006-01-01

Full Text Available Background: Ununited fracture neck of femur in young adults has been tackled in various ways. Methods: Twenty five patients of ununited fracture neck of femur in age group 21-55 years were treated by closed reduction, cancellous screw fixation and fibular strut graft and followed up for 2-6 years. Time gap between injury and operation was 6 weeks to 58 weeks. Five cases were previously fixed with various fixation devices. Results: Osseous union was achieved in 24 cases with average time of 18.16 weeks. Main complication encountered in follow-up was avascular necrosis of femoral head, others were joint stiffness and shortening. Functional end results were good to excellent in 24 cases. Conclusion: Closed reduction with internal fixation by cancellous screw and fibular strut grafting is easy and useful procedure.

Modeling of microencapsulated polymer shell solidification

International Nuclear Information System (INIS)

Boone, T.; Cheung, L.; Nelson, D.; Soane, D.; Wilemski, G.; Cook, R.

1995-01-01

A finite element transport model has been developed and implemented to complement experimental efforts to improve the quality of ICF target shells produced via controlled-mass microencapsulation. The model provides an efficient means to explore the effect of processing variables on the dynamics of shell dimensions, concentricity, and phase behavior. Comparisons with experiments showed that the model successfully predicts the evolution of wall thinning and core/wall density differences. The model was used to efficiently explore and identify initial wall compositions and processing temperatures which resulted in concentricity improvements from 65 to 99%. The evolution of trace amounts of water entering into the shell wall was also tracked in the simulations. Comparisons with phase envelope estimations from modified UNIFAP calculations suggest that the water content trajectory approaches the two-phase region where vacuole formation via microphase separation may occur

Optical absorption of carbon-gold core-shell nanoparticles

Science.gov (United States)

Wang, Zhaolong; Quan, Xiaojun; Zhang, Zhuomin; Cheng, Ping

2018-01-01

In order to enhance the solar thermal energy conversion efficiency, we propose to use carbon-gold core-shell nanoparticles dispersed in liquid water. This work demonstrates theoretically that an absorbing carbon (C) core enclosed in a plasmonic gold (Au) nanoshell can enhance the absorption peak while broadening the absorption band; giving rise to a much higher solar absorption than most previously studied core-shell combinations. The exact Mie solution is used to evaluate the absorption efficiency factor of spherical nanoparticles in the wavelength region from 300 nm to 1100 nm as well as the electric field and power dissipation profiles inside the nanoparticles at specified wavelengths (mostly at the localized surface plasmon resonance wavelength). The field enhancement by the localized plasmons at the gold surfaces boosts the absorption of the carbon particle, resulting in a redshift of the absorption peak with increased peak height and bandwidth. In addition to spherical nanoparticles, we use the finite-difference time-domain method to calculate the absorption of cubic core-shell nanoparticles. Even stronger enhancement can be achieved with cubic C-Au core-shell structures due to the localized plasmonic resonances at the sharp edges of the Au shell. The solar absorption efficiency factor can exceed 1.5 in the spherical case and reach 2.3 in the cubic case with a shell thickness of 10 nm. Such broadband absorption enhancement is in great demand for solar thermal applications including steam generation.

Sound radiation modes of cylindrical surfaces and their application to vibro-acoustics analysis of cylindrical shells

Science.gov (United States)

Sun, Yao; Yang, Tiejun; Chen, Yuehua

2018-06-01

In this paper, sound radiation modes of baffled cylinders have been derived by constructing the radiation resistance matrix analytically. By examining the characteristics of sound radiation modes, it is found that radiation coefficient of each radiation mode increases gradually with the increase of frequency while modal shapes of sound radiation modes of cylindrical shells show a weak dependence upon frequency. Based on understandings on sound radiation modes, vibro-acoustics behaviors of cylindrical shells have been analyzed. The vibration responses of cylindrical shells are described by modified Fourier series expansions and solved by Rayleigh-Ritz method involving Flügge shell theory. Then radiation efficiency of a resonance has been determined by examining whether the vibration pattern is in correspondence with a sound radiation mode possessing great radiation efficiency. Furthermore, effects of thickness and boundary conditions on sound radiation of cylindrical shells have been investigated. It is found that radiation efficiency of thicker shells is greater than thinner shells while shells with a clamped boundary constraint radiate sound more efficiently than simply supported shells under thin shell assumption.

Au-Cu core-shell nanocube-catalyzed click reactions for efficient synthesis of diverse triazoles.

Science.gov (United States)

Madasu, Mahesh; Hsia, Chi-Fu; Huang, Michael H

2017-06-01

Au-Cu core-shell nanocubes and octahedra synthesized in aqueous solution were employed to catalyze a 1,3-dipolar cycloaddition reaction between phenylacetylene and benzyl azide in water at 50 °C for 3 h. Interestingly, the nanocubes were far more efficient in catalyzing this reaction, giving 91% yield of a regioselective 1,4-triazole product, while octahedra only recorded 46% yield. The Au-Cu nanocubes were subsequently employed to catalyze the click reaction between benzyl azide and a broad range of aromatic and aliphatic alkynes. The product yields ranged from 78 to 99%. Clearly the Au-Cu cubes exposing {100} surfaces are an excellent and green catalyst for click reactions.

The shell coal gasification process

Energy Technology Data Exchange (ETDEWEB)

Koenders, L.O.M.; Zuideveld, P.O. [Shell Internationale Petroleum Maatschappij B.V., The Hague (Netherlands)

1995-12-01

Future Integrated Coal Gasification Combined Cycle (ICGCC) power plants will have superior environmental performance and efficiency. The Shell Coal Gasification Process (SCGP) is a clean coal technology, which can convert a wide range of coals into clean syngas for high efficiency electricity generation in an ICGCC plant. SCGP flexibility has been demonstrated for high-rank bituminous coals to low rank lignites and petroleum coke, and the process is well suited for combined cycle power generation, resulting in efficiencies of 42 to 46% (LHV), depending on choice of coal and gas turbine efficiency. In the Netherlands, a 250 MWe coal gasification combined cycle plant based on Shell technology has been built by Demkolec, a development partnership of the Dutch Electricity Generating Board (N.V. Sep). The construction of the unit was completed end 1993 and is now followed by start-up and a 3 year demonstration period, after that the plant will be part of the Dutch electricity generating system.

The Björk-Shiley 70 degree convexo-concave prosthesis strut fracture problem (present state of information).

Science.gov (United States)

Ostermeyer, J; Horstkotte, D; Bennett, J; Huysmans, H; Lindblom, D; Olin, C; Orinius, E; Semb, G

1987-04-01

Between June 1980 and June 1983 4028 Björk-Shiley 70 degree convexo-concave prosthetic heart valves were distributed and implanted in Australia, Canada, Europe and South Africa. As of March 1986, a total of 52 outlet strut fractures (1.29%; 70% CL: 1.1%-1.5%) have been reported from 29 implant institutions in 12 countries. The majority (82.7%) occurred in Europe. Intervals between implantation and fracture were 13 days to 45.3 months (mean: 18.4 months; 70% CL: 16.6 months-20.1 months). The mortality rate after strut fracture was 78.7% (70% CL: 72.5%-84.9%). Upon stratification of the fracture by valve sizes and types it becomes evident that 75% (70% CL: 68.8%-81.2%) of all fractures are related to the sizes 29 mm to 33 mm (which virtually represent the same valve size) and predominantly to mitral valves (p less than 0.01). The large valves again have been stratified into two subsets, namely those fabricated from flanges originally machined as Björk-Shiley 60 degree convexo-concave valves (group I) and later produced valves machined initially to 70 degree specifications (group II). In group I the fracture rate was 5.2% (70% CL: 4.2%-6.2%) versus 1.6% (70% CL: 1.1%-2.1%) in group II (p less than 0.01), which identifies the group I 29 mm-33 mm Björk-Shiley 70 degree convexo-concave valves as the highest risk group for strut fracture. The rates are based upon all available information as of March 16, 1986.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrays of ZnO/CuInxGa1−xSe2 nanocables with tunable shell composition for efficient photovoltaics

International Nuclear Information System (INIS)

Akram, Muhammad Aftab; Javed, Sofia; Xu, Jun; Mujahid, Mohammad; Lee, Chun-Sing

2015-01-01

Arrays of one-dimensional (1D) nanostructure are receiving much attention for their optoelectronic and photovoltaic applications due to their advantages in light absorption, charge separation, and transportation. In this work, arrays of ZnO/CuIn x Ga 1−x Se 2 core/shell nanocables with tunable shell compositions over the full range of 0 ≤ x ≤ 1 have been controllably synthesized. Chemical conversions of ZnO nanorods to a series of ZnO-based nanocables, including ZnO/ZnSe, ZnO/CuSe, ZnO/CuSe/In x Ga 1−x , ZnO/CuSe/(In x Ga 1−x ) 2 Se 3 , and ZnO/CuIn x Ga 1−x Se 2 , are well designed and successfully achieved. Composition-dependent influences of the CuIn x Ga 1−x Se 2 shells on photovoltaic performance are investigated. It is found that the increase in indium content (x) leads to an increase in short-circuit current density (J SC ) but a decrease in open-circuit voltage (V OC ) for the ZnO/CuIn x Ga 1−x Se 2 nanocable solar cells. An array of ZnO/CuIn 0.67 Ga 0.33 Se 2 nanocables with a length of ∼1 μm and a shell thickness of ∼10 nm exhibits a bandgap of 1.20 eV, and yields a maximum power conversion efficiency of 1.74% under AM 1.5 G illumination at an intensity of 100 mW/cm 2 . It dramatically surpasses that (0.22%) of the ZnO/CuIn 0.67 Ga 0.33 Se 2 planar thin-film device. Our work reveals that 1D nanoarray allows efficient photovoltaics without using toxic CdS buffer layer

The indications and donor-site morbidity of tibial cortical strut autografts in the management of defects in long bones.

Science.gov (United States)

Lauthe, O; Soubeyrand, M; Babinet, A; Dumaine, V; Anract, P; Biau, D J

2018-05-01

Aims The primary aim of this study was to determine the morbidity of a tibial strut autograft and characterize the rate of bony union following its use. Patients and Methods We retrospectively assessed a series of 104 patients from a single centre who were treated with a tibial strut autograft of > 5 cm in length. A total of 30 had a segmental reconstruction with continuity of bone, 27 had a segmental reconstruction without continuity of bone, 29 had an arthrodesis and 18 had a nonunion. Donor-site morbidity was defined as any event that required a modification of the postoperative management. Union was assessed clinically and radiologically at a median of 36 months (IQR, 14 to 74). Results Donor-site morbidity occurred in four patients (4%; 95% confidence interval (CI) 1 to 10). One patient had a stress fracture of the tibia, which healed with a varus deformity, requiring an osteotomy. Two patients required evacuation of a haematoma and one developed anterior compartment syndrome which required fasciotomies. The cumulative probability of union was 90% (95% CI 80 to 96) at five years. The type of reconstruction (p = 0.018), continuity of bone (p = 0.006) and length of tibial graft (p = 0.037) were associated with the time to union. Conclusion The tibial strut autograft has a low risk of morbidity and provides adequate bone stock for treating various defects of long bones. Cite this article: Bone Joint J 2018;100-B:667-74.

Compression and contact area of anterior strut grafts in spinal instrumentation: a biomechanical study.

Science.gov (United States)

Pizanis, Antonius; Holstein, Jörg H; Vossen, Felix; Burkhardt, Markus; Pohlemann, Tim

2013-08-26

Anterior bone grafts are used as struts to reconstruct the anterior column of the spine in kyphosis or following injury. An incomplete fusion can lead to later correction losses and compromise further healing. Despite the different stabilizing techniques that have evolved, from posterior or anterior fixating implants to combined anterior/posterior instrumentation, graft pseudarthrosis rates remain an important concern. Furthermore, the need for additional anterior implant fixation is still controversial. In this bench-top study, we focused on the graft-bone interface under various conditions, using two simulated spinal injury models and common surgical fixation techniques to investigate the effect of implant-mediated compression and contact on the anterior graft. Calf spines were stabilised with posterior internal fixators. The wooden blocks as substitutes for strut grafts were impacted using a "pressfit" technique and pressure-sensitive films placed at the interface between the vertebral bone and the graft to record the compression force and the contact area with various stabilization techniques. Compression was achieved either with posterior internal fixator alone or with an additional anterior implant. The importance of concomitant ligament damage was also considered using two simulated injury models: pure compression Magerl/AO fracture type A or rotation/translation fracture type C models. In type A injury models, 1 mm-oversized grafts for impaction grafting provided good compression and fair contact areas that were both markedly increased by the use of additional compressing anterior rods or by shortening the posterior fixator construct. Anterior instrumentation by itself had similar effects. For type C injuries, dramatic differences were observed between the techniques, as there was a net decrease in compression and an inadequate contact on the graft occurred in this model. Under these circumstances, both compression and the contact area on graft could only

Dense Medium Machine Processing Method for Palm Kernel/ Shell ...

African Journals Online (AJOL)

ADOWIE PERE

Cracked palm kernel is a mixture of kernels, broken shells, dusts and other impurities. In ... machine processing method using dense medium, a separator, a shell collector and a kernel .... efficiency, ease of maintenance and uniformity of.

Parameterized Finite Element Modeling and Buckling Analysis of Six Typical Composite Grid Cylindrical Shells

Science.gov (United States)

Lai, Changliang; Wang, Junbiao; Liu, Chuang

2014-10-01

Six typical composite grid cylindrical shells are constructed by superimposing three basic types of ribs. Then buckling behavior and structural efficiency of these shells are analyzed under axial compression, pure bending, torsion and transverse bending by finite element (FE) models. The FE models are created by a parametrical FE modeling approach that defines FE models with original natural twisted geometry and orients cross-sections of beam elements exactly. And the approach is parameterized and coded by Patran Command Language (PCL). The demonstrations of FE modeling indicate the program enables efficient generation of FE models and facilitates parametric studies and design of grid shells. Using the program, the effects of helical angles on the buckling behavior of six typical grid cylindrical shells are determined. The results of these studies indicate that the triangle grid and rotated triangle grid cylindrical shell are more efficient than others under axial compression and pure bending, whereas under torsion and transverse bending, the hexagon grid cylindrical shell is most efficient. Additionally, buckling mode shapes are compared and provide an understanding of composite grid cylindrical shells that is useful in preliminary design of such structures.

Biosorption of divalent Pb, Cd and Zn on aragonite and calcite mollusk shells

Energy Technology Data Exchange (ETDEWEB)

Du Yang; Lian Fei [Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, Tianjin Key Laboratory of Urban Ecology Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071 (China); Zhu Lingyan, E-mail: zhuly@nankai.edu.cn [Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, Tianjin Key Laboratory of Urban Ecology Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071 (China)

2011-07-15

The potential of using mollusk shell powder in aragonite (razor clam shells, RCS) and calcite phase (oyster shells, OS) to remove Pb{sup 2+}, Cd{sup 2+} and Zn{sup 2+} from contaminated water was investigated. Both biogenic sorbents displayed very high sorption capacities for the three metals except for Cd on OS. XRD, SEM and XPS results demonstrated that surface precipitation leading to crystal growth took place during sorption. Calcite OS displayed a remarkably higher sorption capacity to Pb than aragonite RCS, while the opposite was observed for Cd. However, both sorbents displayed similar sorption capacities to Zn. These could be due to the different extent of matching in crystal lattice between the metal bearing precipitate and the substrates. The initial pH of the solution, sorbent's dosage and grain size affected the removal efficiency of the heavy meals significantly, while the organic matter in mollusk shells affected the removal efficiency to a lesser extent. - Highlights: > Mollusk shells display high removal efficiency to heavy metals in contaminated water. > Surface precipitation leading to crystal growth takes place during the sorption. > Crystal structure similarity between precipitates and substrates affects the sorption. > pH, sorbent dosage and grain size of adsorbent affects the removal efficiency. > Organic matter in mollusk shells affects the removal efficiency to a less extent. - Mollusk shells display high sorption ability to heavy metals and crystal structure similarity between precipitates and substrates affects the sorption.

System for combustion of sunflower shells in industrial steam generators

International Nuclear Information System (INIS)

Todoriev, Kh.

2000-01-01

The paper presents an economically efficient solution for reconstruction of steam generators with steam production over 5 t/h using foregoing cyclone chamber for sunflower shells combustion. For average fuel caloricity 9 445 ccal/kg and sunflower shells caloricity between 3 485 and 3 750 ccal/kg, the petroleum saving is 68.78% for an average boiler efficiency 4.6 t/h steam

Laser Doppler Vibrometer Based Examination of the Efficiency of Introducing Artificial Delaminations into Composite Shells

Directory of Open Access Journals (Sweden)

Kustroń Kamila

2015-09-01

Full Text Available During its operation, the laminate shell of the watercraft hull can be exposed to local stability losses caused by the appearance and development of delaminations. The sources of these delaminations are discontinuities, created both in the production process and as a result of bumps of foreign bodies into the hull in operation. In the environment of fatigue loads acting on the hull, the delaminations propagate and lead to the loss of load capacity of the hull structure. There is a need to improve diagnostic systems used in Structural Health Monitoring (SHM of laminate hull elements to detect and monitor the development of the delaminations. Effective diagnostic systems used for delamination assessment base on expert systems. Along with other tools, the expert diagnostic advisory systems make use of the non-destructive examination method which consists in generating elastic waves in the hull shell structure and observing their changes by comparing the recorded signal with damage patterns collected in the expert system database. This system requires introducing certain patterns to its knowledge base, based on the results of experimental examinations performed on specimens with implemented artificial delaminations. The article presents the results of the examination oriented on assessing the delaminations artificially generated in the structure of glass- and carbon-epoxy laminates by introducing local non-adhesive layers with the aid of thin polyethylene film, teflon insert, or thin layer of polyvinyl alcohol. The efficiency of each method was assessed using laser vibrometry. The effect of the depth of delamination position in the laminate on the efficiency of the applied method is documented as well.

Ignition and Flame Stabilization of a Strut-Jet RBCC Combustor with Small Rocket Exhaust

Directory of Open Access Journals (Sweden)

Jichao Hu

2014-01-01

Full Text Available A Rocket Based Combined Cycle combustor model is tested at a ground direct connected rig to investigate the flame holding characteristics with a small rocket exhaust using liquid kerosene. The total temperature and the Mach number of the vitiated air flow, at exit of the nozzle are 1505 K and 2.6, respectively. The rocket base is embedded in a fuel injecting strut and mounted in the center of the combustor. The wall of the combustor is flush, without any reward step or cavity, so the strut-jet is used to make sure of the flame stabilization of the second combustion. Mass flow rate of the kerosene and oxygen injected into the rocket is set to be a small value, below 10% of the total fuel when the equivalence ratio of the second combustion is 1. The experiment has generated two different kinds of rocket exhaust: fuel rich and pure oxygen. Experiment result has shown that, with a relative small total mass flow rate of the rocket, the fuel rich rocket plume is not suitable for ignition and flame stabilization, while an oxygen plume condition is suitable. Then the paper conducts a series of experiments to investigate the combustion characteristics under this oxygen pilot method and found that the flame stabilization characteristics are different at different combustion modes.

Determination of Strain Rate Sensitivity of Micro-struts Manufactured Using the Selective Laser Melting Method

Science.gov (United States)

Gümrük, Recep; Mines, R. A. W.; Karadeniz, Sami

2018-03-01

Micro-lattice structures manufactured using the selective laser melting (SLM) process provides the opportunity to realize optimal cellular materials for impact energy absorption. In this paper, strain rate-dependent material properties are measured for stainless steel 316L SLM micro-lattice struts in the strain rate range of 10-3 to 6000 s-1. At high strain rates, a novel version of the split Hopkinson Bar has been developed. Strain rate-dependent materials data have been used in Cowper-Symonds material model, and the scope and limit of this model in the context of SLM struts have been discussed. Strain rate material data and the Cowper-Symonds model have been applied to the finite element analysis of a micro-lattice block subjected to drop weight impact loading. The model output has been compared to experimental results, and it has been shown that the increase in crush stress due to impact loading is mainly the result of strain rate material behavior. Hence, a systematic methodology has been developed to investigate the impact energy absorption of a micro-lattice structure manufactured using additive layer manufacture (SLM). This methodology can be extended to other micro-lattice materials and configurations, and to other impact conditions.

Adsorption of volatile organic compounds by pecan shell- and almond shell-based granular activated carbons.

Science.gov (United States)

Bansode, R R; Losso, J N; Marshall, W E; Rao, R M; Portier, R J

2003-11-01

The objective of this research was to determine the effectiveness of using pecan and almond shell-based granular activated carbons (GACs) in the adsorption of volatile organic compounds (VOCs) of health concern and known toxic compounds (such as bromo-dichloromethane, benzene, carbon tetrachloride, 1,1,1-trichloromethane, chloroform, and 1,1-dichloromethane) compared to the adsorption efficiency of commercially used carbons (such as Filtrasorb 200, Calgon GRC-20, and Waterlinks 206C AW) in simulated test medium. The pecan shell-based GACs were activated using steam, carbon dioxide or phosphoric acid. An almond shell-based GAC was activated with phosphoric acid. Our results indicated that steam- or carbon dioxide-activated pecan shell carbons were superior in total VOC adsorption to phosphoric acid-activated pecan shell or almond shell carbons, inferring that the method of activation selected for the preparation of activated carbons affected the adsorption of VOCs and hence are factors to be considered in any adsorption process. The steam-activated, pecan shell carbon adsorbed more total VOCs than the other experimental carbons and had an adsorption profile similar to the two coconut shell-based commercial carbons, but had greater adsorption than the coal-based commercial carbon. All the carbons studied adsorbed benzene more effectively than the other organics. Pecan shell, steam-activated and acid-activated GACs showed higher adsorption of 1,1,1-trichloroethane than the other carbons studied. Multivariate analysis was conducted to group experimental carbons and commercial carbons based on their physical, chemical, and adsorptive properties. The results of the analysis conclude that steam-activated and acid-activated pecan shell carbons clustered together with coal-based and coconut shell-based commercial carbons, thus inferring that these experimental carbons could potentially be used as alternative sources for VOC adsorption in an aqueous environment.

Ternary polyplex micelles with PEG shells and intermediate barrier to complexed DNA cores for efficient systemic gene delivery.

Science.gov (United States)

Li, Junjie; Chen, Qixian; Zha, Zengshi; Li, Hui; Toh, Kazuko; Dirisala, Anjaneyulu; Matsumoto, Yu; Osada, Kensuke; Kataoka, Kazunori; Ge, Zhishen

2015-07-10

Simultaneous achievement of prolonged retention in blood circulation and efficient gene transfection activity in target tissues has always been a major challenge hindering in vivo applications of nonviral gene vectors via systemic administration. Herein, we constructed novel rod-shaped ternary polyplex micelles (TPMs) via complexation between the mixed block copolymers of poly(ethylene glycol)-b-poly{N'-[N-(2-aminoethyl)-2-aminoethyl]aspartamide} (PEG-b-PAsp(DET)) and poly(N-isopropylacrylamide)-b-PAsp(DET) (PNIPAM-b-PAsp(DET)) and plasmid DNA (pDNA) at room temperature, exhibiting distinct temperature-responsive formation of a hydrophobic intermediate layer between PEG shells and pDNA cores through facile temperature increase from room temperature to body temperature (~37 °C). As compared with binary polyplex micelles of PEG-b-PAsp(DET) (BPMs), TPMs were confirmed to condense pDNA into a more compact structure, which achieved enhanced tolerability to nuclease digestion and strong counter polyanion exchange. In vitro gene transfection results demonstrated TPMs exhibiting enhanced gene transfection efficiency due to efficient cellular uptake and endosomal escape. Moreover, in vivo performance evaluation after intravenous injection confirmed that TPMs achieved significantly prolonged blood circulation, high tumor accumulation, and promoted gene expression in tumor tissue. Moreover, TPMs loading therapeutic pDNA encoding an anti-angiogenic protein remarkably suppressed tumor growth following intravenous injection into H22 tumor-bearing mice. These results suggest TPMs with PEG shells and facilely engineered intermediate barrier to inner complexed pDNA have great potentials as systemic nonviral gene vectors for cancer gene therapy. Copyright © 2015 Elsevier B.V. All rights reserved.

Pressure Shell Approach to Integrated Environmental Protection

Science.gov (United States)

Kennedy, Kriss J.

2011-01-01

The next generation of exploration mission human systems will require environmental protection such as radiation protection that is effective and efficient. In order to continue human exploration, habitat systems will require special shells to protect astronauts from hostile environments. The Pressure Shell Approach to integrated environmental (radiation) protection is a multi-layer shell that can be used for multifunctional environmental protection. Self-healing, self-repairing nano technologies and sensors are incorporated into the shell. This shell consists of multiple layers that can be tailored for specific environmental protection needs. Mainly, this innovation focuses on protecting crew from exposure to micrometeorites, thermal, solar flares, and galactic cosmic ray (GCR) radiation. The Pressure Shell Approach consists of a micrometeoroid and secondary ejecta protection layer; a thin, composite shell placed in between two layers that is non-structural; an open cavity layer that can be filled with water, regolith, or polyethylene foam; a thicker composite shell that is a structural load bearing that is placed between two layers; and a bladder coating on the interior composite shell. This multi-layer shell creates an effective radiation protection system. Most of its layers can be designed with the materials necessary for specific environments. In situ materials such as water or regolith can be added to the shell design for supplemental radiation protection.

Comparison of Tongue-in-Groove and Columellar Strut on Rotation and Projection in Droopy Nasal Tip: Contribution of a Cap Graft.

Science.gov (United States)

Demir, Uygar Levent

2018-05-01

Underrotation of the nasal tip with narrow nasolabial angle is a common nasal deformity that leads to a long nose appearance, named drooping nose. In these patients, there are various techniques described to correct droopy tip and to achieve a desirable nasal tip rotation such as lateral crural steal, lateral crural overlay, tongue-ingroove, columellar strut graft, tip rotation sutures, cephalic trimming, and others. In this study, the effects of tongue-in-groove (TIG) and columellar strut graft (CS) and the contribution of cap graft on nasal tip rotation and projection were evaluated. Twenty-eight consecutive patients who underwent open approach rhinoplasty by the same senior author (ULD) between January 2015 and December 2016 with the diagnosis of septonasal deformity and droopy nasal tip were included. In 9 of these patients nasal tip was constructed with strut graft, in 6 patients with both strut and cap grafts, in 6 patients with TIG technique and in 7 patients with both TIG and cap graft. Standardized right lateral images were taken preoperatively and 6 months postoperatively to use for further assessments. The nasal tip rotation was evaluated by measuring nasolabial angle (NLA) and the nasal projection (NP) was evaluated by using the Goode method. Finally, the postoperative values of NLA and NP at the 6th month were compared with preoperative recorded values in between groups. Each group showed increase at nasal projection; however, significance was present only in CS graft and TIG groups (P=0.011 and P=0.027 relatively). Each 4 groups showed significant increase in nasal tip rotation. In addition, the comparison of percent changes between preoperative and postoperative NP and NLA revealed no difference (P=0.56 and P=0.431 relatively). In conclusion, the authors argued that TIG and CS graft techniques are both reliable methods to correct droopy nasal tip and using additional cap graft over dome area when required is safe and useful.

Design and optimization of Ag-dielectric core-shell nanostructures for silicon solar cells

Directory of Open Access Journals (Sweden)

Feng-Xiang Chen

2015-09-01

Full Text Available Metal-dielectric core-shell nanostructures have been proposed as a light trapping scheme for enhancing the optical absorption of silicon solar cells. As a potential application of such enhanced effects, the scattering efficiencies of three core-shell structures (Ag@SiO2, Ag@TiO2, and Ag@ZrO2 are discussed using the Mie Scattering theory. For compatibility with experiment results, the core diameter and shell thickness are limited to 100 and 30 nm, respectively, and a weighted scattering efficiency is introduced to evaluate the scattering abilities of different nanoparticles under the solar spectrum AM 1.5. The simulated results indicate that the shell material and thickness are two key parameters affecting the weighted scattering efficiency. The SiO2 is found to be an unsuitable shell medium because of its low refractive index. However, using the high refractive index mediumTiO2 in Ag@TiO2 nanoparticles, only the thicker shell (30 nm is more beneficial for light scattering. The ZrO2 is an intermediate refractive index material, so Ag@ZrO2 nanoparticles are the most effective core-shell nanostructures in these silicon solar cells applications.

Facile synthesis of CdS@TiO2 core–shell nanorods with controllable shell thickness and enhanced photocatalytic activity under visible light irradiation

International Nuclear Information System (INIS)

Dong, Wenhao; Pan, Feng; Xu, Leilei; Zheng, Minrui; Sow, Chorng Haur; Wu, Kai; Xu, Guo Qin

2015-01-01

Graphical abstract: - Highlights: • CdS nanorods were coated with amorphous TiO 2 shells under a mild condition. • The TiO 2 shell thickness can be controlled from 3.5 to 40 nm. • CdS@TiO 2 nanorods exhibit enhanced photocatalytic activities under visible light. • Efficient charge carriers separation leads to the improved photocatalytic activity. - Abstract: Amorphous TiO 2 layers with a controllable thickness from 3.5 to 40 nm were coated on the one-dimensional CdS nanorods surface under mild conditions. Compared to the bare CdS nanorods, the as-prepared CdS@TiO 2 nanorods exhibit enhanced photocatalytic activities for phenol photodecomposition under visible light irradiation. The improved photoactivity is ascribed to the efficient separation of photogenerated electron and hole charge carriers between CdS cores and TiO 2 shells. This study promises a simple approach to fabricating CdS@TiO 2 core–shell structure nanocomposites, and can be applied for other semiconductor cores with TiO 2 shells

Comparative study on thermal performance of natural draft cooling towers with finned shells

International Nuclear Information System (INIS)

Goodarzi, Mohsen

2016-01-01

The cooling efficiency of natural draft cooling towers under crosswind condition should be improved. In the present research work three different externally finned shells were considered for a typical natural draft cooling tower to investigate the cooling improvement. They were numerically simulated under normal and crosswind conditions. Numerical results show that twisting four fin plates over the tower shell along the 45 peripheral angle, could improve the cooling efficiency up to 6.5 %. Because of the periodic shape of the fin plates, the cooling efficiency of the cooling tower with finned shell is less sensitive to the change of wind.

Comparative study on thermal performance of natural draft cooling towers with finned shells

Energy Technology Data Exchange (ETDEWEB)

Goodarzi, Mohsen [Bu-Ali Sina Univ., Hamedan (Iran, Islamic Republic of). Dept. of Mechanical Engineering

2016-10-15

The cooling efficiency of natural draft cooling towers under crosswind condition should be improved. In the present research work three different externally finned shells were considered for a typical natural draft cooling tower to investigate the cooling improvement. They were numerically simulated under normal and crosswind conditions. Numerical results show that twisting four fin plates over the tower shell along the 45 peripheral angle, could improve the cooling efficiency up to 6.5 %. Because of the periodic shape of the fin plates, the cooling efficiency of the cooling tower with finned shell is less sensitive to the change of wind.

Self-Assembly of Fluorescent Hybrid Core-Shell Nanoparticles and Their Application.

Science.gov (United States)

Wang, Chun; Tang, Fu; Wang, Xiaoyu; Li, Lidong

2015-06-24

In this work, a fluorescent hybrid core-shell nanoparticle was prepared by coating a functional polymer shell onto silver nanoparticles via a facile one-pot method. The biomolecule poly-L-lysine (PLL) was chosen as the polymer shell and assembled onto the silver core via the amine-reactive cross-linker, 3,3'-dithiobis(sulfosuccinimidylpropionate). The fluorescent anticancer drug, doxorubicin, was incorporated into the PLL shell through the same linkage. As the cross-linker possesses a thiol-cleavable disulfide bond, disassembly of the PLL shell was observed in the presence of glutathione, leading to controllable doxorubicin release. The silver core there provided an easily modified surface to facilitate the shell coating and ensures the efficient separation of as-prepared nanoparticles from their reaction mixture through centrifugation. Cell assays show that the prepared hybrid fluorescent nanoparticles can internalize into cells possessing excellent biocompatibility prior to the release of doxorubicin, terminating cancer cells efficiently as the doxorubicin is released at the intracellular glutathione level. Such properties are important for designing smart containers for target drug delivery and cellular imaging.

Room-temperature synthesis of core-shell structured magnetic covalent organic frameworks for efficient enrichment of peptides and simultaneous exclusion of proteins.

Science.gov (United States)

Lin, Guo; Gao, Chaohong; Zheng, Qiong; Lei, Zhixian; Geng, Huijuan; Lin, Zian; Yang, Huanghao; Cai, Zongwei

2017-03-28

Core-shell structured magnetic covalent organic frameworks (Fe 3 O 4 @COFs) were synthesized via a facile approach at room temperature. Combining the advantages of high porosity, magnetic responsiveness, chemical stability and selectivity, Fe 3 O 4 @COFs can serve as an ideal absorbent for the highly efficient enrichment of peptides and the simultaneous exclusion of proteins from complex biological samples.

Nonlinear mode interaction in equal-leg angle struts susceptible to cellular buckling.

Science.gov (United States)

Bai, L; Wang, F; Wadee, M A; Yang, J

2017-11-01

A variational model that describes the interactive buckling of a thin-walled equal-leg angle strut under pure axial compression is presented. A formulation combining the Rayleigh-Ritz method and continuous displacement functions is used to derive a system of differential and integral equilibrium equations for the structural component. Solving the equations using numerical continuation reveals progressive cellular buckling (or snaking) arising from the nonlinear interaction between the weak-axis flexural buckling mode and the strong-axis flexural-torsional buckling mode for the first time-the resulting behaviour being highly unstable. Physical experiments conducted on 10 cold-formed steel specimens are presented and the results show good agreement with the variational model.

Sequestering Potential of Peach Nut Shells as an Efficient Sorbent for Sequestering Some Toxic Metal Ions from Aqueous Waste: A Kinetic and Thermodynamic Study

Directory of Open Access Journals (Sweden)

Muhammad Ashraf Shaheen

2016-06-01

Full Text Available The peach nut shells potential as a low cost biosorbent for separation of certain metal ions from aqueous media was investigated. The effects of different parameters such as pH, shaking speed, initial metal ions concentration and their contact time with adsorbent on sorption efficiency of biosorbent was investigated to optimize the parameters for maximum sorption. The FT–IR spectroscopy and TGA were used to characterize the biosorbent. A significant increase in sorption was noted with rise in pH of metal ions solution and maximum sorption was observed at pH 6. The isothermal data was fitted to Langmuir, Dubinin–Radushkevich (D–R, Freundlich isotherms and equilibrium process was best fitted to Langmuir isotherm. The removal efficiency of chemically activated samples was found to be ~35 to 45% greater than raw sample. The results showed that peach nut shell was an effective biosorbent for the remediation of the contaminated water with lead (II, Nickle (II and Chromium (III ions. Being low cost material, PNS has a potential to be exploited in waste water treatment technologies. This study shows that activated PNS exhibited appreciable sorption for Pb, Cr and Ni metals ions (97%, 95% and 94% respectively from aqueous solution even at very low concentration of sorbent. The chemical and thermal activation of peach nut shells enhances the removal efficiency for all the metal ions and from the reported data; it was found that the adsorption ability of Pb ions was greater than nickel and chromium.

Free fibular strut graft in neglected femoral neck fractures in adult

Directory of Open Access Journals (Sweden)

Azam Md Quamar

2009-01-01

Full Text Available Background: Neglected femoral neck fracture in adults still poses a formidable challenge. Existing treatment options varies from osteotomy (with or without graft to osteosynthesis using various implants and grafting techniques (muscle pedicle, vascularized, and nonvascularized fibula. The aim of this study was to assess outcome of nonvascularized fibular strut graft and cancellous screw fixation in neglected femoral neck fractures in the younger age group. Materials and Methods: Medical records of 32 patients of neglected femoral neck fracture, in the age group of 22-45 years (mean 37.8 years, operated between May 1994 to December 2001, were retrospectively reviewed. After the application of inclusion and exclusion criteria, 28 patients having three years minimum follow-up (mean 4.6 years were included. Delay between injury and operation varied from four weeks to 42 weeks (mean 16.4 weeks. Closed reduction was achieved in 17 patients; open reduction through Watson-Jones anterolateral approach was performed in the remaining 15 patients in whom closed reduction failed. The fracture was transfixed with three parallel guide wires. Appropriate sized cannulated lag screw (7 mm was then inserted in two of the wires. Selection of the third guide wire for fibula depended on the space available in both anteroposterior and lateral view. Results: Satisfactory bony union was obtained in 25 patients, of whom in four cases, the union occurred in 10-20° (mean 15° of varus. Nonunion occurred in three patients (9.37%, and aseptic necrosis occurred in another six patients (18.75%. Of the 25 patients where union was achieved, five patients showed excellent results; 14 good and six had poor functional result, as evaluated using modified Anglen criteria. Conclusion: Nonvascularized fibular strut graft along with cancellous screws provides a dependable and technically less-demanding alternative procedure for neglected femoral neck fractures in young adults. Fibula

Intra- and interobserver reliability and intra-catheter reproducibility using frequency domain optical coherence tomography for the evaluation of morphometric stent parameters and qualitative assessment of stent strut coverage

International Nuclear Information System (INIS)

Antonsen, Lisbeth; Thayssen, Per; Junker, Anders; Veien, Karsten Tange; Hansen, Henrik Steen; Hansen, Knud Nørregaard; Hougaard, Mikkel; Jensen, Lisette Okkels

2015-01-01

Purpose: Frequency-domain optical coherence tomography (FD-OCT) is a high-resolution imaging tool (~ 10–15 μm), which enables near-histological in-vivo images of the coronary vessel wall. The use of the technique is increasing, both for research- and clinical purposes. This study sought to investigate the intra- and interobserver reliability, as well as the intra-catheter reproducibility of quantitative FD-OCT-assessment of morphometric stent parameters and qualitative FD-OCT-evaluation of strut coverage in 10 randomly selected 6-month follow-up Nobori® biolimus-eluting stents (N-BESs). Methods: Ten N-BESs (213 cross sectional areas (CSAs) and 1897 struts) imaged with OCT 6 months post-implantation were randomly selected and analyzed by 2 experienced analysts, and the same 10 N-BESs were analyzed by one of the analysts 3 months later. Further, 2 consecutive pullbacks randomly performed in another 10 N-BESs (219 CSAs and 1860 struts) were independently assessed by one of the analysts. Results: The intraobserver variability with regard to relative difference of mean luminal area and mean stent area at the CSA-level was very low: 0.1% ± 1.4% and 0.5% ± 3.2%. Interobserver variability also proved to be low: − 2.1% ± 3.3% and 2.1% ± 4.6%, and moreover, very restricted intra-catheter variation was observed: 0.02% ± 6.8% and − 0.18% ± 5.2%. The intraobserver-, interobserver- and intra-catheter reliability for the qualitative evaluation of strut coverage was found to be: kappa (κ) = 0.91 (95% confidence interval (CI): 0.88–0.93, p < 0.01), κ = 0.88 (95% CI: 0.85–0.91, p < 0.01), and κ = 0.73 (95% CI: 0.68–0.78, p < 0.01), respectively. Conclusions: FD-OCT is a reproducible and reliable imaging tool for quantitative evaluation of stented coronary segments, and for qualitative assessment of strut coverage. - Highlights: • Frequency-domain optical coherence tomography (FD-OCT) is increasingly adopted in the catherization laboratories. • This

Intra- and interobserver reliability and intra-catheter reproducibility using frequency domain optical coherence tomography for the evaluation of morphometric stent parameters and qualitative assessment of stent strut coverage

Energy Technology Data Exchange (ETDEWEB)

Antonsen, Lisbeth, E-mail: Lisbeth.antonsen@rsyd.dk; Thayssen, Per; Junker, Anders; Veien, Karsten Tange; Hansen, Henrik Steen; Hansen, Knud Nørregaard; Hougaard, Mikkel; Jensen, Lisette Okkels

2015-12-15

Purpose: Frequency-domain optical coherence tomography (FD-OCT) is a high-resolution imaging tool (~ 10–15 μm), which enables near-histological in-vivo images of the coronary vessel wall. The use of the technique is increasing, both for research- and clinical purposes. This study sought to investigate the intra- and interobserver reliability, as well as the intra-catheter reproducibility of quantitative FD-OCT-assessment of morphometric stent parameters and qualitative FD-OCT-evaluation of strut coverage in 10 randomly selected 6-month follow-up Nobori® biolimus-eluting stents (N-BESs). Methods: Ten N-BESs (213 cross sectional areas (CSAs) and 1897 struts) imaged with OCT 6 months post-implantation were randomly selected and analyzed by 2 experienced analysts, and the same 10 N-BESs were analyzed by one of the analysts 3 months later. Further, 2 consecutive pullbacks randomly performed in another 10 N-BESs (219 CSAs and 1860 struts) were independently assessed by one of the analysts. Results: The intraobserver variability with regard to relative difference of mean luminal area and mean stent area at the CSA-level was very low: 0.1% ± 1.4% and 0.5% ± 3.2%. Interobserver variability also proved to be low: − 2.1% ± 3.3% and 2.1% ± 4.6%, and moreover, very restricted intra-catheter variation was observed: 0.02% ± 6.8% and − 0.18% ± 5.2%. The intraobserver-, interobserver- and intra-catheter reliability for the qualitative evaluation of strut coverage was found to be: kappa (κ) = 0.91 (95% confidence interval (CI): 0.88–0.93, p < 0.01), κ = 0.88 (95% CI: 0.85–0.91, p < 0.01), and κ = 0.73 (95% CI: 0.68–0.78, p < 0.01), respectively. Conclusions: FD-OCT is a reproducible and reliable imaging tool for quantitative evaluation of stented coronary segments, and for qualitative assessment of strut coverage. - Highlights: • Frequency-domain optical coherence tomography (FD-OCT) is increasingly adopted in the catherization laboratories. • This

Effects of the microbubble shell physicochemical properties on ultrasound-mediated drug delivery to the brain.

Science.gov (United States)

Wu, Shih-Ying; Chen, Cherry C; Tung, Yao-Sheng; Olumolade, Oluyemi O; Konofagou, Elisa E

2015-08-28

Lipid-shelled microbubbles have been used in ultrasound-mediated drug delivery. The physicochemical properties of the microbubble shell could affect the delivery efficiency since they determine the microbubble mechanical properties, circulation persistence, and dissolution behavior during cavitation. Therefore, the aim of this study was to investigate the shell effects on drug delivery efficiency in the brain via blood-brain barrier (BBB) opening in vivo using monodisperse microbubbles with different phospholipid shell components. The physicochemical properties of the monolayer were varied by using phospholipids with different hydrophobic chain lengths (C16, C18, and C24). The dependence on the molecular size and acoustic energy (both pressure and pulse length) were investigated. Our results showed that a relatively small increase in the microbubble shell rigidity resulted in a significant increase in the delivery of 40-kDa dextran, especially at higher pressures. Smaller (3kDa) dextran did not show significant difference in the delivery amount, suggesting that the observed shell effect was molecular size-dependent. In studying the impact of acoustic energy on the shell effects, it was found that they occurred most significantly at pressures causing microbubble destruction (450kPa and 600kPa); by increasing the pulse length to deliver the 40-kDa dextran, the difference between C16 and C18 disappeared while C24 still achieved the highest delivery efficiency. These indicated that the acoustic energy could be used to modulate the shell effects. The acoustic cavitation emission revealed the physical mechanisms associated with different shells. Overall, lipid-shelled microbubbles with long hydrophobic chain length could achieve high delivery efficiency for larger molecules especially with high acoustic energy. Our study, for the first time, offered evidence directly linking the microbubble monolayer shell with their efficacy for drug delivery in vivo. Copyright © 2015

Core@shell@shell structured carbon-based magnetic ternary nanohybrids: Synthesis and their enhanced microwave absorption properties

Science.gov (United States)

Yang, Erqi; Qi, Xiaosi; Xie, Ren; Bai, Zhongchen; Jiang, Yang; Qin, Shuijie; Zhong, Wei; Du, Youwei

2018-05-01

High encapsulation efficiency of core@shell@shell structured carbon-based magnetic ternary nanohybrids have been synthesized in high yield by chemical vapor deposition of acetylene directly over octahedral-shaped Fe2O3 nanoparticles. By controlling the pyrolysis temperature, Fe3O4@Fe3C@carbon nanotubes (CNTs) and Fe@Fe3C@CNTs ternary nanohybrids could be selectively produced. The optimal RL values for the as-prepared ternary nanohybrids could reach up to ca. -46.7, -52.7 and -29.5 dB, respectively. The excellent microwave absorption properties of the obtaiend ternary nanohybrids were proved to ascribe to the quarter-wavelength matching model. Moreover, the as-prepared Fe@Fe3C@CNTs ternary nanohybrids displayed remarkably enhanced EM wave absorption capabilities compared to Fe3O4@Fe3C@CNTs due to their excellent dielectric loss abilities, good complementarities between the dielectric loss and the magnetic loss, and high attenuation constant. Generally, this strategy can be extended to explore other categories of core@shell or core@shell@shell structured carbon-based nanohybrids, which is very beneficial to accelerate the advancements of high performance MAMs.

Thermogravimetric characterization and gasification of pecan nut shells.

Science.gov (United States)

Aldana, Hugo; Lozano, Francisco J; Acevedo, Joaquín; Mendoza, Alberto

2015-12-01

This study focuses on the evaluation of pecan nut shells as an alternative source of energy through pyrolysis and gasification. The physicochemical characteristics of the selected biomass that can influence the process efficiency, consumption rates, and the product yield, as well as create operational problems, were determined. In addition, the thermal decomposition kinetics necessary for prediction of consumption rates and yields were determined. Finally, the performance of a downdraft gasifier fed with pecan nut shells was analyzed in terms of process efficiency and exit gas characteristics. It was found that the pyrolytic decomposition of the nut shells can be modeled adequately using a single equation considering two independent parallel reactions. The performance of the gasification process can be influenced by the particle size and air flow rate, requiring a proper combination of these parameters for reliable operation and production of a valuable syngas. Copyright © 2015 Elsevier Ltd. All rights reserved.

Measurement of critical mass for an assembly of bare uranium shells

International Nuclear Information System (INIS)

Myers, W.L.; Goulding, C.A.; Hollas, C.L.

1997-01-01

As part of the research into nuclear measurement techniques, a series of measurements was performed that have applications to criticality safety and nuclear material handling. The critical mass of a set of bare, enriched-uranium metal hemispherical shells, known as the Rocky Flats shells, was measured for an assembly having an inside radius of 2.347 cm. The critical mass value was extrapolated from a series of subcritical measurements using three different kinds of sources (AmBe, AmF, and 252 Cf) placed at the center of the shells. Two kinds of neutron detection configurations (a 1% efficiency and a 25% efficiency configuration) were used to make the measurements

Preparation of n-tetradecane-containing microcapsules with different shell materials by phase separation method

Energy Technology Data Exchange (ETDEWEB)

Yang, Rui [Department of Chemical Engineering, Tsinghua University, Beijing (China); Zhang, Yan; Zhang, Qingwu [Department of Chemical Engineering, China University of Mining and Technology, Beijing (China); Wang, Xin; Zhang, Yinping [Department of Building Science, Tsinghua University, Beijing (China)

2009-10-15

Microcapsules for thermal energy storage and heat-transfer enhancement have attracted great attention. Microencapsulation of n-tetradecane with different shell materials was carried out by phase separation method in this paper. Acrylonitrile-styrene copolymer (AS), acrylonitrile-styrene-butadiene copolymer (ABS) and polycarbonate (PC) were used as the shell materials. The structures, morphologies and the thermal capacities of the microcapsules were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The ternary phase diagrams showed the potential encapsulation capabilities of the three shell materials. The effects of the shell/core ratio and the molecular weight of the shell material on the encapsulation efficiency and the thermal capacity of the microcapsules were also discussed. Microcapsules with melting enthalpy > 100 J/g, encapsulation efficiency 66-75%, particle size<1 {mu}m were obtained for all three shell materials. (author)

Fracture and embolization of a Celect inferior vena cava filter strut to the liver: A Case Report

Energy Technology Data Exchange (ETDEWEB)

Kim, So Hee; Song, Yun Gyu [Dept. of Radiology, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon (Korea, Republic of)

2017-07-15

Inferior vena cava (IVC) filters are typically used for prophylaxis against pulmonary embolism. A new version of the Günther Tulip filter, the Celect IVC filter was introduced in April 2007. To the best of our knowledge, there are no reports commenting on Celect IVC filter fracture and fragment embolization to liver. We report a case in which the strut of the Celect IVC filter embolized to the liver.

Fracture and embolization of a Celect inferior vena cava filter strut to the liver: A Case Report

International Nuclear Information System (INIS)

Kim, So Hee; Song, Yun Gyu

2017-01-01

Inferior vena cava (IVC) filters are typically used for prophylaxis against pulmonary embolism. A new version of the Günther Tulip filter, the Celect IVC filter was introduced in April 2007. To the best of our knowledge, there are no reports commenting on Celect IVC filter fracture and fragment embolization to liver. We report a case in which the strut of the Celect IVC filter embolized to the liver

Synthesis and characterization of ZnSe:Fe/ZnSe core/shell nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Yang, Lin; Zhu, Jianguo, E-mail: yanglin_1028@163.com; Xiao, Dingquan

2014-04-15

High-quality ZnSe:Fe/ZnSe core/shell nanocrystals were prepared via a hydrothermal microemulsion technique. Effective surface passivation of monodisperse ZnSe:Fe nanocrystals is achieved by overcoating them with a ZnSe shell. The samples were characterized by means of XRD, EDX, TEM, PSD, XPS, photoluminescence, and Raman spectrum. The results show that the as-synthesized nanocrystals are cubic zinc blende ZnSe structure with high purity and the average particle size of ZnSe:Fe/ZnSe core/shell nanocrystal is larger than that of ZnSe:Fe core. The growth of ZnSe shell causes a small red shift in PL spectra, and then the PL quantum yield (QY) increases from 16% before shell growth to the maximum of 37% after increasing shell thickness up to 1.2 monolayers (ML). Moreover, both transverse optic (TO) and longitudinal optic (LO) phonon modes of ZnSe are shifted toward lower frequency as compared with the reported ones. -- Highlights: • ZnSe:Fe/ZnSe core/shell QDs were prepared by a hydrothermal microemulsion method. • ZnSe shell efficiently passivates surface defects by serving as a physical barrier. • The particle size and PL properties can be turned with the growth of ZnSe shell. • The luminescence efficiency and stability of QDs could be improved in this manner.

Automatic determination of 3D orientations of fossilized oyster shells from a densely packed Miocene shell bed

Science.gov (United States)

Puttonen, Ana; Harzhauser, Mathias; Puttonen, Eetu; Mandic, Oleg; Székely, Balázs; Molnár, Gábor; Pfeifer, Norbert

2018-02-01

Shell beds represent a useful source of information on various physical processes that cause the depositional condition. We present an automated method to calculate the 3D orientations of a large number of elongate and platy objects (fossilized oyster shells) on a sedimentary bedding plane, developed to support the interpretation of possible depositional patterns, imbrications, or impact of local faults. The study focusses on more than 1900 fossil oyster shells exposed in a densely packed Miocene shell bed. 3D data were acquired by terrestrial laser scanning on an area of 459 m2 with a resolution of 1 mm. Bivalve shells were manually defined as 3D-point clouds of a digital surface model and stored in an ArcGIS database. An individual shell coordinate system (ISCS) was virtually embedded into each shell and its orientation was determined relative to the coordinate system of the entire, tectonically tilted shell bed. Orientation is described by the rotation angles roll, pitch, and yaw in a Cartesian coordinate system. This method allows an efficient measurement and analysis of the orientation of thousands of specimens and is a major advantage compared to the traditional 2D approach, which measures only the azimuth (yaw) angles. The resulting data can variously be utilized for taphonomic analyses and the reconstruction of prevailing hydrodynamic regimes and depositional environments. For the first time, the influence of possible post-sedimentary vertical displacements can be quantified with high accuracy. Here, the effect of nearby fault lines—present in the reef—was tested on strongly tilted oyster shells, but it was found out that the fault lines did not have a statistically significant effect on the large tilt angles. Aside from the high reproducibility, a further advantage of the method is its non-destructive nature, which is especially suitable for geoparks and protected sites such as the studied shell bed.

NIF Double Shell outer/inner shell collision experiments

Science.gov (United States)

Merritt, E. C.; Loomis, E. N.; Wilson, D. C.; Cardenas, T.; Montgomery, D. S.; Daughton, W. S.; Dodd, E. S.; Desjardins, T.; Renner, D. B.; Palaniyappan, S.; Batha, S. H.; Khan, S. F.; Smalyuk, V.; Ping, Y.; Amendt, P.; Schoff, M.; Hoppe, M.

2017-10-01

Double shell capsules are a potential low convergence path to substantial alpha-heating and ignition on NIF, since they are predicted to ignite and burn at relatively low temperatures via volume ignition. Current LANL NIF double shell designs consist of a low-Z ablator, low-density foam cushion, and high-Z inner shell with liquid DT fill. Central to the Double Shell concept is kinetic energy transfer from the outer to inner shell via collision. The collision determines maximum energy available for compression and implosion shape of the fuel. We present results of a NIF shape-transfer study: two experiments comparing shape and trajectory of the outer and inner shells at post-collision times. An outer-shell-only target shot measured the no-impact shell conditions, while an `imaging' double shell shot measured shell conditions with impact. The `imaging' target uses a low-Z inner shell and is designed to perform in similar collision physics space to a high-Z double shell but can be radiographed at 16keV, near the viable 2DConA BL energy limit. Work conducted under the auspices of the U.S. DOE by LANL under contract DE-AC52-06NA25396.

Safety studies conducted on pecan shell fiber, a food ingredient produced from ground pecan shells

Directory of Open Access Journals (Sweden)

Laurie Dolan

Full Text Available Use of pecan shell fiber in human food is presently limited, but could increase pending demonstration of safety. In a 91-day rat study, pecan shell fiber was administered at dietary concentrations of 0 (control, 50 000, 100 000 or 150 000 ppm. There was no effect of the ingredient on body weight of males or females or food consumption of females. Statistically significant increases in food consumption were observed throughout the study in 100 000 and 150 000 ppm males, resulting in intermittent decreases in food efficiency (150 000 ppm males only that were not biologically relevant. All animals survived and no adverse clinical signs or functional changes were attributable to the test material. There were no toxicologically relevant changes in hematology, clinical chemistry or urinalysis parameters or organ weights in rats ingesting pecan shell fiber. Any macroscopic or microscopic findings were incidental, of normal variation and/or of minimal magnitude for test substance association. Pecan shell fiber was non-mutagenic in a bacterial reverse mutation test and non-clastogenic in a mouse peripheral blood micronucleus test. Based on these results, pecan shell fiber has an oral subchronic (13-week no observable adverse effect level (NOAEL of 150 000 ppm in rats and is not genotoxic at the doses analyzed. Keywords: Pecan shell, Fiber, Rat, Diet, Toxicity, Mutagenicity

Shell Thickness Dependence of Interparticle Energy Transfer in Core-Shell ZnSe/ZnSe Quantum Dots Doping with Europium

Science.gov (United States)

Liu, Ni; Li, Shuxin; Wang, Caifeng; Li, Jie

2018-04-01

Low-toxic core-shell ZnSe:Eu/ZnS quantum dots (QDs) were prepared through two steps in water solution: nucleation doping and epitaxial shell grown. The structural and morphological characteristics of ZnSe/ZnS:Eu QDs with different shell thickness were explored by transmission electron microscopy (TEM) and X-ray diffraction (XRD) results. The characteristic photoluminescence (PL) intensity of Eu ions was enhanced whereas that of band-edge luminescence and defect-related luminescence of ZnSe QDs was decreased with increasing shell thickness. The transformation of PL intensity revealed an efficient energy transfer process between ZnSe and Eu. The PL intensity ratio of Eu ions ( I 613) to ZnSe QDs ( I B ) under different shell thickness was systemically analyzed by PL spectra and time-resolved PL spectra. The obtained results were in agreement with the theory analysis results by the kinetic theory of energy transfer, revealing that energy was transmitted in the form of dipole-electric dipole interaction. This particular method of adjusting luminous via changing the shell thickness can provide valuable insights towards the fundamental understanding and application of QDs in the field of optoelectronics.

Novel extrapolation method in the Monte Carlo shell model

International Nuclear Information System (INIS)

Shimizu, Noritaka; Abe, Takashi; Utsuno, Yutaka; Mizusaki, Takahiro; Otsuka, Takaharu; Honma, Michio

2010-01-01

We propose an extrapolation method utilizing energy variance in the Monte Carlo shell model to estimate the energy eigenvalue and observables accurately. We derive a formula for the energy variance with deformed Slater determinants, which enables us to calculate the energy variance efficiently. The feasibility of the method is demonstrated for the full pf-shell calculation of 56 Ni, and the applicability of the method to a system beyond the current limit of exact diagonalization is shown for the pf+g 9/2 -shell calculation of 64 Ge.

Size-exclusion chromatography using core-shell particles.

Science.gov (United States)

Pirok, Bob W J; Breuer, Pascal; Hoppe, Serafine J M; Chitty, Mike; Welch, Emmet; Farkas, Tivadar; van der Wal, Sjoerd; Peters, Ron; Schoenmakers, Peter J

2017-02-24

Size-exclusion chromatography (SEC) is an indispensable technique for the separation of high-molecular-weight analytes and for determining molar-mass distributions. The potential application of SEC as second-dimension separation in comprehensive two-dimensional liquid chromatography demands very short analysis times. Liquid chromatography benefits from the advent of highly efficient core-shell packing materials, but because of the reduced total pore volume these materials have so far not been explored in SEC. The feasibility of using core-shell particles in SEC has been investigated and contemporary core-shell materials were compared with conventional packing materials for SEC. Columns packed with very small core-shell particles showed excellent resolution in specific molar-mass ranges, depending on the pore size. The analysis times were about an order of magnitude shorter than what could be achieved using conventional SEC columns. Copyright © 2016 Elsevier B.V. All rights reserved.

Safety studies conducted on pecan shell fiber, a food ingredient produced from ground pecan shells.

Science.gov (United States)

Dolan, Laurie; Matulka, Ray; Worn, Jeffrey; Nizio, John

2016-01-01

Use of pecan shell fiber in human food is presently limited, but could increase pending demonstration of safety. In a 91-day rat study, pecan shell fiber was administered at dietary concentrations of 0 (control), 50 000, 100 000 or 150 000 ppm. There was no effect of the ingredient on body weight of males or females or food consumption of females. Statistically significant increases in food consumption were observed throughout the study in 100 000 and 150 000 ppm males, resulting in intermittent decreases in food efficiency (150 000 ppm males only) that were not biologically relevant. All animals survived and no adverse clinical signs or functional changes were attributable to the test material. There were no toxicologically relevant changes in hematology, clinical chemistry or urinalysis parameters or organ weights in rats ingesting pecan shell fiber. Any macroscopic or microscopic findings were incidental, of normal variation and/or of minimal magnitude for test substance association. Pecan shell fiber was non-mutagenic in a bacterial reverse mutation test and non-clastogenic in a mouse peripheral blood micronucleus test. Based on these results, pecan shell fiber has an oral subchronic (13-week) no observable adverse effect level (NOAEL) of 150 000 ppm in rats and is not genotoxic at the doses analyzed.

Biosorption of rare earth elements, thorium and uranium using Buccinum tenuissimum shell biomass

International Nuclear Information System (INIS)

Wang, Yudan; Koto, Yusuke; Sakamoto, Nobuo; Kano, Naoki; Imaizumi, Hiroshi

2010-01-01

In order to evaluate the efficiency of shell biomass as sorbent for rare earth elements (REEs), thorium (Th) and uranium (U), sorption experiment from multi-element solutions containing known amount of REEs, Th and U using Buccinum tenuissimum shell was explored. Furthermore, to confirm the characteristics of the shell biomass, the surface morphology, the crystal structure, and the specific surface area of the shell (both original sample and the heat-treatment (480degC, 6h) sample) was determined. Consequently, the following matters have been mainly clarified. (1) By heat-treatment (480degC, 6h), the crystal structure of the shell biomass was transformed from aragonite (CaCO 3 ) into calcite (CaCO 3 ) phase, and the specific surface area of the biomass have decreased remarkably (i.e., by a factor of less than one eighth). (2) The shell biomass (both original sample and the heat-treated sample) showed excellent sorption capacity for REEs, although the sorption capacity decreases slightly after heat-treatment. (3) Adsorption isotherms using the shell biomass can be described by Langmuir and Freundlich isotherms satisfactorily for REEs, but not for Th and U in this work. (4) Shell biomass (usually treated as waste material) could be an efficient sorbent for REEs in future. (author)

Semiconducting, Magnetic or Superconducting Nanoparticles encapsulated in Carbon Shells by RAPET method.

Directory of Open Access Journals (Sweden)

Aharon Gedanken

2008-06-01

Full Text Available An efficient, solvent-free, environmentally friendly, RAPET (Reactions under Autogenic Pressure at Elevated Temperaturesynthetic approach is discussed for the fabrication of core-shell nanostructures. The semiconducting, magnetic orsuperconducting nanoparticles are encapsulated in a carbon shell. RAPET is a one-step, thermal decomposition reaction ofchemical compound (s followed by the formation of core-shell nanoparticles in a closed stainless steel reactor. Therepresentative examples are discussed, where a variety of nanomaterials are trapped in situ in a carbon shell that offersfascinating properties.

Investigation on Selective Laser Melting AlSi10Mg Cellular Lattice Strut: Molten Pool Morphology, Surface Roughness and Dimensional Accuracy

Directory of Open Access Journals (Sweden)

Xuesong Han

2018-03-01

Full Text Available AlSi10Mg inclined struts with angle of 45° were fabricated by selective laser melting (SLM using different scanning speed and hatch spacing to gain insight into the evolution of the molten pool morphology, surface roughness, and dimensional accuracy. The results show that the average width and depth of the molten pool, the lower surface roughness and dimensional deviation decrease with the increase of scanning speed and hatch spacing. The upper surface roughness is found to be almost constant under different processing parameters. The width and depth of the molten pool on powder-supported zone are larger than that of the molten pool on the solid-supported zone, while the width changes more significantly than that of depth. However, if the scanning speed is high enough, the width and depth of the molten pool and the lower surface roughness almost keep constant as the density is still high. Therefore, high dimensional accuracy and density as well as good surface quality can be achieved simultaneously by using high scanning speed during SLMed cellular lattice strut.

Investigation on Selective Laser Melting AlSi10Mg Cellular Lattice Strut: Molten Pool Morphology, Surface Roughness and Dimensional Accuracy.

Science.gov (United States)

Han, Xuesong; Zhu, Haihong; Nie, Xiaojia; Wang, Guoqing; Zeng, Xiaoyan

2018-03-07

AlSi10Mg inclined struts with angle of 45° were fabricated by selective laser melting (SLM) using different scanning speed and hatch spacing to gain insight into the evolution of the molten pool morphology, surface roughness, and dimensional accuracy. The results show that the average width and depth of the molten pool, the lower surface roughness and dimensional deviation decrease with the increase of scanning speed and hatch spacing. The upper surface roughness is found to be almost constant under different processing parameters. The width and depth of the molten pool on powder-supported zone are larger than that of the molten pool on the solid-supported zone, while the width changes more significantly than that of depth. However, if the scanning speed is high enough, the width and depth of the molten pool and the lower surface roughness almost keep constant as the density is still high. Therefore, high dimensional accuracy and density as well as good surface quality can be achieved simultaneously by using high scanning speed during SLMed cellular lattice strut.

UHPFRC in large span shell structures

NARCIS (Netherlands)

Ter Maten, R.N.; Grunewald, S.; Walraven, J.C.

2013-01-01

Ultra-High Performance Fibre-Reinforced Concrete (UHPFRC) is an innovative concrete type with a high compressive strength and a far more durable character compared to conventional concrete. UHPFRC can be applied in structures with aesthetic appearance and high material efficiency. Shell structures

Study on modal characteristics of perforated shell using effective Young's modulus

International Nuclear Information System (INIS)

Jhung, Myung Jo; Yu, Seon Oh

2011-01-01

Research highlights: → The effective Young's modulus of perforated shell is proposed for modal analysis. → The penetration pattern is almost negligible for effective elastic constants. → The frequency of perforated shell decreases significantly due to the hole effect. - Abstract: For the perforated cylindrical shell submerged in fluid, it is almost impossible to develop a finite element model due to the necessity of the fine meshing of the shell and the fluid at the same time. This necessitates the use of solid shell with effective material properties. Unfortunately the effective elastic constants are not found in any references even though the ASME code is suggesting those for perforated plate. Therefore in this study the effective material properties of perforated shell are suggested by performing several finite element analyses with respect to the ligament efficiencies.

Preparation and characterization of antibacterial Au/C core-shell composite

Energy Technology Data Exchange (ETDEWEB)

Gao Yanhong [Department of Chemistry and Institute of Nanochemistry, Jinan University, 601 Huangpudadaoxi Road, Guangzhou 510632, Guangdong (China); Centers for Disease Control and Prevention of Guangdong Province, Guangzhou 510300, Guangdong (China); Zhang Nianchun [Department of Chemistry and Institute of Nanochemistry, Jinan University, 601 Huangpudadaoxi Road, Guangzhou 510632, Guangdong (China); Zhong Yuwen [Centers for Disease Control and Prevention of Guangdong Province, Guangzhou 510300, Guangdong (China); Cai Huaihong [Department of Chemistry and Institute of Nanochemistry, Jinan University, 601 Huangpudadaoxi Road, Guangzhou 510632, Guangdong (China); Liu Yingliang, E-mail: tliuyl@jnu.edu.cn [Department of Chemistry and Institute of Nanochemistry, Jinan University, 601 Huangpudadaoxi Road, Guangzhou 510632, Guangdong (China)

2010-09-01

An environment-friendly oxidation-reduction method was used to prepare Au/C core-shell composite using carbon as core and gold as shell. The chemical structures and morphologies of Au/C core-shell composite and carbon sphere were characterized by X-ray diffraction, transmission electron microscope, energy dispersion X-ray spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS). The antibacterial properties of the Au/C core-shell composite against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Candida albicans (C. albicans) were examined by the disk diffusion assay and minimal inhibition concentration (MIC) methods. In addition, antibacterial ability of Au/C core-shell composite was observed by atomic force microscope. Results demonstrated that gold homogeneously supported on the surface of carbon spheres without aggregation and showed efficient antibacterial abilities.

Modeling of absorption and scattering properties of core -shell nanoparticles for application as nanoantenna in optical domain

Science.gov (United States)

Devi, Jutika; Saikia, Rashmi; Datta, Pranayee

2016-10-01

The present paper describes the study of core-shell nanoparticles for application as nanoantenna in the optical domain. To obtain the absorption and extinction efficiencies as well as the angular distribution of the far field radiation pattern and the resonance wavelengths for these metal-dielectric, dielectric-metal and metal-metal core-shell nanoparticles in optical domain, we have used Finite Element Method based COMSOL Multiphysics Software and Mie Theory. From the comparative study of the extinction efficiencies of core-shell nanoparticles of different materials, it is found that for silica - gold core - shell nanoparticles, the resonant wavelength is greater than that of the gold - silver, silver-gold and gold-silica core - shell nanoparticles and also the radiation pattern of the silica-gold core-shell nanoparticle is the most suitable one from the point of view of directivity. The dielectric functions of the core and shell material as well as of the embedded matrix are extremely important and plays a very major role to tune the directivity and resonance wavelength. Such highly controllable parameters of the dielectric - metal core - shell nanoparticles make them suitable for efficient coupling of optical radiation into nanoscale structures for a broad range of applications in the field of communications.

Modeling of absorption and scattering properties of core -shell nanoparticles for application as nanoantenna in optical domain

International Nuclear Information System (INIS)

Devi, Jutika; Datta, Pranayee; Saikia, Rashmi

2016-01-01

The present paper describes the study of core-shell nanoparticles for application as nanoantenna in the optical domain. To obtain the absorption and extinction efficiencies as well as the angular distribution of the far field radiation pattern and the resonance wavelengths for these metal-dielectric, dielectric-metal and metal-metal core-shell nanoparticles in optical domain, we have used Finite Element Method based COMSOL Multiphysics Software and Mie Theory. From the comparative study of the extinction efficiencies of core-shell nanoparticles of different materials, it is found that for silica - gold core - shell nanoparticles, the resonant wavelength is greater than that of the gold - silver, silver-gold and gold-silica core - shell nanoparticles and also the radiation pattern of the silica-gold core-shell nanoparticle is the most suitable one from the point of view of directivity. The dielectric functions of the core and shell material as well as of the embedded matrix are extremely important and plays a very major role to tune the directivity and resonance wavelength. Such highly controllable parameters of the dielectric - metal core - shell nanoparticles make them suitable for efficient coupling of optical radiation into nanoscale structures for a broad range of applications in the field of communications. (paper)

Fabrication of Te@Au core-shell hybrids for efficient ethanol oxidation

Science.gov (United States)

Jin, Huile; Wang, Demeng; Zhao, Yuewu; Zhou, Huan; Wang, Shun; Wang, Jichang

2012-10-01

Using Au nanoparticles to catalyze the oxidation of alcohols has garnered increasing attention due to its potential application in direct alcohol fuel cells. In this research Te@Au core-shell hybrids were fabricated for the catalytic oxidation of ethanol, where the preparation procedure involved the initial production of Te crystals with different microstructures and the subsequent utilization of the Te crystal as a template and reducing agent for the production of Te@Au hybrids. The as-prepared core-shell hybrids were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction techniques. Electrochemical measurements illustrate that the hybrids have great electrocatalytic activity and stability toward ethanol oxidation in alkaline media. The enhanced electrocatalytic property may be attributed to the cooperative effects between the metal and semiconductor and the presence of a large number of active sites on the hybrids surface.

Shell Venster

International Nuclear Information System (INIS)

De Wit, P.; Looijesteijn, B.; Regeer, B.; Stip, B.

1995-03-01

In the bi-monthly issues of 'Shell Venster' (window on Shell) attention is paid to the activities of the multinational petroleum company Shell Nederland and the Koninklijke/Shell Groep by means of non-specialist articles

BOWOOSS: bionic optimized wood shells with sustainability

Science.gov (United States)

Pohl, Göran

2011-04-01

In architecture, shell construction is used for the most efficient, large spatial structures. Until now the use of wood rather played a marginal role, implementing those examples of architecture, although this material offers manifold advantages, especially against the background of accelerating shortage of resources and increasing requirements concerning the energy balance. Regarding the implementation of shells, nature offers a wide range of suggestions. The focus of the examinations is on the shells of marine plankton, especially of diatoms, whose richness in species promises the discovery of entirely new construction principles. The project is targeting at transferring advantageous features of these organisms on industrial produced, modular wood shell structures. Currently a transfer of these structures in CAD - models is taking place, helping to perform stress analysis by computational methods. Micro as well as macro structures are the subject of diverse consideration, allowing to draw the necessary conclusions for an architectural design. The insights of these tests are the basis for the development of physical models on different scales, which are used to verify the different approaches. Another important aim which is promoted in the project is to enhance the competitiveness of timber construction. Downsizing of the prefabricated structural elements leads to considerable lower transportation costs as abnormal loads can be avoided as far as possible and means of transportation can be loaded with higher efficiency so that an important contribution to the sustainability in the field of architecture can also be made.

Nonlinear Vibration and Mode Shapes of FG Cylindrical Shells

Directory of Open Access Journals (Sweden)

Saeed Mahmoudkhani

Full Text Available Abstract The nonlinear vibration and normal mode shapes of FG cylindrical shells are investigated using an efficient analytical method. The equations of motion of the shell are based on the Donnell’s non-linear shallow-shell, and the material is assumed to be gradually changed across the thickness according to the simple power law. The solution is provided by first discretizing the equations of motion using the multi-mode Galerkin’s method. The nonlinear normal mode of the system is then extracted using the invariant manifold approach and employed to decouple the discretized equations. The homotopy analysis method is finally used to determine the nonlinear frequency. Numerical results are presented for the backbone curves of FG cylindrical shells, nonlinear mode shapes and also the nonlinear invariant modal surfaces. The volume fraction index and the geometric properties of the shell are found to be effective on the type of nonlinear behavior and also the nonlinear mode shapes of the shell. The circumferential half-wave numbers of the nonlinear mode shapes are found to change with time especially in a thinner cylinder.

Core–shell quantum dots: Properties and applications

Energy Technology Data Exchange (ETDEWEB)

Vasudevan, D., E-mail: vasudevand@rediffmail.com [Electrodics and electrocatalysis division, CSIR-CECRI, Karaikudi 630006 (India); Gaddam, Rohit Ranganathan [Amity Institute of Nanotechnology, Amity University, Noida 201301 (India); Trinchi, Adrian; Cole, Ivan [CSIRO Materials Science and Engineering, Clayton South MDC, 3169 (Australia)

2015-07-05

Fluorescent quantum dots (QDs) are semiconducting nanocrystals (NCs) that find numerous applications in areas, such as bio labelling, sensors, lasers, light emitting diodes and medicine. Core–shell quantum dots were developed to improve the photoluminescence efficiency of single quantum dots. Capping their surface with organic ligands as well as their extraction into aqueous media enables their use in sensing applications. The current review highlights the importance and applications of core shell quantum dots as well as their surface modifications and applications in the field of medicine and as sensors for chemical and biochemical analysis.

Core–shell quantum dots: Properties and applications

International Nuclear Information System (INIS)

Vasudevan, D.; Gaddam, Rohit Ranganathan; Trinchi, Adrian; Cole, Ivan

2015-01-01

Fluorescent quantum dots (QDs) are semiconducting nanocrystals (NCs) that find numerous applications in areas, such as bio labelling, sensors, lasers, light emitting diodes and medicine. Core–shell quantum dots were developed to improve the photoluminescence efficiency of single quantum dots. Capping their surface with organic ligands as well as their extraction into aqueous media enables their use in sensing applications. The current review highlights the importance and applications of core shell quantum dots as well as their surface modifications and applications in the field of medicine and as sensors for chemical and biochemical analysis

Pentachlorophenol removal from aqueous matrices by sorption with almond shell residues

International Nuclear Information System (INIS)

Estevinho, B.N.; Ratola, N.; Alves, A.; Santos, L.

2006-01-01

Sorption with activated carbon has been the technique preferred for pentachlorophenol (PCP) removal from contaminated waters, but regeneration needs and high operation costs are supporting a renewed interest in the search for alternative sorbents. Among them, almond shell, an agricultural by-product, provides interesting economical advantages, once shells account for 50% (in mass) of the whole almond. In this work, the capacity of almond shells to remove PCP from waters without previous activation was studied in batch conditions. While PCP analysis was performed solid-phase microextraction (SPME) followed by gas chromatography with electron capture detection (GC-ECD), mercury porosimetry and Fourier transform infrared spectroscopy (FTIR) provided a preliminary physical and chemical characterization of the sorbent. Almond shells were essentially a macroporous material, with an average surface area of 12.9 ± 2.8 m 2 /g. The efficiency of PCP removal was 93 ± 14%, in 24 h, with an initial concentration of 100 μg/l PCP and 5 μg PCP/g shell. Isotherm data adjusted better to Freundlich equation, where K F and 1/n were 0.075 ± 0.081 mg 1-1/n l 1/n and 1.882 ± 0.289, respectively. Average desorption efficiency was 7%, indicating strong adsorption capacity. Results proved that almond shells may be an excellent low-cost alternative for PCP removal from contaminated waters

Yolk@Shell Nanoarchitectures with Bimetallic Nanocores-Synthesis and Electrocatalytic Applications.

Science.gov (United States)

Guiet, Amandine; Unmüssig, Tobias; Göbel, Caren; Vainio, Ulla; Wollgarten, Markus; Driess, Matthias; Schlaad, Helmut; Polte, Jörg; Fischer, Anna

2016-10-10

In the present paper, we demonstrate a versatile approach for the one-pot synthesis of metal oxide yolk@shell nanostructures filled with bimetallic nanocores. This novel approach is based on the principles of hydrophobic nanoreactor soft-templating and is exemplified for the synthesis of various AgAu NP @tin-rich ITO (AgAu@ITO TR ) yolk@shell nanomaterials. Hydrophobic nanoreactor soft-templating thereby takes advantage of polystyrene-block-poly(4-vinylpiridine) inverse micelles as two-compartment nanoreactor template, in which the core and the shell of the micelles serve as metal and metal oxide precursor reservoir, respectively. The composition, size and number of AuAg bimetallic nanoparticles incorporated within the ITO TR yolk@shell can easily be tuned. The conductivity of the ITO TR shell and the bimetallic composition of the AuAg nanoparticles, the as-synthesized AuAg NP @ITO TR yolk@shell materials could be used as efficient electrocatalysts for electrochemical glucose oxidation with improved onset potential when compared to their gold counterpart.

CdS/ZnS core-shell nanocrystal photosensitizers for visible to UV upconversion.

Science.gov (United States)

Gray, Victor; Xia, Pan; Huang, Zhiyuan; Moses, Emily; Fast, Alexander; Fishman, Dmitry A; Vullev, Valentine I; Abrahamsson, Maria; Moth-Poulsen, Kasper; Lee Tang, Ming

2017-08-01

Herein we report the first example of nanocrystal (NC) sensitized triplet-triplet annihilation based photon upconversion from the visible to ultraviolet (vis-to-UV). Many photocatalyzed reactions, such as water splitting, require UV photons in order to function efficiently. Upconversion is one possible means of extending the usable range of photons into the visible. Vis-to-UV upconversion is achieved with CdS/ZnS core-shell NCs as the sensitizer and 2,5-diphenyloxazole (PPO) as annihilator and emitter. The ZnS shell was crucial in order to achieve any appreciable upconversion. From time resolved photoluminescence and transient absorption measurements we conclude that the ZnS shell affects the NC and triplet energy transfer (TET) from NC to PPO in two distinct ways. Upon ZnS growth the surface traps are passivated thus increasing the TET. The shell, however, also acts as a tunneling barrier for TET, reducing the efficiency. This leads to an optimal shell thickness where the upconversion quantum yield ( Φ ' UC ) is maximized. Here the maximum Φ ' UC was determined to be 5.2 ± 0.5% for 4 monolayers of ZnS shell on CdS NCs.

Importance-truncated shell model for multi-shell valence spaces

Energy Technology Data Exchange (ETDEWEB)

Stumpf, Christina; Vobig, Klaus; Roth, Robert [Institut fuer Kernphysik, TU Darmstadt (Germany)

2016-07-01

The valence-space shell model is one of the work horses in nuclear structure theory. In traditional applications, shell-model calculations are carried out using effective interactions constructed in a phenomenological framework for rather small valence spaces, typically spanned by one major shell. We improve on this traditional approach addressing two main aspects. First, we use new effective interactions derived in an ab initio approach and, thus, establish a connection to the underlying nuclear interaction providing access to single- and multi-shell valence spaces. Second, we extend the shell model to larger valence spaces by applying an importance-truncation scheme based on a perturbative importance measure. In this way, we reduce the model space to the relevant basis states for the description of a few target eigenstates and solve the eigenvalue problem in this physics-driven truncated model space. In particular multi-shell valence spaces are not tractable otherwise. We combine the importance-truncated shell model with refined extrapolation schemes to approximately recover the exact result. We present first results obtained in the importance-truncated shell model with the newly derived ab initio effective interactions for multi-shell valence spaces, e.g., the sdpf shell.

Multibody dynamic analysis using a rotation-free shell element with corotational frame

Science.gov (United States)

Shi, Jiabei; Liu, Zhuyong; Hong, Jiazhen

2018-03-01

Rotation-free shell formulation is a simple and effective method to model a shell with large deformation. Moreover, it can be compatible with the existing theories of finite element method. However, a rotation-free shell is seldom employed in multibody systems. Using a derivative of rigid body motion, an efficient nonlinear shell model is proposed based on the rotation-free shell element and corotational frame. The bending and membrane strains of the shell have been simplified by isolating deformational displacements from the detailed description of rigid body motion. The consistent stiffness matrix can be obtained easily in this form of shell model. To model the multibody system consisting of the presented shells, joint kinematic constraints including translational and rotational constraints are deduced in the context of geometric nonlinear rotation-free element. A simple node-to-surface contact discretization and penalty method are adopted for contacts between shells. A series of analyses for multibody system dynamics are presented to validate the proposed formulation. Furthermore, the deployment of a large scaled solar array is presented to verify the comprehensive performance of the nonlinear shell model.

MicroShell Minimalist Shell for Xilinx Microprocessors

Science.gov (United States)

Werne, Thomas A.

2011-01-01

MicroShell is a lightweight shell environment for engineers and software developers working with embedded microprocessors in Xilinx FPGAs. (MicroShell has also been successfully ported to run on ARM Cortex-M1 microprocessors in Actel ProASIC3 FPGAs, but without project-integration support.) Micro Shell decreases the time spent performing initial tests of field-programmable gate array (FPGA) designs, simplifies running customizable one-time-only experiments, and provides a familiar-feeling command-line interface. The program comes with a collection of useful functions and enables the designer to add an unlimited number of custom commands, which are callable from the command-line. The commands are parameterizable (using the C-based command-line parameter idiom), so the designer can use one function to exercise hardware with different values. Also, since many hardware peripherals instantiated in FPGAs have reasonably simple register-mapped I/O interfaces, the engineer can edit and view hardware parameter settings at any time without stopping the processor. MicroShell comes with a set of support scripts that interface seamlessly with Xilinx's EDK tool. Adding an instance of MicroShell to a project is as simple as marking a check box in a library configuration dialog box and specifying a software project directory. The support scripts then examine the hardware design, build design-specific functions, conditionally include processor-specific functions, and complete the compilation process. For code-size constrained designs, most of the stock functionality can be excluded from the compiled library. When all of the configurable options are removed from the binary, MicroShell has an unoptimized memory footprint of about 4.8 kB and a size-optimized footprint of about 2.3 kB. Since MicroShell allows unfettered access to all processor-accessible memory locations, it is possible to perform live patching on a running system. This can be useful, for instance, if a bug is

Carbon−Silicon Core−Shell Nanowires as High Capacity Electrode for Lithium Ion Batteries

KAUST Repository

Cui, Li-Feng

2009-09-09

We introduce a novel design of carbon-silicon core-shell nanowires for high power and long life lithium battery electrodes. Amorphous silicon was coated onto carbon nanofibers to form a core-shell structure and the resulted core-shell nanowires showed great performance as anode material. Since carbon has a much smaller capacity compared to silicon, the carbon core experiences less structural stress or damage during lithium cycling and can function as a mechanical support and an efficient electron conducting pathway. These nanowires have a high charge storage capacity of ∼2000 mAh/g and good cycling life. They also have a high Coulmbic efficiency of 90% for the first cycle and 98-99.6% for the following cycles. A full cell composed of LiCoO2 cathode and carbon-silicon core-shell nanowire anode is also demonstrated. Significantly, using these core-shell nanowires we have obtained high mass loading and an area capacity of ∼4 mAh/cm2, which is comparable to commercial battery values. © 2009 American Chemical Society.

Arrays of ZnO/CuIn{sub x}Ga{sub 1−x}Se{sub 2} nanocables with tunable shell composition for efficient photovoltaics

Energy Technology Data Exchange (ETDEWEB)

Akram, Muhammad Aftab; Javed, Sofia [Center of Super-Diamond and Advanced Films (COSDAF), Department of Physics and Materials Science, City University of Hong Kong, Hong Kong (Hong Kong); City University of Hong Kong, Shenzhen Research Institute, Shenzhen 518057 (Hong Kong); School of Chemical and Materials Engineering, National University of Sciences and Technology, Sector H-12, Islamabad 44000 (Pakistan); Xu, Jun, E-mail: apjunxu@hfut.edu.cn [School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei 230009 (China); Mujahid, Mohammad, E-mail: principal@scme.nust.edu.pk [School of Chemical and Materials Engineering, National University of Sciences and Technology, Sector H-12, Islamabad 44000 (Pakistan); Lee, Chun-Sing, E-mail: c.s.lee@cityu.edu.hk [Center of Super-Diamond and Advanced Films (COSDAF), Department of Physics and Materials Science, City University of Hong Kong, Hong Kong (Hong Kong); City University of Hong Kong Shenzhen Research Institute, Shenzhen 518057 (Hong Kong)

2015-05-28

Arrays of one-dimensional (1D) nanostructure are receiving much attention for their optoelectronic and photovoltaic applications due to their advantages in light absorption, charge separation, and transportation. In this work, arrays of ZnO/CuIn{sub x}Ga{sub 1−x}Se{sub 2} core/shell nanocables with tunable shell compositions over the full range of 0 ≤ x ≤ 1 have been controllably synthesized. Chemical conversions of ZnO nanorods to a series of ZnO-based nanocables, including ZnO/ZnSe, ZnO/CuSe, ZnO/CuSe/In{sub x}Ga{sub 1−x}, ZnO/CuSe/(In{sub x}Ga{sub 1−x}){sub 2}Se{sub 3}, and ZnO/CuIn{sub x}Ga{sub 1−x}Se{sub 2}, are well designed and successfully achieved. Composition-dependent influences of the CuIn{sub x}Ga{sub 1−x}Se{sub 2} shells on photovoltaic performance are investigated. It is found that the increase in indium content (x) leads to an increase in short-circuit current density (J{sub SC}) but a decrease in open-circuit voltage (V{sub OC}) for the ZnO/CuIn{sub x}Ga{sub 1−x}Se{sub 2} nanocable solar cells. An array of ZnO/CuIn{sub 0.67}Ga{sub 0.33}Se{sub 2} nanocables with a length of ∼1 μm and a shell thickness of ∼10 nm exhibits a bandgap of 1.20 eV, and yields a maximum power conversion efficiency of 1.74% under AM 1.5 G illumination at an intensity of 100 mW/cm{sup 2}. It dramatically surpasses that (0.22%) of the ZnO/CuIn{sub 0.67}Ga{sub 0.33}Se{sub 2} planar thin-film device. Our work reveals that 1D nanoarray allows efficient photovoltaics without using toxic CdS buffer layer.

A finite-element for the analysis of shell intersections

International Nuclear Information System (INIS)

Koves, W.J.; Nair, S.

1994-01-01

The analysis of discontinuity stresses at shell intersections is a problem of great importance in several major industries. Some of the major areas of interest are pressure-containing equipment, such as reactors and piping, in the nuclear and fossil power industry; pressure vessels and heat exchangers in the petrochemical industry; bracing in offshore oil platforms; and aerospace structures. A specialized shell-intersection finite element, which is compatible with adjoining shell elements, has been developed that has the capability of physically representing the complex three-dimensional geometry and stress state at shell intersections. The element geometry is a contoured shape that matches a wide variety of practical nozzle configurations used in ASME Code pressure vessel construction, and allows computational rigor. A closed-form theory of elasticity solution was used to compute the stress state and strain energy in the element. The concept of an energy-equivalent nodal displacement and force vector set was then developed to allow complete compatibility with adjoining shell elements and retain the analytical rigor within the element. This methodology provides a powerful and robust computation scheme that maintains the computational efficiency of shell element solutions. The shell-intersection element was then applied to the cylinder-sphere and cylinder-cylinder intersection problems

Core/shell colloidal quantum dot exciplex states for the development of highly efficient quantum-dot-sensitized solar cells.

Science.gov (United States)

Wang, Jin; Mora-Seró, Iván; Pan, Zhenxiao; Zhao, Ke; Zhang, Hua; Feng, Yaoyu; Yang, Guang; Zhong, Xinhua; Bisquert, Juan

2013-10-23

Searching suitable panchromatic QD sensitizers for expanding the light-harvesting range, accelerating charge separation, and retarding charge recombination is an effective way to improve power conversion efficiency (PCE) of quantum-dot-sensitized solar cells (QDSCs). One possible way to obtain a wide absorption range is to use the exciplex state of a type-II core/shell-structured QDs. In addition, this system could also provide a fast charge separation and low charge-recombination rate. Herein, we report on using a CdTe/CdSe type-II core/shell QD sensitizer with an absorption range extending into the infrared region because of its exciplex state, which is covalently linked to TiO2 mesoporous electrodes by dropping a bifunctional linker molecule mercaptopropionic acid (MPA)-capped QD aqueous solution onto the film electrode. High loading and a uniform distribution of QD sensitizer throughout the film electrode thickness have been confirmed by energy dispersive X-ray (EDX) elemental mapping. The accelerated electron injection and retarded charge-recombination pathway in the built CdTe/CdSe QD cells in comparison with reference CdSe QD-based cells have been confirmed by impedance spectroscopy, fluorescence decay, and intensity-modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS) analysis. With the combination of the high QD loading and intrinsically superior optoelectronic properties of type-II core/shell QD (wide absorption range, fast charge separation, and slow charge recombination), the resulting CdTe/CdSe QD-based regenerative sandwich solar cells exhibit a record PCE of 6.76% (J(sc) = 19.59 mA cm(-2), V(oc) = 0.606 V, and FF = 0.569) with a mask around the active film under a full 1 sun illumination (simulated AM 1.5), which is the highest reported to date for liquid-junction QDSCs.

Optical properties of core-shell and multi-shell nanorods

Science.gov (United States)

Mokkath, Junais Habeeb; Shehata, Nader

2018-05-01

We report a first-principles time dependent density functional theory study of the optical response modulations in bimetallic core-shell (Na@Al and Al@Na) and multi-shell (Al@Na@Al@Na and Na@Al@Na@Al: concentric shells of Al and Na alternate) nanorods. All of the core-shell and multi-shell configurations display highly enhanced absorption intensity with respect to the pure Al and Na nanorods, showing sensitivity to both composition and chemical ordering. Remarkably large spectral intensity enhancements were found in a couple of core-shell configurations, indicative that optical response averaging based on the individual components can not be considered as true as always in the case of bimetallic core-shell nanorods. We believe that our theoretical results would be useful in promising applications depending on Aluminum-based plasmonic materials such as solar cells and sensors.

Multistage process for the production of bioethanol from almond shell.

Science.gov (United States)

Kacem, Imen; Koubaa, Mohamed; Maktouf, Sameh; Chaari, Fatma; Najar, Taha; Chaabouni, Moncef; Ettis, Nadia; Ellouz Chaabouni, Semia

2016-07-01

This work describes the feasibility of using almond shell as feedstock for bioethanol production. A pre-treatment step was carried out using 4% NaOH for 60min at 121°C followed by 1% sulfuric acid for 60min at 121°C. Enzymatic saccharification of the pre-treated almond shell was performed using Penicillium occitanis enzymes. The process was optimized using a hybrid design with four parameters including the incubation time, temperature, enzyme loads, and polyethylene glycol (PEG) concentration. The optimum hydrolysis conditions led to a sugar yield of 13.5%. A detoxification step of the enzymatic hydrolysate was carried out at pH 5 using 1U/ml of laccase enzyme produced by Polyporus ciliatus. Fermenting efficiency of the hydrolysates was greatly improved by laccase treatment, increasing the ethanol yield from 30% to 84%. These results demonstrated the efficiency of using almond shell as a promising source for bioethanol production. Copyright © 2016 Elsevier Ltd. All rights reserved.

Trabecular bone structure and strength - remodelling and repair

DEFF Research Database (Denmark)

Mosekilde, Lis; Ebbesen, Ebbe Nils; Erikstrup, Lise Tornvig

2000-01-01

vertical and horizontal struts reaching a certain magnitude and thereby inducing buckling under compression. 4) Microdamage and microfractures will occur - mainly in these very loaded vertical struts. The microfractures will be repaired by microcallus formation, and these calluses will later be removed...... can never be isolated in vivo, other factors need to be investigated: The interplay between the cortical shell and the trabecular network; transmission of load; the interplay between soft tissues (cartilage, connective tissue, muscle) and bone; the shock absorbing capacity of the discs...

The energy efficiency ratio of heat storage in one shell-and-one tube phase change thermal energy storage unit

International Nuclear Information System (INIS)

Wang, Wei-Wei; Wang, Liang-Bi; He, Ya-Ling

2015-01-01

Highlights: • A parameter to indicate the energy efficiency ratio of PCTES units is defined. • The characteristics of the energy efficiency ratio of PCTES units are reported. • A combined parameter of the physical properties of the working mediums is found. • Some implications of the energy efficiency ratio in design of PCTES units are analyzed. - Abstract: From aspect of energy consuming to pump heat transfer fluid, there is no sound basis on which to create an optimum design of a thermal energy storage unit. Thus, it is necessary to develop a parameter to indicate the energy efficiency of such unit. This paper firstly defines a parameter that indicates the ratio of heat storage of phase change thermal energy storage unit to energy consumed in pumping heat transfer fluid, which is called the energy efficiency ratio, then numerically investigates the characteristics of this parameter. The results show that the energy efficiency ratio can clearly indicate the energy efficiency of a phase change thermal energy storage unit. When the fluid flow of a heat transfer fluid is in a laminar state, the energy efficiency ratio is larger than in a turbulent state. The energy efficiency ratio of a shell-and-tube phase change thermal energy storage unit is more sensitive to the outer tube diameter. Under the same working conditions, within the heat transfer fluids studied, the heat storage property of the phase change thermal energy storage unit is best for water as heat transfer fluid. A combined parameter is found to indicate the effects of both the physical properties of phase change material and heat transfer fluid on the energy efficiency ratio

Diseño e implementación de una tienda electrónica mediante STRUTS y SOAP

OpenAIRE

López Valladolid, Carmen Rocío

2009-01-01

Gracias al uso de Internet como medio de comunicación, las aplicaciones Web han cobrado una gran importancia y su uso se ha hecho muy común. Esta fuerte demanda de aplicaciones Web ha hecho que hayan nacido una serie de frameworks que facilitan su desarrollo. Este texto presenta una aplicación Web estándar implementada con Struts, uno de los frameworks OpenSource con más aceptación de los disponibles en el mercado para el desarrollo de aplicaciones Web. Esta aplicación se completa con una int...

Reduced Magnetism in Core–Shell Magnetite@MOF Composites

Energy Technology Data Exchange (ETDEWEB)

Elsaidi, Sameh K.; Sinnwell, Michael A.; Banerjee, Debasis; Devaraj, Arun; Kukkadapu, Ravi K.; Droubay, Timothy C.; Nie, Zimin; Kovarik, Libor; Murugesan, Vijayakumar; Manandhar, Sandeep; Nandasiri, Manjula I.; McGrail, Bernard P.; Thallapally, Praveen K.

2017-10-17

Rare-earth elements (REEs) have significant commercial and military uses.1-3 However, REE extraction through conventional mining processes is expensive and feasible at only a few locations worldwide. Alternative methods are needed to produce REEs from more geographically disperse resources and in a cost effective, environmental friendly manner.4,5 Among various sources, geothermal brine, used for generating geothermal energy can possess attractive concentrations (ppb to ppm level) of REEs along with other dissolved metal ions.6 A system that can selectively trap the REEs using an existing geothermal power plant infrastructure would be an attractive additional revenue stream for the plant operator that could accelerate the development and deployment of geothermal plants in the United States and rest of the world.7,8 Here, we demonstrate a magnetic core-shell approach that can effectively extract REEs in their ionic form from aqueous solution with up to 99.99% removal efficiency. The shell, composed of thermally and chemically stable functionalized metal-organic framework (MOF), is grown over a synthesized Fe3O4 magnetic core. Magnetic susceptibility of the particles was found to decline significantly after in situ growth of a MOF shell, which resulted from oxidation of Fe2+ species of the magnetite (Fe3O4) to Fe3+ species (maghemite). The core-shell particles can be completely removed from the mixture under an applied magnetic field, offering a practical, economic, and efficient REE-removal process.

Spin density and orbital optimization in open shell systems: A rational and computationally efficient proposal

Energy Technology Data Exchange (ETDEWEB)

Giner, Emmanuel, E-mail: gnrmnl@unife.it; Angeli, Celestino, E-mail: anc@unife.it [Dipartimento di Scienze Chimiche e Famaceutiche, Universita di Ferrara, Via Fossato di Mortara 17, I-44121 Ferrara (Italy)

2016-03-14

The present work describes a new method to compute accurate spin densities for open shell systems. The proposed approach follows two steps: first, it provides molecular orbitals which correctly take into account the spin delocalization; second, a proper CI treatment allows to account for the spin polarization effect while keeping a restricted formalism and avoiding spin contamination. The main idea of the optimization procedure is based on the orbital relaxation of the various charge transfer determinants responsible for the spin delocalization. The algorithm is tested and compared to other existing methods on a series of organic and inorganic open shell systems. The results reported here show that the new approach (almost black-box) provides accurate spin densities at a reasonable computational cost making it suitable for a systematic study of open shell systems.

L-shell dielectronic recombination for 0-like ions

International Nuclear Information System (INIS)

Omar, G.; Semedal, R.; Shahin, F.; El-Sherbini, T.H.

2007-01-01

In electron-Ion (e/I) collisions, a free electron may be captured by a positively charged ion having bound electrons with a simultaneous, excitation. This radiationless capture, most probably, creates resonance (d) states. These d- states may stabilize by emission of radiation (x-rays). This two-step process is known as Dielectronic recombination (D R). At high incident-electron energy, D R dominates over the radiative recombination (R R) and three- body recombination (Tbr) processes. Thus, D R is one of the most effective recombination for ionisation balance in solar corona and artificial plasma . In addition, the D R rates are needed for the development of nuclear fusion plasma. Thus, D R is still an interesting process m both experimental and theoretical research. Previously we have done the D R rates for 0-like AL 5+ , Cl 9+ Ti 14+ and Zn 22+ ions with K-shell excitation. In this work, the D R rates are calculated for the same ions, but with L-shell excitation. It is found that, the peak values of the D R rates for L-shell excitation are 1000 times larger than that for K-shell excitation. This means that, D R process is the most efficient mechanism for outer-shell excitations. It is found also that, the Dr rates for L-shell excitation peak at Kt = 6 Ry, 22 Ry for AL 5+ and Ti 14+ ions respectively. These Kt values are much smaller than that for for K-shell excitation

Analysis of Experimental Research on Cyclones with Cylindrical and Spiral Shells

Directory of Open Access Journals (Sweden)

Aleksandras Chlebnikovas

2012-12-01

Full Text Available The conducted investigation is aimed at providing information on air flow parameters in the cylindrical and spiral shell (devices are designed for separating solid particles from air flow having tangent flow inlet. Experimental research has employed multi-cyclones created by the Department of Environmental Protection at Vilnius Gediminas Technical University. The study is focused on investigating and comparing the distribution of the dynamic pressure of the airflow in six-channel cyclones inside the structures of devices. The paper establishes and estimates the efficiency of air cleaning changing air phase parameters using different particulate matters. The efficiency of the cyclone has been defined applying the weighted method based on LAND 28-98/M-08 methodology. The article presents the results of experimental research on the air cleaning efficiency of cylindrical and spiral shells using 20 µm glass and clay particulate matter under the initial concentration that may vary from 500 mg/m3 to 15 g/m3 using semi-rings with windows at different positions. The obtained results has shown that the maximum efficiency of the cylindrical shell increases up to 87,3 % while the initial concentration of glass makes 15 g/m3.Article in Lithuanian

Pecan shell-based granular activated carbon for treatment of chemical oxygen demand (COD) in municipal wastewater.

Science.gov (United States)

Bansode, R R; Losso, J N; Marshall, W E; Rao, R M; Portier, R J

2004-09-01

The present investigation was undertaken to compare the adsorption efficiency of pecan shell-based granular activated carbon with the adsorption efficiency of the commercial carbon Filtrasorb 200 with respect to uptake of the organic components responsible for the chemical oxygen demand (COD) of municipal wastewater. Adsorption efficiencies for these two sets of carbons (experimental and commercial) were analyzed by the Freundlich adsorption model. The results indicate that steam-activated and acid-activated pecan shell-based carbons had higher adsorption for organic matter measured as COD, than carbon dioxide-activated pecan shell-based carbon or Filtrasorb 200 at all the carbon dosages used during the experiment. The higher adsorption may be related to surface area as the two carbons with the highest surface area also had the highest organic matter adsorption. These results show that granular activated carbons made from agricultural waste (pecan shells) can be used with greater effectiveness for organic matter removal from municipal wastewater than a coal-based commercial carbon. Copyright 2004 Elsevier Ltd.

Study on modal characteristics of perforated shell using effective Young's modulus

Energy Technology Data Exchange (ETDEWEB)

Jhung, Myung Jo, E-mail: mjj@kins.re.kr [Korea Institute of Nuclear Safety, 19 Guseong-dong, Yuseong-gu, Daejeon 305-338 (Korea, Republic of); Yu, Seon Oh [Korea Institute of Nuclear Safety, 19 Guseong-dong, Yuseong-gu, Daejeon 305-338 (Korea, Republic of)

2011-06-15

Research highlights: > The effective Young's modulus of perforated shell is proposed for modal analysis. > The penetration pattern is almost negligible for effective elastic constants. > The frequency of perforated shell decreases significantly due to the hole effect. - Abstract: For the perforated cylindrical shell submerged in fluid, it is almost impossible to develop a finite element model due to the necessity of the fine meshing of the shell and the fluid at the same time. This necessitates the use of solid shell with effective material properties. Unfortunately the effective elastic constants are not found in any references even though the ASME code is suggesting those for perforated plate. Therefore in this study the effective material properties of perforated shell are suggested by performing several finite element analyses with respect to the ligament efficiencies.

Plasmonic Photovoltaic Cells with Dual-Functional Gold, Silver, and Copper Half-Shell Arrays.

Science.gov (United States)

Wu, Ling; Kim, Gyu Min; Nishi, Hiroyasu; Tatsuma, Tetsu

2017-09-12

Solid-state photovoltaic cells based on plasmon-induced charge separation (PICS) have attracted growing attention during the past decade. However, the power conversion efficiency (PCE) of the previously reported devices, which are generally loaded with dispersed metal nanoparticles as light absorbers, has not been sufficiently high. Here we report simpler plasmonic photovoltaic cells with interconnected Au, Ag, and Cu half-shell arrays deposited on SiO 2 @TiO 2 colloidal crystals, which serve both as a plasmonic light absorber and as a current collector. The well-controlled and easily prepared plasmonic structure allows precise comparison of the PICS efficiency between different plasmonic metal species. The cell with the Ag half-shell array has higher photovoltaic performance than the cells with Au and Cu half-shell arrays because of the high population of photogenerated energetic electrons, which gives a high electron injection efficiency and suppressed charge recombination probability, achieving the highest PCE among the solid-state PICS devices even without a hole transport layer.

Core–shell heterostructured metal oxide arrays enable superior light-harvesting and hysteresis-free mesoscopic perovskite solar cells

KAUST Repository

Mahmood, Khalid; Swain, Bhabani Sankar; Amassian, Aram

2015-01-01

To achieve highly efficient mesoscopic perovskite solar cells (PSCs), the structure and properties of an electron transport layer (ETL) or material (ETM) have been shown to be of supreme importance. Particularly, the core-shell heterostructured mesoscopic ETM architecture has been recognized as a successful electrode design, because of its large internal surface area, superior light-harvesting efficiency and its ability to achieve fast charge transport. Here we report the successful fabrication of a hysteresis-free, 15.3% efficient PSC using vertically aligned ZnO nanorod/TiO2 shell (ZNR/TS) core-shell heterostructured ETMs for the first time. We have also added a conjugated polyelectrolyte polymer into the growth solution to promote the growth of high aspect ratio (AR) ZNRs and substantially improve the infiltration of the perovskite light absorber into the ETM. The PSCs based on the as-synthesized core-shell ZnO/TiO2 heterostructured ETMs exhibited excellent performance enhancement credited to the superior light harvesting capability, larger surface area, prolonged charge-transport pathways and lower recombination rate. The unique ETM design together with minimal hysteresis introduces core-shell ZnO/TiO2 heterostructures as a promising mesoscopic electrode approach for the fabrication of efficient PSCs. This journal is © The Royal Society of Chemistry.

Vibration isolation design for periodically stiffened shells by the wave finite element method

Science.gov (United States)

Hong, Jie; He, Xueqing; Zhang, Dayi; Zhang, Bing; Ma, Yanhong

2018-04-01

Periodically stiffened shell structures are widely used due to their excellent specific strength, in particular for aeronautical and astronautical components. This paper presents an improved Wave Finite Element Method (FEM) that can be employed to predict the band-gap characteristics of stiffened shell structures efficiently. An aero-engine casing, which is a typical periodically stiffened shell structure, was employed to verify the validation and efficiency of the Wave FEM. Good agreement has been found between the Wave FEM and the classical FEM for different boundary conditions. One effective wave selection method based on the Wave FEM has thus been put forward to filter the radial modes of a shell structure. Furthermore, an optimisation strategy by the combination of the Wave FEM and genetic algorithm was presented for periodically stiffened shell structures. The optimal out-of-plane band gap and the mass of the whole structure can be achieved by the optimisation strategy under an aerodynamic load. Results also indicate that geometric parameters of stiffeners can be properly selected that the out-of-plane vibration attenuates significantly in the frequency band of interest. This study can provide valuable references for designing the band gaps of vibration isolation.

Band engineering in core/shell ZnTe/CdSe for photovoltage and efficiency enhancement in exciplex quantum dot sensitized solar cells.

Science.gov (United States)

Jiao, Shuang; Shen, Qing; Mora-Seró, Iván; Wang, Jin; Pan, Zhenxiao; Zhao, Ke; Kuga, Yuki; Zhong, Xinhua; Bisquert, Juan

2015-01-27

Even though previously reported CdTe/CdSe type-II core/shell QD sensitizers possess intrinsic superior optoelectronic properties (such as wide absorption range, fast charge separation, and slow charge recombination) in serving as light absorbers, the efficiency of the resultant solar cell is still limited by the relatively low photovoltage. To further enhance photovoltage and cell efficiency accordingly, ZnTe/CdSe type-II core/shell QDs with much larger conduction band (CB) offset in comparison with that of CdTe/CdSe (1.22 eV vs 0.27 eV) are adopted as sensitizers in the construction of quantum dot sensitized solar cells (QDSCs). The augment of band offset produces an increase of the charge accumulation across the QD/TiO2 interface under illumination and induces stronger dipole effects, therefore bringing forward an upward shift of the TiO2 CB edge after sensitization and resulting in enhancement of the photovoltage of the resultant cell devices. The variation of relative chemical capacitance, Cμ, between ZnTe/CdSe and reference CdTe/CdSe cells extracted from impedance spectroscopy (IS) characterization under dark and illumination conditions clearly demonstrates that, under light irradiation conditions, the sensitization of ZnTe/CdSe QDs upshifts the CB edge of TiO2 by the level of ∼ 50 mV related to that in the reference cell and results in the enhancement of V(oc) of the corresponding cell devices. In addition, charge extraction measurements have also confirmed the photovoltage enhancement in the ZnTe/CdSe cell related to reference CdTe/CdSe cell. Furthermore, transient grating (TG) measurements have revealed a faster electron injection rate for the ZnTe/CdSe-based QDSCs in comparison with the CdSe cells. The resultant ZnTe/CdSe QD-based QDSCs exhibit a champion power conversion efficiency of 7.17% and a certified efficiency of 6.82% under AM 1.5 G full one sun illumination, which is, as far as we know, one of the highest efficiencies for liquid-junction QDSCs.

Enzymatic production of N-acetyl-d-glucosamine from crayfish shell wastes pretreated via high pressure homogenization.

Science.gov (United States)

Wei, Guoguang; Zhang, Alei; Chen, Kequan; Ouyang, Pingkai

2017-09-01

This study presents an efficient pretreatment of crayfish shell using high pressure homogenization that enables N-acetyl-d-glucosamine (GlcNAc) production by chitinase. Firstly, the chitinase from Serratia proteamaculans NJ303 was screened for its ability to degrade crayfish shell and produce GlcNAc as the sole product. Secondly, high pressure homogenization, which caused the crayfish shell to adopt a fluffy netted structure that was characterized by Scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), was evaluated as the best pretreatment method. In addition, the optimal conditions of high pressure homogenization of crayfish shell were determined to be five cycles at a pressure of 400bar, which achieved a yield of 3.9g/L of GlcNAc from 25g/L of crayfish shell in a batch enzymatic reaction over 1.5h. The results showed high pressure homogenization might be an efficient method for direct utilization of crayfish shell for enzymatic production of GlcNAc. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hi shells, supershells, shell-like objects, and ''worms''

International Nuclear Information System (INIS)

Heiles, C.

1984-01-01

We present photographic representations of the combination of two Hi surveys, so as to eliminate the survey boundaries at Vertical BarbVertical Bar = 10 0 . We also present high-contrast photographs for particular velocities to exhibit weak Hi features. All of these photographs were used to prepare a new list of Hi shells, supershells, and shell-like objects. We discuss the structure of three shell-like objects that are associated with high-velocity gas, and with gas at all velocities that is associated with radio continuum loops I, II, and III. We use spatial filtering to find wiggly gas filaments: ''worms'': crawling away from the galactic plane in the inner Galaxy. The ''worms'' are probably parts of shells that are open at the top; such shells should be good sources of hot gas for the galactic halo

A general and high-yield galvanic displacement approach to Au-M (M = Au, Pd, and Pt) core-shell nanostructures with porous shells and enhanced electrocatalytic performances.

Science.gov (United States)

Kuai, Long; Geng, Baoyou; Wang, Shaozhen; Sang, Yan

2012-07-23

In this work, we utilize the galvanic displacement synthesis and make it a general and efficient method for the preparation of Au-M (M = Au, Pd, and Pt) core-shell nanostructures with porous shells, which consist of multilayer nanoparticles. The method is generally applicable to the preparation of Au-Au, Au-Pd, and Au-Pt core-shell nanostructures with typical porous shells. Moreover, the Au-Au isomeric core-shell nanostructure is reported for the first time. The lower oxidation states of Au(I), Pd(II), and Pt(II) are supposed to contribute to the formation of porous core-shell nanostructures instead of yolk-shell nanostructures. The electrocatalytic ethanol oxidation and oxygen reduction reaction (ORR) performance of porous Au-Pd core-shell nanostructures are assessed as a typical example for the investigation of the advantages of the obtained core-shell nanostructures. As expected, the Au-Pd core-shell nanostructure indeed exhibits a significantly reduced overpotential (the peak potential is shifted in the positive direction by 44 mV and 32 mV), a much improved CO tolerance (I(f)/I(b) is 3.6 and 1.63 times higher), and an enhanced catalytic stability in comparison with Pd nanoparticles and Pt/C catalysts. Thus, porous Au-M (M = Au, Pd, and Pt) core-shell nanostructures may provide many opportunities in the fields of organic catalysis, direct alcohol fuel cells, surface-enhanced Raman scattering, and so forth. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Au/ZnS core/shell nanocrystals as an efficient anode photocatalyst in direct methanol fuel cells.

Science.gov (United States)

Chen, Wei-Ta; Lin, Yin-Kai; Yang, Ting-Ting; Pu, Ying-Chih; Hsu, Yung-Jung

2013-10-04

Au/ZnS core/shell nanocrystals with controllable shell thicknesses were synthesized using a cysteine-assisted hydrothermal method. Incorporating Au/ZnS nanocrystals into the traditional Pt-catalyzed half-cell reaction led to a 43.3% increase in methanol oxidation current under light illumination, demonstrating their promising potential for metal/semiconductor hybrid nanocrystals as the anode photocatalyst in direct methanol fuel cells.

Multilevel Optimization Framework for Hierarchical Stiffened Shells Accelerated by Adaptive Equivalent Strategy

Science.gov (United States)

Wang, Bo; Tian, Kuo; Zhao, Haixin; Hao, Peng; Zhu, Tianyu; Zhang, Ke; Ma, Yunlong

2017-06-01

In order to improve the post-buckling optimization efficiency of hierarchical stiffened shells, a multilevel optimization framework accelerated by adaptive equivalent strategy is presented in this paper. Firstly, the Numerical-based Smeared Stiffener Method (NSSM) for hierarchical stiffened shells is derived by means of the numerical implementation of asymptotic homogenization (NIAH) method. Based on the NSSM, a reasonable adaptive equivalent strategy for hierarchical stiffened shells is developed from the concept of hierarchy reduction. Its core idea is to self-adaptively decide which hierarchy of the structure should be equivalent according to the critical buckling mode rapidly predicted by NSSM. Compared with the detailed model, the high prediction accuracy and efficiency of the proposed model is highlighted. On the basis of this adaptive equivalent model, a multilevel optimization framework is then established by decomposing the complex entire optimization process into major-stiffener-level and minor-stiffener-level sub-optimizations, during which Fixed Point Iteration (FPI) is employed to accelerate convergence. Finally, the illustrative examples of the multilevel framework is carried out to demonstrate its efficiency and effectiveness to search for the global optimum result by contrast with the single-level optimization method. Remarkably, the high efficiency and flexibility of the adaptive equivalent strategy is indicated by compared with the single equivalent strategy.

Dynamical efficiency of collisionless magnetized shocks in relativistic jets

Science.gov (United States)

Aloy, Miguel A.; Mimica, Petar

2011-09-01

The so-called internal shock model aims to explain the light-curves and spectra produced by non-thermal processes originated in the flow of blazars and gamma-ray bursts. A long standing question is whether the tenuous collisionless shocks, driven inside a relativistic flow, are efficient enough to explain the amount of energy observed as compared with the expected kinetic power of the outflow. In this work we study the dynamic efficiency of conversion of kinetic-to-thermal/magnetic energy of internal shocks in relativistic magnetized outflows. We find that the collision between shells with a non-zero relative velocity can yield either two oppositely moving shocks (in the frame where the contact surface is at rest), or a reverse shock and a forward rarefaction. For moderately magnetized shocks (magnetization σ ~= 0.1), the dynamic efficiency in a single two-shell interaction can be as large as 40%. Hence, the dynamic efficiency of moderately magnetized shocks is larger than in the corresponding unmagnetized two-shell interaction. We find that the efficiency is only weakly dependent on the Lorentz factor of the shells and, thus internal shocks in the magnetized flow of blazars and gamma-ray bursts are approximately equally efficient.

Facile synthesis and microwave absorbability of C@Ni–NiO core–shell hybrid solid sphere and multi-shelled NiO hollow sphere

International Nuclear Information System (INIS)

Wu, Hongjing; Wu, Guanglei; Wu, Qiaofeng; Wang, Liuding

2014-01-01

We reported the preparation of C@Ni–NiO core–shell hybrid solid spheres or multi-shelled NiO hollow spheres by combining a facile hydrothermal route with a calcination process in H 2 or air atmosphere, respectively. The synthesized C@Ni–NiO core–shell solid spheres with diameters of approximately 2–6 μm were in fact built from dense NiO nanoparticles coated by random two-dimensional metal Ni nanosheets without any visible pores. The multi-shelled NiO hollow spheres were built from particle-like ligaments and there are a lot of pores with size of several nanometers on the surface. Combined Raman spectra with X-ray photoelectron spectra (XPS), it suggested that the defects in the samples play a limited role in the dielectric loss. Compared with the other samples, the permeability of the samples calcined in H 2 and air was increased slightly and the natural resonance frequency shifted to higher frequency (7, 11 and 14 GHz, respectively), leading to an enhancement of microwave absorption property. For the sample calcined in H 2 , an optimal reflection loss less than − 10 was obtained at 7 GHz with a matching thickness of 5.0 mm. Our study demonstrated the potential application of C@Ni–NiO core–shell hybrid solid sphere or multi-shelled NiO hollow sphere as a more efficient electromagnetic (EM) wave absorber. - Highlights: • C@Ni–NiO core–shell hybrid solid sphere was synthesized by a facile method. • Multi-shelled NiO hollow sphere was synthesized by a facile method. • It suggested that the defects in the samples play a limited role in dielectric loss. • The permeability of the samples calcined in H 2 and air was increased. • Microwave absorbability of C@Ni–NiO core–shell hybrid solid sphere was investigated

Bifunctional Au@TiO_2 core–shell nanoparticle films for clean water generation by photocatalysis and solar evaporation

International Nuclear Information System (INIS)

Huang, Jian; He, Yurong; Wang, Li; Huang, Yimin; Jiang, Baocheng

2017-01-01

Highlights: • Au@TiO_2 core-shell nanoparticles were prepared in this study. • Bifunctional films for photocatalysis and solar evaporation were designed. • The evaporation and photodegradation with core-shell structures were investigated. - Abstract: With water scarcity becoming an increasingly critical issue for modern society, solar seawater desalination represents a promising approach to mitigating water shortage. In addition, solar seawater desalination shows great potential for mitigating the energy crisis due to its high photo-thermal conversion efficiency. However, the increasing contamination of seawater makes it difficult to generate clean water through simple desalination processes. In this work, clean water is generated by a newly designed bifunctional Au@TiO_2 core-shell nanoparticle film with a high photo-thermal conversion efficiency that is capable of photocatalysis and solar evaporation for seawater desalination. Bifunctional films of Au@TiO_2 core-shell nanoparticles with good stability were prepared. It was found that the formation of the core-shell structures played a key role in promoting the photo-thermal conversion efficiency and the evaporation of seawater, while the photocatalytic function demonstrated herein could contribute to the purification of polluted seawater. Furthermore, the film structure can serve to concentrate the NPs for the photo-reaction, as well as heat for water evaporation, improving both the photo-reaction efficiency and photo-thermal conversion efficiency. This efficient approach to solar seawater desalination, which combines evaporation with the photodegradation of pollutants, could help to address the dual issues of water scarcity and water pollution.

The use of dendrimers as high-performance shells for round-trip energy transfer: efficient trans-cis photoisomerization from an excited triplet state produced within a dendrimer shell.

Science.gov (United States)

Miura, Yousuke; Momotake, Atsuya; Takeuchi, Keiichirou; Arai, Tatsuo

2011-01-01

A series of stilbene-cored poly(benzyl ether) dendrimers with benzophenone peripheries were synthesized and their photophysical and photochemical properties were studied. Fluorescence studies revealed that singlet-singlet energy transfer (SSET) from the stilbene core to the benzophenone units took place efficiently in dendrimers of all generations. Similarly, phosphorescence and time-resolved spectroscopic measurements indicated efficient triplet-triplet energy transfer (TTET) from the benzophenone periphery to the stilbene core. Upon excitation at 310 nm, the stilbene core isomerizes via an energy round trip within the dendrimer shell. The quantum yields for the energy round trip (Φ(ERT)), defined as the product of the quantum yields of SSET, intersystem crossing, and TTET (Φ(ERT) = Φ(SS)Φ(isc)Φ(TT)), were extremely high for all generations--99%, 95% and 94% for G1, G2, and G3, respectively--which means that the excitation energy of the dendrimer core was transferred to the dendrimer periphery and back to the core almost quantitatively. The quantum yield for photoisomerization of G1-G3 via an energy round trip was higher than for other stilbene-cored dendrimers, which mainly isomerize from the excited singlet state. Photostability in the dendrimers was also demonstrated and discussed.

Gasification of ‘Loose’ Groundnut Shells in a Throathless Downdraft Gasifier

Directory of Open Access Journals (Sweden)

Aondoyila Kuhe

2015-07-01

Full Text Available In this paper, gasification potential of biomass residue was investigated using a laboratory scale throatless downdraft gasifier. Experimental results of groundnut shell was gasified in the throatless downdraft gasifier to produce a clean gas with a calorific value of around 5.92 MJ/Nm3 and a combustible fraction of 45% v/v. Low moisture (8.6% and ash content (3.19% are the main advantages of groundnut shells for gasification. It is suggested that gasification of shell waste products is a clean energy alternative to fossil fuels. The product gas can be used efficiently for heating and possible usage in internal combustion engines.

Core-Shell Composite Fibers for High-Performance Flexible Supercapacitor Electrodes.

Science.gov (United States)

Lu, Xiaoyan; Shen, Chen; Zhang, Zeyang; Barrios, Elizabeth; Zhai, Lei

2018-01-31

Core-shell nanofibers containing poly(acrylic acid) (PAA) and manganese oxide nanoparticles as the core and polypyrrole (PPy) as the shell were fabricated through electrospinning the solution of PAA and manganese ions (PAA/Mn 2+ ). The obtained nanofibers were stabilized by Fe 3+ through the interaction between Fe 3+ ions and carboxylate groups. Subsequent oxidation of Mn 2+ by KMnO 4 produced uniform manganese dioxide (MnO 2 ) nanoparticles in the fibers. A PPy shell was created on the fibers by immersing the fibers in a pyrrole solution where the Fe 3+ ions in the fiber polymerized the pyrrole on the fiber surfaces. In the MnO 2 @PAA/PPy core-shell composite fibers, MnO 2 nanoparticles function as high-capacity materials, while the PPy shell prevents the loss of MnO 2 during the charge/discharge process. Such a unique structure makes the composite fibers efficient electrode materials for supercapacitors. The gravimetric specific capacity of the MnO 2 @PAA/PPy core-shell composite fibers was 564 F/g based on cyclic voltammetry curves at 10 mV/s and 580 F/g based on galvanostatic charge/discharge studies at 5 A/g. The MnO 2 @PAA/PPy core-shell composite fibers also present stable cycling performance with 100% capacitance retention after 5000 cycles.

Free vibration analysis of delaminated composite shells using different shell theories

International Nuclear Information System (INIS)

Nanda, Namita; Sahu, S.K.

2012-01-01

Free vibration response of laminated composite shells with delamination is presented using the finite element method based on first order shear deformation theory. The shell theory used is the extension of dynamic, shear deformable theory according to the Sanders' first approximation for doubly curved shells, which can be reduced to Love's and Donnell's theories by means of tracers. An eight-noded C 0 continuity, isoparametric quadrilateral element with five degrees of freedom per node is used in the formulation. For modeling the delamination, multipoint constraint algorithm is incorporated in the finite element code. The natural frequencies of the delaminated cylindrical (CYL), spherical (SPH) and hyperbolic paraboloid (HYP) shells are determined by using the above mentioned shell theories, namely Sanders', Love's, and Donnell's. The validity of the present approach is established by comparing the authors' results with those available in the literature. Additional studies on free vibration response of CYL, SPH and HYP shells are conducted to assess the effects of delamination size and number of layers considering all three shell theories. It is shown that shell theories according to Sanders and Love always predict practically identical frequencies. Donnell's theory gives reliable results only for shallow shells. Moreover, the natural frequency is found to be very sensitive to delamination size and number of layers in the shell.

Pd@Pt Core–Shell Nanoparticles with Branched Dandelion-like Morphology as Highly Efficient Catalysts for Olefin Reduction

Science.gov (United States)

A facile synthesis based on the addition of ascorbic acid to a mixture of Na2PdCl4, K2PtCl6, and Pluronic P123 results in highly branched core–shell nanoparticles (NPs) with a micro–mesoporous dandelion-like morphology comprising Pd core and Pt shell. The slow reduction kinetics ...

MHD computation of feedback of resistive-shell instabilities in the reversed field pinch

International Nuclear Information System (INIS)

Zita, E.J.; Prager, S.C.

1992-05-01

MHD computation demonstrates that feedback can sustain reversal and reduce loop voltage in resistive-shell reversed field pinch (RFP) plasmas. Edge feedback on ∼2R/a tearing modes resonant near axis is found to restore plasma parameters to nearly their levels with a close-fitting conducting shell. When original dynamo modes are stabilized, neighboring tearing modes grow to maintain the RFP dynamo more efficiently. This suggests that experimentally observed limits on RFP pulselengths to the order of the shell time can be overcome by applying feedback to a few helical modes

Nanosized yolk–shell Fe{sub 3}O{sub 4}@Zr(OH){sub x} spheres for efficient removal of Pb(II) from aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Pan, Shunlong [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Li, Jiansheng, E-mail: lijsh@mail.njust.edu.cn [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Wan, Gaojie; Liu, Chao [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Fan, Wenhong, E-mail: fanwh@buaa.edu.cn [Department of Environmental Science and Engineering, School of Chemistry and Environment, Beihang University, Beijing 100191 (China); Wang, Lianjun, E-mail: wanglj@mail.njust.edu.cn [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China)

2016-05-15

Highlights: • Well dispersed and easy separated nanoadsorbents with stable chemical property are highly desired. • Fe{sub 3}O{sub 4}@Zr(OH){sub x} yolk–shell nanospheres (YSNs) nanoadsorbents were prepared. • Enhanced Pb(II) adsorption capacity of 310.8 mg/g was achieved on Fe{sub 3}O{sub 4}@Zr(OH){sub x} YSNs based on Zr weight. • The cavities in Fe{sub 3}O{sub 4}@Zr(OH){sub x} YSNs is responsible for the improved performance. - Abstract: In this work, Fe{sub 3}O{sub 4}@Zr(OH){sub x} yolk–shell nanospheres (YSNs) were synthesized via a two-step process and further examined as adsorbents for the removal of Pb(II). To understand the hollow structure on the adsorption properties of Pb(II), another adsorbent without hollow cavities, i.e., Fe{sub 3}O{sub 4}@SiO{sub 2}@Zr(OH){sub x} core–shell nanospheres (CSNs), was also prepared for comparison. The adsorption results showed that Fe{sub 3}O{sub 4}@Zr(OH){sub x} YSNs exhibited 41.6% higher Pb(II) adsorption capacity as compared to that of Fe{sub 3}O{sub 4}@SiO{sub 2}@Zr(OH){sub x} CSNs. The isotherm was well fitted to Langmuir adsorption model with q{sub max} value of 310.8 mg/g after normalized by the weight of Zr in Fe{sub 3}O{sub 4}@Zr(OH){sub x} YSNs. Scanning transmission electron microscopy (STEM) mapping results revealed that the existence of cavities between Fe{sub 3}O{sub 4} cores and Zr(OH){sub x} shells is responsible for the improved adsorption performance. XPS analysis indicated the surface hydroxyl groups played a key role in the Pb(II) adsorption. The removal efficiency of Pb(II) was maintained above 90% in five consecutive adsorption–desorption cycles.

Composted oyster shell as lime fertilizer is more effective than fresh oyster shell.

Science.gov (United States)

Lee, Young Han; Islam, Shah Md Asraful; Hong, Sun Joo; Cho, Kye Man; Math, Renukaradhya K; Heo, Jae Young; Kim, Hoon; Yun, Han Dae

2010-01-01

Physio-chemical changes in oyster shell were examined, and fresh and composted oyster shell meals were compared as lime fertilizers in soybean cultivation. Structural changes in oyster shell were observed by AFM and FE-SEM. We found that grains of the oyster shell surface became smoother and smaller over time. FT-IR analysis indicated the degradation of a chitin-like compound of oyster shell. In chemical analysis, pH (12.3+/-0.24), electrical conductivity (4.1+/-0.24 dS m(-1)), and alkaline powder (53.3+/-1.12%) were highest in commercial lime. Besides, pH was higher in composted oyster shell meal (9.9+/-0.53) than in fresh oyster shell meal (8.4+/-0.32). The highest organic matter (1.1+/-0.08%), NaCl (0.54+/-0.03%), and moisture (15.1+/-1.95%) contents were found in fresh oyster shell meal. A significant higher yield of soybean (1.33 t ha(-1)) was obtained by applying composted oyster shell meal (a 21% higher yield than with fresh oyster shell meal). Thus composting of oyster shell increases the utility of oyster shell as a liming material for crop cultivation.

Singular problems in shell theory. Computing and asymptotics

Energy Technology Data Exchange (ETDEWEB)

Sanchez-Palencia, Evariste [Institut Jean Le Rond d' Alembert, Paris (France); Millet, Olivier [La Rochelle Univ. (France). LEPTIAB; Bechet, Fabien [Metz Univ. (France). LPMM

2010-07-01

It is known that deformations of thin shells exhibit peculiarities such as propagation of singularities, edge and internal layers, piecewise quasi inextensional deformations, sensitive problems and others, leading in most cases to numerical locking phenomena under several forms, and very poor quality of computations for small relative thickness. Most of these phenomena have a local and often anisotropic character (elongated in some directions), so that efficient numerical schemes should take them in consideration. This book deals with various topics in this context: general geometric formalism, analysis of singularities, numerical computing of thin shell problems, estimates for finite element approximation (including non-uniform and anisotropic meshes), mathematical considerations on boundary value problems in connection with sensitive problems encountered for very thin shells; and others. Most of numerical computations presented here use an adaptive anisotropic mesh procedure which allows a good computation of the physical peculiarities on one hand, and the possibility to perform automatic computations (without a previous mathematical description of the singularities) on the other. The book is recommended for PhD students, postgraduates and researchers who want to improve their knowledge in shell theory and in particular in the areas addressed (analysis of singularities, numerical computing of thin and very thin shell problems, sensitive problems). The lecture of the book may not be continuous and the reader may refer directly to the chapters concerned. (orig.)

Effect of Core-Shell Ag@TiO2 Volume Ratio on Characteristics of TiO2-Based DSSCs

Directory of Open Access Journals (Sweden)

Ho Chang

2014-01-01

Full Text Available This paper aims to develop photoanode material required by dye-sensitized solar cells. The material prepared is in the form of Ag@TiO2 core-shell-type nanocomposites. This material is used to replace the titanium oxide powder commonly used in general DSSCs. The prepared Ag@TiO2 core-shell-type nanocomposites are mixed with Degussa P25 TiO2 in different proportions. Triton X-100 is added and polyethylene glycol (PEG at 20 wt% is used as a polymer additive. This study tests the particle size and material properties of Ag@TiO2 core-shell-type nanocomposites and measures the photoelectric conversion efficiency and IPCE of DSSCs. Experimental results show that the DSSC prepared by Ag@TiO2 core-shell-type nanocomposites can achieve a photoelectric conversion efficiency of 3.67%. When Ag@TiO2 core-shell-type nanocomposites are mixed with P25 nanoparticles in specific proportions, and when the thickness of the photoelectrode thin film is 28 μm, the photoelectric conversion efficiency can reach 6.06%, with a fill factor of 0.52, open-circuit voltage of 0.64V, and short-circuit density of 18.22 mAcm−2. Compared to the DSSC prepared by P25 TiO2 only, the photoelectric conversion efficiency can be raised by 38% under the proposed approach.

On the core-mass-shell-luminosity relation for shell-burning stars

International Nuclear Information System (INIS)

Jeffery, C.S.; Saint Andrews Univ.

1988-01-01

Core-mass-shell-luminosity relations for several types of shell-burning star have been calculated using simultaneous differential equations derived from simple homology approximations. The principal objective of obtaining a mass-luminosity relation for helium giants was achieved. This relation gives substantially higher luminosities than the equivalent relation for H-shell stars with core masses greater than 1 solar mass. The algorithm for calculating mass-luminosity relations in this fashion was investigated in detail. Most of the assumptions regarding the physics in the shell do not play a critical role in determining the core-mass-shell-luminosity relation. The behaviour of the core-mass-core-radius relation for a growing degenerate core as a single unique function of mass and growth rate needs to be defined before a single core-mass-shell-luminosity relation for all H-shell stars can be obtained directly from the homology approximations. (author)

Synthesis of Multicolor Core/Shell NaLuF4:Yb3+/Ln3+@CaF2 Upconversion Nanocrystals

Directory of Open Access Journals (Sweden)

Hui Li

2017-02-01

Full Text Available The ability to synthesize high-quality hierarchical core/shell nanocrystals from an efficient host lattice is important to realize efficacious photon upconversion for applications ranging from bioimaging to solar cells. Here, we describe a strategy to fabricate multicolor core @ shell α-NaLuF4:Yb3+/Ln3+@CaF2 (Ln = Er, Ho, Tm upconversion nanocrystals (UCNCs based on the newly established host lattice of sodium lutetium fluoride (NaLuF4. We exploited the liquid-solid-solution method to synthesize the NaLuF4 core of pure cubic phase and the thermal decomposition approach to expitaxially grow the calcium fluoride (CaF2 shell onto the core UCNCs, yielding cubic core/shell nanocrystals with a size of 15.6 ± 1.2 nm (the core ~9 ± 0.9 nm, the shell ~3.3 ± 0.3 nm. We showed that those core/shell UCNCs could emit activator-defined multicolor emissions up to about 772 times more efficient than the core nanocrystals due to effective suppression of surface-related quenching effects. Our results provide a new paradigm on heterogeneous core/shell structure for enhanced multicolor upconversion photoluminescence from colloidal nanocrystals.

Variation in Orthologous Shell-Forming Proteins Contribute to Molluscan Shell Diversity.

Science.gov (United States)

Jackson, Daniel J; Reim, Laurin; Randow, Clemens; Cerveau, Nicolas; Degnan, Bernard M; Fleck, Claudia

2017-11-01

Despite the evolutionary success and ancient heritage of the molluscan shell, little is known about the molecular details of its formation, evolutionary origins, or the interactions between the material properties of the shell and its organic constituents. In contrast to this dearth of information, a growing collection of molluscan shell-forming proteomes and transcriptomes suggest they are comprised of both deeply conserved, and lineage specific elements. Analyses of these sequence data sets have suggested that mechanisms such as exon shuffling, gene co-option, and gene family expansion facilitated the rapid evolution of shell-forming proteomes and supported the diversification of this phylum specific structure. In order to further investigate and test these ideas we have examined the molecular features and spatial expression patterns of two shell-forming genes (Lustrin and ML1A2) and coupled these observations with materials properties measurements of shells from a group of closely related gastropods (abalone). We find that the prominent "GS" domain of Lustrin, a domain believed to confer elastomeric properties to the shell, varies significantly in length between the species we investigated. Furthermore, the spatial expression patterns of Lustrin and ML1A2 also vary significantly between species, suggesting that both protein architecture, and the regulation of spatial gene expression patterns, are important drivers of molluscan shell evolution. Variation in these molecular features might relate to certain materials properties of the shells of these species. These insights reveal an important and underappreciated source of variation within shell-forming proteomes that must contribute to the diversity of molluscan shell phenotypes. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Off-shell CHY amplitudes

Energy Technology Data Exchange (ETDEWEB)

Lam, C.S., E-mail: Lam@physics.mcgill.ca [Department of Physics, McGill University, Montreal, Q.C., H3A 2T8 (Canada); Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Yao, York-Peng, E-mail: yyao@umich.edu [Department of Physics, The University of Michigan Ann Arbor, MI 48109 (United States)

2016-06-15

The Cachazo–He–Yuan (CHY) formula for on-shell scattering amplitudes is extended off-shell. The off-shell amplitudes (amputated Green's functions) are Möbius invariant, and have the same momentum poles as the on-shell amplitudes. The working principles which drive the modifications to the scattering equations are mainly Möbius covariance and energy momentum conservation in off-shell kinematics. The same technique is also used to obtain off-shell massive scalars. A simple off-shell extension of the CHY gauge formula which is Möbius invariant is proposed, but its true nature awaits further study.

High performance of PbSe/PbS core/shell quantum dot heterojunction solar cells: short circuit current enhancement without the loss of open circuit voltage by shell thickness control.

Science.gov (United States)

Choi, Hyekyoung; Song, Jung Hoon; Jang, Jihoon; Mai, Xuan Dung; Kim, Sungwoo; Jeong, Sohee

2015-11-07

We fabricated heterojunction solar cells with PbSe/PbS core shell quantum dots and studied the precisely controlled PbS shell thickness dependency in terms of optical properties, electronic structure, and solar cell performances. When the PbS shell thickness increases, the short circuit current density (JSC) increases from 6.4 to 11.8 mA cm(-2) and the fill factor (FF) enhances from 30 to 49% while the open circuit voltage (VOC) remains unchanged at 0.46 V even with the decreased effective band gap. We found that the Fermi level and the valence band maximum level remain unchanged in both the PbSe core and PbSe/PbS core/shell with a less than 1 nm thick PbS shell as probed via ultraviolet photoelectron spectroscopy (UPS). The PbS shell reduces their surface trap density as confirmed by relative quantum yield measurements. Consequently, PbS shell formation on the PbSe core mitigates the trade-off relationship between the open circuit voltage and the short circuit current density. Finally, under the optimized conditions, the PbSe core with a 0.9 nm thick shell yielded a power conversion efficiency of 6.5% under AM 1.5.

Au/BiOCl heterojunction within mesoporous silica shell as stable plasmonic photocatalyst for efficient organic pollutants decomposition under visible light

International Nuclear Information System (INIS)

Yan, Xiaoqing; Zhu, Xiaohui; Li, Renhong; Chen, Wenxing

2016-01-01

Highlights: • A heterojunction of Au/BiOCl was fabricated within the mesoporous silica shell. • The compact contact between Au and BiOCl enables electrons back flow from Au to BiOCl. • Au/BiOCl@mSiO 2 plasmonic photocatalyst shows efficient visible light photoactivity. • Hydroxyl radicals are the main oxidants in formaldehyde and Rhodamine B decomposition. - Abstract: A new mesoporous silica protected plasmonic photocatalyst, Au/BiOCl@mSiO 2 , was prepared by a modified AcHE method and a subsequent UV light induced photodeposition process. The surfactant-free heterojunction allows the electrons spontaneously flow from Au to nearby BiOCl surface, leading to the accumulation of positive charges on Au surface, and negative charges on Bi species under visible light. Au/BiOCl@mSiO 2 exhibits high visible light photocatalytic efficiency in complete oxidation of aqueous formaldehyde and Rhodamin B. We showed that a positive relationship exists between the LSPR effect and rate enhancements, and leads to a hypothesis that the metallic Au LSPR enhances the photocatalytic rates on nearby semiconductors by transferring energetic electrons to BiOCl and increasing the steady-state concentration of active ·OH species by a multi-electron reduction of molecular oxygen. The ·OH species is the main oxidant in photocatalytic transformations, whose intensity is greatly enhanced in the dye-involving systems due to the synergetic effect between LSPR and dye sensitization processes. In addition, the mesoporous SiO 2 shell not only inhibits the over growth of BiOCl nanocrystals within the silica frameworks, but also protects the dissolution of chloride or Au species into aqueous solution, which ultimately makes the Au/BiOCl@mSiO 2 catalysts rather stable during photocatalysis.

TiO2 nanocrystals decorated Z-schemed core-shell CdS-CdO nanorod arrays as high efficiency anodes for photoelectrochemical hydrogen generation.

Science.gov (United States)

Li, Chia-Hsun; Hsu, Chan-Wei; Lu, Shih-Yuan

2018-07-01

TiO 2 nanocrystals decorated core-shell CdS-CdO nanorod arrays, TiO 2 @CdO/CdS NR, were fabricated as high efficiency anodes for photoelctrochemical hydrogen generation. The novel sandwich heterostructure was constructed from first growth of CdS nanorod arrays on a fluorine doped tin oxide (FTO) substrate with a hydrothermal process, followed by in situ generation of CdO thin films of single digit nanometers from the CdS nanorod surfaces through thermal oxidation, and final decoration of TiO 2 nanocrystals of 10-20 nm via a successive ionic layer absorption and reaction process. The core-shell CdS-CdO heterostructure possesses a Z-scheme band structure to enhance interfacial charge transfer, facilitating effective charge separation to suppress electron-hole recombination within CdS for much improved current density generation. The final decoration of TiO 2 nanocrystals passivates surface defects and trap states of CdO, further suppressing surface charge recombination for even higher photovoltaic conversion efficiencies. The photoelectrochemical performances of the plain CdS nanorod array were significantly improved with the formation of the sandwich heterostructure, achieving a photo current density of 3.2 mA/cm 2 at 1.23 V (vs. RHE), a 141% improvement over the plain CdS nanorod array and a 32% improvement over the CdO/CdS nanorod array. Copyright © 2018 Elsevier Inc. All rights reserved.

Multi-yolk-shell SnO2/Co3Sn2@C Nanocubes with High Initial Coulombic Efficiency and Oxygen Reutilization for Lithium Storage.

Science.gov (United States)

Su, Liwei; Xu, Yawei; Xie, Jian; Wang, Lianbang; Wang, Yuanhao

2016-12-28

The challenging problems of SnO 2 anode material for lithium ion batteries are the poor electronic conductivity and the low oxygen reutilization due to the irreversibility of Li 2 O generated in the initial discharge leading to a theoretical initial Coulombic efficiency (ICE) of only 52.4%. Different from these strategies, this work proposes a novel strategy to level up the oxygen reutilization in SnO 2 by introducing Co 3 Sn 2 nanoalloys which can release Co atoms to reversibly react with Li 2 O instead. According to this protocol, multi-yolk-shell SnO 2 /Co 3 Sn 2 @C nanocubes are designed and successfully prepared using hollow CoSn(OH) 6 nanocubes as precursors followed a hydrothermal carbon coating and calcination treatment. The unique multi-yolk-shell nanostructure offers adequate breathing space for the volumetric deformation during long-term cycling. Moreover, the removal of Li 2 O allows a high electronic conductivity and resultant rate performance. As a result, the efficient reutilization of oxygen enables a high ICE of 71.7% and a reversible capacity of 1003 mA h g -1 after 200 cycles at 100 mA g -1 . Cyclic voltammetry, cycling performance at different voltage windows, and X-ray photoelectron spectroscopy confirm the proposed mechanism. This strategy employing oxygen-poor metals or alloys provides a novel approach to enhance the oxygen reutilization in SnO 2 for higher reversibility.

The s-process in massive stars: the Shell C-burning contribution

Science.gov (United States)

Pignatari, Marco; Gallino, R.; Baldovin, C.; Wiescher, M.; Herwig, F.; Heger, A.; Heil, M.; Käppeler, F.

In massive stars the s¡ process (slow neutron capture process) is activated at different tempera- tures, during He¡ burning and during convective shell C¡ burning. At solar metallicity, the neu- tron capture process in the convective C¡ shell adds a substantial contribution to the s¡ process yields made by the previous core He¡ burning, and the final results carry the signature of both processes. With decreasing metallicity, the contribution of the C¡ burning shell to the weak s¡ process rapidly decreases, because of the effect of the primary neutron poisons. On the other hand, also the s¡ process efficiency in the He core decreases with metallicity.

Hierarchical tailoring of strut architecture to control permeability of additive manufactured titanium implants.

Science.gov (United States)

Zhang, Z; Jones, D; Yue, S; Lee, P D; Jones, J R; Sutcliffe, C J; Jones, E

2013-10-01

Porous titanium implants are a common choice for bone augmentation. Implants for spinal fusion and repair of non-union fractures must encourage blood flow after implantation so that there is sufficient cell migration, nutrient and growth factor transport to stimulate bone ingrowth. Additive manufacturing techniques allow a large number of pore network designs. This study investigates how the design factors offered by selective laser melting technique can be used to alter the implant architecture on multiple length scales to control and even tailor the flow. Permeability is a convenient parameter that characterises flow, correlating to structure openness (interconnectivity and pore window size), tortuosity and hence flow shear rates. Using experimentally validated computational simulations, we demonstrate how additive manufacturing can be used to tailor implant properties by controlling surface roughness at a microstructual level (microns), and by altering the strut ordering and density at a mesoscopic level (millimetre). Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

Inner-shell excitation and ionic fragmentation of molecules

International Nuclear Information System (INIS)

Hitchcock, A.P.; Tyliszczak, T.; Cavell, R.G.

1997-01-01

Inner-shell excitation and associated decay spectroscopies are site specific probes of electronic and geometrical structure and photoionization dynamics. X-ray absorption probes the geometric and electronic structure, while time-of-flight mass spectrometry with multi-coincidence detection provides information on the photofragmentation dynamics of the initially produced inner-shell state. Auger decay of inner-shell excited and ionised states is an efficient source of multiply charged ions. The charge separation and fragmentation of these species, studied by photoelectron-photoion-photoion coincidence (also called charge separation mass spectrometry) gives insights into bonding and electronic structure. In molecules, the dependence of the fragmentation process on the X-ray energy can reveal cases of site and/or state selective fragmentation. At the ALS the authors have examined the soft X-ray spectroscopy and ionic fragmentation of a number of molecules, including carboranes, silylenes, phosphorus halides, SF 6 and CO 2 . Their work is illustrated using results from the carborane and PF 3 studies

Inner-shell excitation and ionic fragmentation of molecules

Energy Technology Data Exchange (ETDEWEB)

Hitchcock, A.P.; Tyliszczak, T. [McMaster Univ., Hamilton, Ontario (Canada); Cavell, R.G. [Univ. of Alberta, Edmonton (Canada)] [and others

1997-04-01

Inner-shell excitation and associated decay spectroscopies are site specific probes of electronic and geometrical structure and photoionization dynamics. X-ray absorption probes the geometric and electronic structure, while time-of-flight mass spectrometry with multi-coincidence detection provides information on the photofragmentation dynamics of the initially produced inner-shell state. Auger decay of inner-shell excited and ionised states is an efficient source of multiply charged ions. The charge separation and fragmentation of these species, studied by photoelectron-photoion-photoion coincidence (also called charge separation mass spectrometry) gives insights into bonding and electronic structure. In molecules, the dependence of the fragmentation process on the X-ray energy can reveal cases of site and/or state selective fragmentation. At the ALS the authors have examined the soft X-ray spectroscopy and ionic fragmentation of a number of molecules, including carboranes, silylenes, phosphorus halides, SF{sub 6} and CO{sub 2}. Their work is illustrated using results from the carborane and PF{sub 3} studies.

Wavefunction effects in inner shell ionization of light atoms by protons

International Nuclear Information System (INIS)

Aashamar, K.; Amundsen, P.A.

An efficient computer code for calculating the impact parameter distribution of atomic ionization probabilities caused by charged particle impact, has been developed. The programme is based on the semiclassical approximation, and it allows the use of an arbitrary atomic central potential for deriving the one-electron orbitals that form the basis for the description of the atomic states. Extensive calculations are reported for proton induced K-shell ionization in carbon and neon, covering energies in the range 0.1-10 MeV. Some calculations on proton-argon L-shell ionization are also reported. Comparison of the results obtained using (screened) hydrogenic potentials and the recently reported energy- optimized effective atomic central potentials, respectively demonstrates that wavefunction effects are generally important for inner-shell ionization of light atoms. The agreement between theory and experiment in the K-shell case is improved for fast collisions upon using better wavefunctions. (Auth.)

Low temperature grown ZnO@TiO{sub 2} core shell nanorod arrays for dye sensitized solar cell application

Energy Technology Data Exchange (ETDEWEB)

Goh, Gregory Kia Liang [Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology, and Research), 3 Research Link, 117602 Singapore (Singapore); Le, Hong Quang, E-mail: lehq@imre.a-star.edu.sg [Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology, and Research), 3 Research Link, 117602 Singapore (Singapore); Huang, Tang Jiao; Hui, Benjamin Tan Tiong [Department of Materials Science and Engineering (DMSE), Faculty of Engineering National University of Singapore (NUS) BLK E3A, #04-10, 7 Engineering Drive 1, Singapore 117574 (Singapore)

2014-06-01

High aspect ratio ZnO nanorod arrays were synthesized on fluorine-doped tin oxide glasses via a low temperature solution method. By adjusting the growth condition and adding polyethylenimine, ZnO nanorod arrays with tunable length were successfully achieved. The ZnO@TiO{sub 2} core shells structures were realized by a fast growth method of immersion into a (NH{sub 4}){sub 2}·TiF{sub 6} solution. Transmission electron microscopy, X-ray Diffraction and energy dispersive X-ray measurements all confirmed the existence of a titania shell uniformly covering the ZnO nanorod's surface. Results of solar cell testing showed that addition of a TiO{sub 2} shell to the ZnO nanorod significantly increased short circuit current (from 4.2 to 5.2 mA/cm{sup 2}), open circuit voltage (from 0.6 V to 0.8 V) and fill factor (from 42.8% to 73.02%). The overall cell efficiency jumped from 1.1% for bare ZnO nanorod to 3.03% for a ZnO@TiO{sub 2} core shell structured solar cell with a 18–22 nm shell thickness, a nearly threefold increase. - Graphical abstract: The synthesis process of coating TiO{sub 2} shell onto ZnO nanorod core is shown schematically. A thin, uniform, and conformal shell had been grown on the surface of the ZnO core after immersing in the (NH{sub 4}){sub 2}·TiF{sub 6} solution for 5–15 min. - Highlights: • ZnO@TiO{sub 2} core shell nanorod has been grown on FTO substrate using low temperature solution method. • TEM, XRD, EDX results confirmed the existing of titana shell, uniformly covered rod's surface. • TiO{sub 2} shell suppressed recombination, demonstrated significant enhancement in cell's efficiency. • Core shell DSSC's efficiency achieved as high as 3.03%, 3 times higher than that of ZnO nanorods.

Predictable Particle Engineering: Programming the Energy Level, Carrier Generation, and Conductivity of Core-Shell Particles.

Science.gov (United States)

Yuan, Conghui; Wu, Tong; Mao, Jie; Chen, Ting; Li, Yuntong; Li, Min; Xu, Yiting; Zeng, Birong; Luo, Weiang; Yu, Lingke; Zheng, Gaofeng; Dai, Lizong

2018-06-20

Core-shell structures are of particular interest in the development of advanced composite materials as they can efficiently bring different components together at nanoscale. The advantage of this structure greatly relies on the crucial design of both core and shell, thus achieving an intercomponent synergistic effect. In this report, we show that decorating semiconductor nanocrystals with a boronate polymer shell can easily achieve programmable core-shell interactions. Taking ZnO and anatase TiO 2 nanocrystals as inner core examples, the effective core-shell interactions can narrow the band gap of semiconductor nanocrystals, change the HOMO and LUMO levels of boronate polymer shell, and significantly improve the carrier density of core-shell particles. The hole mobility of core-shell particles can be improved by almost 9 orders of magnitude in comparison with net boronate polymer, while the conductivity of core-shell particles is at most 30-fold of nanocrystals. The particle engineering strategy is based on two driving forces: catechol-surface binding and B-N dative bonding and having a high ability to control and predict the shell thickness. Also, this approach is applicable to various inorganic nanoparticles with different components, sizes, and shapes.

Water Quality of Trickling Biological Periwinkle Shells Filter for ...

African Journals Online (AJOL)

Studies were carried on the design, efficiency and economics of trickling biological periwinkle shells filter in recirculating aquaculture systems for catfish production. The designed biofilter and other system components were constructed, assembled and commissioned for pilot catfish production. The system with the designed ...

Funzionalizzazione della mandibola dopo ricostruzione con lembo libero rivascolarizzato di fibula "single strut". Al di là del deficit di verticalità.

OpenAIRE

Gessaroli, Manlio

2009-01-01

Obiettivi: Valutare la modalità  più efficace per la riabilitazione funzionale del limbo libero di fibula "single strut", dopo ampie resezioni per patologia neoplastica maligna del cavo orale. Metodi: Da una casistica di 62 ricostruzioni microvascolari con limbo libero di fibula, 11 casi sono stati selezionati per essere riabilitati mediante protesi dentale a supporto implantare. 6 casi sono stati trattati senza ulteriori procedure chirurgiche ad eccezione dell'implantologia (gruppo 1), a...

Dominant thermogravimetric signatures of lignin in cashew shell as compared to cashew shell cake.

Science.gov (United States)

Gangil, Sandip

2014-03-01

Dominant thermogravimetric signatures related to lignin were observed in cashew shell as compared to these signatures in cashew shell cake. The phenomenon of weakening of lignin from cashew shell to cashew shell cake was explained on the basis of changes in the activation energies. The pertinent temperature regimes responsible for the release of different constituents of both the bio-materials were identified and compared. The activation energies of cashew shell and cashew shell cake were compared using Kissinger-Akahira-Sunose method. Thermogravimetric profiling of cashew shell and cashew shell cake indicated that these were different kinds of bio-materials. Copyright © 2013 Elsevier Ltd. All rights reserved.

Shell coal IGCCS with carbon capture. Conventional gas quench vs. innovative configurations

Energy Technology Data Exchange (ETDEWEB)

Martellia, E.; Consonni, S. [Politecnico di Milano, Via Scalabrini 76, Piacenza (Italy); Kreutz, T. [Princeton University, Guyot Hall, Room 129, Princeton, NJ (United States); Carbo, M.; Jansen, D. [Energy research Centre of the Netherlands ECN, P.O. Box 1, 1755 ZG, Petten (Netherlands)

2011-11-15

The Shell coal integrated gasification combined cycle (IGCC) based on the gas quench system is one of the most fuel flexible and energy efficient gasification processes because is dry feed and employs high temperature syngas coolers capable of rising high pressure steam. Indeed the efficiency of a Shell IGCC with the best available technologies is calculated to be 47-48%. However the system looses many percentage points of efficiency (up to 10) when introducing carbon capture. To overcome this penalty, two approaches have been proposed. In the first, the expensive syngas coolers are replaced by a 'partial water quench' where the raw syngas stream is cooled and humidified via direct injection of hot water. This design is less costly, but also less efficient. The second approach retains syngas coolers but instead employs novel water-gas shift (WGS) configurations that requires substantially less steam to obtain the same degree of CO conversion to CO2, and thus increases the overall plant efficiency. We simulate and optimize these novel configurations, provide a detailed thermodynamic and economic analysis and investigate how these innovations alter the plant's efficiency, cost and complexity.

Experimental Damage Identification of a Model Reticulated Shell

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Jing Xu

2017-04-01

Full Text Available The damage identification of a reticulated shell is a challenging task, facing various difficulties, such as the large number of degrees of freedom (DOFs, the phenomenon of modal localization and transition, and low modeling accuracy. Based on structural vibration responses, the damage identification of a reticulated shell was studied. At first, the auto-regressive (AR time series model was established based on the acceleration responses of the reticulated shell. According to the changes in the coefficients of the AR model between the damaged conditions and the undamaged condition, the damage of the reticulated shell can be detected. In addition, the damage sensitive factors were determined based on the coefficients of the AR model. With the damage sensitive factors as the inputs and the damage positions as the outputs, back-propagation neural networks (BPNNs were then established and were trained using the Levenberg–Marquardt algorithm (L–M algorithm. The locations of the damages can be predicted by the back-propagation neural networks. At last, according to the experimental scheme of single-point excitation and multi-point responses, the impact experiments on a K6 shell model with a scale of 1/10 were conducted. The experimental results verified the efficiency of the proposed damage identification method based on the AR time series model and back-propagation neural networks. The proposed damage identification method can ensure the safety of the practical engineering to some extent.

Dependences of optical properties of spherical two-layered nanoparticles on parameters of gold core and material shell

International Nuclear Information System (INIS)

Pustovalov, V.K.; Astafyeva, L.G.; Zharov, V.P.

2013-01-01

Modeling of nonlinear dependences of optical properties of spherical two-layered gold core and some material shell nanoparticles (NPs) placed in water on parameters of core and shell was carried out on the basis of the extended Mie theory. Efficiency cross-sections of absorption, scattering and extinction of radiation with wavelength 532 nm by core–shell NPs in the ranges of core radii r 00 =5–40 nm and of relative NP radii r 1 /r 00 =1–8 were calculated (r 1 —radius of two-layered nanoparticle). Shell materials were used with optical indexes in the ranges of refraction n 1 =0.2–1.5 and absorption k 1 =0–3.5 for the presentation of optical properties of wide classes of shell materials (including dielectrics, metals, polymers, vapor shell around gold core). Results show nonlinear dependences of optical properties of two-layered NPs on optical indexes of shell material, core r 00 and relative NP r 1 /r 00 radii. Regions with sharp decrease and increase of absorption, scattering and extinction efficiency cross-sections with changing of core and shell parameters were investigated. These dependences should be taken into account for applications of two-layered NPs in laser nanomedicine and optical diagnostics of tissues. The results can be used for experimental investigation of shell formation on NP core and optical determination of geometrical parameters of core and shell of two-layered NPs. -- Highlights: • Absorption, scattering and extinction of two-layered nanoparticles are studied. • Shell materials change in wide regions of materials (metals, dielectrics, vapor). • Effect of sharp decrease and increase of optical characteristics is established. • Explanation of sharp decreasing and increasing optical characteristics is presented

Ultrafast light matter interaction in CdSe/ZnS core-shell quantum dots

Science.gov (United States)

Yadav, Rajesh Kumar; Sharma, Rituraj; Mondal, Anirban; Adarsh, K. V.

2018-04-01

Core-shell quantum dot are imperative for carrier (electron and holes) confinement in core/shell, which provides a stage to explore the linear and nonlinear optical phenomena at the nanoscalelimit. Here we present a comprehensive study of ultrafast excitation dynamics and nonlinear optical absorption of CdSe/ZnS core shell quantum dot with the help of ultrafast spectroscopy. Pump-probe and time-resolved measurements revealed the drop of trapping at CdSe surface due to the presence of the ZnS shell, which makes more efficient photoluminescence. We have carried out femtosecond transient absorption studies of the CdSe/ZnS core-shell quantum dot by irradiation with 400 nm laser light, monitoring the transients in the visible region. The optical nonlinearity of the core-shell quantum dot studied by using the Z-scan technique with 120 fs pulses at the wavelengths of 800 nm. The value of two photon absorption coefficients (β) of core-shell QDs extracted as80cm/GW, and it shows excellent benchmark for the optical limiting onset of 2.5GW/cm2 with the low limiting differential transmittance of 0.10, that is an order of magnitude better than graphene based materials.

Study of shrimp shell derivatives for treating of low-level radioactive liquid wastes

Energy Technology Data Exchange (ETDEWEB)

Hayeripour, S. [Tonkabon Islamic Azad Univ., Tonkabon (Iran, Islamic Republic of). College of the Environment; Malmasi, S. [North Tehran Islamic Azad Univ., Tehran (Iran, Islamic Republic of). College of the Environment

2006-07-01

Chitin derivatives can be used to treat liquid wastes that include heavy metals of radionuclides. In this study, 4 types of chitin derivatives from shrimp shell waste were investigated for their potential in decontaminating and treating low-level radioactive liquid waste (LLW). The adsorption of caesium (Cs); cobalt (Co); and manganese (Mn) isotopes on chitin derivatives were investigated using a batch and column system with variations in diameter, pH, and length of treatment. Chitin derivatives included shrimp shells; de-mineralized shrimp shells; chitin extracted from shrimp shells; and chitosan extracted from shrimp shell waste. Three types of simulated solutions were prepared to study and compare adsorption performance: (1) a mono cationic solution consisting of stable isotopes; (2) a solution containing 3 stable cations; and (3) a simulated radioactive waste containing Cs-137, Co-60, and Mn-54. Results of the experiments showed that all 4 chitin derivatives were capable of adsorbing the isotopes. Despite its low pH, chitosan showed the highest adsorption efficiency. It was concluded that shrimps shells provided unreliable results under different operating conditions. The demineralized shells were suitable for removing Co from solutions. Row shells were not recommended as a suitable adsorbent for radionuclides removal. 14 refs., 2 tabs., 6 figs.

Removal of Arsenic with Oyster Shell: Experimental Measurements

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Md. Atiqur Rahman, , and

2008-12-01

Full Text Available Oyster shell has tremendous potential as a remediation material for the removal of arsenic from groundwater. A single arsenic removal system was developed with oyster shell for tube well water containing arsenic. The system removes arsenic from water by adsorption through fine oyster shell. Various conditions that affect the adsorption/desorption of arsenic were investigated. Adsorption column methods showed the removal of As(III under the following conditions: initial As concentration, 100 µg /L; oyster shell amount, 6 g; particle size, <355µm ; treatment flow rate, 1.7 mL/min; and pH 6.5. Arsenic concentration of the treated water were below the Bangladesh drinking water standard of 50 µg/L for As. The desorption efficiencies with 2M of KOH after the treatment of groundwater were in the range of 80-83%. A combination of techniques was used to measure the pH, conductivity, cations and anions. The average concentrations of other inorganic constituents of health concern (Na, K, Ca, Mg and Fe in treated water were below their respective WHO guideline for drinking. The present study might provide new avenues to achieve the arsenic concentrations required for drinking water recommended by Bangladesh and the World Health Organization (WHO.

Shell-like structures

CERN Document Server

Altenbach, Holm

2011-01-01

In this volume, scientists and researchers from industry discuss the new trends in simulation and computing shell-like structures. The focus is put on the following problems: new theories (based on two-dimensional field equations but describing non-classical effects), new constitutive equations (for materials like sandwiches, foams, etc. and which can be combined with the two-dimensional shell equations), complex structures (folded, branching and/or self intersecting shell structures, etc.) and shell-like structures on different scales (for example: nano-tubes) or very thin structures (similar

Analysis of thermal-plastic response of shells of revolution by numerical integration

International Nuclear Information System (INIS)

Leonard, J.W.

1975-01-01

An economic technique for the numerical analysis of the elasto-plastic behaviour of shells of revolution would be of considerable value in the nuclear reactor industry. A numerical method based on the numerical integration of the governing shell equations has been shown, for elastic cases, to be more efficient than the finite element method when applied to shells of revolution. In the numerical integration method, the governing differential equations of motion are converted into a set of initial-value problems. Each initial-value problem is integrated numerically between meridional boundary points and recombined so as to satisfy boundary conditions. For large-deflection elasto-plastic behaviour, the equations are nonlinear and, hence, are recombined in an iterative manner using the Newton-Raphson procedure. Suppression techniques are incorporated in order to eliminate extraneous solutions within the numerical integration procedure. The Reissner-Meissner shell theory for shells of revolution is adopted to account for large deflection and higher-order rotation effects. The computer modelling of the equations is quite general in that specific shell segment geometries, e.g. cylindrical, spherical, toroidal, conical segments, and any combinations thereof can be handled easily. (Auth.)

Finite element modeling of shell shape in the freshwater turtle Pseudemys concinna reveals a trade-off between mechanical strength and hydrodynamic efficiency.

Science.gov (United States)

Rivera, Gabriel; Stayton, C Tristan

2011-10-01

Aquatic species can experience different selective pressures on morphology in different flow regimes. Species inhabiting lotic regimes often adapt to these conditions by evolving low-drag (i.e., streamlined) morphologies that reduce the likelihood of dislodgment or displacement. However, hydrodynamic factors are not the only selective pressures influencing organismal morphology and shapes well suited to flow conditions may compromise performance in other roles. We investigated the possibility of morphological trade-offs in the turtle Pseudemys concinna. Individuals living in lotic environments have flatter, more streamlined shells than those living in lentic environments; however, this flatter shape may also make the shells less capable of resisting predator-induced loads. We tested the idea that "lotic" shell shapes are weaker than "lentic" shell shapes, concomitantly examining effects of sex. Geometric morphometric data were used to transform an existing finite element shell model into a series of models corresponding to the shapes of individual turtles. Models were assigned identical material properties and loaded under identical conditions, and the stresses produced by a series of eight loads were extracted to describe the strength of the shells. "Lotic" shell shapes produced significantly higher stresses than "lentic" shell shapes, indicating that the former is weaker than the latter. Females had significantly stronger shell shapes than males, although these differences were less consistent than differences between flow regimes. We conclude that, despite the potential for many-to-one mapping of shell shape onto strength, P. concinna experiences a trade-off in shell shape between hydrodynamic and mechanical performance. This trade-off may be evident in many other turtle species or any other aquatic species that also depend on a shell for defense. However, evolution of body size may provide an avenue of escape from this trade-off in some cases, as changes in

The Adsorption Efficiency of Chemically Prepared Activated Carbon from Cola Nut Shells by on Methylene Blue

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Julius Ndi Nsami

2013-01-01

Full Text Available The adsorption of methylene blue from aqueous solution onto activated carbon prepared from cola nut shell has been investigated under batch mode. The influence of major parameters governing the efficiency of the process such as, solution pH, sorbent dose, initial concentration, and contact time on the removal process was investigated. The time-dependent experimental studies showed that the adsorption quantity of methylene blue increases with initial concentration and decreasing adsorbent dosage. The equilibrium time of 180 min was observed and maximum adsorption was favoured at pH 3.5. The dye removal using 0.1 g of adsorbent was more than 90%. This dosage (0.1 g was considered as the optimum dosage to remove methylene blue from aqueous solutions. The equilibrium adsorption data were analyzed by the Freundlich, Langmuir adsorption isotherm models. The kinetics of methylene blue solution was discussed by pseudo-first-order, pseudo-second-order, and Elovich models. The adsorption process follows the Elovich rate kinetic model, having a correlation coefficient in the range between 0.9811 and 1.

Cocoa Shell: A By-Product with Great Potential for Wide Application.

Science.gov (United States)

Panak Balentić, Jelena; Ačkar, Đurđica; Jokić, Stela; Jozinović, Antun; Babić, Jurislav; Miličević, Borislav; Šubarić, Drago; Pavlović, Nika

2018-06-09

Solving the problem of large quantities of organic waste, which represents an enormous ecological and financial burden for all aspects of the process industry, is a necessity. Therefore, there is an emerged need to find specific solutions to utilize raw materials as efficiently as possible in the production process. The cocoa shell is a valuable by-product obtained from the chocolate industry. It is rich in protein, dietary fiber, and ash, as well as in some other valuable bioactive compounds, such as methylxanthines and phenolics. This paper gives an overview of published results related to the cocoa shell, mostly on important bioactive compounds and possible applications of the cocoa shell in different areas. The cocoa shell, due to its nutritional value and high-value bioactive compounds, could become a desirable raw material in a large spectrum of functional, pharmaceutical, or cosmetic products, as well as in the production of energy or biofuels in the near future.

Cocoa Shell: A By-Product with Great Potential for Wide Application

Directory of Open Access Journals (Sweden)

Jelena Panak Balentić

2018-06-01

Full Text Available Solving the problem of large quantities of organic waste, which represents an enormous ecological and financial burden for all aspects of the process industry, is a necessity. Therefore, there is an emerged need to find specific solutions to utilize raw materials as efficiently as possible in the production process. The cocoa shell is a valuable by-product obtained from the chocolate industry. It is rich in protein, dietary fiber, and ash, as well as in some other valuable bioactive compounds, such as methylxanthines and phenolics. This paper gives an overview of published results related to the cocoa shell, mostly on important bioactive compounds and possible applications of the cocoa shell in different areas. The cocoa shell, due to its nutritional value and high-value bioactive compounds, could become a desirable raw material in a large spectrum of functional, pharmaceutical, or cosmetic products, as well as in the production of energy or biofuels in the near future.

Extensions to a nonlinear finite-element axisymmetric shell model based on Reissner's shell theory

International Nuclear Information System (INIS)

Cook, W.A.

1981-01-01

Extensions to shell analysis not usually associated with shell theory are described in this paper. These extensions involve thick shells, nonlinear materials, a linear normal stress approximation, and a changing shell thickness. A finite element shell-of-revolution model has been developed to analyze nuclear material shipping containers under severe impact conditions. To establish the limits for this shell model, the basic assumptions used in its development were studied; these are listed in this paper. Several extensions were evident from the study of these limits: a thick shell, a plastic hinge, and a linear normal stress

Supramolecular core-shell nanoparticles for photoconductive device applications

Science.gov (United States)

Cheng, Chih-Chia; Chen, Jem-Kun; Shieh, Yeong-Tarng; Lee, Duu-Jong

2016-08-01

We report a breakthrough discovery involving supramolecular-based strategies to construct novel core-shell heterojunction nanoparticles with hydrophilic adenine-functionalized polythiophene (PAT) as the core and hydrophobic phenyl-C61-butyric acid methyl ester (PCBM) as the shell, which enables the conception of new functional supramolecular assemblies for constructing functional nanomaterials for applications in optoelectronic devices. The generated nanoparticles exhibit uniform spherical shape, well-controlled tuning of particle size with narrow size distributions, and excellent electrochemical stability in solution and the solid state owing to highly efficient energy transfer from PAT to PCBM. When the PAT/PCBM nanoparticles were fabricated into a photoconducting layer in an electronic device, the resulting device showed excellent electric conduction characteristics, including an electrically-tunable voltage-controlled switch, and high short-circuit current and open-circuit voltage. These observations demonstrate how the self-assembly of PAT/PCBM into specific nanostructures may help to promote efficient charge generation and transport processes, suggesting potential for a wide variety of applications as a promising candidate material for bulk heterojunction polymer devices.

Nanocellulose Derivative/Silica Hybrid Core-Shell Chiral Stationary Phase: Preparation and Enantioseparation Performance

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Xiaoli Zhang

2016-05-01

Full Text Available Core-shell silica microspheres with a nanocellulose derivative in the hybrid shell were successfully prepared as a chiral stationary phase by a layer-by-layer self-assembly method. The hybrid shell assembled on the silica core was formed using a surfactant as template by the copolymerization reaction of tetraethyl orthosilicate and the nanocellulose derivative bearing triethoxysilyl and 3,5-dimethylphenyl groups. The resulting nanocellulose hybrid core-shell chiral packing materials (CPMs were characterized and packed into columns, and their enantioseparation performance was evaluated by high performance liquid chromatography. The results showed that CPMs exhibited uniform surface morphology and core-shell structures. Various types of chiral compounds were efficiently separated under normal and reversed phase mode. Moreover, chloroform and tetrahydrofuran as mobile phase additives could obviously improve the resolution during the chiral separation processes. CPMs still have good chiral separation property when eluted with solvent systems with a high content of tetrahydrofuran and chloroform, which proved the high solvent resistance of this new material.

Bright x-ray stainless steel K-shell source development at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

May, M. J.; Fournier, K. B.; Colvin, J. D.; Barrios, M. A.; Dewald, E. L.; Moody, J.; Patterson, J. R.; Schneider, M.; Widmann, K. [Lawrence Livermore National Laboratory, P.O. Box 808 L170, Livermore, California 94551 (United States); Hohenberger, M.; Regan, S. P. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

2015-06-15

High x-ray conversion efficiency (XRCE) K-shell sources are being developed for high energy density experiments for use as backlighters and for the testing of materials exposed to high x-ray fluxes and fluences. Recently, sources with high XRCE in the K-shell x-ray energy range of iron and nickel were investigated at the National Ignition Facility (NIF). The x-ray conversion efficiency in the 5–9 keV spectral range was determined to be 6.8% ± 0.3%. These targets were 4.1 mm diameter, 4 mm tall hollow epoxy tubes having a 50 μm thick wall supporting a tube of 3 to 3.5 μm thick stainless steel. The NIF laser deposited ∼460 kJ of 3ω light into the target in a 140 TW, 3.3 ns square pulse. The absolute x-ray emission of the source was measured by two calibrated Dante x-ray spectrometers. Time resolved images filtered for the Fe K-shell were recorded to follow the heating of the target. Time integrated high-resolution spectra were recorded in the K-shell range.

Free Vibration Characteristics of Cylindrical Shells Using a Wave Propagation Method

Directory of Open Access Journals (Sweden)

A. Ghoshal

2001-01-01

Full Text Available In the present paper, concept of a periodic structure is used to study the characteristics of the natural frequencies of a complete unstiffened cylindrical shell. A segment of the shell between two consecutive nodal points is chosen to be a periodic structural element. The present effort is to modify Mead and Bardell's approach to study the free vibration characteristics of unstiffened cylindrical shell. The Love-Timoshenko formulation for the strain energy is used in conjunction with Hamilton's principle to compute the natural propagation constants for two shell geometries and different circumferential nodal patterns employing Floquet's principle. The natural frequencies were obtained using Sengupta's method and were compared with those obtained from classical Arnold-Warburton's method. The results from the wave propagation method were found to compare identically with the classical methods, since both the methods lead to the exact solution of the same problem. Thus consideration of the shell segment between two consecutive nodal points as a periodic structure is validated. The variations of the phase constants at the lower bounding frequency for the first propagation band for different nodal patterns have been computed. The method is highly computationally efficient.

Simulations of the Light Scattering Properties of Metal/Oxide Core/Shell Nanospheres

International Nuclear Information System (INIS)

Ruffino, F.; Piccitto, G.; Grimaldi, M.G.; Ruffino, F.; Grimaldi, M.G.

2014-01-01

Given the importance of the optical properties of metal/dielectric core/shell nanoparticles, in this work we focus our attention on the light scattering properties, within the Mie framework, of some specific categories of these noteworthy nano structures. In particular, we report theoretical results of angle-dependent light scattering intensity and scattering efficiency for Ag/Ag 2 O, Al/Al 2 O 2 , Cu/Cu 2 O, Pd/PdO, and Ti/TiO 2 core/shell nanoparticles as a function of the core radius/shell thickness ratio and on a relative comparison. The results highlight the light scattering characteristics of these systems as a function of the radius/shell thickness ratio, helping in the choice of the more suitable materials and sizes for specific applications (i.e., dynamic light scattering for biological and molecular recognition, increasing light trapping in thin-film silicon, organic solar cells for achieving a higher photocurrent).

Isogeometric shell formulation based on a classical shell model

KAUST Repository

Niemi, Antti

2012-09-04

This paper constitutes the first steps in our work concerning isogeometric shell analysis. An isogeometric shell model of the Reissner-Mindlin type is introduced and a study of its accuracy in the classical pinched cylinder benchmark problem presented. In contrast to earlier works [1,2,3,4], the formulation is based on a shell model where the displacement, strain and stress fields are defined in terms of a curvilinear coordinate system arising from the NURBS description of the shell middle surface. The isogeometric shell formulation is implemented using the PetIGA and igakit software packages developed by the authors. The igakit package is a Python package used to generate NURBS representations of geometries that can be utilised by the PetIGA finite element framework. The latter utilises data structures and routines of the portable, extensible toolkit for scientific computation (PETSc), [5,6]. The current shell implementation is valid for static, linear problems only, but the software package is well suited for future extensions to geometrically and materially nonlinear regime as well as to dynamic problems. The accuracy of the approach in the pinched cylinder benchmark problem and present comparisons against the h-version of the finite element method with bilinear elements. Quadratic, cubic and quartic NURBS discretizations are compared against the isoparametric bilinear discretization introduced in [7]. The results show that the quadratic and cubic NURBS approximations exhibit notably slower convergence under uniform mesh refinement as the thickness decreases but the quartic approximation converges relatively quickly within the standard variational framework. The authors future work is concerned with building an isogeometric finite element method for modelling nonlinear structural response of thin-walled shells undergoing large rigid-body motions. The aim is to use the model in a aeroelastic framework for the simulation of flapping wings.

Distributed microscopic actuation analysis of paraboloidal membrane shells of different geometric parameters

Science.gov (United States)

Yue, Honghao; Lu, Yifan; Deng, Zongquan; Tzou, Hornsen

2018-03-01

Paraboloidal membrane shells of revolution are commonly used as key components for advanced aerospace structures and aviation mechanical systems. Due to their high flexibility and low damping property, active vibration control is of significant importance for these in-orbit membrane structures. To explore the dynamic control behavior of space flexible paraboloidal membrane shells, precision distributed actuation and control effectiveness of free-floating paraboloidal membrane shells with piezoelectric actuators are investigated. Governing equations of the shell structronic system are presented first. Then, distributed control forces and control actions are formulated. A transverse mode shape function of the paraboloidal shell based on the membrane approximation theory and specified boundary condition is assumed in the modal control force analysis. The actuator induced modal control forces on the paraboloidal shell are derived. The expressions of microscopic local modal control forces are obtained by shrinking the actuator area into infinitesimal and the four control components are investigated respectively to predict the spatial microscopic actuation behavior. Geometric parameter (height-radius ratio and shell thickness) effects on the modal actuation behavior are explored when evaluating the micro-control efficiency. Four different cases are discussed and the results reveal the fact that shallow (e.g., antennas/reflectors) and deep (e.g., rocket/missile fairing) paraboloidal shells exhibit totally different modal actuation behaviors due to their curvature differences. Analytical results in this paper can serve as guidelines for optimal actuator placement for vibration control of different paraboloidal structures.

Energy storage in ferroelectric polymer nanocomposites filled with core-shell structured polymer@BaTiO3 nanoparticles: understanding the role of polymer shells in the interfacial regions.

Science.gov (United States)

Zhu, Ming; Huang, Xingyi; Yang, Ke; Zhai, Xing; Zhang, Jun; He, Jinliang; Jiang, Pingkai

2014-11-26

The interfacial region plays a critical role in determining the electrical properties and energy storage density of dielectric polymer nanocomposites. However, we still know a little about the effects of electrical properties of the interfacial regions on the electrical properties and energy storage of dielectric polymer nanocomposites. In this work, three types of core-shell structured polymer@BaTiO3 nanoparticles with polymer shells having different electrical properties were used as fillers to prepare ferroelectric polymer nanocomposites. All the polymer@BaTiO3 nanoparticles were prepared by surface-initiated reversible-addition-fragmentation chain transfer (RAFT) polymerization, and the polymer shells were controlled to have the same thickness. The morphology, crystal structure, frequency-dependent dielectric properties, breakdown strength, leakage currents, energy storage capability, and energy storage efficiency of the polymer nanocomposites were investigated. On the other hand, the pure polymers having the same molecular structure as the shells of polymer@BaTiO3 nanoparticles were also prepared by RAFT polymerization, and their electrical properties were provided. Our results show that, to achieve nanocomposites with high discharged energy density, the core-shell nanoparticle filler should simultaneously have high dielectric constant and low electrical conductivity. On the other hand, the breakdown strength of the polymer@BaTiO3-based nanocomposites is highly affected by the electrical properties of the polymer shells. It is believed that the electrical conductivity of the polymer shells should be as low as possible to achieve nanocomposites with high breakdown strength.

Studies on bioactive peptide from Chinese soft-shelled turtle ...

African Journals Online (AJOL)

This paper dealt with a novel anti-hypertensive collagen peptide from Chinese soft-shelled turtle (Pelodiscus sinensis), which was an efficient inhibitor of angiotensin converting enzyme (ACE, EC 3.4.15.1). ACE plays an important physiological role in the regulation of blood pressure by virtue of the rennin angiotensin ...

Synthesis of low density foam shells for inertial confinement fusion experiments

International Nuclear Information System (INIS)

Lattaud, Cecile

2011-01-01

This work deals with the fabrication process of low density foam shells and the sharp control of their shape (diameter, thickness, density, sphericity, non-concentricity). During this PhD we focused on the non-concentricity criterion which has to be lower than 1%. The shells are synthesized using a microencapsulation process leading to a double emulsion and followed by a thermal polymerization at 60 C. According to the literature, three major parameters, the density of the three phases, the deformations of the shells along the process and the kinetics of the polymerization have a direct influence on the shells non-concentricity. The results obtained showed that when the density gap between the internal water phase and the organic phase increases, the TMPTMA shells non-concentricity improves. A density gap of 0.078 g.cm -3 at 60 C, leads to an average non-concentricity of 2.4% with a yield of shells of 58%. It was also shown that the synthesis process can be considered as reproducible. While using the same internal water phase, equivalent non-concentricity results are obtained using either a straight tube, a tube with areas of constriction or a short wound tube. The time required to fix the shell's shape is at least 20 minutes with thermal polymerization. So, it seems that the time spent by the shells inside the rotating flask allows the centering of the internal water phase inside the organic phase, whatever the circulation process used. In order to get higher polymerization rates and to avoid destabilization phenomena, we then focused our study on photo polymerization. When the synthesis is performed using a UV lamp with an efficient light intensity, the shells have a slightly higher thickness than the shells synthesized by thermal polymerization. Moreover, a really higher yield, around 80%, is achieved with UV polymerization. However, the average non-concentricity of the shells synthesized lays around 20%, which is really high compared to the 2.4% average

Strain in GaAs / InAs core-shell nanowire heterostructures grown on GaAs

Energy Technology Data Exchange (ETDEWEB)

Biermanns, Andreas; Davydok, Anton; Pietsch, Ullrich [Universitaet Siegen, Festkoerperphysik (Germany); Rieger, Torsten; Lepsa, Mihail Ion [Peter Gruenberg Institut 9, Forschungszentrum Juelich (Germany); JARA - Fundamentals of Future Information Technology (Germany)

2012-07-01

The growth of semiconductor nanowires (NWs) has attracted significant interest in recent years due to the possible fabrication of novel semiconductor devices for future electronic and opto-electronic applications. Compared to planar heterostructures, the nanowire approach offers an advantage regarding the possibility to form heterostructures between highly lattice mismatched systems, because the free surface of the nanowires allows to relieve the strain more efficiently. One particular way to form heterostructures in the NW geometry, is the fabrication of core-shell devices, in which a NW core is surrounded by a shell of different material. The understanding of the mutual strain between core and shell, as well as the relaxation behavior of the system are crucial for the fabrication of functional devices. In this contribution we report on first X-ray diffraction measurements of GaAs-core/InAs-shell nanowires grown on GaAs(111) by molecular beam epitaxy. Using symmetric- and grazing-incidence X-ray diffraction, the relaxation state of the InAs shell as well as the strain in the GaAs core are measured as function of the InAs shell thickness, showing a gradual relaxation behavior of the shell.

Locking plate and fibular strut-graft augmentation in the reconstruction of unicameral bone cyst of proximal femur in the paediatric population.

Science.gov (United States)

Jamshidi, Khodamorad; Mirkazemi, Masoud; Izanloo, Azra; Mirzaei, Alireza

2018-01-01

Several therapeutic strategies have been used for managing unicameral bone cyst (UBC) of the proximal femur. However, there is insufficient evidence to support one treatment over another, and the optimal treatment is controversial. This study aims at describing our experience with surgical reconstruction of paediatric UBCs of the proximal femur using a proximal locking plate and fibular strut allograft. In total, 14 consecutive paediatric patients with Dormans types IB (four cases) and IIB (10 cases) UBC were assessed. Mean patient age was 8.6 ± 2.3 years, and mean follow-up period was 41.7 ± 29.8 months. Six patients (42.8%) were referred with a pathologic fracture. Clinical/radiological outcome and complication rates were evaluated at the final follow-up session. No cysts were Capanna's class III (recurrence) or IV (no response). Complete healing (Capanna's class I) was seen in ten cysts, while four other cysts healed with residual radiolucent areas (Capanna's class II). Mean healing period was 14.1 ± 5.1 (9-24 months). One patient had superficial infection, one heterotopic ossification, and one mild coxa vara, and mean Musculoskeletal Tumor Society (MSTS) score was 99.5%. According to our results, locking plate and fibular strut graft in Dormans classification types IB and IIB results in a favorable outcome in managing UBC of the proximal femur in the paediatric population.

Elastic stability of cylindrical shells with soft elastic cores: Biomimicking natural tubular structures

Science.gov (United States)

Karam, Gebran Nizar

1994-01-01

Thin walled cylindrical shell structures are widespread in nature: examples include plant stems, porcupine quills, and hedgehog spines. All have an outer shell of almost fully dense material supported by a low density, cellular core. In nature, all are loaded in combination of axial compression and bending: failure is typically by buckling. Natural structures are often optimized. Here we have analyzed the elastic buckling of a thin cylindrical shell supported by an elastic core to show that this structural configuration achieves significant weight saving over a hollow cylinder. The results of the analysis are compared with data from an extensive experimental program on uniaxial compression and four point bending tests on silicone rubber shells with and without compliant foam cores. The analysis describes the results of the mechanical tests well. Characterization of the microstructures of several natural tubular structures with foamlike cores (plant stems, quills, and spines) revealed them to be close to the optimal configurations predicted by the analytical model. Biomimicking of natural cylindrical shell structures and evolutionary design processes may offer the potential to increase the mechanical efficiency of engineering cylindrical shells.

One-step synthesis of shell/core structural boron and nitrogen co-doped graphitic carbon/nanodiamond as efficient electrocatalyst for the oxygen reduction reaction in alkaline media

International Nuclear Information System (INIS)

Liu, Xiaoxu; Wang, Yanhui; Dong, Liang; Chen, Xi; Xin, Guoxiang; Zhang, Yan; Zang, Jianbing

2016-01-01

Shell/core structural boron and nitrogen co-doped graphitic carbon/nanodiamond (BN-C/ND) non-noble metal catalyst has been synthesized by a simple one-step heat-treatment of the mixture with nanodiamond, melamine, boric acid and FeCl 3 . In the process of the surface graphitization of nanodiamond with catalysis by FeCl 3 , B and N atoms from the decomposition of boric acid and melamine were directly introduced into the graphite lattice to form B, N co-doped graphitic carbon shell, while the core still retained the diamond structure. Electrochemical measurements of the BN-C/ND catalyst show much higher electrocatalytic activities towards oxygen reduction reaction (ORR) in alkaline medium than its analogues doped with B or N alone (B-C/ND or N-C/ND). The high catalytic activity of BN-C/ND is attributed to the synergetic effect caused by co-doping of C/ND with B and N. Meanwhile, the BN-C/ND exhibits an excellent electrochemical stability due to the special shell/core structure. There is almost no alteration occurred in the cyclic voltammetry measurements for BN-C/ND before and after 5000 cycles. All experimental results prove that the BN-C/ND may be exploited as a potentially efficient and inexpensive non-noble metal cathode catalyst for ORR to substitute Pt-based catalysts in fuel cells.

Core-shell fluorescent silica nanoparticles for sensing near-neutral pH values

International Nuclear Information System (INIS)

Gao, F.; Chen, X.; Ye, Q.; Yao, Z.; Guo, X.; Wang, L.

2011-01-01

pH-responsive fluorescent core-shell silica nanoparticles (SiNPs) were prepared by encapsulating the pH-sensitive fluorophore 8-hydroxypyrene-1,3, 6-trisulfonate into their silica shell via a facile reverse microemulsion method. The resulting SiNPs were characterized by SEM, TEM, fluorescence lifetime spectroscopy, photobleaching experiments, and photoluminescence. The core-shell structure endows the SiNPs with reduced photobleaching, excellent photostability, minimized solvatachromic shift, and increased fluorescence efficiency compared to the free fluorophore in aqueous solution. The dynamic range for sensing pH ranges from 5. 5 to 9. 0. The nanosensors show excellent stability, are highly reproducible, and enable rapid detection of pH. The results obtained with the SiNPs are in good agreement with data obtained with a glass electrode. (author)

Molluscan shell colour.

Science.gov (United States)

Williams, Suzanne T

2017-05-01

The phylum Mollusca is highly speciose, and is the largest phylum in the marine realm. The great majority of molluscs are shelled, including nearly all bivalves, most gastropods and some cephalopods. The fabulous and diverse colours and patterns of molluscan shells are widely recognised and have been appreciated for hundreds of years by collectors and scientists alike. They serve taxonomists as characters that can be used to recognise and distinguish species, however their function for the animal is sometimes less clear and has been the focus of many ecological and evolutionary studies. Despite these studies, almost nothing is known about the evolution of colour in molluscan shells. This review summarises for the first time major findings of disparate studies relevant to the evolution of shell colour in Mollusca and discusses the importance of colour, including the effects of visual and non-visual selection, diet and abiotic factors. I also summarise the evidence for the heritability of shell colour in some taxa and recent efforts to understand the molecular mechanisms underpinning synthesis of shell colours. I describe some of the main shell pigments found in Mollusca (carotenoids, melanin and tetrapyrroles, including porphyrins and bile pigments), and their durability in the fossil record. Finally I suggest that pigments appear to be distributed in a phylogenetically relevant manner and that the synthesis of colour is likely to be energetically costly. © 2016 Cambridge Philosophical Society.

Zirconium(IV) oxide: New coating material for nanoresonators for shell-isolated nanoparticle-enhanced Raman spectroscopy

Science.gov (United States)

Krajczewski, Jan; Abdulrahman, Heman Burhanalden; Kołątaj, Karol; Kudelski, Andrzej

2018-03-01

One tool that can be used for determining the structure and composition of surfaces of various materials (even in in situ conditions) is shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). In SHINERS measurements, the surface under investigation is covered with a layer of surface-protected plasmonic nanoparticles, and then the Raman spectrum of the surface analysed is recorded. The plasmonic cores of the used core-shell structures act as electromagnetic nanoresonators, significantly locally enhancing the intensity of the electric field of the incident radiation, leading to a large increase in the efficiency of the generation of the Raman signal from molecules in the close proximity to the deposited SHINERS nanoresonators. A protective layer (from transparent dielectrics such as SiO2, Al2O3 or TiO2) prevents direct interaction between the plasmonic metal and the analysed surface (such interactions may lead to changes in the structure of the surface) and, in the case of plasmonic cores other than gold cores, the dielectric layer increases the chemical stability of the metal core. In this contribution, we show for the first time that core-shell nanoparticles having a silver core (both a solid and hollow one) and a shell of zirconium(IV) oxide are very efficient SHINERS nanoresonators that are significantly more stable in acidic and alkaline media than the silver-silica core-shell structures typically used for SHINERS experiments.

Biofiltration of methanol in an organic biofilter using peanut shells as medium.

Science.gov (United States)

Ramirez-Lopez, E M; Corona-Hernandez, J; Avelar-Gonzalez, F J; Omil, F; Thalasso, F

2010-01-01

Biofiltration consists of a filter-bed of organic matter serving both as carrier for the active biomass and as nutrient supply, through which the polluted gas passes. The selection of a suitable medium material is of major importance to ensure optimum biofilter efficiency. Peanut shells are an agricultural byproduct locally available in large quantities at a low price in most tropical and sub-tropical countries. A previous study showed that peanut shells are physically and chemically suitable for biofiltration. This paper presents the results obtained during a six month biofiltration experiment using peanut shells as medium and methanol as air pollutant. It is shown that peanut shells are potentially suitable as biofiltration medium, since degradation rates of up to 30 kg MeOH/m(3)d with an empty bed residence time of 19s was obtained. The biofilter showed a good resistance to shock load and no operational problems were observed.

Evaluating the bio-energy potential of groundnut shell and sugarcane bagasse waste composite

Directory of Open Access Journals (Sweden)

Olatunde Ajani Oyelaran

2015-12-01

Full Text Available An assessment has been carried out on bio-coal briquettes from coal with sugarcane bagasse and coal with groundnut shell. Proximate analyses and elemental compositions of the coal and biomasses were determined. Different samples of briquettes were produced by blending varying composition of the coal with the biomasses in the ratio of 100:0; 90:10, 80:20, 70:30, 60:40, 50:50, 40:60 and 0: 100, using calcium carbonate as a desulfurizing agent and cassava starch as a binder. A manual hydraulically operated briquetting machine was used with the pressure kept at 5MPa. The results of the properties evaluated shows that biomass increases the burning efficiency of briquettes with increase in the biomass material, increasing combustion rate, faster ignition, producing lesser ash and fewer pollutants. Results obtained shows that the calorific value of briquettes produced from coal-groundnut shells and coal-sugarcane bagasse ranges from 16.94 - 20.81 and 17.31 – 21.03 MJ/kg respectively. The ignition time ranges from 6.9 – 12.5 minutes for coal-groundnut shells briquettes while that of coal-sugarcane bagasse ranges from 6.5 – 11.1 minutes. The bio-coal blends with sugarcane bagasse were better than that of groundnut shells. However, both sugarcane bagasse and groundnut shells produce bio-coal briquettes that are very efficient, providing sufficient heat as at the time necessary, generating less smoke and gases (e.g sulphur that are harmful to environment, and generating less ash, as these have adverse effect during cooking.

Sexual selection on land snail shell ornamentation: a hypothesis that may explain shell diversity

Directory of Open Access Journals (Sweden)

Schilthuizen Menno

2003-06-01

Full Text Available Abstract Background Many groups of land snails show great interspecific diversity in shell ornamentation, which may include spines on the shell and flanges on the aperture. Such structures have been explained as camouflage or defence, but the possibility that they might be under sexual selection has not previously been explored. Presentation of the hypothesis The hypothesis that is presented consists of two parts. First, that shell ornamentation is the result of sexual selection. Second, that such sexual selection has caused the divergence in shell shape in different species. Testing the hypothesis The first part of the hypothesis may be tested by searching for sexual dimorphism in shell ornamentation in gonochoristic snails, by searching for increased variance in shell ornamentation relative to other shell traits, and by mate choice experiments using individuals with experimentally enhanced ornamentation. The second part of the hypothesis may be tested by comparing sister groups and correlating shell diversity with degree of polygamy. Implications of the hypothesis If the hypothesis were true, it would provide an explanation for the many cases of allopatric evolutionary radiation in snails, where shell diversity cannot be related to any niche differentiation or environmental differences.

Core - shell upconversion nanoparticle - semiconductor heterostructures for photodynamic therapy

Science.gov (United States)

Dou, Qing Qing; Rengaramchandran, Adith; Selvan, Subramanian Tamil; Paulmurugan, Ramasamy; Zhang, Yong

2015-02-01

Core-shell nanoparticles (CSNPs) with diverse chemical compositions have been attracting greater attention in recent years. However, it has been a challenge to develop CSNPs with different crystal structures due to the lattice mismatch of the nanocrystals. Here we report a rational design of core-shell heterostructure consisting of NaYF4:Yb,Tm upconversion nanoparticle (UCN) as the core and ZnO semiconductor as the shell for potential application in photodynamic therapy (PDT). The core-shell architecture (confirmed by TEM and STEM) enables for improving the loading efficiency of photosensitizer (ZnO) as the semiconductor is directly coated on the UCN core. Importantly, UCN acts as a transducer to sensitize ZnO and trigger the generation of cytotoxic reactive oxygen species (ROS) to induce cancer cell death. We also present a firefly luciferase (FLuc) reporter gene based molecular biosensor (ARE-FLuc) to measure the antioxidant signaling response activated in cells during the release of ROS in response to the exposure of CSNPs under 980 nm NIR light. The breast cancer cells (MDA-MB-231 and 4T1) exposed to CSNPs showed significant release of ROS as measured by aminophenyl fluorescein (APF) and ARE-FLuc luciferase assays, and ~45% cancer cell death as measured by MTT assay, when illuminated with 980 nm NIR light.

Windows PowerShell 20 Bible

CERN Document Server

Lee, Thomas; Schill, Mark E; Tanasovski, Tome

2011-01-01

Here's the complete guide to Windows PowerShell 2.0 for administrators and developers Windows PowerShell is Microsoft's next-generation scripting and automation language. This comprehensive volume provides the background that IT administrators and developers need in order to start using PowerShell automation in exciting new ways. It explains what PowerShell is, how to use the language, and specific ways to apply PowerShell in various technologies. Windows PowerShell is Microsoft's standard automation tool and something that every Windows administrator will eventually have to understand; this b

Gold-Pluronic core-shell nanoparticles: synthesis, characterization and biological evaluation

Energy Technology Data Exchange (ETDEWEB)

Simon, Timea; Boca, Sanda [Babes-Bolyai University, Nanobiophotonics and Laser Microspectroscopy Center, Interdisciplinary Research Institute on Bio-Nano-Sciences and Faculty of Physics (Romania); Biro, Dominic [Sapientia University, Department of Mechanical Engineering, Faculty of Technical and Human Sciences (Romania); Baldeck, Patrice [Universite Joseph Fourier and CNRS, Laboratoire Interdisciplinaire de Physique, UMR 5588, CNRS (France); Astilean, Simion, E-mail: simion.astilean@phys.ubbcluj.ro [Babes-Bolyai University, Nanobiophotonics and Laser Microspectroscopy Center, Interdisciplinary Research Institute on Bio-Nano-Sciences and Faculty of Physics (Romania)

2013-04-15

This study presents the synthesis of gold-Pluronic core-shell nanoparticles by a two-step method and investigates their biological impact on cancer cells, specifically nanoparticle internalization and cytotoxicity. Uniform, 9-10-nm-sized, hydrophobic gold nanoparticles were synthesized in organic phase by reducing gold salt with oleylamine, after which oleylamine-protected gold nanoparticles were phase-transferred into aqueous medium using Pluronic F127 block copolymer, resulting in gold-Pluronic core-shell nanoparticles with a mean hydrodynamic diameter of {approx}35 nm. The formation and phase-transfer of gold nanoparticles were analyzed by UV-Vis absorption spectroscopy, transmission electron microscopy, and dynamic light scattering. The obtained gold-Pluronic core-shell nanoparticles proved to be highly stable in salted solution. Cytotoxicity tests showed no modification of cellular viability in the presence of properly purified particles. Furthermore, dark-field cellular imaging demonstrated that gold-Pluronic nanoparticles were able to be efficiently uptaken by cells, being internalized through nonspecific endocytosis. The high stability, proven biocompatibility, and imaging properties of gold-Pluronic core-shell nanoparticles hold promise for relevant intracellular applications, with such a design providing the feasibility to combine all multiple functionalities in one nanoparticle for simultaneous detection and imaging.

Gold–Pluronic core–shell nanoparticles: synthesis, characterization and biological evaluation

International Nuclear Information System (INIS)

Simon, Timea; Boca, Sanda; Biro, Dominic; Baldeck, Patrice; Astilean, Simion

2013-01-01

This study presents the synthesis of gold–Pluronic core–shell nanoparticles by a two-step method and investigates their biological impact on cancer cells, specifically nanoparticle internalization and cytotoxicity. Uniform, 9–10-nm-sized, hydrophobic gold nanoparticles were synthesized in organic phase by reducing gold salt with oleylamine, after which oleylamine-protected gold nanoparticles were phase-transferred into aqueous medium using Pluronic F127 block copolymer, resulting in gold–Pluronic core–shell nanoparticles with a mean hydrodynamic diameter of ∼35 nm. The formation and phase-transfer of gold nanoparticles were analyzed by UV–Vis absorption spectroscopy, transmission electron microscopy, and dynamic light scattering. The obtained gold–Pluronic core–shell nanoparticles proved to be highly stable in salted solution. Cytotoxicity tests showed no modification of cellular viability in the presence of properly purified particles. Furthermore, dark-field cellular imaging demonstrated that gold–Pluronic nanoparticles were able to be efficiently uptaken by cells, being internalized through nonspecific endocytosis. The high stability, proven biocompatibility, and imaging properties of gold–Pluronic core–shell nanoparticles hold promise for relevant intracellular applications, with such a design providing the feasibility to combine all multiple functionalities in one nanoparticle for simultaneous detection and imaging.

Studies on II-VI and III-V semiconductor nanostructures. Introduction of the core/shell/shell structure and development of CdSe nanocrystals in an automatized procedure; Untersuchungen an II-VI und III-V Halbleiternanostrukturen. Einfuehrung der Core/shell/shell-Struktur und Darstellung von CdSe-Nanokristallen in einem automatisierten Verfahren

Energy Technology Data Exchange (ETDEWEB)

Mekis, I.

2005-11-15

The work in this dissertation is focused on the development and characterization of fluorescent II-VI and III-V-Nanomaterials. Highly luminescent and photostable Nanocrystals with narrow size distributions were prepared. It was shown that nearly monodisperse CdSe-Nanocrystals could be prepared from Cd(Ac){sub 2} and TOPSe in a mixture of TOPO/TOP/HDA/TDPA. Nearly monodisperse CdSe/CdS-Core/shell-Nanocrystals have been prepared in a one-pot-synthesis by injection of H{sub 2}S-Gas into a freshly prepared crude solution of CdSe. The passivation of the CdSe-core with an inorganic shell of CdS resulted in the drastic improvement of the photoluminescence-efficiency of the colloidal solution. Reproducible room-temperature quantum yields reached up to a value of 85%. Photostability investigations have proved the enhanced stability of CdSe/CdS-Nanocrystals compared to CdSe-Nanocrystals under illumination with UV-Light. A novel type of luminescent semiconductor nanocrystal structure has been developed, consisting of a CdSe core and two anorganic shells. Highly fluorescent and nearly monodisperse CdSe/CdS/ZnS- and CdSe/ZnSe/ZnS-Core/shell/shell-nanocrystals have been prepared via organometallic- and acetate-precursors. The Core/she ll/shell particles reached reproducible room-temperature quantum yields up to 85%. Photostability investigations among CdSe-core, CdSe/CdS-Core/shell- and CdSe/CdS/ZnS- Core/shell/-shell-nanocrystals under illumination with UV-light have proved the highest photostability of the Core/shell/shell-particles. The photostabilities of CdSe/ZnSe/ZnS-and CdSe/ZnS-nanocrystals were compared under illumination with intense laser-beam in air. Another part of this work focused on the development of an automated synthesis procedure of CdSe-nanocrystals by constructing and implementing a flow-reactor system. The size and structure of prepared nanocrystals depended considerably on the Cd:Se-precursorratio and the flow-rate. The preparation of CdSe using Cd(Ac)2

Analytic Solution to Shell Boundary – Value Problems

Directory of Open Access Journals (Sweden)

Yu. I. Vinogradov

2015-01-01

Full Text Available Object of research is to find analytical solution to the shell boundary – value problems, i.e. to consider the solution for a class of problems concerning the mechanics of hoop closed shells strain.The objective of work is to create an analytical method to define a stress – strain state of shells under non-axisymmetric loading. Thus, a main goal is to derive the formulas – solutions of the linear ordinary differential equations with variable continuous coefficients.The partial derivative differential equations of mechanics of shells strain by Fourier's method of variables division are reduced to the system of the differential equations with ordinary derivatives. The paper presents the obtained formulas to define solutions of the uniform differential equations and received on their basis formulas to define a particular solution depending on a type of the right parts of the differential equations.The analytical algorithm of the solution of a boundary task uses an approach to transfer the boundary conditions to the randomly chosen point of an interval of changing independent variable through the solution of the canonical matrix ordinary differential equation with the subsequent solution of system of algebraic equations for compatibility of boundary conditions at this point. Efficiency of algorithm is based on the fact that the solution of the ordinary differential equations is defined as the values of Cauchy – Krylova functions, which meet initial arbitrary conditions.The results of researches presented in work are useful to experts in the field of calculus mathematics, dealing with solution of systems of linear ordinary differential equations and creation of effective analytical computing methods to solve shell boundary – value problems.

TWO-DIMENSIONAL APPROXIMATION OF EIGENVALUE PROBLEMS IN SHELL THEORY: FLEXURAL SHELLS

Institute of Scientific and Technical Information of China (English)

无

2000-01-01

The eigenvalue problem for a thin linearly elastic shell, of thickness 2e, clamped along its lateral surface is considered. Under the geometric assumption on the middle surface of the shell that the space of inextensional displacements is non-trivial, the authors obtain, as ε→0,the eigenvalue problem for the two-dimensional"flexural shell"model if the dimension of the space is infinite. If the space is finite dimensional, the limits of the eigenvalues could belong to the spectra of both flexural and membrane shells. The method consists of rescaling the variables and studying the problem over a fixed domain. The principal difficulty lies in obtaining suitable a priori estimates for the scaled eigenvalues.

Remarkable efficiency of phosphate removal: Ferrate(VI)-induced in situ sorption on core-shell nanoparticles.

Science.gov (United States)

Kralchevska, Radina P; Prucek, Robert; Kolařík, Jan; Tuček, Jiří; Machala, Libor; Filip, Jan; Sharma, Virender K; Zbořil, Radek

2016-10-15

Despite the importance of phosphorus as a nutrient for humans and its role in ecological sustainability, its high abundance, resulting in large part from human activities, causes eutrophication that negatively affects the environment and public health. Here, we present the use of ferrate(VI) as an alternative agent for removing phosphorus from aqueous media. We address the mechanism of phosphate removal as a function of the Fe/P mass ratio and the pH value of the solution. The isoelectric point of γ-Fe2O3 nanoparticles, formed as dominant Fe(VI) decomposition products, was identified to play a crucial role in predicting their efficiency in removing of phosphates. Importantly, it was found that the removal efficiency dramatically changes if Fe(VI) is added before (ex-situ conditions) or after (in-situ conditions) the introduction of phosphates into water. Removal under in-situ conditions showed remarkable sorption capacity of 143.4 mg P per gram of ferric precipitates due to better accessibility of active surface sites on in-situ formed ferric oxides/oxyhydroxides. At pH = 6.0-7.0, complete removal of phosphates was observed at a relatively low Fe/P mass ratio (5:1). The results show that phosphates are removed from water solely by sorption on the surface of γ-Fe2O3/γ-FeOOH core/shell nanoparticles. The advantages of Fe(VI) utilization include its environmentally friendly nature, the possibility of easy separation of the final product from water by a magnetic field or by natural settling, and the capacity for successful phosphate elimination at pH values near the neutral range and at low Fe/P mass ratios. Copyright © 2016 Elsevier Ltd. All rights reserved.

Zero-valent iron treatment of dark brown colored coffee effluent: Contributions of a core-shell structure to pollutant removals.

Science.gov (United States)

Tomizawa, Mayuka; Kurosu, Shunji; Kobayashi, Maki; Kawase, Yoshinori

2016-12-01

The decolorization and total organic carbon (TOC) removal of dark brown colored coffee effluent by zero-valent iron (ZVI) have been systematically examined with solution pH of 3.0, 4.0, 6.0 and 8.0 under oxic and anoxic conditions. The optimal decolorization and TOC removal were obtained at pH 8.0 with oxic condition. The maximum efficiencies of decolorization and TOC removal were 92.6 and 60.2%, respectively. ZVI presented potential properties for pollutant removal at nearly neutral pH because of its core-shell structure in which shell or iron oxide/hydroxide layer on ZVI surface dominated the decolorization and TOC removal of coffee effluent. To elucidate the contribution of the core-shell structure to removals of color and TOC at the optimal condition, the characterization of ZVI surface by scanning electron microscopy (SEM) with an energy dispersive X-ray spectroscope (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) was conducted. It was confirmed that the core-shell structure was formed and the shell on ZVI particulate surface and the precipitates formed during the course of ZVI treatment consisted of iron oxides and hydroxides. They were significantly responsible for decolorization and TOC removal of coffee effluent via adsorption to shell on ZVI surface and inclusion into the precipitates rather than the oxidative degradation by OH radicals and the reduction by emitted electrons. The presence of dissolved oxygen (DO) enhanced the formation of the core-shell structure and as a result improved the efficiency of ZVI treatment for the removal of colored components in coffee effluents. ZVI was found to be an efficient material toward the treatment of coffee effluents. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dye-sensitized Pt@TiO2 core–shell nanostructures for the efficient photocatalytic generation of hydrogen

Directory of Open Access Journals (Sweden)

Jun Fang

2014-03-01

Full Text Available Pt@TiO2 core–shell nanostructures were prepared through a hydrothermal method. The dye-sensitization of these Pt@TiO2 core–shell structures allows for a high photocatalytic activity for the generation of hydrogen from proton reduction under visible-light irradiation. When the dyes and TiO2 were co-excited through the combination of two irradiation beams with different wavelengths, a synergic effect was observed, which led to a greatly enhanced H2 generation yield. This is attributed to the rational spatial distribution of the three components (dye, TiO2, Pt, and the vectored transport of photogenerated electrons from the dye to the Pt particles via the TiO2 particle bridge.

Dynamic model of open shell structures buried in poroelastic soils

Science.gov (United States)

Bordón, J. D. R.; Aznárez, J. J.; Maeso, O.

2017-08-01

This paper is concerned with a three-dimensional time harmonic model of open shell structures buried in poroelastic soils. It combines the dual boundary element method (DBEM) for treating the soil and shell finite elements for modelling the structure, leading to a simple and efficient representation of buried open shell structures. A new fully regularised hypersingular boundary integral equation (HBIE) has been developed to this aim, which is then used to build the pair of dual BIEs necessary to formulate the DBEM for Biot poroelasticity. The new regularised HBIE is validated against a problem with analytical solution. The model is used in a wave diffraction problem in order to show its effectiveness. It offers excellent agreement for length to thickness ratios greater than 10, and relatively coarse meshes. The model is also applied to the calculation of impedances of bucket foundations. It is found that all impedances except the torsional one depend considerably on hydraulic conductivity within the typical frequency range of interest of offshore wind turbines.

Fabrication of hierarchical core-shell polydopamine@MgAl-LDHs composites for the efficient enrichment of radionuclides

Energy Technology Data Exchange (ETDEWEB)

Zhu, Kairuo [Key Laboratory of Novel Thin Film Solar Cells, Institute of Plasma Physics, Chinese Academy Sciences, P.O. Box 1126, Hefei, 230031 (China); Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, 215123 (China); Lu, Songhua; Gao, Yang; Zhang, Rui; Tan, Xiaoli [Key Laboratory of Novel Thin Film Solar Cells, Institute of Plasma Physics, Chinese Academy Sciences, P.O. Box 1126, Hefei, 230031 (China); Chen, Changlun, E-mail: clchen@ipp.ac.cn [Key Laboratory of Novel Thin Film Solar Cells, Institute of Plasma Physics, Chinese Academy Sciences, P.O. Box 1126, Hefei, 230031 (China); Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, 215123 (China); AAM Research Group, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

2017-02-28

Highlights: • Novel hierarchical core/shell structured PDA@MgAl-LDHs were prepared. • PDA@MgAl-LDHs exhibited higher sorption ability for U(VI) and Eu(III). • PDA@MgAl-LDHs were promising materials for the enrichment of radionuclides. - Abstract: Novel hierarchical core/shell structured polydopamine@MgAl-layered double hydroxides (PDA@MgAl-LDHs) composites involving MgAl-layered double hydroxide shells and PDA cores were fabricated thought one-pot coprecipitation assembly and methodically characterized by X-ray diffraction, Fourier transformed infrared spectroscopy, scanning/transmission electron microscopy, selected area electron diffraction, elemental mapping, thermogravimetric analysis and X-ray photoelectron spectroscopy technologies. U(VI) and Eu(III) sorption experiments showed that the PDA@MgAl-LDHs exhibited higher sorption ability with a maximum sorption capacity of 142.86 and 76.02 mg/g at 298 K and pH 4.5, respectively. More importantly, according to XPS analyses, U(VI) and Eu(III) were sorbed on PDA@MgAl-LDHs via oxygen-containing functional groups, and the chemical affinity of U(VI) by oxygen-containing functional groups is higher than that of Eu(III). These observations show great expectations in the enrichment of radionuclides from aquatic environments by PDA@MgAl-LDHs.

Revisiting chameleon gravity: Thin-shell and no-shell fields with appropriate boundary conditions

International Nuclear Information System (INIS)

Tamaki, Takashi; Tsujikawa, Shinji

2008-01-01

We derive analytic solutions of a chameleon scalar field φ that couples to a nonrelativistic matter in the weak gravitational background of a spherically symmetric body, paying particular attention to a field mass m A inside of the body. The standard thin-shell field profile is recovered by taking the limit m A r c →∞, where r c is a radius of the body. We show the existence of ''no-shell'' solutions where the field is nearly frozen in the whole interior of the body, which does not necessarily correspond to the 'zero-shell' limit of thin-shell solutions. In the no-shell case, under the condition m A r c >>1, the effective coupling of φ with matter takes the same asymptotic form as that in the thin-shell case. We study experimental bounds coming from the violation of equivalence principle as well as solar-system tests for a number of models including f(R) gravity and find that the field is in either the thin-shell or the no-shell regime under such constraints, depending on the shape of scalar-field potentials. We also show that, for the consistency with local gravity constraints, the field at the center of the body needs to be extremely close to the value φ A at the extremum of an effective potential induced by the matter coupling.

Transport comparison of multiwall carbon nanotubes by contacting outer shell and all shells.

Science.gov (United States)

Luo, Qiang; Cui, A-Juan; Zhang, Yi-Guang; Lu, Chao; Jin, Ai-Zi; Yang, Hai-Fang; Gu, Chang-Zhi

2010-11-01

Carbon nanotubes, particularly multiwall carbon nanotubes (MWCNTs) can serve as interconnects in nanoelectronic devices and integrated circuits because of their extremely large current-carrying capacity. Many experimental results about the transport properties of individual MWCNTs by contacting outer shell or all shells have been reported. In this work, a compatible method with integrated circuit manufacturing process was presented to compare the transport property of an individual multiwall carbon nanotube (MWCNT) by contacting outer shell only and all shells successively. First of the Ti/Au electrodes contacting outer shell only were fabricated onto the nanotube through the sequence of electron beam lithography (EBL) patterning, metal deposition and lift-off process. After the characterization of its transport property, focused ion beam (FIB) was used to drill holes through the same nanotube at the as-deposited electrodes. Then new contact to the holes and electrodes were made by ion-induced deposition of tungsten from W(CO)6 precursor gas. The transport results indicated that the new contact to all shells can clear up the intershell resistance and the electrical conductance of the tube can be improved about 8 times compared to that of by contacting outer shell only.

Process Development of Gallium Nitride Phosphide Core-Shell Nanowire Array Solar Cell

Science.gov (United States)

Chuang, Chen

Dilute Nitride GaNP is a promising materials for opto-electronic applications due to its band gap tunability. The efficiency of GaNxP1-x /GaNyP1-y core-shell nanowire solar cell (NWSC) is expected to reach as high as 44% by 1% N and 9% N in the core and shell, respectively. By developing such high efficiency NWSCs on silicon substrate, a further reduction of the cost of solar photovoltaic can be further reduced to 61$/MWh, which is competitive to levelized cost of electricity (LCOE) of fossil fuels. Therefore, a suitable NWSC structure and fabrication process need to be developed to achieve this promising NWSC. This thesis is devoted to the study on the development of fabrication process of GaNxP 1-x/GaNyP1-y core-shell Nanowire solar cell. The thesis is divided into two major parts. In the first parts, previously grown GaP/GaNyP1-y core-shell nanowire samples are used to develop the fabrication process of Gallium Nitride Phosphide nanowire solar cell. The design for nanowire arrays, passivation layer, polymeric filler spacer, transparent col- lecting layer and metal contact are discussed and fabricated. The property of these NWSCs are also characterized to point out the future development of Gal- lium Nitride Phosphide NWSC. In the second part, a nano-hole template made by nanosphere lithography is studied for selective area growth of nanowires to improve the structure of core-shell NWSC. The fabrication process of nano-hole templates and the results are presented. To have a consistent features of nano-hole tem- plate, the Taguchi Method is used to optimize the fabrication process of nano-hole templates.

Shell structure and orbit bifurcations in finite fermion systems

Science.gov (United States)

Magner, A. G.; Yatsyshyn, I. S.; Arita, K.; Brack, M.

2011-10-01

We first give an overview of the shell-correction method which was developed by V.M. Strutinsky as a practicable and efficient approximation to the general self-consistent theory of finite fermion systems suggested by A.B. Migdal and collaborators. Then we present in more detail a semiclassical theory of shell effects, also developed by Strutinsky following original ideas of M.C. Gutzwiller. We emphasize, in particular, the influence of orbit bifurcations on shell structure. We first give a short overview of semiclassical trace formulae, which connect the shell oscillations of a quantum system with a sum over periodic orbits of the corresponding classical system, in what is usually called the "periodic orbit theory". We then present a case study in which the gross features of a typical double-humped nuclear fission barrier, including the effects of mass asymmetry, can be obtained in terms of the shortest periodic orbits of a cavity model with realistic deformations relevant for nuclear fission. Next we investigate shell structures in a spheroidal cavity model which is integrable and allows for far-going analytical computation. We show, in particular, how period-doubling bifurcations are closely connected to the existence of the so-called "superdeformed" energy minimum which corresponds to the fission isomer of actinide nuclei. Finally, we present a general class of radial power-law potentials which approximate well the shape of a Woods-Saxon potential in the bound region, give analytical trace formulae for it and discuss various limits (including the harmonic oscillator and the spherical box potentials).

Three-dimensional strutted graphene grown by substrate-free sugar blowing for high-power-density supercapacitors

Science.gov (United States)

Wang, Xuebin; Zhang, Yuanjian; Zhi, Chunyi; Wang, Xi; Tang, Daiming; Xu, Yibin; Weng, Qunhong; Jiang, Xiangfen; Mitome, Masanori; Golberg, Dmitri; Bando, Yoshio

2013-12-01

Three-dimensional graphene architectures in the macroworld can in principle maintain all the extraordinary nanoscale properties of individual graphene flakes. However, current 3D graphene products suffer from poor electrical conductivity, low surface area and insufficient mechanical strength/elasticity; the interconnected self-supported reproducible 3D graphenes remain unavailable. Here we report a sugar-blowing approach based on a polymeric predecessor to synthesize a 3D graphene bubble network. The bubble network consists of mono- or few-layered graphitic membranes that are tightly glued, rigidly fixed and spatially scaffolded by micrometre-scale graphitic struts. Such a topological configuration provides intimate structural interconnectivities, freeway for electron/phonon transports, huge accessible surface area, as well as robust mechanical properties. The graphene network thus overcomes the drawbacks of presently available 3D graphene products and opens up a wide horizon for diverse practical usages, for example, high-power high-energy electrochemical capacitors, as highlighted in this work.

Three-dimensional strutted graphene grown by substrate-free sugar blowing for high-power-density supercapacitors

Science.gov (United States)

Wang, Xuebin; Zhang, Yuanjian; Zhi, Chunyi; Wang, Xi; Tang, Daiming; Xu, Yibin; Weng, Qunhong; Jiang, Xiangfen; Mitome, Masanori; Golberg, Dmitri; Bando, Yoshio

2013-01-01

Three-dimensional graphene architectures in the macroworld can in principle maintain all the extraordinary nanoscale properties of individual graphene flakes. However, current 3D graphene products suffer from poor electrical conductivity, low surface area and insufficient mechanical strength/elasticity; the interconnected self-supported reproducible 3D graphenes remain unavailable. Here we report a sugar-blowing approach based on a polymeric predecessor to synthesize a 3D graphene bubble network. The bubble network consists of mono- or few-layered graphitic membranes that are tightly glued, rigidly fixed and spatially scaffolded by micrometre-scale graphitic struts. Such a topological configuration provides intimate structural interconnectivities, freeway for electron/phonon transports, huge accessible surface area, as well as robust mechanical properties. The graphene network thus overcomes the drawbacks of presently available 3D graphene products and opens up a wide horizon for diverse practical usages, for example, high-power high-energy electrochemical capacitors, as highlighted in this work. PMID:24336225

Shell report 2001; Les personnes, la planete, les profits. Shell rapport 2001

Energy Technology Data Exchange (ETDEWEB)

NONE

2002-07-01

In 2001, Shell saw mixed results across the social, environmental and economic spectrum. In order to contribute to the sustainable development, the Group is on track towards meeting its target to reduce greenhouse gas emissions to 10 % below 1990 levels by the end of 2002, although there was a significant increase in spill volumes and greenhouse gas emissions rose. Shell has articulated the business case and defined seven principles of sustainable development for use across the Group in business plans and daily operations: generating robust profitability; delivering value to customers; protecting the environment; managing resources; respecting and safeguarding people; benefiting communities; and working with stakeholders. Key points from the Shell Report include: in the framework of Managing, an independent review of the Shell Nigeria Community Development programme and testing of a human rights assessment tool in Shell South Africa and the implementing of a new Diversity and Inclusiveness Standard; in the framework of the economy the cost improvements of 5,1 billion dollars, ahead of target, the second highest earnings ever in difficult market conditions and the election of Shell top brand for fifth year running by motorists; in the framework of the Social, the safety performance, the avoidance of 100 contracts for incompatibility with Shell Business Principles; in the framework of the Environment, the publication of the Fresh water usage report for the first time, the Greenhouse gas emissions, the increase of spills as a result of a small number of incidents including a pipeline rupture in Nigeria and a well blow out in Oman. The economic, environmental and social data of the Shell Report are externally verified. (A.L.B.)

Silica diatom shells tailored with Au nanoparticles enable sensitive analysis of molecules for biological, safety and environment applications

KAUST Repository

Onesto, V.; Villani, M.; Coluccio, M. L.; Majewska, R.; Alabastri, A.; Battista, E.; Schirato, A.; Calestani, D.; Coppedé , N.; Cesarelli, M.; Amato, F.; Di Fabrizio, Enzo M.; Gentile, F.

2018-01-01

Diatom shells are a natural, theoretically unlimited material composed of silicon dioxide, with regular patterns of pores penetrating through their surface. For their characteristics, diatom shells show promise to be used as low cost, highly efficient drug carriers, sensor devices or other micro-devices. Here, we demonstrate diatom shells functionalized with gold nanoparticles for the harvesting and detection of biological analytes (bovine serum albumin—BSA) and chemical pollutants (mineral oil) in low abundance ranges, for applications in bioengineering, medicine, safety, and pollution monitoring.

Silica diatom shells tailored with Au nanoparticles enable sensitive analysis of molecules for biological, safety and environment applications

KAUST Repository

Onesto, V.

2018-04-19

Diatom shells are a natural, theoretically unlimited material composed of silicon dioxide, with regular patterns of pores penetrating through their surface. For their characteristics, diatom shells show promise to be used as low cost, highly efficient drug carriers, sensor devices or other micro-devices. Here, we demonstrate diatom shells functionalized with gold nanoparticles for the harvesting and detection of biological analytes (bovine serum albumin—BSA) and chemical pollutants (mineral oil) in low abundance ranges, for applications in bioengineering, medicine, safety, and pollution monitoring.

Octahedral core–shell cuprous oxide/carbon with enhanced electrochemical activity and stability as anode for lithium ion batteries

International Nuclear Information System (INIS)

Xiang, Jiayuan; Chen, Zhewei; Wang, Jianming

2015-01-01

Highlights: • Core–shell octahedral Cu 2 O/C is prepared by a one-step method. • Carbon shell is amorphous and uniformly decorated at the Cu 2 O octahedral core. • Core–shell Cu 2 O/C exhibits markedly enhanced capability and reversibility. • Carbon shell provides fast ion/electron transfer channel. • Core–shell structure is stable during cycling. - Abstract: Core–shell Cu 2 O/C octahedrons are synthesized by a simple hydrothermal method with the help of carbonization of glucose, which reduces Cu(II) to Cu(I) at low temperature and further forms carbon shell coating at high temperature. SEM and TEM images indicate that the carbon shell is amorphous with thickness of ∼20 nm wrapping the Cu 2 O octahedral core perfectly. As anode of lithium ion batteries, the core–shell Cu 2 O/C composite exhibits high and stable columbic efficiency (98%) as well as a reversible capacity of 400 mAh g −1 after 80 cycles. The improved electrochemical performance is attributed to the novel core–shell structure, in which the carbon shell reduces the electrode polarization and promotes the charge transfer at active material/electrolyte interface, and also acts as a stabilizer to keep the octahedral structure integrity during discharge–charge processes

Iridium-decorated palladium-platinum core-shell catalysts for oxygen reduction reaction in proton exchange membrane fuel cell.

Science.gov (United States)

Wang, Chen-Hao; Hsu, Hsin-Cheng; Wang, Kai-Ching

2014-08-01

Carbon-supported Pt, Pd, Pd-Pt core-shell (Pt(shell)-Pd(core)/C) and Ir-decorated Pd-Pt core-shell (Ir-decorated Pt(shell)-Pd(core)/C) catalysts were synthesized, and their physical properties, electrochemical behaviors, oxygen reduction reaction (ORR) characteristics and proton exchange membrane fuel cell (PEMFC) performances were investigated herein. From the XRD patterns and TEM images, Ir-decorated Pt(shell)-Pd(core)/C has been confirmed that Pt was deposited on the Pd nanoparticle which had the core-shell structure. Ir-decorated Pt(shell)-Pd(core)/C has more positive OH reduction peak than Pt/C, which is beneficial to weaken the binding energy of Pt-OH during the ORR. Thus, Ir-decorated Pt(shell)-Pd(core)/C has higher ORR activity than Pt/C. The maximum power density of H2-O2 PEMFC using Ir-decorated Pt(shell)-Pd(core)/C is 792.2 mW cm(-2) at 70°C, which is 24% higher than that using Pt/C. The single-cell accelerated degradation test of PEMFC using Ir-decorated Pt(shell)-Pd(core)/C shows good durability by the potential cycling of 40,000 cycles. This study concludes that Ir-decorated Pt(shell)-Pd(core)/C has the low Pt content, but it can facilitate the low-cost and high-efficient PEMFC. Copyright © 2013 Elsevier Inc. All rights reserved.

Sonochemiluminescence observation of lipid- and polymer-shelled ultrasound contrast agents in 1.2 MHz focused ultrasound field.

Science.gov (United States)

Qiao, Yangzi; Cao, Hua; Zhang, Shusheng; Yin, Hui; Wan, Mingxi

2013-01-01

Ultrasound contrast agents (UCAs) are frequently added into the focused ultrasound field as cavitation nuclei to enhance the therapeutic efficiency. Since their presence will distort the pressure field and make the process unpredictable, comprehension of their behaviors especially the active zone spatial distribution is an important part of better monitoring and using of UCAs. As shell materials can strongly alter the acoustic behavior of UCAs, two different shells coated UCAs, lipid-shelled and polymer-shelled UCAs, in a 1.2 MHz focused ultrasound field were studied by the Sonochemiluminescence (SCL) method and compared. The SCL spatial distribution of lipid-shelled group differed from that of polymer-shelled group. The shell material and the character of focused ultrasound field work together to the SCL distribution, causing the lipid-shelled group to have a maximum SCL intensity in pre-focal region at lower input power than that of polymer-shelled group, and a brighter SCL intensity in post-focal region at high input power. The SCL inactive area of these two groups both increased with the input power. The general behavior of the UCAs can be studied by both the average SCL intensity and the backscatter signals. As polymer-shelled UCAs are more resistant to acoustic pressure, they had a higher destruction power and showed less reactivation than lipid-shelled ones. Copyright © 2012 Elsevier B.V. All rights reserved.

Ellipsoidal all-dielectric Fano resonant core-shell metamaterials

Science.gov (United States)

Reena, Reena; Kalra, Yogita; Kumar, Ajeet

2018-06-01

In this paper, ellipsoidal core (Si) and shell (SiO2) metamaterial has been proposed for highly directional properties. At the wavelength of magnetic resonance, Fano dip occurs in the backward scattering cross section and forward scattering enhancement takes place at the same wavelength so that there is an increment in the directivity. Effect on the directivity by changing the length of ellipsoidal nanoparticle along semi-axes has been analyzed. Two Fano resonances have been observed by decreasing the length of the nanoparticle along the semi-axis having electric polarization, where first and second Fano resonances are attributed to the dipole and quadrupole moments, respectively. These Fano resonant wavelengths in ellipsoidal nanoparticle exhibit higher directivity than the Kerker's type scattering or forward scattering shown by symmetrical structures like sphere. So, this core-shell metamaterial can act as an efficient directional nanoantenna.

Pickering emulsion: A novel template for microencapsulated phase change materials with polymer–silica hybrid shell

International Nuclear Information System (INIS)

Yin, Dezhong; Ma, Li; Liu, Jinjie; Zhang, Qiuyu

2014-01-01

MePCMs (microencapsulated phase change materials) with covalently bonded SiO 2 /polymer hybrid as shell were fabricated via Pickering emulsion polymerization stabilized solely by organically-modified SiO 2 particles. Morphology and core–shell structure of these microcapsules were observed by scanning electron microscopy (SEM). Thermal properties of microencapsulated 1-dodecanol were determined using DSC (differential scanning calorimetry) and TGA (thermal gravimetric analysis). The results indicate that mass ratio of St (styrene)/DVB (divinylbenzene)/dodecanol has great effect on the morphology, inner structure, microencapsulation efficiency and durability of resultant MePCMs. When ratio of St/DVB/dodecanol was 5/1/12, dodecanol content of as much as 62.8% is obtained and the utility efficiency of dodecanol reaches 94.2%. The prepared MePCMs present good durability and thermal reliability. 2.2% of core material leached away the microcapsule after suspended in water for 10 days and 5.8% of core material leached after 2000 accelerated thermal cycling. Our study demonstrated that Pickering emulsion polymerization is a simple and robust method for the preparation of MePCMs with polymer–inorganic hybrids as shell. - Highlights: • We fabricated MePCM via surfactant-free Pickering emulsion polymerization. • The shell of MePCM was composed of PS/SiO 2 organic–inorganic hybrids. • The phase change enthalpy of MePCM is 125.0 J g −1 and the utility efficiency of 1-dodecanol reached 94.2%. • Only 2.2% and 5.8% of core material lost after durability test and 2000 accelerated thermal cycling respectively

Experimental investigation of the influence of internal frames on the vibroacoustic behavior of a stiffened cylindrical shell using wavenumber analysis

Science.gov (United States)

Meyer, V.; Maxit, L.; Renou, Y.; Audoly, C.

2017-09-01

The understanding of the influence of non-axisymmetric internal frames on the vibroacoustic behavior of a stiffened cylindrical shell is of high interest for the naval or aeronautic industries. Several numerical studies have shown that the non-axisymmetric internal frame can increase the radiation efficiency significantly in the case of a mechanical point force. However, less attention has been paid to the experimental verification of this statement. That is why this paper proposes to compare the radiation efficiency estimated experimentally for a stiffened cylindrical shell with and without internal frames. The experimental process is based on scanning laser vibrometer measurements of the vibrations on the surface of the shell. A transform of the vibratory field in the wavenumber domain is then performed. It allows estimating the far-field radiated pressure with the stationary phase theorem. An increase of the radiation efficiency is observed in the low frequencies. Analysis of the velocity field in the physical and wavenumber spaces allows highlighting the coupling of the circumferential orders at the origin of the increase in the radiation efficiency.

Local shell-to-shell energy transfer via nonlocal interactions in fluid ...

Indian Academy of Sciences (India)

However, the shell-to-shell energy transfer rate is found to be local and forward. .... interaction was strong, but the energy exchange occurred predominantly between ..... The wave-number range considered is in the inverse cascade regime.

Biodiesel Production from Castor Oil by Using Calcium Oxide Derived from Mud Clam Shell

Directory of Open Access Journals (Sweden)

S. Ismail

2016-01-01

Full Text Available The catalytic potential of calcium oxide synthesized from mud clam shell as a heterogeneous catalyst for biodiesel production was studied. The mud clam shell calcium oxide was characterized using particle size analyzer, Fourier transform infrared spectroscopy, scanning electron microscopy, and BET gas sorption analyzer. The catalyst performance of mud clam shell calcium oxide was studied in the transesterification of castor oil as biodiesel. Catalyst characterization and transesterification study results of synthesized catalyst proved the efficiency of the natural derived catalyst for biodiesel production. A highest biodiesel yield of 96.7% was obtained at optimal parameters such as 1 : 14 oil-to-methanol molar ratio, 3% w/w catalyst concentration, 60°C reaction temperature, and 2-hour reaction time. Catalyst reusability test shows that the synthesized calcium oxide from mud clam shell is reusable up to 5 times.

Removal of Nickel from Aqueous Solution by Hard-Shell Pistachios

Directory of Open Access Journals (Sweden)

Shayan Shamohammadi

2013-08-01

Full Text Available Nickel is one of the heavy metals which commonly can be found in industrial wastewater. Many studies have been done on agricultural waste for the removal of nickel from aqueous solutions. The purpose of this study is to identify hard-shell pistachios as a local attraction for removal of nickel from aqueous solution. Nickel adsorption isotherm models are studied using shell pistachios. Pistachio shell was chosen which its particle size is between 800-600 microns. The stock solution of nickel ions was prepared mixing nickel nitrate with distilled water. The results showed that the maximum absorption efficiency occurs (73.3% at pH=8. Also, it was shown that with increasing adsorbent dose, equilibrium time decreased within constant concentration. Examination of uptake isotherm models showed that models of Freundlich, BET, Radke-Praunitz, Redlich-Peterson and Sips describe data in 97% level of confidence well,  however Freundlich and Sips isotherm models has the lowest error factor 0.10597 and 0/10598 respectively and the highest correlation coefficient (0.9785. Comparison of adsorbent capacity within removal of nickel from aqueous solution shows that Pistachio shell with special absorbent surface of 1.7 m2/g and uptake capacity of 0.3984 mg/g is proper than adsorbents of Kaolinite, Bagasse, sludge-ash.

Fabrication and micro-photoluminescence property of CdSe/CdS core/shell nanowires

Energy Technology Data Exchange (ETDEWEB)

Dai, Guozhang; Gou, Guangyang; Wu, Zeming; Chen, Yu; Li, Hongjian [Central South University, Hunan Key Laboratory for Super-microstructure and Ultrafast Process, School of Physics and Electronics, Changsha, Hunan (China); Wan, Qiang [Hunan University, School of Physics and Electronics, Changsha (China); Zou, Bingsuo [Beijing Institute of Technology, Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing (China)

2015-04-01

Hetero-epitaxial CdSe/CdS core/shell nanowires (NWs) were prepared by a source-controllable chemical vapor deposition method. A two-stage growth mechanism was proposed to the growth process of the core/shell NWs. Micro-photoluminescence (μ-PL) property of individual NW was studied by a confocal microscopy system. The pure CdSe NW emits a red light with peak at 712.3 nm, which is inconsistent with the CdSe band-edge emission. The CdSe/CdS core/shell NW emits two apparent peaks, one is an intensive red emission peak centered at 715.2 nm and the other is a weak green emission peak located at 516.2 nm. The room temperature μ-PL spectrum shows that the PL intensity of CdSe NW was evidently promoted by coating the CdS shell, and this is because CdS improves the surface state optimizing the energy band structure of CdSe NW. The as-synthesized CdSe/CdS core/shell NW has more efficient PL quantum yields than pure CdSe NW and may find potential applications in nanoscale photonic devices. (orig.)

Fabrication and micro-photoluminescence property of CdSe/CdS core/shell nanowires

International Nuclear Information System (INIS)

Dai, Guozhang; Gou, Guangyang; Wu, Zeming; Chen, Yu; Li, Hongjian; Wan, Qiang; Zou, Bingsuo

2015-01-01

Hetero-epitaxial CdSe/CdS core/shell nanowires (NWs) were prepared by a source-controllable chemical vapor deposition method. A two-stage growth mechanism was proposed to the growth process of the core/shell NWs. Micro-photoluminescence (μ-PL) property of individual NW was studied by a confocal microscopy system. The pure CdSe NW emits a red light with peak at 712.3 nm, which is inconsistent with the CdSe band-edge emission. The CdSe/CdS core/shell NW emits two apparent peaks, one is an intensive red emission peak centered at 715.2 nm and the other is a weak green emission peak located at 516.2 nm. The room temperature μ-PL spectrum shows that the PL intensity of CdSe NW was evidently promoted by coating the CdS shell, and this is because CdS improves the surface state optimizing the energy band structure of CdSe NW. The as-synthesized CdSe/CdS core/shell NW has more efficient PL quantum yields than pure CdSe NW and may find potential applications in nanoscale photonic devices. (orig.)

Kinetic study of Chromium VI adsorption onto palm kernel shell activated carbon

Science.gov (United States)

Mohammad, Masita; Sadeghi Louyeh, Shiva; Yaakob, Zahira

2018-04-01

Heavy metal contamination of industrial effluent is one of the significant environmental problems due to their toxicity and its accumulation throughout the food chain. Adsorption is one of the promising methods for removal of heavy metals from aqua solution because of its simple technique, efficient, reliable and low-cost due to the utilization of residue from the agricultural industry. In this study, activated carbon from palm kernel shells has been produced through chemical activation process using zinc chloride as an activating agent and carbonized at 800 °C. Palm kernel shell activated carbon, PAC was assessed for its efficiency to remove Chromium (VI) ions from aqueous solutions through a batch adsorption process. The kinetic mechanisms have been analysed using Lagergren first-order kinetics model, second-order kinetics model and intra-particle diffusion model. The characterizations such as BET surface area, surface morphology, SEM-EDX have been done. The result shows that the activation process by ZnCl2 was successfully improved the porosity and modified the functional group of palm kernel shell. The result shows that the maximum adsorption capacity of Cr is 11.40mg/g at 30ppm initial metal ion concentration and 0.1g/50mL of adsorbent concentration. The adsorption process followed the pseudo second orders kinetic model.

Analysis of thermal-plastic response of shells of revolution by numerical integration

International Nuclear Information System (INIS)

Leonard, J.W.

1975-01-01

A numerical method based instead on the numerical integration of the governing shell equations has been shown, for elastic cases, to be more efficient than the finite element method when applied to shells of revolution. In the numerical integration method, the governing differential equations of motions are converted into a set of initial-value problems. Each initial-value problem is integrated numerically between meridional boundary points and recombined so as to satisfy boundary conditions. For large-deflection elasto-plastic behavior, the equations are nonlinear and, hence, are recombined in an iterative manner using the Newton-Raphson procedure. Suppression techniques are incorporated in order to eliminate extraneous solutions within the numerical integration procedure. The Reissner-Meissner shell theory for shells of revolution is adopted to account for large deflection and higher-order rotation effects. The computer modelling of the equations is quite general in that specific shell segment geometries, e.g. cylindrical, spherical, toroidal, conical segments, and any combinations thereof can be handled easily. The elasto-plastic constitutive relations adopted are in accordance with currently recommended constitutive equations for inelastic design analysis of FFTF Components. The Von Mises yield criteria and associated flow rule is used and the kinematic hardening law is followed. Examples are considered in which stainless steels common to LMFBR application are used

Multi-shelled ZnCo2O4 yolk-shell spheres for high-performance acetone gas sensor

Science.gov (United States)

Xiong, Ya; Zhu, Zongye; Ding, Degong; Lu, Wenbo; Xue, Qingzhong

2018-06-01

In the present study, multi-shelled ZnCo2O4 yolk-shell spheres have been successfully prepared by using carbonaceous microspheres as templates. It is found that the multi-shelled ZnCo2O4 yolk-shell spheres based sensor shows optimal sensing performances (response value of 38.2, response/recovery time of 19 s/71 s) toward 500 ppm acetone at 200 °C. In addition, this sensor exhibits a low detection limit of 0.5 ppm acetone (response value of 1.36) and a good selectivity toward hydrogen, methane, ethanol, ammonia and carbon dioxide. Furthermore, it is demonstrated that acetone gas response of multi-shelled ZnCo2O4 yolk-shell spheres is significantly better than that of ZnCo2O4 nanotubes and ZnCo2O4 nanosheets. High acetone response of the multi-shelled ZnCo2O4 yolk-shell spheres is attributed to the enhanced gas accessibility of the multi-shell morphology caused by the small crystalline size and high specific surface area while the short response/recovery time is mainly related to the rapid gas diffusion determined by the highly porous structure. Our work puts forward an exciting opportunity in designing various yolk-shelled structures for multipurpose applications.

Influence of Shell Thickness on the Colloidal Stability of Magnetic Core-Shell Particle Suspensions.

Science.gov (United States)

Neville, Frances; Moreno-Atanasio, Roberto

2018-01-01

We present a Discrete Element study of the behavior of magnetic core-shell particles in which the properties of the core and the shell are explicitly defined. Particle cores were considered to be made of pure iron and thus possessed ferromagnetic properties, while particle shells were considered to be made of silica. Core sizes ranged between 0.5 and 4.0 μm with the actual particle size of the core-shell particles in the range between 0.6 and 21 μm. The magnetic cores were considered to have a magnetization of one tenth of the saturation magnetization of iron. This study aimed to understand how the thickness of the shell hinders the formation of particle chains. Chain formation was studied with different shell thicknesses and particle sizes in the presence and absence of an electrical double layer force in order to investigate the effect of surface charge density on the magnetic core-shell particle interactions. For core sizes of 0.5 and 4.0 μm the relative shell thicknesses needed to hinder the aggregation process were approximately 0.4 and 0.6 respectively, indicating that larger core sizes are detrimental to be used in applications in which no flocculation is needed. In addition, the presence of an electrical double layer, for values of surface charge density of less than 20 mC/m 2 , could stop the contact between particles without hindering their vertical alignment. Only when the shell thickness was considerably larger, was the electrical double layer able to contribute to the full disruption of the magnetic flocculation process.

Pre-Stressing Timber-Based Plate Tensegrity Structures

DEFF Research Database (Denmark)

Falk, Andreas; Kirkegaard, Poul Henning

2012-01-01

Tensile structures occur in numerous varieties utilising combinations of tension and compression. Introducing structural plates in the basic tensegrity unit and tensegric assemblies varies the range of feasible topologies and provides the structural system with an integrated surface. The present...... paper considers the concept of plate tensegrity based on CLT plates (cross-laminated timber). It combines the principles of tensegrity with the principles of plate shells and is characterised by a plate shell stabilised by struts and cables. The paper deals with material aspects and robustness of timber...

Eco-friendly synthesis of core-shell structured (TiO2/Li2CO3) nanomaterials for low cost dye-sensitized solar cells.

Science.gov (United States)

Karuppuchamy, S; Brundha, C

2016-12-01

Core-shell structured TiO 2 /Li 2 CO 3 electrode was successfully synthesized by eco-friendly solution growth technique. TiO 2 /Li 2 CO 3 electrodes were characterized using X-ray Diffractometer (XRD), Scanning electron microscopy (SEM) and photocurrent-voltage measurements. The synthesized core-shell electrode material was sensitized with tetrabutylammonium cis-di(thiocyanato)-N,N'-bis(4-carboxylato-4'-carboxylic acid-2,2'-bipyridine)ruthenate(II) (N-719). The performance of dye-sensitized solar cells (DSCs) based on N719 dye modified TiO 2 /Li 2 CO 3 electrodes was investigated. The effect of various shell thickness on the photovoltaic performance of the core-shell structured electrode is also investigated. We found that Li 2 CO 3 shells of all thicknesses perform as inert barriers which improve open-circuit voltage (V oc ) of the DSCs. The energy conversion efficiency was greatly dependent on the thickness of Li 2 CO 3 on TiO 2 film, and the highest efficiency of 3.7% was achieved at the optimum Li 2 CO 3 shell layer. Copyright © 2015 Elsevier Inc. All rights reserved.

Effects of dietary humic substances on egg production and egg shell ...

African Journals Online (AJOL)

STORAGESEVER

2009-03-20

Mar 20, 2009 ... including 30 and 90 ppm dietary humic acid in liquid form, respectively. ... shell strength without affecting egg production and feed efficiency compared to control ..... Caecal metabolites and microbial populations in chickens consuming ... tation on the performance of laying hens fed with diets based on corn.

Interelectron correlations in photoionization of outer shells near inner shell thresholds

International Nuclear Information System (INIS)

Amusia, M Ya; Chernysheva, L V; Drukarev, E G

2015-01-01

We have studied the role of virtual excitations of inner shells upon outer shell photoionization. The calculations were performed in the frames of the Random Phase Approximation with Exchange (RPAE) and its generalized version GRPAE that take into account variation of the atomic field due to electron elimination and the inner vacancies decay. We apply both analytic approximation and numeric computations. The results are presented for 3p electrons in Ar and for 4d-electrons in Pd near inner shells thresholds. The effect considered proved to be quite noticeable. (paper)

Efficient simultaneous removal of U(VI) and Cu(II) from aqueous solution using core-shell nZVI@SA/CMC-Ca beads

International Nuclear Information System (INIS)

Shuhong Hu; Xiaoyan Lin; Wenhui Zhao; Ministry of Education, Sichuan; Xuegang Luo

2018-01-01

Core-shell nanoscale zero-valent iron@alginate/carboxymethyl cellulose sodium composite loaded with calcium (nZVI@SA/CMC-Ca) beads were synthesized in this study using coaxial electronic injection method. The adsorbent structure was characterized via FT-IR, SEM, EDX and XPS. The adsorption behavior of U(VI) and Cu(II) on core-shell nZVI@SA/CMC-Ca beads was studied under various experimental parameters like pH, contact time and temperature. The isotherm and the kinetic data, pertaining to the adsorption of U(VI) and Cu(II) by core-shell nZVI@SA/CMC-Ca beads obeyed both the Langmuir and Freundlich isotherms model and the pseudo-second-order kinetics model, respectively. The thermodynamic parameters revealed the spontaneous and endothermic nature of the adsorption. The experiment of regeneration and reusability suggested core-shell nZVI@SA/CMC-Ca bead was a regenerated material. (author)

Wrinkling of Pressurized Elastic Shells

KAUST Repository

Vella, Dominic; Ajdari, Amin; Vaziri, Ashkan; Boudaoud, Arezki

2011-01-01

We study the formation of localized structures formed by the point loading of an internally pressurized elastic shell. While unpressurized shells (such as a ping-pong ball) buckle into polygonal structures, we show that pressurized shells

Gold nanorod@iron oxide core-shell heterostructures: synthesis, characterization, and photocatalytic performance.

Science.gov (United States)

Li, Yue; Zhao, Junwei; You, Wenlong; Cheng, Danhong; Ni, Weihai

2017-03-17

Iron oxides are directly coated on the surface of cetyl-trimethylammonium bromide (CTAB)-capped gold nanorods (AuNRs) in aqueous solutions at room temperature, which results in AuNR@Fe 2 O 3 , AuNR@Fe 3 O 4 , and AuNR@Fe 2 O 3 @Fe 3 O 4 core-shell heterostructures. The iron oxide shells are uniform, smooth, with characteristic porous structure, and their thickness can be readily tuned. The shell formation is highly dependent on the reaction parameters including pH and CTAB concentration. The Fe 2 O 3 shell is amorphous and exhibits nearly zero remanence and coercivity, while the Fe 3 O 4 shell is ferromagnetic with a low saturation magnetization of about 0.5 emu g -1 due to its low crystallinity and the porous structure. At elevated temperatures achieved by plasmonic heating of the Au core, the Fe 2 O 3 shell transforms from amorphous to γ-Fe 2 O 3 and α-Fe 2 O 3 phases, while the Fe 3 O 4 phase disappears because of the oxidation of Fe 2+ . A 1.4-fold increase of photocatalytic performance is observed due to the plasmonic resonance provided by the Au core. The photocatalytic efficiency of Fe 3 O 4 is about 1.7-fold higher than Fe 2 O 3 as more surface defects are present on the Fe 3 O 4 shell, promoting the adsorption and activation of reagents on the surface during the catalytic reactions. This approach can be readily extended to other nanostructures including Au spherical nanoparticles and nanostars. These highly uniform and multifunctional core-shell heterostructures can be of great potential in a variety of energy, magnetic, and environment applications.

Equivalent Young's Modulus of Perforated Shell with Square Penetration Pattern

Energy Technology Data Exchange (ETDEWEB)

Jhung, Myung Jo; Ryu, Yong Ho [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

2011-05-15

The analysis of a plate or shell perforated with a large number of holes, by finite element method for instance, was a very costly and time-consuming technique which solves only one particular problem. But it is possible to model the perforated plate or shell and to analyze it and it is no more time-consuming theses days due to the rapid development of the computer and software. However, if a perforated plate or shell is submerged in fluid it is almost impossible to model and analyze it as is and the fluid at the same time, which is needed to investigate the effect of the fluid structure interaction. The simplest way to avoid time consuming and costly analysis of perforated plate or shell submerged in fluid is to replace the perforated plate or shell by an equivalent solid one considering weakening effect of holes. Many authors have proposed experimental or theoretical method to solve this problem for the plate. Slot and O'Donnell determined the effective elastic constants for the thick perforated plates by equating strains in the equivalent solid material to the average strains in the perforated material. O'Donnell also presented those of thin perforated plates. These results are implemented in Article A-8000 of Appendix A to the ASME code Section III, which contains a method of analysis for flat perforated plates when subjected to directly applied loads or loadings resulting from structural interaction with adjacent members. Unfortunately the effective elastic constants for the perforated shell are not found in any references. Therefore in this study the modal characteristics of the perforated shell are investigated and the equivalent material properties of perforated shell are suggested by performing several finite element analyses with respect to the ligament efficiencies

Instant Windows PowerShell

CERN Document Server

Menon, Vinith

2013-01-01

Get to grips with a new technology, understand what it is and what it can do for you, and then get to work with the most important features and tasks. A practical, hands-on tutorial approach that explores the concepts of PowerShell in a friendly manner, taking an adhoc approach to each topic.If you are an administrator who is new to PowerShell or are looking to get a good grounding in these new features, this book is ideal for you. It's assumed that you will have some experience in PowerShell and Windows Server, as well being familiar with the PowerShell command-line.

Coal option. [Shell Co

Energy Technology Data Exchange (ETDEWEB)

1978-01-01

This paper notes the necessity of developing an international coal trade on a very large scale. The role of Shell in the coal industry is examined; the regions in which Shell companies are most active are Australia, Southern Africa, Indonesia; Europe and North America. Research is being carried out on marketing and transportation, especially via slurry pipelines; coal-oil emulsions; briquets; fluidized-bed combustion; recovery of coal from potential waste material; upgrading of low-rank coals; unconventional forms of mining; coal conversion (the Shell/Koppers high-pressure coal gasification process). Techniques for cleaning flue gas (the Shell Flue Gas Desulfurization process) are being examined.

Synthesis of Small Au-Ag Core-Shell Cubes, Cuboctahedra, and Octahedra with Size Tunability and Their Optical and Photothermal Properties.

Science.gov (United States)

Chiang, Chieh; Huang, Michael H

2015-12-02

Aqueous phase synthesis of small Au-Ag core-shell nanocubes, cuboctahedra, and octahedra is achieved through the deposition of Ag shells on small octahedral Au cores. These nanocrystals show efficient photothermal activity and can assemble into supercrystals. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nuclear shell theory

CERN Document Server

de-Shalit, Amos; Massey, H S W

1963-01-01

Nuclear Shell Theory is a comprehensive textbook dealing with modern methods of the nuclear shell model. This book deals with the mathematical theory of a system of Fermions in a central field. It is divided into three parts. Part I discusses the single particle shell model. The second part focuses on the tensor algebra, two-particle systems. The last part covers three or more particle systems. Chapters on wave functions in a central field, tensor fields, and the m-Scheme are also presented. Physicists, graduate students, and teachers of nuclear physics will find the book invaluable.

Wrinkling of Pressurized Elastic Shells

KAUST Repository

Vella, Dominic

2011-10-01

We study the formation of localized structures formed by the point loading of an internally pressurized elastic shell. While unpressurized shells (such as a ping-pong ball) buckle into polygonal structures, we show that pressurized shells are subject to a wrinkling instability. We study wrinkling in depth, presenting scaling laws for the critical indentation at which wrinkling occurs and the number of wrinkles formed in terms of the internal pressurization and material properties of the shell. These results are validated by numerical simulations. We show that the evolution of the wrinkle length with increasing indentation can be understood for highly pressurized shells from membrane theory. These results suggest that the position and number of wrinkles may be used in combination to give simple methods for the estimation of the mechanical properties of highly pressurized shells. © 2011 American Physical Society.

One pot synthesis, growth mechanism and optical properties of Zn{sub 1-x}Cd{sub x}Se graded core/shell and alloy nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Sonawane, Kiran G. [Department of Physics, University of Pune, Pune 411 007 (India); Patil, K.R. [Centre for Materials Characterization, National Chemical Laboratory, Pune 411 008 (India); Mahamuni, Shailaja, E-mail: shailajamahamuni@yahoo.co.in [Department of Physics, University of Pune, Pune 411 007 (India)

2013-03-15

Comparatively higher photoluminescence yield along with robustness of core/shell semiconductor nanocrystals make them attractive candidates for studying intricate quantum size effects. Here, we report, one pot synthesis of Zn{sub 1-x}Cd{sub x}Se graded core/shell structures by exploiting change in the reactivity of precursors. Optical and structural measurements indicate formation of graded structure. Growth mechanism probed by inductively coupled plasma atomic emission spectroscopy shows formation of graded core/shell structure, with CdSe rich core and ZnSe rich shell. Annealing these nanocrystals, in chemical bath, leads to diffusion of Cd from core to shell region. Formation of Zn{sub 1-x}Cd{sub x}Se alloy is also observed in X-ray photoelectron spectroscopic measurements, confirming the diffusion of Cd from core to shell region. Substantially high photoluminescence quantum efficiency of 60% with narrow line width of about 27 nm, was observed and is attributable to the reduced strain due to graded core/shell structure. - Highlights: Black-Right-Pointing-Pointer Graded CdSe/ZnSe core-shell nanocrystals are synthesized exploiting reactivity of precursors. Black-Right-Pointing-Pointer Growth mechanism is probed using ICP-AES spectroscopy. Black-Right-Pointing-Pointer Reduced strain leads to luminescence efficiency as high as 60%. Black-Right-Pointing-Pointer Alloy formation by annealing in chemical bath is probed using XPS.

Synthesis and Plasmonic Understanding of Core/Satellite and Core Shell Nanostructures

Science.gov (United States)

Ruan, Qifeng

Localized surface plasmon resonance, which stems from the collective oscillations of conduction-band electrons, endows Au nanocrystals with unique optical properties. Au nanocrystals possess extremely large scattering/absorption cross-sections and enhanced local electromagnetic field, both of which are synthetically tunable. Moreover, when Au nanocrystals are closely placed or hybridized with semiconductors, the coupling and interaction between the individual components bring about more fascinating phenomena and promising applications, including plasmon-enhanced spectroscopies, solar energy harvesting, and cancer therapy. The continuous development in the field of plasmonics calls for further advancements in the preparation of high-quality plasmonic nanocrystals, the facile construction of hybrid plasmonic nanostructures with desired functionalities, as well as deeper understanding and efficient utilization of the interaction between plasmonic nanocrystals and semiconductor components. In this thesis, I developed a seed-mediated growth method for producing size-controlled Au nanospheres with high monodispersity and assembled Au nanospheres of different sizes into core/satellite nanostructures for enhancing Raman signals. For investigating the interactions between Au nanocrystals and semiconductors, I first prepared (Au core) (TiO2 shell) nanostructures, and then studied their synthetically controlled plasmonic properties and light-harvesting applications. Au nanocrystals with spherical shapes are desirable in plasmon-coupled systems owing to their high geometrical symmetry, which facilitates the analysis of electrodynamic responses in a classical electromagnetic framework and the investigation of quantum tunneling and nonlocal effects. I prepared remarkably uniform Au nanospheres with diameters ranging from 20 nm to 220 nm using a simple seed-mediated growth method associated with mild oxidation. Core/satellite nanostructures were assembled out of differently sized

Stability of charged thin shells

International Nuclear Information System (INIS)

Eiroa, Ernesto F.; Simeone, Claudio

2011-01-01

In this article we study the mechanical stability of spherically symmetric thin shells with charge, in Einstein-Maxwell and Einstein-Born-Infeld theories. We analyze linearized perturbations preserving the symmetry, for shells around vacuum and shells surrounding noncharged black holes.

Finite-difference analysis of shells impacting rigid barriers

International Nuclear Information System (INIS)

Pirotin, S.D.; Witmer, E.A.

1977-01-01

Nuclear power plants must be protected from the adverse effects of missile impacts. A significant category of missile impact involves deformable structures (pressure vessel components, whipping pipes) striking relatively rigid targets (concrete walls, bumpers) which act as protective devices. The response and interaction of these structures is needed to assess the adequacy of these barriers for protecting vital safety related equipment. The present investigation represents an initial attempt to develop an efficient numerical procedure for predicting the deformations and impact force time-histories of shells which impact upon a rigid target. The general large-deflection equations of motion of the shell are expressed in finite-difference form in space and integrated in time through application of the central-difference temporal operator. The effect of material nonlinearities is treated by a mechanical sublayer material model which handles the strain-hardening, Bauschinger, and strain-rate effects. The general adequacy of this shell treatment has been validated by comparing predictions with the results of various experiments in which structures have been subjected to well-defined transient forcing functions (typically high-explosive impulse loading). The 'new' ingredient addressed in the present study involves an accounting for impact interaction and response of both the target structure and the attacking body. (Auth.)

Strongly luminescent InP/ZnS core-shell nanoparticles.

Science.gov (United States)

Haubold, S; Haase, M; Kornowski, A; Weller, H

2001-05-18

The wide-bandgap semiconducting material, zinc sulfide, has been coated on indium phosphide nanoclusters to a 1-2-Å thickness. The resulting InP-ZnS core-shell particle (as shown in the TEM image; scale 1 cm=5 nm) exhibits bright luminescence at room temperature with quantum efficiencies as high as 23 %. © 2001 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.

Highly efficient enrichment of low-abundance intact proteins by core-shell structured Fe3O4-chitosan@graphene composites.

Science.gov (United States)

Zhang, Peng; Fang, Xiaoni; Yan, Guoquan; Gao, Mingxia; Zhang, Xiangmin

2017-11-01

In proteomics research, the screening and monitoring of disease biomarkers is still a major challenge, mainly due to their low concentration in biological samples. However, the universal enrichment of intact proteins has not been further studied. In this work, we developed a Fe 3 O 4 -chitosan@graphene (Fe 3 O 4 -CS@G) core-shell composite to enrich low-abundance proteins from biological samples. Fe 3 O 4 -CS@G composite holds chitosan layer decorated Fe 3 O 4 core, which improves the hydrophilicity of materials greatly. Meanwhile, the graphene nanosheets shell formed via electrostatic assembly endows the composite with huge surface area (178m 2 /g). The good water dispersibility ensures the sufficient contact opportunities between graphene composites and proteins, and the large surface area provides enough adsorption sites for the enrichment of proteins. Using Fe 3 O 4 -CS@G, four standard proteins Cyt-c, BSA, Myo and OVA were enriched with better adsorption capacity and recovery rate, compared with previously reported magnetic graphene composites. Additionally, the mechanism of compared to" is corrected into "compared with". proteins adsorption on Fe 3 O 4 -CS@G was further studied, which indicates that hydrophobic and electrostatic interaction work together to facilitate the universal and efficient enrichment of proteins. Human plasma sample was employed to further evaluate the enrichment performance of Fe 3 O 4 -CS@G. Eventually, 123 proteins were identified from one of SAX fractions of human plasma, which is much better than commercial Sep-pak C18 enrichment column (39 proteins). All these outstanding performances suggest that Fe 3 O 4 -CS@G is an ideal platform for the enrichment of low-abundance intact proteins and thus holds great potential to facilitate the identification of biomarkers from biological samples in proteomics research. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis and characterization of noble metal–titania core–shell nanostructures with tunable shell thickness

Directory of Open Access Journals (Sweden)

Bartosz Bartosewicz

2017-10-01

Full Text Available Core–shell nanostructures have found applications in many fields, including surface enhanced spectroscopy, catalysis and solar cells. Titania-coated noble metal nanoparticles, which combine the surface plasmon resonance properties of the core and the photoactivity of the shell, have great potential for these applications. However, the controllable synthesis of such nanostructures remains a challenge due to the high reactivity of titania precursors. Hence, a simple titania coating method that would allow better control over the shell formation is desired. A sol–gel based titania coating method, which allows control over the shell thickness, was developed and applied to the synthesis of Ag@TiO2 and Au@TiO2 with various shell thicknesses. The morphology of the synthesized structures was investigated using scanning electron microscopy (SEM. Their sizes and shell thicknesses were determined using tunable resistive pulse sensing (TRPS technique. The optical properties of the synthesized structures were characterized using UV–vis spectroscopy. Ag@TiO2 and Au@TiO2 structures with shell thickness in the range of ≈40–70 nm and 90 nm, for the Ag and Au nanostructures respectively, were prepared using a method we developed and adapted, consisting of a change in the titania precursor concentration. The synthesized nanostructures exhibited significant absorption in the UV–vis range. The TRPS technique was shown to be a very useful tool for the characterization of metal–metal oxide core–shell nanostructures.

Shell supports

DEFF Research Database (Denmark)

Almegaard, Henrik

2004-01-01

A new statical and conceptual model for membrane shell structures - the stringer system - has been found. The principle was first published at the IASS conference in Copenhagen (OHL91), and later the theory has been further developed (ALMO3)(ALMO4). From the analysis of the stringer model it can...... be concluded that all membrane shells can be described by a limited number of basic configurations of which quite a few have free edges....

The use of waste mussel shells for the adsorption of dyes and heavy metals

Science.gov (United States)

Papadimitriou, Chrysi A.; Krey, Grigorios; Stamatis, Nikolaos; Kallaniotis, Argyris

2016-04-01

Mussel culture is very important sector of the Greek agricultural economy. The majority of mussel culture activities take place in the area of Central Macedonia, Greece, 60% of total mussel production in Greece producing almost 12 tons of waste mussels shells on a daily basis. Currently there is no legislation concerning the disposal of mussel shells. In the present study the waste shells were used for the removal of dyes and heavy metals from aqueous solutions while powdered mussel shells were added in activated sludge processes for the removal of hexavalent chromium. Mussel shells were cleaned, dried and then crushed in order to form a powder. Powdered mussels shells were used in standard adsorption experiments for the removal of methylene blue and methyl red as well as for the removal of Cr (VI), Cd and Cu. Moreover the powdered mussel shells were added in laboratory scale activated sludge reactors treating synthetic wastewater with hexavalent chromium, in order investigate the effects in activated sludge processes and their potential attribution to the removal of hexavalent chromium. Adsorption experiments indicated almost 100% color removal, while adsorption was directly proportional to the amount of powdered mussel shells added in each case. The isotherms calculated for the case of methylene blue indicated similar adsorption capacity and properties to those of the commercially available activated carbon SAE 2, Norit. High removal efficiencies were observed for the metals, especially in the case of chromium and copper. The addition of powdered mussel shells in the activated sludge processes enhanced the removal of chromium and phosphorus, while enabled the formation of heavier activated sludge flocs and thus enhanced the settling properties of the activated sludge.

Shell coal IGCCS with carbon capture: Conventional gas quench vs. innovative configurations

International Nuclear Information System (INIS)

Martelli, Emanuele; Kreutz, Thomas; Carbo, Michiel; Consonni, Stefano; Jansen, Daniel

2011-01-01

Highlights: → We aim at defining the preferred IGCC design for dry feed gasifiers with CO 2 capture. → Multiple options of syngas cooling, humidification, and WGS are considered. → Plants are designed, modeled, numerically optimized and costs are carefully assessed. → Partial water quench has poor efficiency but low capital cost, then good performance. → Gas quench with the ECN staged WGS design has the best thermo-economic performance. -- Abstract: The Shell coal integrated gasification combined cycle (IGCC) based on the gas quench system is one of the most fuel flexible and energy efficient gasification processes because is dry feed and employs high temperature syngas coolers capable of rising high pressure steam. Indeed the efficiency of a Shell IGCC with the best available technologies is calculated to be 47-48%. However the system looses many percentage points of efficiency (up to 10) when introducing carbon capture. To overcome this penalty, two approaches have been proposed. In the first, the expensive syngas coolers are replaced by a 'partial water quench' where the raw syngas stream is cooled and humidified via direct injection of hot water. This design is less costly, but also less efficient. The second approach retains syngas coolers but instead employs novel water-gas shift (WGS) configurations that requires substantially less steam to obtain the same degree of CO conversion to CO 2 , and thus increases the overall plant efficiency. We simulate and optimize these novel configurations, provide a detailed thermodynamic and economic analysis and investigate how these innovations alter the plant's efficiency, cost and complexity.

Serial optical coherence tomography assessment of malapposed struts after everolimus-eluting stent implantation. A subanalysis from the HEAL-EES study

Energy Technology Data Exchange (ETDEWEB)

Ishida, Kohki [Cardiology Department, Cardiovascular Institute, Hospital Clínic, Institut d' Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona (Spain); Otsuki, Shuji [Division of Cardiology, Teikyo University Hospital, Tokyo (Japan); Giacchi, Giuseppe; Ortega-Paz, Luis [Cardiology Department, Cardiovascular Institute, Hospital Clínic, Institut d' Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona (Spain); Shiratori, Yoshitaka [Division of Cardiology, Teikyo University Hospital, Tokyo (Japan); Freixa, Xavier; Martín-Yuste, Victoria; Masotti, Mónica; Sabaté, Manel [Cardiology Department, Cardiovascular Institute, Hospital Clínic, Institut d' Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona (Spain); Brugaletta, Salvatore, E-mail: sabrugal@clinic.ub.es [Cardiology Department, Cardiovascular Institute, Hospital Clínic, Institut d' Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona (Spain)

2017-01-15

Background: Incomplete stent apposition (ISA) is related to stent thrombosis, which is a serious adverse event. We aim to assess the time-course of ISA after 2nd generation everolimus-eluting stent (EES) implantation. Methods: In HEAL-EES study, we enrolled 36 patients who underwent percutaneous coronary intervention (PCI) with EES. OCT imaging was performed at baseline and follow-up. Patients were randomized 1:1:1 into 3 groups according to the time in which follow-up was performed: group A (6-month), group B (9-month), and group C (12-month). In this subanalysis, patients who had ISA segments at baseline and/or follow-up OCT were analyzed. Result: At baseline, among 41 lesions in 36 patients, 20 lesions in 18 patients had ISA segments and were analyzed. At baseline, there were 3.0% ISA struts in group A (n = 8), 2.8% in group B (n = 4), and 4.5% in group C (n = 8). At follow-up, ISA struts were present in 0.09%, 0.16% and 0.64%; respectively in groups A, B, and C. At follow-up, there was a significant decrease in the frequency of ISA: group A 3.0% vs. 0.09% (p < 0.001), group B 2.8% vs. 0.16% (p < 0.001), and group C 4.5% vs. 0.64% (p < 0.001). In group A, there was one late acquired ISA at follow-up. Conclusions: In patients undergoing 2nd generation EES implantation, area of acute ISA assessed by OCT, was almost resolved at 6-month follow-up. - Highlights: • Time-course of incomplete stent apposition of everolimus-eluting stent was assessed. • Serial optical coherence tomography images at baseline and follow-up were evaluated. • Acute incomplete stent apposition was almost resolved as early as at 6 months.

A refined element-based Lagrangian shell element for geometrically nonlinear analysis of shell structures

Directory of Open Access Journals (Sweden)

Woo-Young Jung

2015-04-01

Full Text Available For the solution of geometrically nonlinear analysis of plates and shells, the formulation of a nonlinear nine-node refined first-order shear deformable element-based Lagrangian shell element is presented. Natural co-ordinate-based higher order transverse shear strains are used in present shell element. Using the assumed natural strain method with proper interpolation functions, the present shell element generates neither membrane nor shear locking behavior even when full integration is used in the formulation. Furthermore, a refined first-order shear deformation theory for thin and thick shells, which results in parabolic through-thickness distribution of the transverse shear strains from the formulation based on the third-order shear deformation theory, is proposed. This formulation eliminates the need for shear correction factors in the first-order theory. To avoid difficulties resulting from large increments of the rotations, a scheme of attached reference system is used for the expression of rotations of shell normal. Numerical examples demonstrate that the present element behaves reasonably satisfactorily either for the linear or for geometrically nonlinear analysis of thin and thick plates and shells with large displacement but small strain. Especially, the nonlinear results of slit annular plates with various loads provided the benchmark to test the accuracy of related numerical solutions.

Preparation of core-shell structured CaCO3 microspheres as rapid and recyclable adsorbent for anionic dyes

Science.gov (United States)

Zhao, Mengen; Chen, Zhenhua; Lv, Xinyan; Zhou, Kang; Zhang, Jie; Tian, Xiaohan; Ren, Xiuli; Mei, Xifan

2017-09-01

Core-shell structured CaCO3 microspheres (MSs) were prepared by a facile, one-pot method at room temperature. The adsorbent dosage and adsorption time of the obtained CaCO3 MSs were investigated. The results suggest that these CaCO3 MSs can rapidly and efficiently remove 99-100% of anionic dyes within the first 2 min. The obtained CaCO3 MSs have a high Brunauer-Emmett-Teller surface area (211.77 m2 g-1). In addition, the maximum adsorption capacity of the obtained CaCO3 MSs towards Congo red was 99.6 mg g-1. We also found that the core-shell structured CaCO3 MSs have a high recycling capability for removing dyes from water. Our results demonstrate that the prepared core-shell structured CaCO3 MSs can be used as an ideal, rapid, efficient and recyclable adsorbent to remove dyes from aqueous solution.

Statistical Mechanics of Thin Spherical Shells

Directory of Open Access Journals (Sweden)

Andrej Košmrlj

2017-01-01

Full Text Available We explore how thermal fluctuations affect the mechanics of thin amorphous spherical shells. In flat membranes with a shear modulus, thermal fluctuations increase the bending rigidity and reduce the in-plane elastic moduli in a scale-dependent fashion. This is still true for spherical shells. However, the additional coupling between the shell curvature, the local in-plane stretching modes, and the local out-of-plane undulations leads to novel phenomena. In spherical shells, thermal fluctuations produce a radius-dependent negative effective surface tension, equivalent to applying an inward external pressure. By adapting renormalization group calculations to allow for a spherical background curvature, we show that while small spherical shells are stable, sufficiently large shells are crushed by this thermally generated “pressure.” Such shells can be stabilized by an outward osmotic pressure, but the effective shell size grows nonlinearly with increasing outward pressure, with the same universal power-law exponent that characterizes the response of fluctuating flat membranes to a uniform tension.

Temporal structures in shell models

DEFF Research Database (Denmark)

Okkels, F.

2001-01-01

The intermittent dynamics of the turbulent Gledzer, Ohkitani, and Yamada shell-model is completely characterized by a single type of burstlike structure, which moves through the shells like a front. This temporal structure is described by the dynamics of the instantaneous configuration of the shell...

Expert system development (ESD) shell

International Nuclear Information System (INIS)

Padmini, S.; Diwakar, M.P.; Rathode, N.C.; Bairi, B.R.

1991-01-01

An Expert System Development (ESD) Shell design implementation is desribed in detail. The shell provides high-level generic facilities for Knowledge Representation (KR) and inferencing and tools for developing user interfaces. Powerful set of tools in the shell relieves much of the programming burden in the ES development. The shell is written in PROLOG under IBM PC/AT. KR facilities are based on two very powerful formalisms namely, frames and rules. Inference Engine (IE) draws most of its power from unification and backward reasoning strategy in PROLOG. This basic mechanism is enhanced further by incorporating both forward and backward chaining of rules and frame-based inferencing. Overall programming style integrates multiple paradigms including logic, object oriented, access-oriented and imperative programming. This permits ES designer a lot of flexibility in organizing inference control. Creation and maintainance of knowledge base is a major activity. The shell, therefore, provides number of facilities to simplify these tasks. Shell design also takes note of the fact that final success of any system depends on end-user satisfaction and hence provides features to build use-friendly interfaces. The shell also provides a set of interfacing predicates so that it can be embedded within any PROLOG program to incorporate functionalilty of the shell in the user program. (author). 10 refs., 8 figs

Screening natural antioxidants in peanut shell using DPPH-HPLC-DAD-TOF/MS methods.

Science.gov (United States)

Qiu, Jiying; Chen, Leilei; Zhu, Qingjun; Wang, Daijie; Wang, Wenliang; Sun, Xin; Liu, Xiaoyong; Du, Fangling

2012-12-15

Peanut shell, a byproduct in oil production, is rich in natural antioxidants. Here, a rapid and efficient method using DPPH-HPLC-DAD-TOF/MS was used for the first time to screen antioxidants in peanut shell. The method is based on the hypothesis that upon reaction with 1, 1-diphenyl-2-picrylhydrazyl (DPPH), the peak areas of compounds with potential antioxidant activities in the HPLC chromatogram will be significantly reduced or disappeared, and the identity confirmation could be achieved by HPLC-DAD-TOF/MS technique. With this method, three compounds possessing potential antioxidant activities were found abundantly in the methanolic extract of peanut shell. They were identified as 5,7-dihydroxychromone, eriodictyol, and luteolin. The contents of these compounds were 0.59, 0.92, and 2.36 mg/g, respectively, and luteolin possessed the strongest radical scavenging capacity. DPPH-HPLC-DAD-TOF/MS assay facilitated rapid identification and determination of natural antioxidants in peanut shell, which may be helpful for value-added utilization of peanut processing byproducts. Copyright © 2012 Elsevier Ltd. All rights reserved.

Activated carbons prepared from hazelnut shells, walnut shells and peanut shells for high CO2 adsorption

Directory of Open Access Journals (Sweden)

Lewicka Katarzyna

2017-06-01

Full Text Available Research treats about producing activated carbons for CO2 capture from hazelnut shells (HN, walnut shells (WN and peanut shells (PN. Saturated solution of KOH was used as an activating agent in ratio 1:1. Samples were carbonized in the furnace in the range of temperatures 600°C–900°C. Properties of carbons were tested by N2 adsorption method, using BET equation, DFT method and volumetric CO2 adsorption method. With the increase of carbonization temperature specific surface area of studied samples increased. The largest surface area was calculated for samples carbonized at 900°C and the highest values of CO2 adsorption had samples: PN900 at 0°C (5.5 mmol/g and WN900 at 25°C (4.34 mmol/g. All of the samples had a well-developed microporous structure.

Facile in situ synthesis of wurtzite ZnS/ZnO core/shell heterostructure with highly efficient visible-light photocatalytic activity and photostability

Science.gov (United States)

Xiao, Jian-Hua; Huang, Wei-Qing; Hu, Yong-sheng; Zeng, Fan; Huang, Qin-Yi; Zhou, Bing-Xin; Pan, Anlian; Li, Kai; Huang, Gui-Fang

2018-02-01

High photocatalytic activity and photostability are the pursuit of the goal for designing promising photocatalysts. Herein, using ZnO to encapsulate ZnS nanoparticles is proposed as an effective strategy to enhance photocatalytic activity and anti-photocorrosion. The ZnS/ZnO core/shell heterostructures are obtained via an annealing treatment of ZnS nanoparticles produced by a facile wet chemical approach. Due to its small size, the nascent cubic sphalerite ZnS (s-ZnS) converts into a hexagonal wurtzite ZnS (w-ZnS)/ZnO core/shell structure after annealing treatment. In situ oxidation leads to increasing ZnO, simultaneously decreasing the w-ZnS content in the resultant w-ZnS/ZnO with thermal annealing time. The w-ZnS/ZnO core/shell heterostructures show high photocatalytic activity, demonstrated by the photodegradation rate of methylene blue being up to ten-fold and seven-fold higher than that of s-ZnS under UV and visible light irradiation, respectively, and the high capability of degrading rhodamine B. The enhanced photocatalytic activity may be attributed to the large specific surface and improved charge carrier separation at the core/shell interface. Moreover, it displays high photostability owing to the protection of the ZnO shell, greatly inhibiting the photocorrosion of ZnS. This facile in situ oxidation is effective and easily scalable, providing opportunities for developing novel core/shell structure photocatalysts with high activity and photostability.

Separation of oil palm shell and kernel by using kaolinite media

Directory of Open Access Journals (Sweden)

Sukpong Sirinupong

2003-05-01

Full Text Available The objective of this research is to investigate the possibility of using kaolinite from Ranong province as media in the oil palm shell and kernel separation process by means of heavy media separation. The effect of specific gravity of the slurry, type and amount of dispersant and type of clays on suspension of media and efficiency of separation were studied. It was found that the specific gravity of oil palm shell and kernel are 1.40 and 1.20 respectively. While the average specific gravity of kaolinite grade MRD-B85, RANONG-325 and commercial clay from Univanich Group. PCL., are 2.54, 2.65 and 2.46 respectively. It was apparent that the viscosity of clay slurry increased with the specific gravity of the slurry. For MRD-B85 and RANONG- 325 clays which have the average particle sizes of 10 and 12 microns, the pH of their slurries of about 5.84 and 6.33 respectively were obtained and at these conditions stability of the slurry rarely occurred and they could not be used for separation. However, these clays can also be utilized as media when dispersant such asCalgon or sodium silicate is applied to their slurries. It was found that the efficiency of separation depends on specific gravity and viscosity of the slurry, type and particle size of kaolinite and dosage of dispersant. The optimum separating conditions for MRD-B85 clay were the dosage of Calgon of 0.15% (or 1.5 kg/t of clay at the specific gravity of the slurry of 1.20-1.24 (27-32% Solids in which a pH of 6.14 and viscosity of 104 cP to very low value (could not be measured were obtained. Thus, kernel yielded 97.57-100% and shell contamination of 1.48-6.32% was achieved. While sodium silicate was applied to the slurry about 0.15% at the specific gravity of 1.22, pH of 6.74 and viscosity of 238 cP were obtained and kernel could be recovered 100% with shell contamination of 8.36%. When 0.15% Calgon or 0.25% sodium silicate was introduced to the RANONG-325 clay slurry at the specific gravity

Core-shell nanoreactors for efficient aqueous biphasic catalysis.

Science.gov (United States)

Zhang, Xuewei; Cardozo, Andrés F; Chen, Si; Zhang, Wenjing; Julcour, Carine; Lansalot, Muriel; Blanco, Jean-François; Gayet, Florence; Delmas, Henri; Charleux, Bernadette; Manoury, Eric; D'Agosto, Franck; Poli, Rinaldo

2014-11-17

Water-borne phosphine-functionalized core-cross-linked micelles (CCM) consisting of a hydrophobic core and a hydrophilic shell were obtained as stable latexes by reversible addition-fragmentation chain transfer (RAFT) in water in a one-pot, three-step process. Initial homogeneous aqueous-phase copolymerization of methacrylic acid (MAA) and poly(ethylene oxide) methyl ether methacrylate (PEOMA) is followed by copolymerization of styrene (S) and 4-diphenylphosphinostyrene (DPPS), yielding P(MAA-co-PEOMA)-b-P(S-co-DPPS) amphiphilic block copolymer micelles (M) by polymerization-induced self-assembly (PISA), and final micellar cross-linking with a mixture of S and diethylene glycol dimethacrylate. The CCM were characterized by dynamic light scattering and NMR spectroscopy to evaluate size, dispersity, stability, and the swelling ability of various organic substrates. Coordination of [Rh(acac)(CO)2 ] (acac=acetylacetonate) to the core-confined phosphine groups was rapid and quantitative. The CCM and M latexes were then used, in combination with [Rh(acac)(CO)2 ], to catalyze the aqueous biphasic hydroformylation of 1-octene, in which they showed high activity, recyclability, protection of the activated Rh center by the polymer scaffold, and low Rh leaching. The CCM latex gave slightly lower catalytic activity but significantly less Rh leaching than the M latex. A control experiment conducted in the presence of the sulfoxantphos ligand pointed to the action of the CCM as catalytic nanoreactors with substrate and product transport into and out of the polymer core, rather than as a surfactant in interfacial catalysis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and characterization of thermal energy storage microencapsulated n-dodecanol with acrylic polymer shell

International Nuclear Information System (INIS)

Ma, Yanjie; Zong, Jiwen; Li, Wei; Chen, Long; Tang, Xiaofen; Han, Na; Wang, Jianping; Zhang, Xingxiang

2015-01-01

Two kinds of (microencapsulated phase change materials) MicroPCMs with acrylic-based copolymer as shell and n-dodecanol as core were successfully fabricated via suspension-like polymerization and photo-induced microencapsulation, respectively. Morphology and core–shell structure were observed by (field emission scanning electron microscope) FE-SEM. Thermal properties of the microencapsulated n-dodecanol were investigated by (differential scanning calorimeter) DSC and (thermogravimetric analysis) TGA. The results indicate that the mass ratio of core to shell has great influence on the morphology, inner structure, microencapsulated efficiency and durability of the microcapsules. Besides, the effects of various solvents and UV irridiation time on the microcapsule surface were discussed as well. In the experiment carried out, metal-ion complexation was conducted by the reaction between Mn ion and carboxyl groups on copolymer shell to enhance the performance of the microcapsules with n-dodecanol encapsulated. As the results indicate, the physicochemical properties and thermal conductivity of the shell were improved after Mn ion complexation reaction. Supercooling phenomenon of n-dodecanol was depressed to some extent. In the end, the thermo-regulated fiber containing acrylic-based copolymer microcapsules was fabricated, and thermo-regulated performance test of the fiber was also conducted. - Graphical abstract: (a)∼(d) schematic diagram of microencapsulation and (e) microcapsule with core–shell structure. - Highlights: • Microencapsulated n-dodecanol with acrylic polymer shell. • Microencapsulated n-dodecanol was fabricated by photo-induced microencapsulation. • Acrylic-based copolymer microcapsules with manganese-ion complexation

Optimization of ship inner shell to improve the safety of seagoing transport ship

Directory of Open Access Journals (Sweden)

Yan-Yun YU

2013-09-01

Full Text Available A practical Ship Inner Shell Optimization Method (SISOM, the purpose of which is to improve the safety of the seagoing transport ship by decreasing the maximum Still Water Bending Moment (SWBM of the hull girder under all typical loading conditions, is presented in this paper. The objective of SISOM is to make the maximum SWBM minimum, and the section areas of the inner shell are taken as optimization variables. The main requirements of the ship performances, such as cargo hold capacity, propeller and rudder immersion, bridge visibility, damage stability and prevention of pollution etc., are taken as constraints. The penalty function method is used in SISOM to change the above nonlinear constraint problem into an unconstrained one, which is then solved by applying the steepest descent method. After optimization, the optimal section area distribution of the inner shell is obtained, and the shape of inner shell is adjusted according to the optimal section area. SISOM is applied to a product oil tanker and a bulk carrier, and the maximum SWBM of the two ships is significantly decreased by changing the shape of inner shell plate slightly. The two examples prove that SISOM is highly efficient and valuable to engineering practice.

Nonlinear viscoelastic behavior of shells of revolution under arbitrary loading

International Nuclear Information System (INIS)

Leonard, J.W.; Arbaki-Kanjoori, F.

1975-01-01

The requirement of some structural components such as propulsion systems and gas turbines to operate at high temperatures and pressures make the accurate evaluation of the creep phenomenon exigent (in fast breeder reactor for example). For the expected increases in operating temperatures and pressures, it becomes necessary to perform a thorough analysis of integral structural components of nuclear power plants throughout their life span. Since a large class of structures operating at elevated temperatures are composed of rotationally symmetric shells, a solution technique can be developed which involves the numerical integration of the governing shell equations. This method has been successfully applied to the static and dynamic analysis of thin elastic shells of revolution and for some cases of inelastic material behavior. It has been shown to render solutions efficiently and accurately, usually with only a fraction of computer time and storage requirements and data manipulation that is required for other numerical schemes such as the finite element method. Furthermore, the numerical integration method allows more flexibility for varying the integration step lengths than does the finite difference method and can provide uniform accuracy throughout the analysis. For nonlinear viscoelastic behavior the numerical integration technique is expected to provide similar efficiency to that obtained for the elastic problems. The computer program developed can accept time variation of material properties. Since a single form for the material constitutive law cannot encompass all materials, provisions are made so that the analysis of a very large class of material behavior can be accomplished

Calculation of plastic deformation of a conical shell with the transformation of inner surface into outer one

Directory of Open Access Journals (Sweden)

A. I. Uvarov

2014-01-01

Full Text Available An analytical model of plastic deformation of a conical shell with the transformation of internal surface into outer one was developed with a use of the kinematic method. The shell material was assumed to be perfectly plastic. The theory of thin shells and the kinematic theorem of limit equilibrium were utilized in this work. Both geometric and physical nonlinearities were taken into account. Dependences for calculating radius of curvature of the intensive deformation zones, value of chain ring deformation and values of the deforming force as a function of axial displacement were determined. Analysis showed the possibility of using a conical shell to absorb energy with high efficiency. Obtained results could be used for calculation and selection of optimal parameters of the energy-absorbing elements in shock absorbers.

Dyson shells: a retrospective

Science.gov (United States)

Bradbury, Robert J.

2001-08-01

More than 40 years have passed since Freeman Dyson suggested that advanced technological civilizations are likely to dismantle planets in their solar systems to harvest all of the energy their stars wastefully radiate into space. Clearly this was an idea that was ahead of its time. Since that time, dozens of SETI searches have been conducted and almost all of them have focused their attention on stars which by definition cannot be the advanced civilizations that Dyson envisioned. I will review the data that created the confusion between Dyson spheres and Dyson shells. The sources that disprove Dyson spheres while still allowing Dyson shells will be discussed. The use of outmoded ideas that have biased the few searches for Dyson Shells that have occurred will be pointed out. An update of the concept of Dyson shells to include our current knowledge of biotechnology, nanotechnology and computer science will be explored. Finally, an approach to setting limits on the abundance of Dyson shells in our galaxy using existing optical astronomical data and future optical satellites will be proposed.

r-Adaptive mesh generation for shell finite element analysis

International Nuclear Information System (INIS)

Cho, Maenghyo; Jun, Seongki

2004-01-01

An r-adaptive method or moving grid technique relocates a grid so that it becomes concentrated in the desired region. This concentration improves the accuracy and efficiency of finite element solutions. We apply the r-adaptive method to computational mesh of shell surfaces, which is initially regular and uniform. The r-adaptive method, given by Liao and Anderson [Appl. Anal. 44 (1992) 285], aggregate the grid in the region with a relatively high weight function without any grid-tangling. The stress error estimator is calculated in the initial uniform mesh for a weight function. However, since the r-adaptive method is a method that moves the grid, shell surface geometry error such as curvature error and mesh distortion error will increase. Therefore, to represent the exact geometry of a shell surface and to prevent surface geometric errors, we use the Naghdi's shell theory and express the shell surface by a B-spline patch. In addition, using a nine-node element, which is relatively less sensitive to mesh distortion, we try to diminish mesh distortion error in the application of an r-adaptive method. In the numerical examples, it is shown that the values of the error estimator for a cylinder, hemisphere, and torus in the overall domain can be reduced effectively by using the mesh generated by the r-adaptive method. Also, the reductions of the estimated relative errors are demonstrated in the numerical examples. In particular, a new functional is proposed to construct an adjusted mesh configuration by considering a mesh distortion measure as well as the stress error function. The proposed weight function provides a reliable mesh adaptation method after a parameter value in the weight function is properly chosen

Mussel Shell Impaction in the Esophagus

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Sunmin Kim

2013-03-01

Full Text Available Mussels are commonly used in cooking around the world. The mussel shell breaks more easily than other shells, and the edge of the broken mussel shell is sharp. Impaction can ultimately cause erosion, perforation and fistula. Aside from these complications, the pain can be very intense. Therefore, it is essential to verify and remove the shell as soon as possible. In this report we describe the process of diagnosing and treating mussel shell impaction in the esophagus. Physicians can overlook this unusual foreign body impaction due to lack of experience. When physicians encounter a patient with severe chest pain after a meal with mussels, mussel shell impaction should be considered when diagnosing and treating the patient.

Plate shell structures of glass

DEFF Research Database (Denmark)

Bagger, Anne

to their curved shape. A plate shell structure maintains a high stiffness-to-weight ratio, while facilitating the use of plane structural elements. The study focuses on using laminated glass panes for the load bearing facets. Various methods of generating a plate shell geometry are suggested. Together with Ghent......, such as facet size, imperfections, and connection characteristics. The critical load is compared to that of a similar, but smoothly curved, shell structure. Based on the investigations throughout the study, a set of guidelines for the structural design of plate shells of glass is proposed....

Transferrin targeted core-shell nanomedicine for combinatorial delivery of doxorubicin and sorafenib against hepatocellular carcinoma.

Science.gov (United States)

Malarvizhi, Giridharan Loghanathan; Retnakumari, Archana Payickattu; Nair, Shantikumar; Koyakutty, Manzoor

2014-11-01

Combinatorial drug delivery is an attractive, but challenging requirement of next generation cancer nanomedicines. Here, we report a transferrin-targeted core-shell nanomedicine formed by encapsulating two clinically used single-agent drugs, doxorubicin and sorafenib against liver cancer. Doxorubicin was loaded in poly(vinyl alcohol) nano-core and sorafenib in albumin nano-shell, both formed by a sequential freeze-thaw/coacervation method. While sorafenib from the nano-shell inhibited aberrant oncogenic signaling involved in cell proliferation, doxorubicin from the nano-core evoked DNA intercalation thereby killing >75% of cancer cells. Upon targeting using transferrin ligands, the nanoparticles showed enhanced cellular uptake and synergistic cytotoxicity in ~92% of cells, particularly in iron-deficient microenvironment. Studies using 3D spheroids of liver tumor indicated efficient penetration of targeted core-shell nanoparticles throughout the tissue causing uniform cell killing. Thus, we show that rationally designed core-shell nanoparticles can effectively combine clinically relevant single-agent drugs for exerting synergistic activity against liver cancer. Transferrin-targeted core-shell nanomedicine encapsulating doxorubicin and sorafenib was studied as a drug delivery system against hepatocellular carcinoma, resulting in enhanced and synergistic therapeutic effects, paving the way towards potential future clinical applications of similar techniques. Copyright © 2014 Elsevier Inc. All rights reserved.

A study of the compartmentalization of core-shell nanoparticles through fluorescence energy transfer of dopants

Energy Technology Data Exchange (ETDEWEB)

Chavez, Jorge L; Jiang Hui; Duran, Randolph S, E-mail: rduran@lsu.edu [Department of Chemistry, University of Florida, PO Box 117200, Gainesville, FL 32611 (United States)

2010-02-05

Hybrid organic-inorganic templates and core-shell nanoparticles were used as models to study the communication between fluorescent probes placed inside nanoparticles. The hybrid templates were prepared on the basis of a mixed-surfactant system using octadecyltrimethoxysilane as a reactive amphiphile. The core-shell particles were obtained after coating of the templates with a siloxane shell, using the silanol groups on their surface. Atomic force microscopy imaging showed that the templates were made of a flexible material that flattened significantly after deposition on a substrate and evaporation of the solvent. Pyrene was sequestered by the templates in an aqueous suspension, which placed it in a nonpolar environment, as observed by its fluorescence response. Subsequently, double-doped templates were prepared by sequestering coumarin 153 (C153), with pyrene-doped hybrid templates. The communication between these probes was studied on the basis of their spectral properties, by means of fluorescence resonance energy transfer (FRET). Energy transfer between the dyes with efficiencies up to 55% was observed. Similarly, double-doped core-shell particles prepared on the basis of the hybrid templates were doped with this pair of dyes. Despite the presence of the shell, which was intended to increment the average separation between the probes, interaction of the dyes was observed, although with lower efficiencies. A similar study was performed with C153 and 4-(dicyanomethylene)-2-methyl-6-p-(dimethylamino)styryl-4H-pyran (DCM). FRET studies indicated that the probes were placed in proximity to each other. We confirmed these observations by means of fluorescence lifetime measurements, which showed a decrease in the lifetime of the donor upon addition of the acceptor.

From harmful Microcystis blooms to multi-functional core-double-shell microsphere bio-hydrochar materials.

Science.gov (United States)

Bi, Lei; Pan, Gang

2017-11-13

Harmful algal blooms (HABs) induced by eutrophication is becoming a serious global environmental problem affecting public health and aquatic ecological sustainability. A novel strategy for the utilization of biomass from HABs was developed by converting the algae cells into hollow mesoporous bio-hydrochar microspheres via hydrothermal carbonization method. The hollow microspheres were used as microreactors and carriers for constructing CaO 2 core-mesoporous shell-CaO 2 shell microspheres (OCRMs). The CaO 2 shells could quickly increase dissolved oxygen to extremely anaerobic water in the initial 40 min until the CaO 2 shells were consumed. The mesoporous shells continued to act as regulators restricting the release of oxygen from CaO 2 cores. The oxygen-release time using OCRMs was 7 times longer than when directly using CaO 2 . More interestingly, OCRMs presented a high phosphate removal efficiency (95.6%) and prevented the pH of the solution from rising to high levels in comparison with directly adding CaO 2 due to the OH - controlled-release effect of OCRMs. The distinct core-double-shell micro/nanostructure endowed the OCRMs with triple functions for oxygen controlled-release, phosphorus removal and less impact on water pH. The study is to explore the possibility to prepare smarter bio-hydrochar materials by utilizing algal blooms.

Fluorescence Quenching of Alpha-Fetoprotein by Gold Nanoparticles: Effect of Dielectric Shell on Non-Radiative Decay

Science.gov (United States)

Zhu, Jian; Li, Jian-Jun; Wang, A.-Qing; Chen, Yu; Zhao, Jun-Wu

2010-09-01

Fluorescence quenching spectrometry was applied to study the interactions between gold colloidal nanoparticles and alpha-fetoprotein (AFP). Experimental results show that the gold nanoparticles can quench the fluorescence emission of adsorbed AFP effectively. Furthermore, the intensity of fluorescence emission peak decreases monotonously with the increasing gold nanoparticles content. A mechanism based on surface plasmon resonance-induced non-radiative decay was investigated to illuminate the effect of a dielectric shell on the fluorescence quenching ability of gold nanoparticles. The calculation results show that the increasing dielectric shell thickness may improve the monochromaticity of fluorescence quenching. However, high energy transfer efficiency can be obtained within a wide wavelength band by coating a thinner dielectric shell.

Nanostructued core–shell Sn nanowires @ CNTs with controllable thickness of CNT shells for lithium ion battery

Energy Technology Data Exchange (ETDEWEB)

Zhong, Yu; Li, Xifei; Zhang, Yong; Li, Ruying [Department of Mechanical and Materials Engineering, University of Western Ontario, London, Ontario N6A 5B9 (Canada); Cai, Mei [General Motors Research and Development Center, Warren, MI 48090-9055 (United States); Sun, Xueliang, E-mail: xsun@eng.uwo.ca [Department of Mechanical and Materials Engineering, University of Western Ontario, London, Ontario N6A 5B9 (Canada)

2015-03-30

Graphical abstract: - Highlights: • Sn nanowires encapsulated in CNTs directly grew on current collectors. • The thickness of CNTs were controlled via growth time, gas flow rate and synthesis temperature. • Thick CNTs contributed to a better capacity retention while thin CNTs led to a higher capacity. • The core–shell structures formed in one-step CVD process. - Abstract: Core–shell structure of Sn nanowires encapsulated in amorphous carbon nanotubes (Sn@CNTs) with controlled thickness of CNT shells was in situ prepared via chemical vapor deposition (CVD) method. The thickness of CNT shells was accurately controlled from 4 to 99 nm by using different growth time, flow rate of hydrocarbon gas (C{sub 2}H{sub 4}) and synthesis temperature. The microstructure and composition of the coaxial Sn@CNTs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high resolution transmission electron microscopy (HRTEM) techniques. Moreover, the Sn@CNTs were studied as anode materials for Li-ion batteries and showed excellent cycle performance. The capacity was affected by the thickness of outer CNT shells: thick CNT shells contributed to a better retention while thin CNT shells led to a higher capacity. The thin CNT shell of 6 nm presented the highest capacity around 630 mAh g{sup −1}.

Nanostructued core–shell Sn nanowires @ CNTs with controllable thickness of CNT shells for lithium ion battery

International Nuclear Information System (INIS)

Zhong, Yu; Li, Xifei; Zhang, Yong; Li, Ruying; Cai, Mei; Sun, Xueliang

2015-01-01

Graphical abstract: - Highlights: • Sn nanowires encapsulated in CNTs directly grew on current collectors. • The thickness of CNTs were controlled via growth time, gas flow rate and synthesis temperature. • Thick CNTs contributed to a better capacity retention while thin CNTs led to a higher capacity. • The core–shell structures formed in one-step CVD process. - Abstract: Core–shell structure of Sn nanowires encapsulated in amorphous carbon nanotubes (Sn@CNTs) with controlled thickness of CNT shells was in situ prepared via chemical vapor deposition (CVD) method. The thickness of CNT shells was accurately controlled from 4 to 99 nm by using different growth time, flow rate of hydrocarbon gas (C 2 H 4 ) and synthesis temperature. The microstructure and composition of the coaxial Sn@CNTs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high resolution transmission electron microscopy (HRTEM) techniques. Moreover, the Sn@CNTs were studied as anode materials for Li-ion batteries and showed excellent cycle performance. The capacity was affected by the thickness of outer CNT shells: thick CNT shells contributed to a better retention while thin CNT shells led to a higher capacity. The thin CNT shell of 6 nm presented the highest capacity around 630 mAh g −1

Utilization of Pine Nut Shell derived carbon as an efficient alternate for the sequestration of phthalates from aqueous system

Directory of Open Access Journals (Sweden)

Umair A. Qureshi

2014-12-01

Full Text Available This study highlights the importance of a cheap bio waste; Pine Nut Shell (PNS, from which a carbon is synthesized that can efficiently remove toxic phthalates from an aqueous system. PNS derived carbon shows high affinity toward phthalates in descending order along with adsorption capacity i.e., dibutyl phthalate (DBP 5.65 mg/g > diallyl phthalate (DAP 3.64 mg/g > diethyl phthalate (DEP and 2.87 mg/g > dimethyl phthalate (DMP 2.48 mg/g. Different characterization techniques such as FTIR, elemental analysis, point of zero electric charge (PZC, SEM, EDX and BET were employed to investigate the binding sites and surface area of the adsorbent. Adsorption experiments were performed both in batch and column modes. Equilibrium studies showed that the Langmuir isotherm fits best to experimental data. Kinetically, adsorption phenomena obeyed pseudo second order. Furthermore, thermodynamic results expressed the exothermic nature of adsorption on the basis of negative value of enthalpy change. Column sorption method was also adapted to check the feasibility of the adsorption process through the investigation of flow rate, breakthrough curve and pre-concentration factor which is found to be 13 for DMP and DEP and 16 for DAP and DBP. Methanol was found to be best solvent for the recovery of phthalates. Application in real water samples also showed good efficiency of PNS derived carbon for the removal of phthalates.

Extensions to a nonlinear finite element axisymmetric shell model based on Reissner's shell theory

International Nuclear Information System (INIS)

Cook, W.A.

1981-01-01

A finite element shell-of-revolution model has been developed to analyze shipping containers under severe impact conditions. To establish the limits for this shell model, I studied the basic assumptions used in its development; these are listed in this paper. Several extensions were evident from the study of these limits: a thick shell, a plastic hinge, and a linear normal stress. (orig./HP)

Core-Shell-Corona Micelles with a Responsive Shell.

Science.gov (United States)

Gohy, Jean-François; Willet, Nicolas; Varshney, Sunil; Zhang, Jian-Xin; Jérôme, Robert

2001-09-03

A reactor for the synthesis of gold nanoparticles is one of the uses of a poly(styrene)-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) triblock copolymer (PS-b-P2VP-b-PEO) which forms core-shell-corona micelles in water. Very low polydispersity spherical micelles are observed that consist of a PS core surrounded by a pH-sensitive P2VP shell and a corona of PEO chains end-capped by a hydroxyl group. The corona can act as a site for attaching responsive or sensing molecules. © 2001 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.

Dye-Sensitized Solar Cells Based on TiO_2 Nanotube and Shelled Arrayed Structures

International Nuclear Information System (INIS)

Zhang, Jie; Kusumawati, Yuly; Pauporté, Thierry

2016-01-01

Anatase TiO_2 nanostructure arrays were synthetized starting from a template made of self-standing ZnO NWs prepared by an electrodeposition technique. By controlling the liquid phase deposition step, the obtained structures could be varied from free-standing nanotube (NT) arrays with controlled morphology to hierarchical spiky radiating core-shell rods. The nanotubes were made of assembled nanocrystals with an average size of 7–8 nm. The structures were investigated as n-type layers in DSSCs. The efficiency was enhanced for the core-shell layer and by starting with longer initial ZnO NW templates. The limitation of the cell efficiency was shown related to the specific surface area and dye loading. The cell functioning was in-depth investigated by electrochemical impedance spectroscopy over a large applied voltage range and compared to a cell based on a nanoparticle TO_2 mesoporous layer. A slow recombination rate was found. The enhancement of electron transport with nanocrystallite size explained the conductivity results. We also found that the prepared structures presented a high charge collection efficiency.

Effect of storage of shelled Moringa oleifera seeds from reaping time on turbidity removal.

Science.gov (United States)

Golestanbagh, M; Ahamad, I S; Idris, A; Yunus, R

2011-09-01

Moringa oleifera is an indigenous plant to Malaysia whose seeds are used for water purification. Many studies on Moringa oleifera have shown that it is highly effective as a natural coagulant for turbidity removal. In this study, two different methods for extraction of Moringa's active ingredient were investigated. Results of sodium chloride (NaCl) and distilled water extraction of Moringa oleifera seeds showed that salt solution extraction was more efficient than distilled water in extracting Moringa's active coagulant ingredient. The optimum dosage of shelled Moringa oleifera seeds extracted by the NaCl solution was comparable with that of the conventional chemical coagulant alum. Moreover, the turbidity removal efficiency was investigated for shelled Moringa oleifera seeds before drying in the oven under different storage conditions (i.e. open and closed containers at room temperature, 27 °C) and durations (fresh, and storage for 2, 4, 6 and 8 weeks from the time the seeds were picked from the trees). Our results indicate that there are no significant differences in coagulation efficiencies and, accordingly, turbidity removals between the examined storage conditions and periods.

Biomineral repair of abalone shell apertures.

Science.gov (United States)

Cusack, Maggie; Guo, Dujiao; Chung, Peter; Kamenos, Nicholas A

2013-08-01

The shell of the gastropod mollusc, abalone, is comprised of nacre with an outer prismatic layer that is composed of either calcite or aragonite or both, depending on the species. A striking characteristic of the abalone shell is the row of apertures along the dorsal margin. As the organism and shell grow, new apertures are formed and the preceding ones are filled in. Detailed investigations, using electron backscatter diffraction, of the infill in three species of abalone: Haliotis asinina, Haliotis gigantea and Haliotis rufescens reveals that, like the shell, the infill is composed mainly of nacre with an outer prismatic layer. The infill prismatic layer has identical mineralogy as the original shell prismatic layer. In H. asinina and H. gigantea, the prismatic layer of the shell and infill are made of aragonite while in H. rufescens both are composed of calcite. Abalone builds the infill material with the same high level of biological control, replicating the structure, mineralogy and crystallographic orientation as for the shell. The infill of abalone apertures presents us with insight into what is, effectively, shell repair. Copyright © 2013 Elsevier Inc. All rights reserved.

Influence of heat treatment on hole transfer dynamics in core-shell quantum dot/organic hole conductor hybrid films

Science.gov (United States)

Sun, Mingye; Zheng, Youjin; Zhang, Lei; Zhao, Liping; Zhang, Bing

2017-08-01

The influence of heat treatment on hole transfer (HT) processes from the CdSe/ZnS and CdSe/CdS/ZnS quantum dots (QDs) to 4,4‧,4″-Tris(carbazol-9-yl)-triphenylamine (TCTA) in QD/TCTA hybrid films has been researched with time-resolved photoluminescence (PL) spectroscopy. The PL dynamic results demonstrated a heat-treatment-temperature-dependent HT process from the core-shell CdSe QDs to TCTA. The HT rates and efficiencies can be effectively increased due to reduced distance between core-shell CdSe QDs and TCTA after heat treatment. The CdS shell exhibited a more obvious effect on HT from the core-shell CdSe QDs to TCTA than on electron transfer to TiO2, due to higher barrier for holes to tunnel through CdS shell and larger effective mass of holes in CdS than electrons. These results indicate that heat treatment would be an effective means to further optimize solid-state QD sensitized solar cells and rational design of CdS shell is significant.

Oxidation driven ZnS Core-ZnO shell photocatalysts under controlled oxygen atmosphere for improved photocatalytic solar water splitting

Science.gov (United States)

Bak, Daegil; Kim, Jung Hyeun

2018-06-01

Zinc type photocatalysts attract great attentions in solar hydrogen production due to their easy availability and benign environmental characteristics. Spherical ZnS particles are synthesized with a facile hydrothermal method, and they are further used as core materials to introduce ZnO shell layer surrounding the core part by partial oxidation under controlled oxygen contents. The resulting ZnS core-ZnO shell photocatalysts represent the heterostructural type II band alignment. The existence of oxide layer also influences on proton adsorption power with an aid of strong base cites derived from highly electronegative oxygen atoms in ZnO shell layer. Photocatalytic water splitting reaction is performed to evaluate catalyst efficiency under standard one sun condition, and the highest hydrogen evolution rate (1665 μmolg-1h-1) is achieved from the sample oxidized at 16.2 kPa oxygen pressure. This highest hydrogen production rate is achieved in cooperation with increased light absorption and promoted charge separations. Photoluminescence analysis reveals that the improved visible light response is obtained after thermal oxidation process due to the oxygen vacancy states in the ZnO shell layer. Therefore, overall photocatalytic efficiency in solar hydrogen production is enhanced by improved charge separations, crystallinity, and visible light responses from the ZnS core-ZnO shell structures induced by thermal oxidation.

ZIF-67-derived hollow nanocages with layered double oxides shell as high-Efficiency catalysts for CO oxidation

Science.gov (United States)

Kong, Wenpeng; Li, Jing; Chen, Yao; Ren, Yuqing; Guo, Yonghua; Niu, Shengli; Yang, Yanzhao

2018-04-01

Constructing non-precious hybrid metal oxides with specific morphology as cost-effective and highly efficient catalysts is a promising way for the automotive exhaust purification. In this work, we report a facile strategy for the fabrication of a unique hollow Co-Ni layered double oxides (HLDO) nanocages by using zeolitic imidazole frameworks (ZIFs) as template. The synthesis of intermediate core-shell and hollow Co-Ni layered double hydroxides (HLDH) nanoflakes as well as the corresponding Co-Ni oxides products were successfully controlled, and the formation process was also explained. Among ZIF-67-derived oxides, HLDO exhibits excellent catalytic activities (complete conversion of CO into CO2 at 118 °C) and long-term stability for CO oxidation. The remarkable catalytic activities of HLDO can be attributed to high surface area (258 m2 g-1) inherited from the HLDH, which could provide more active sites for CO oxidation. In addition, active oxygen species indicated by the O 1 s XPS spectrum and improved synergistic effect between NiO and Co3O4 reflected by H2-TPR, further explain the enhanced performance of the HLDO catalysts. The presented strategy for controlled design and synthesis of hollow multicomponent metal oxides will provide prospects in developing highly effective catalysts.

Au@TiO2 yolk-shell nanostructures for enhanced performance in both photoelectric and photocatalytic solar conversion

Science.gov (United States)

He, Qinrong; Sun, Hang; Shang, Yinxing; Tang, Yanan; She, Ping; Zeng, Shan; Xu, Kongliang; Lu, Guolong; Liang, Song; Yin, Shengyan; Liu, Zhenning

2018-05-01

Solar energy conversion is an important field gaining increasing interest. Herein, bio-inspired Au@TiO2 yolk-shell nanoparticles (NPs) have been prepared via a facial one-pot hydrothermal approach. The Au@TiO2 yolk-shell NPs can self-assemble into 3D-structure to form photoelectrode for photoelectric conversion. The obtained photoelectrode demonstrates a swift and stable photocurrent of 3.5 μA/cm2, which is 4.2 and 1.6 times higher than those of the photocurrents generated by the counterparts of commercial TiO2 and Au@TiO2 core-shell NPs, respectively. Moreover, compared to the commercial TiO2 and Au@TiO2 core-shell NPs, the Au@TiO2 yolk-shell NPs also exhibit superior photocatalytic activity, delivering a H2 evolution rate of 4.92 mmol/g h. The performance improvement observed for the Au@TiO2 yolk-shell NPs is likely contributed by two synergistic factors, i.e. the incorporation of AuNPs and the unique hollow structure, which benefit the activity by simultaneously enhancing light utilization, charge separation and reaction site accessibility. The rational design and fabrication of Au@TiO2 yolk-shell NPs hold great promise for future application in efficient solar energy conversion.

Core-Shell Columns in High-Performance Liquid Chromatography: Food Analysis Applications

Science.gov (United States)

Preti, Raffaella

2016-01-01

The increased separation efficiency provided by the new technology of column packed with core-shell particles in high-performance liquid chromatography (HPLC) has resulted in their widespread diffusion in several analytical fields: from pharmaceutical, biological, environmental, and toxicological. The present paper presents their most recent applications in food analysis. Their use has proved to be particularly advantageous for the determination of compounds at trace levels or when a large amount of samples must be analyzed fast using reliable and solvent-saving apparatus. The literature hereby described shows how the outstanding performances provided by core-shell particles column on a traditional HPLC instruments are comparable to those obtained with a costly UHPLC instrumentation, making this novel column a promising key tool in food analysis. PMID:27143972

Porous Core-Shell Nanostructures for Catalytic Applications

Science.gov (United States)

Ewers, Trevor David

Porous core-shell nanostructures have recently received much attention for their enhanced thermal stability. They show great potential in the field of catalysis, as reactant gases can diffuse in and out of the porous shell while the core particle is protected from sintering, a process in which particles coalesce to form larger particles. Sintering is a large problem in industry and is the primary cause of irreversible deactivation. Despite the obvious advantages of high thermal stability, porous core-shell nanoparticles can be developed to have additional interactive properties from the combination of the core and shell together, rather than just the core particle alone. This dissertation focuses on developing new porous core-shell systems in which both the core and shell take part in catalysis. Two types of systems are explored; (1) yolk-shell nanostructures with reducible oxide shells formed using the Kirkendall effect and (2) ceramic-based porous oxide shells formed using sol-gel chemistry. Of the Kirkendall-based systems, Au FexOy and Cu CoO were synthesized and studied for catalytic applications. Additionally, ZnO was explored as a potential shelling material. Sol-gel work focused on optimizing synthetic methods to allow for coating of small gold particles, which remains a challenge today. Mixed metal oxides were explored as a shelling material to make dual catalysts in which the product of a reaction on the core particle becomes a reactant within the shell.

Strut fracture and disc embolization of a Björk-Shiley mitral valve prosthesis: localization of embolized disc by computerized axial tomography.

Science.gov (United States)

Larrieu, A J; Puglia, E; Allen, P

1982-08-01

The case of a patient who survived strut fracture and embolization of a Björk-Shiley mitral prosthetic disc is presented. Prompt surgical treatment was directly responsible for survival. In addition, computerized axial tomography of the abdomen aided in localizing and retrieving the embolized disc, which was lodged at the origin of the superior mesenteric artery. A review of similar case reports from the literature supports our conclusions that the development of acute heart failure and absent or muffled prosthetic heart sounds in a patient with a Björk-Shiley prosthetic heart valve inserted prior to 1978 should raise the possibility of valve dysfunction and lead to early reoperation.

Material heterogeneity in cancellous bone promotes deformation recovery after mechanical failure.

Science.gov (United States)

Torres, Ashley M; Matheny, Jonathan B; Keaveny, Tony M; Taylor, David; Rimnac, Clare M; Hernandez, Christopher J

2016-03-15

Many natural structures use a foam core and solid outer shell to achieve high strength and stiffness with relatively small amounts of mass. Biological foams, however, must also resist crack growth. The process of crack propagation within the struts of a foam is not well understood and is complicated by the foam microstructure. We demonstrate that in cancellous bone, the foam-like component of whole bones, damage propagation during cyclic loading is dictated not by local tissue stresses but by heterogeneity of material properties associated with increased ductility of strut surfaces. The increase in surface ductility is unexpected because it is the opposite pattern generated by surface treatments to increase fatigue life in man-made materials, which often result in reduced surface ductility. We show that the more ductile surfaces of cancellous bone are a result of reduced accumulation of advanced glycation end products compared with the strut interior. Damage is therefore likely to accumulate in strut centers making cancellous bone more tolerant of stress concentrations at strut surfaces. Hence, the structure is able to recover more deformation after failure and return to a closer approximation of its original shape. Increased recovery of deformation is a passive mechanism seen in biology for setting a broken bone that allows for a better approximation of initial shape during healing processes and is likely the most important mechanical function. Our findings suggest a previously unidentified biomimetic design strategy in which tissue level material heterogeneity in foams can be used to improve deformation recovery after failure.

Blanket options for high-efficiency fusion power

International Nuclear Information System (INIS)

Usher, J.L.; Lazareth, O.W.; Fillo, J.A.; Horn, F.L.; Powell, J.R.

1980-01-01

The efficiencies of blankets for fusion reactors are usually in the range of 30 to 40%, limited by the operating temperatures (500 0 C) of conventional structural materials such as stainless steels. In this project two-zone blankets are proposed; these blankets consist of a low-temperature shell surrounding a high-temperature interior zone. A survey of nucleonics and thermal hydraulic parameters has led to a reference blanket design consisting of a water-cooled stainless steel shell around a BeO, ZrO 2 interior (cooled by argon) utilizing Li 2 O for tritium breeding. In this design, approximately 60% of the fusion energy is deposited in the high-temperature interior. The maximum argon temperature is 2230 0 C leading to an overall efficiency estimate of 55 to 60% for this reference case

Fusion blankets for high-efficiency power cycles

International Nuclear Information System (INIS)

Usher, J.L.; Lazareth, O.W.; Fillo, J.A.; Horn, F.L.; Powell, J.R.

1980-01-01

The efficiencies of blankets for fusion reactors are usually in the range of 30 to 40%, limited by the operating temperatures (500 0 C) of conventional structural materials such as stainless steels. In this project two-zone blankets are proposed; these blankets consist of a low-temperature shell surrounding a high-temperature interior zone. A survey of nucleonics and thermal hydraulic parameters has led to a reference blanket design consisting of a water-cooled stainless steel shell around a BeO, ZrO 2 interior (cooled by argon) utilizing Li 2 O for tritium breeding. In this design, approximately 60% of the fusion energy is deposited in the high-temperature interior. The maximum argon temperature is 2230 0 C leading to an overall efficiency estimate of 55 to 60% for this reference case

Fusion blanket for high-efficiency power cycles

International Nuclear Information System (INIS)

Usher, J.L.; Powell, J.R.; Fillo, J.A.; Horn, F.L.; Lazareth, O.W.; Taussig, R.

1980-01-01

The efficiencies of blankets for fusion reactors are usually in the range of 30 to 40%, limited by the operating temperature (500 0 C) of conventional structural materials such as stainless steels. In this project two-zone blankets are proposed; these blankets consist of a low-temperature shell surrounding a high-temperature interior zone. A survey of nucleonics and thermal hydraulic parameters has led to a reference blanket design consisting of a water-cooled stainless steel shell around a BeO, ZrO 2 interior (cooled by Ar) utilizing Li 2 O for tritium breeding. In this design, approx. 60% of the fusion energy is deposited in the high-temperature interior. The maximum Ar temperature is 2230 0 C leading to an overall efficiency estimate of 55 to 60% for this reference case

Fusion blankets for high-efficiency power cycles

International Nuclear Information System (INIS)

Usher, J.L.; Lazareth, O.W.; Fillo, J.A.; Horn, F.L.; Powell, J.R.

1981-01-01

The efficiencies of blankets for fusion reactors are usually in the range of 30 to 40%, limited by the operating temperatures (500 deg C) of conventional structural materials such as stainless steels. In this project 'two-zone' blankets are proposed; these blankets consist of a low-temperature shell surrounding a high-temperature interior zone. A survey of nucleonics and thermal hydraulic parameters has led to a reference blanket design consisting of a water-cooled stainless steel shell around a BeO, ZrO 2 interior (cooled by argon) utilizing Li 2 O for tritium breeding. In this design, approximately 60% of the fusion energy is deposited in the high-temperature interior. The maximum argon temperature is 2230 deg C leading to an overall efficiency estimate of 55 to 60% for this reference case. (author)

Ge/Si core/shell quantum dots in alumina: tuning the optical absorption by the core and shell size

Directory of Open Access Journals (Sweden)

Nekić Nikolina

2017-03-01

Full Text Available Ge/Si core/shell quantum dots (QDs recently received extensive attention due to their specific properties induced by the confinement effects of the core and shell structure. They have a type II confinement resulting in spatially separated charge carriers, the electronic structure strongly dependent on the core and shell size. Herein, the experimental realization of Ge/Si core/shell QDs with strongly tunable optical properties is demonstrated. QDs embedded in an amorphous alumina glass matrix are produced by simple magnetron sputtering deposition. In addition, they are regularly arranged within the matrix due to their self-assembled growth regime. QDs with different Ge core and Si shell sizes are made. These core/shell structures have a significantly stronger absorption compared to pure Ge QDs and a highly tunable absorption peak dependent on the size of the core and shell. The optical properties are in agreement with recent theoretical predictions showing the dramatic influence of the shell size on optical gap, resulting in 0.7 eV blue shift for only 0.4 nm decrease at the shell thickness. Therefore, these materials are very promising for light-harvesting applications.

Chemical Structure, Ensemble and Single-Particle Spectroscopy of Thick-Shell InP-ZnSe Quantum Dots.

Science.gov (United States)

Reid, Kemar R; McBride, James R; Freymeyer, Nathaniel J; Thal, Lucas B; Rosenthal, Sandra J

2018-02-14

Thick-shell (>5 nm) InP-ZnSe colloidal quantum dots (QDs) grown by a continuous-injection shell growth process are reported. The growth of a thick crystalline shell is attributed to the high temperature of the growth process and the relatively low lattice mismatch between the InP core and ZnSe shell. In addition to a narrow ensemble photoluminescence (PL) line-width (∼40 nm), ensemble and single-particle emission dynamics measurements indicate that blinking and Auger recombination are reduced in these heterostructures. More specifically, high single-dot ON-times (>95%) were obtained for the core-shell QDs, and measured ensemble biexciton lifetimes, τ 2x ∼ 540 ps, represent a 7-fold increase compared to InP-ZnS QDs. Further, high-resolution energy dispersive X-ray (EDX) chemical maps directly show for the first time significant incorporation of indium into the shell of the InP-ZnSe QDs. Examination of the atomic structure of the thick-shell QDs by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) reveals structural defects in subpopulations of particles that may mitigate PL efficiencies (∼40% in ensemble), providing insight toward further synthetic refinement. These InP-ZnSe heterostructures represent progress toward fully cadmium-free QDs with superior photophysical properties important in biological labeling and other emission-based technologies.

Studies of dust shells around stars

International Nuclear Information System (INIS)

Bedijn, P.J.

1977-01-01

This thesis deals with some aspects of circumstellar dust shells. This dust shell, emitting infrared radiation, is described by way of its absorptive and emissive properties as well as by the transfer of radiation through the dust shell itself. Model calculations are compared to experimental results and agree reasonably well. The author also discusses the dynamics of the extended shells of gas and dust around newly formed stars

Transfer of pharmacopoeial liquid chromatography reversedphase methods for determination of related compounds in diclofenac sodium and metamizole sodium from conventional to core-shell column

Directory of Open Access Journals (Sweden)

Katerina Brezovska

2015-04-01

Full Text Available Core-shell silica particles were developed as a new material for chromatographic stationary phases in order to provide fast and high efficiency separations of small and large molecules and complex samples, at pressures compatible with conventional HPLC equipment. The aim of our work was to show the applicability of the HPLC columns based on a core-shell technology for determination of related substances in diclofenac sodium and in metamizole sodium using the methods described in the corresponding monographs of the European pharmacopoeia. The obtained results have shown that the proposed methods can be successfully transferred on core shell column, with suitable adjustment of injection volume and flow rate. The advantage of using core-shell column is fast and highly efficient separation on conventional HPLC equipment with increased sensitivity of the method and high throughput of the analysis, providing enhanced lab productivity and reduced costs.

Crystalline-Amorphous Core−Shell Silicon Nanowires for High Capacity and High Current Battery Electrodes

KAUST Repository

Cui, Li-Feng

2009-01-14

Silicon is an attractive alloy-type anode material for lithium ion batteries because of its highest known capacity (4200 mAh/g). However silicon\\'s large volume change upon lithium insertion and extraction, which causes pulverization and capacity fading, has limited its applications. Designing nanoscale hierarchical structures is a novel approach to address the issues associated with the large volume changes. In this letter, we introduce a core-shell design of silicon nanowires for highpower and long-life lithium battery electrodes. Silicon crystalline- amorphous core-shell nanowires were grown directly on stainless steel current collectors by a simple one-step synthesis. Amorphous Si shells instead of crystalline Si cores can be selected to be electrochemically active due to the difference of their lithiation potentials. Therefore, crystalline Si cores function as a stable mechanical support and an efficient electrical conducting pathway while amorphous shells store Li ions. We demonstrate here that these core-shell nanowires have high charge storage capacity (̃1000 mAh/g, 3 times of carbon) with ̃90% capacity retention over 100 cycles. They also show excellent electrochemical performance at high rate charging and discharging (6.8 A/g, ̃20 times of carbon at 1 h rate). © 2009 American Chemical Society.

Covarying Shell Growth Parameters and the Regulation of Shell Shape in Marine Bivalves: A Case Study on Tellinoidea

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Jean Béguinot

2014-01-01

Full Text Available Specific parameters characterising shell shape may arguably have a significant role in the adaptation of bivalve molluscs to their particular environments. Yet, such functionally relevant shape parameters (shell outline elongation, dissymmetry, and ventral convexity are not those parameters that the animal may directly control. Rather than shell shape, the animal regulates shell growth. Accordingly, an alternative, growth-based description of shell-shape is best fitted to understand how the animal may control the achieved shell shape. The key point is, in practice, to bring out the link between those two alternative modes of shell-shape descriptions, that is, to derive the set of equations which connects the growth-based shell-shape parameters to the functionally relevant shell-shape parameters. Thus, a preliminary object of this note is to derive this set of equations as a tool for further investigations. A second object of this work is to provide an illustrative example of implementation of this tool. I report on an unexpected negative covariance between growth-based parameters and show how this covariance results in a severe limitation of the range of interspecific variability of the degree of ventral convexity of the shell outline within the superfamily Tellinoidea. Hypotheses are proposed regarding the constraints possibly at the origin of this limitation of interspecific variability.

Camellia oleifera shell as an alternative feedstock for furfural production using a high surface acidity solid acid catalyst.

Science.gov (United States)

Zhang, Luxin; He, Yunfei; Zhu, Yujie; Liu, Yuting; Wang, Xiaochang

2018-02-01

This paper focuses on the high-value transformation of camellia oleifera shell, which is an agricultural waste enriched in hemicellulose. An efficient catalytic route employing sulfonated swelling mesoporous polydivinylbenzene (PDVB-SO 3 H) as catalyst in monophasic or biphasic solvents was developed for the conversion of raw camellia oleifera shell into furfural. The reaction parameters were evaluated and optimized for improving the furfural yield. It was found that the solvent greatly influenced the hydrolysis of camellia oleifera shells, and the highest furfural yield of 61.3% was obtained in "γ-butyrolactone + water" system when the feedstock-to-catalyst ratio was 2 for 30 min at 443 K. Camellia oleifera shell exhibited a high potential as feedstock to produce furfural in high yields. The outcome of this study provides an attractive utilization option to camellia oleifera shell, which is currently burned or discarded for producing a bio-based chemical. Copyright © 2017 Elsevier Ltd. All rights reserved.

Engineered inorganic core/shell nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Mélinon, Patrice, E-mail: patrice.melinon@univ-lyon1.fr [Institut Lumière matière Université Claude Bernard Lyon 1 et CNRS et OMNT, Domaine Scientifique de la Doua, Bâtiment Léon Brillouin, 43 Boulevard du 11 Novembre 1918, F 69622 Villeurbanne (France); Begin-Colin, Sylvie [IPCMS et OMNT, 23 rue du Loess BP 43, 67034 STRASBOURG Cedex 2 (France); Duvail, Jean Luc [IMN UMR 6502 et OMNT Campus Sciences : 2 rue de la Houssinire, BP32229, 44322 Nantes Cedex3 (France); Gauffre, Fabienne [SPM et OMNT : Institut des sciences chimiques de Rennes - UMR 6226, 263 Avenue du General Leclerc, CS 74205, 35042 RENNES Cedex (France); Boime, Nathalie Herlin [IRAMIS-NIMBE, Laboratoire Francis Perrin (CEA CNRS URA 2453) et OMNT, Bat 522, CEA Saclay, 91191 Gif sur Yvette Cedex (France); Ledoux, Gilles [Institut Lumière Matière Université Claude Bernard Lyon 1 et CNRS et OMNT, Domaine Scientifique de la Doua, Bâtiment Alfred Kastler 43 Boulevard du 11 Novembre 1918 F 69622 Villeurbanne (France); Plain, Jérôme [Universit de technologie de Troyes LNIO-ICD, CNRS et OMNT 12 rue Marie Curie - CS 42060 - 10004 Troyes cedex (France); Reiss, Peter [CEA Grenoble, INAC-SPrAM, UMR 5819 CEA-CNRS-UJF et OMNT, Grenoble cedex 9 (France); Silly, Fabien [CEA, IRAMIS, SPEC, TITANS, CNRS 2464 et OMNT, F-91191 Gif sur Yvette (France); Warot-Fonrose, Bénédicte [CEMES-CNRS, Université de Toulouse et OMNT, 29 rue Jeanne Marvig F 31055 Toulouse (France)

2014-10-20

It has been for a long time recognized that nanoparticles are of great scientific interest as they are effectively a bridge between bulk materials and atomic structures. At first, size effects occurring in single elements have been studied. More recently, progress in chemical and physical synthesis routes permitted the preparation of more complex structures. Such structures take advantages of new adjustable parameters including stoichiometry, chemical ordering, shape and segregation opening new fields with tailored materials for biology, mechanics, optics magnetism, chemistry catalysis, solar cells and microelectronics. Among them, core/shell structures are a particular class of nanoparticles made with an inorganic core and one or several inorganic shell layer(s). In earlier work, the shell was merely used as a protective coating for the core. More recently, it has been shown that it is possible to tune the physical properties in a larger range than that of each material taken separately. The goal of the present review is to discuss the basic properties of the different types of core/shell nanoparticles including a large variety of heterostructures. We restrict ourselves on all inorganic (on inorganic/inorganic) core/shell structures. In the light of recent developments, the applications of inorganic core/shell particles are found in many fields including biology, chemistry, physics and engineering. In addition to a representative overview of the properties, general concepts based on solid state physics are considered for material selection and for identifying criteria linking the core/shell structure and its resulting properties. Chemical and physical routes for the synthesis and specific methods for the study of core/shell nanoparticle are briefly discussed.

Microbial Degradation of Lobster Shells to Extract Chitin Derivatives for Plant Disease Management

Directory of Open Access Journals (Sweden)

Gayathri Ilangumaran

2017-05-01

Full Text Available Biodegradation of lobster shells by chitinolytic microorganisms are an environment safe approach to utilize lobster processing wastes for chitin derivation. In this study, we report degradation activities of two microbes, “S223” and “S224” isolated from soil samples that had the highest rate of deproteinization, demineralization and chitinolysis among ten microorganisms screened. Isolates S223 and S224 had 27.3 and 103.8 protease units mg-1 protein and 12.3 and 11.2 μg ml-1 of calcium in their samples, respectively, after 1 week of incubation with raw lobster shells. Further, S223 contained 23.8 μg ml-1 of N-Acetylglucosamine on day 3, while S224 had 27.3 μg ml-1 on day 7 of incubation with chitin. Morphological observations and 16S rDNA sequencing suggested both the isolates were Streptomyces. The culture conditions were optimized for efficient degradation of lobster shells and chitinase (∼30 kDa was purified from crude extract by affinity chromatography. The digested lobster shell extracts induced disease resistance in Arabidopsis by induction of defense related genes (PR1 > 500-fold, PDF1.2 > 40-fold upon Pseudomonas syringae and Botrytis cinerea infection. The study suggests that soil microbes aid in sustainable bioconversion of lobster shells and extraction of chitin derivatives that could be applied in plant protection.

Carbon isotopes in mollusk shell carbonates

Science.gov (United States)

McConnaughey, Ted A.; Gillikin, David Paul

2008-10-01

Mollusk shells contain many isotopic clues about calcification physiology and environmental conditions at the time of shell formation. In this review, we use both published and unpublished data to discuss carbon isotopes in both bivalve and gastropod shell carbonates. Land snails construct their shells mainly from respired CO2, and shell δ13C reflects the local mix of C3 and C4 plants consumed. Shell δ13C is typically >10‰ heavier than diet, probably because respiratory gas exchange discards CO2, and retains the isotopically heavier HCO3 -. Respired CO2 contributes less to the shells of aquatic mollusks, because CO2/O2 ratios are usually higher in water than in air, leading to more replacement of respired CO2 by environmental CO2. Fluid exchange with the environment also brings additional dissolved inorganic carbon (DIC) into the calcification site. Shell δ13C is typically a few ‰ lower than ambient DIC, and often decreases with age. Shell δ13C retains clues about processes such as ecosystem metabolism and estuarine mixing. Ca2+ ATPase-based models of calcification physiology developed for corals and algae likely apply to mollusks, too, but lower pH and carbonic anhydrase at the calcification site probably suppress kinetic isotope effects. Carbon isotopes in biogenic carbonates are clearly complex, but cautious interpretation can provide a wealth of information, especially after vital effects are better understood.

Dynamic centering of liquid shells

International Nuclear Information System (INIS)

Tsamopoulos, J.A.; Brown, R.A.

1987-01-01

The moderate-amplitude axisymmetric oscillations of an inviscid liquid shell surrounding an incompressible gas bubble are calculated by a multiple-time-scale expansion for initial deformations composed of two-lobed perturbations of the shell and a displacement of the bubble from the center of mass of the liquid. Two types of small-amplitude motion are identified and lead to very different nonlinear dynamic interactions, as described by the results valid up to second order in the amplitude of the initial deformation. In the ''bubble mode,'' the oscillations of the captive bubble and the liquid shell are exactly in phase and the bubble vibrates about its initial eccentric location. The bubble moves toward the center of the drop when the shell is perturbed into a ''sloshing mode'' of oscillation where both interfaces move out of phase. These results explain the centering of liquid shells observed in several experiments

Hollow Pd/MOF Nanosphere with Double Shells as Multifunctional Catalyst for Hydrogenation Reaction.

Science.gov (United States)

Wan, Mingming; Zhang, Xinlu; Li, Meiyan; Chen, Bo; Yin, Jie; Jin, Haichao; Lin, Lin; Chen, Chao; Zhang, Ning

2017-10-01

A new type of hollow nanostructure featured double metal-organic frameworks shells with metal nanoparticles (MNPs) is designed and fabricated by the methods of ship in a bottle and bottle around the ship. The nanostructure material, hereinafter denoted as Void@HKUST-1/Pd@ZIF-8, is confirmed by the analyses of photograph, transmission electron microscopy, scanning electron microscopy, powder X-ray diffraction, inductively coupled plasma, and N 2 sorption. It possesses various multifunctionally structural characteristics such as hollow cavity which can improve mass transfer, the adjacent of the inner HKUST-1 shell to the void which enables the matrix of the shell to host and well disperse MNPs, and an outer ZIF-8 shell which acts as protective layer against the leaching of MNPs and a sieve to guarantee molecular-size selectivity. This makes the material eligible candidates for the heterogeneous catalyst. As a proof of concept, the liquid-phase hydrogenation of olefins with different molecular sizes as a model reaction is employed. It demonstrates the efficient catalytic activity and size-selectivity of Void@HKUST-1/Pd@ZIF-8. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Shells and Patterns

Science.gov (United States)

Sutley, Jane

2009-01-01

"Shells and Patterns" was a project the author felt would easily put smiles on the faces of her fifth-graders, and teach them about unity and the use of watercolor pencils as well. It was thrilling to see the excitement in her students as they made their line drawings of shells come to life. For the most part, they quickly got the hang of…

Four-loop on-shell integrals. MS-on-shell relation and g-2

Energy Technology Data Exchange (ETDEWEB)

Marquard, P.

2013-12-15

We present first results towards a full four-loop calculation for both the anomalous magnetic moment of the muon and the MS-on-shell relation. The calculation requires the detailed study of an up to now not considered class of diagrams, so-called on-shell diagrams, at four-loop order.

Recent developments in anisotropic heterogeneous shell theory

CERN Document Server

Grigorenko, Alexander Ya; Grigorenko, Yaroslav M; Vlaikov, Georgii G

2016-01-01

This volume focuses on the relevant general theory and presents some first applications, namely those based on classical shell theory. After a brief introduction, during which the history and state-of-the-art are discussed, the first chapter presents the mechanics of anisotropic heterogeneous shells, covering all relevant assumptions and the basic relations of 3D elasticity, classical and refined shell models. The second chapter examines the numerical techniques that are used, namely discrete orthogonalization, spline-collocation and Fourier series, while the third highlights applications based on classical theory, in particular, the stress-strain state of shallow shells, non-circular shells, shells of revolution, and free vibrations of conical shells. The book concludes with a summary and an outlook bridging the gap to the second volume.

Core/shell Fe{sub 3}O{sub 4}/BiOI nanoparticles with high photocatalytic activity and stability

Energy Technology Data Exchange (ETDEWEB)

Zheng, Liyun, E-mail: zhengliyun@126.com [Hebei University of Engineering, College of Materials Science and Engineering (China); Wang, Shuling; Zhao, Lixin [Hebei University of Engineering, College of Mechanical and Equipment Engineering (China); Zhao, Shuguo [Handan Polytechnic College, Mechanical and Electrical Department (China)

2016-11-15

Core/shell Fe{sub 3}O{sub 4}/BiOI nanoparticles with BiOI sheath have been synthesized by a solvothermal reaction method and were characterized by transmission electron microscopy (TEM) with an energy dispersive spectrum (EDS), high-resolution TEM and X-ray diffraction (XRD). Their photocatalytic activities were evaluated by methylene blue (MB) under the simulated solar light. The results indicate that the spherical Fe{sub 3}O{sub 4} particles were coated with BiOI sheath when the sample were synthesized at 160 °C with ethylene glycol and deionized water, forming a core/shell structure. The degradation rate of MB assisted with the core/shell Fe{sub 3}O{sub 4}/BiOI catalysts reached 98 % after 40-min irradiation. The catalytic performance enhancement of the core/shell Fe{sub 3}O{sub 4}/BiOI catalysts mainly attributes to the band structure that can improve the generation efficiency, separation and transfer process of the photo-induced electron–hole pairs and decrease their recombination. The magnetic Fe{sub 3}O{sub 4} core not only contributes to the efficient separation of electron and holes, but also helps catalysts be collected conveniently using a magnet for reuse. After five repeated trials, the degradation rate of MB still maintains over 90 % and the saturated magnetization of the catalysts remains 51.5 emu/g, which indicate that the core/shell Fe{sub 3}O{sub 4}/BiOI nanoparticles have excellent photocatalytic stability and are recyclable for decomposing organic pollutants under visible light irradiation.

A kinetic Monte Carlo study of coarsening resistance of novel core/shell precipitates

International Nuclear Information System (INIS)

Zhang, Xuan; Gao, Wenpei; Bellon, Pascal; Averback, Robert S.; Zuo, Jian-Min

2014-01-01

A novel approach towards the design of coarsening-resistant nanoprecipitates in structural alloys was investigated by kinetic Monte Carlo (KMC) simulation. The approach is motivated by recent experimental results in Cu–Nb–W alloys showing that room temperature ion irradiation resulted in W nanoprecipitation, leading to exceptional stability of W-rich-core/Nb-rich-shell nanoprecipitates formed following thermal annealing (Zhang et al., 2013 [11]). Here, image simulations of atomically resolved scanning transmission electron microscopy are performed to establish that these W nanoprecipitates are highly ramified. Thermal precipitate coarsening in an A–B–C ternary alloy similar to Cu–Nb–W is then studied by KMC simulations, where the highly immiscible and refractory C solute atoms are initially distributed into fractal nanoprecipitates, or cores, which become coated by a shell of B atoms during elevated temperature annealing. Compared with nanoprecipitates generated by compact C cores, the ramified nanoprecipitates result in exceptionally high trapping efficiency of B solute atoms during thermal coarsening, and the efficiency increases with the cluster size. The KMC results are analyzed and rationalized by noting that, owing to the Gibbs–Thomson effect, when the curvatures of the shell of the precipitates are zero or negative, the microstructure is coarsening-resistant. Such morphology can be realized by facets, or by dynamic balance within positive, negative and zero curvatures

Ni3Si(Al)/a-SiOx core shell nanoparticles: characterization, shell formation, and stability

Science.gov (United States)

Pigozzi, G.; Mukherji, D.; Gilles, R.; Barbier, B.; Kostorz, G.

2006-08-01

We have used an electrochemical selective phase dissolution method to extract nanoprecipitates of the Ni3Si-type intermetallic phase from two-phase Ni-Si and Ni-Si-Al alloys by dissolving the matrix phase. The extracted nanoparticles are characterized by transmission electron microscopy, energy-dispersive x-ray spectrometry, x-ray powder diffraction, and electron powder diffraction. It is found that the Ni3Si-type nanoparticles have a core-shell structure. The core maintains the size, the shape, and the crystal structure of the precipitates that existed in the bulk alloys, while the shell is an amorphous phase, containing only Si and O (SiOx). The shell forms around the precipitates during the extraction process. After annealing the nanoparticles in nitrogen at 700 °C, the tridymite phase recrystallizes within the shell, which remains partially amorphous. In contrast, on annealing in air at 1000 °C, no changes in the composition or the structure of the nanoparticles occur. It is suggested that the shell forms after dealloying of the matrix phase, where Si atoms, the main constituents of the shell, migrate to the surface of the precipitates.

Performance Evaluation of the Effect of waste paper on Groundnut Shell Briquette

Directory of Open Access Journals (Sweden)

Olatunde A Oyelaran

2015-07-01

Full Text Available Current energy shortage and environmental issues resulting from the use of fossil fuels have lead to exploitation of renewable energy resources that includes municipal waste and agricultural residues. These residues are available, indigenous and are environmental friendly but some can not be used directly in combustion process due high moisture content and low volumetric energy unless by briquetting. The study was undertaken to assess the combustion characteristic of binderless briquettes produced from waste paper and groundnut shell. Combustion characteristics investigated were ignition time, burning time, calorific values, burning rate, specific fuel consumption, fuel efficiency and water boiling time. The calorific values of the briquettes ranged from 19.51 - 19.92 MJ/kg, while the thermal efficiency ranges between 13.75 – 21.64%, other results shows that the average burning rate between 0.511 and 1.133 kg/hr and the specific fuel consumption ranges between 0.087 and 0.131 J/g. The recorded boiling time values were between 17.5 and 30.0 minutes for cold start and 15.0 and 20.0 minutes for hot start. The results shows that waste paper and groundnut shell up to 25% in composition composite briquettes were found to have good combustion characteristics which qualify them as alternative to firewood for domestic and industrial energy. However, production of briquettes from waste paper and groundnut shell at mixing ratio of 85:15 was found to comparatively better from all experiment conducted.

Efficient color mixing through étendue conservation using freeform optics

Science.gov (United States)

Sorgato, Simone; Mohedano, Rubén.; Chaves, Julio; Cvetkovic, Aleksandra; Hernández, Maikel; Benitez, Pablo; Miñano, Juan C.; Thienpont, Hugo; Duerr, Fabian

2015-08-01

Today's SSL illumination market shows a clear trend to high flux packages with higher efficiency and higher CRI, realized by means of multiple color chips and phosphors. Such light sources require the optics to provide both near- and far-field color mixing. This design problem is particularly challenging for collimated luminaries, since traditional diffusers cannot be employed without enlarging the exit aperture and reducing brightness. Furthermore, diffusers compromise the light output ratio (efficiency) of the lamps to which they are applied. A solution, based on Köhler integration, consisting of a spherical cap comprising spherical microlenses on both its interior and exterior sides was presented in 2012. The diameter of this so-called Shell-Mixer was 3 times that of the chip array footprint. A new version of the Shell-Mixer, based on the Edge Ray Principle and conservation of etendue, where neither the outer shape of the cap nor the surfaces of the lenses are constrained to spheres or 2D Cartesian ovals will be shown in this work. The new shell is freeform, only twice as large as the original chip-array and equals the original model in terms of color uniformity, brightness and efficiency.

Three-dimensional free vibration of functionally graded truncated conical shells subjected to thermal environment

Energy Technology Data Exchange (ETDEWEB)

Malekzadeh, P., E-mail: p_malekz@yahoo.com [Department of Mechanical Engineering, Persian Gulf University, Bushehr 75168 (Iran, Islamic Republic of); Fiouz, A.R.; Sobhrouyan, M. [Department of Civil Engineering, Persian Gulf University, Bushehr 75168 (Iran, Islamic Republic of)

2012-01-15

A three-dimensional (3D) free vibration analysis of the functionally graded (FG) truncated conical shells subjected to thermal environment is presented. The material properties are assumed to be temperature-dependent and graded in the radius direction, which can vary according to a simple power law distribution. The initial thermal stresses are obtained accurately by solving the thermoelastic equilibrium equations and by considering the two-dimensional axisymmetric temperature distribution in the shell. The differential quadrature method (DQM) as an efficient and accurate numerical tool is adopted to solve the thermal and thermo-mechanical governing equations. For this purpose, a mapping technique is employed to transform the cross section of the shell into the computational domain of DQM. The convergence behavior of the method is numerically demonstrated and comparison studies with the available solutions in the literature are performed. The effects of temperature dependence of material properties, geometrical parameters, material graded index, thermal and mechanical boundary conditions on the frequency parameters of the FG truncated conical shells are carried out. - Highlights: Black-Right-Pointing-Pointer 3D free vibration analysis of the functionally graded truncated conical shells is presented. Black-Right-Pointing-Pointer Two-dimensional axisymmetric temperature distribution in the shell is assumed. Black-Right-Pointing-Pointer The material properties are assumed to be temperature-dependent. Black-Right-Pointing-Pointer Initial thermal stresses due to thermal environment are evaluated accurately and included. Black-Right-Pointing-Pointer Representing the effects of different parameters on the non-dimensional frequencies.

Fabrication of Foam Shells for ICF Experiments

Science.gov (United States)

Czechowicz, D. G.; Acenas, O.; Flowers, J. S.; Nikroo, A.; Paguio, R. R.; Schroen, D. G.; Streit, J.; Takagi, M.

2004-11-01

The General Atomics/Schafer team has developed processes to fabricate foam shells targets suitable for ICF experiments. The two most common chemical systems used to produce foam shells have been resorcinol-formaldehyde (R/F) aerogel and divinylbenzene (DVB). Spherical targets have been made in the form of shells and beads having diameters ranging from approximately 0.5 mm to 4.0 mm, and having densities from approximately 100 mg/cc to 250 mg/cc. The work on R/F foam shells has been concentrated on 1) shell fabrication process improvement to obtain high yields ( ˜25%) and 2) depositing a reliable permeation barrier to provide shells for ongoing direct drive experiments at LLE. Development of divinylbenzene foam shells has been mainly directed towards Inertial Fusion Energy applications (at densities as low as 30 mg/cc) and recently for shells for experiments at LLE. Details of the relevant metrology and properties of these foams as well as the range of targets currently available will be discussed.

separation of oil palm kernel and shell mixture using soil and palm

African Journals Online (AJOL)

user

shape and size of the nuts and a good industrial raw material [3]. ... Large-scale mills have automated hydro-cyclone machines with high separation efficiency, however, clay-baths and hydro cyclones are known for their high energy and water consumption .... A mixture of kernel/shell weighing 20kg were poured into pot 1 ...

Radar attenuation in Europa's ice shell: Obstacles and opportunities for constraining the shell thickness and its thermal structure

Science.gov (United States)

Kalousová, Klára; Schroeder, Dustin M.; Soderlund, Krista M.

2017-03-01

Young surface and possible recent endogenic activity make Europa one of the most exciting solar system bodies and a primary target for spacecraft exploration. Future Europa missions are expected to carry ice-penetrating radar instruments designed to investigate its subsurface thermophysical structure. Several authors have addressed the radar sounders' performance at icy moons, often ignoring the complex structure of a realistic ice shell. Here we explore the variation in two-way radar attenuation for a variety of potential thermal structures of Europa's shell (determined by reference viscosity, activation energy, tidal heating, surface temperature, and shell thickness) as well as for low and high loss temperature-dependent attenuation model. We found that (i) for all investigated ice shell thicknesses (5-30 km), the radar sounder will penetrate between 15% and 100% of the total thickness, (ii) the maximum penetration depth varies laterally, with deepest penetration possible through cold downwellings, (iii) direct ocean detection might be possible for shells of up to 15 km thick if the signal travels through cold downwelling ice or the shell is conductive, (iv) even if the ice/ocean interface is not directly detected, penetration through most of the shell could constrain the deep shell structure through returns from deep non-ocean interfaces or the loss of signal itself, and (v) for all plausible ice shells, the two-way attenuation to the eutectic point is ≲30 dB which shows a robust potential for longitudinal investigation of the ice shell's shallow thermophysical structure.

Vibration of liquid-filled thin shells

International Nuclear Information System (INIS)

Kalnins, A.

1979-01-01

This paper describes the analysis of free and forced vibration of a thin, axisymmetric shell, which contains some liquid. The axis of symmetry is vertical. Only such vibration is considered which can be produced by a horizontal movement of the base of shell. The objective of this paper is to examine the response of the coupled shell-liquid system for a frequency range lying between zero and the lowest natural sloshing frequency of the liquid. The mass of the liquid is modeled by a stationary and one or more sloshing masses. It is shown how the stationary mass can be incorporated in the vibration analysis of the shell and how to natural frequency of the coupled shell-liquid system can be obtained from a simple formula, if the lowest natural frequency of the shell, plus the stationary mass of the liquid, can be determined. A numerical example is given. (orig.)

On-shell and half-shell effects of the coulomb potential in quantum mechanics

NARCIS (Netherlands)

Maag, Jan Willem de

1984-01-01

In dit proefschrift wordt de Coulomb potentiaal in de nietrelativistische quantummechanica bestudeerd. Met gebruik van een streng wiskundige beschrijving onderzoeken we, in het bijzonder, on-shell en off-shell eigenschappen. De overeenkomsten en de verschillen met het geval van een glad afgeschermde

Creep buckling of shell structures

International Nuclear Information System (INIS)

Miyazaki, Noriyuki; Hagihara, Seiya

2015-01-01

The present article contains a review of the literatures on the creep buckling of shell structures published from late 1950's to recent years. In this article, the creep buckling studies on circular cylindrical shells, spherical shells, partial cylindrical shells and other shells are reviewed in addition to creep buckling criteria. Creep buckling is categorized into two types. One is the creep buckling due to quasi-static instability, in which the critical time for creep buckling is determined by tracing a creep deformation versus time curve. The other is the creep buckling due to kinetic instability, in which the critical time can be determined by examining the shape of total potential energy in the vicinity of a quasi-static equilibrium state. Bifurcation buckling and snap-through buckling during creep deformation belong to this type of creep buckling. A few detailed descriptions are given to the bifurcation and snap-through type of creep buckling based on the present authors' works. (author)

Decision 99-8 : Shell Canada Limited application to construct and operate an oil sands bitumen upgrader in the Fort Saskatchewan area : Shell Canada Products Limited application to amend refinery approval in the Fort Saskatchewan area

International Nuclear Information System (INIS)

1999-01-01

The Alberta Energy and Utilities Board considered an application by Shell Canada Limited to construct and operate an oil sands bitumen upgrader on Shell's property adjoining the existing Scotford refinery in the County of Strathcona. The upgrader would process bitumen from Shell's proposed Muskeg River Mine, located 70 km north of Fort McMurray, and other feedstocks available in the area. The Board also considered an application for an amendment to the existing Scotford refinery approval, Industrial Development Permit 89-10, for the processing of 3.75 million cubic metres per year of sour conversion feedstock. Under a coordinated application process, Shell filed a joint Shell Scotford Upgrader application/Environmental Impact Assessment. Issues considered with respect to these applications were: technology selection, air/health, sulphur recovery, noise/traffic, and land use conflict. Shell stated that its Scotford refinery is the most energy efficient refinery in the Americas and that is has the highest liquid yield per unit volume of crude oil feedstock of any refinery in the world. The refinery's hydrocracking capacity would make it possible to use hydro-conversion technology for its upgrader which is environmentally advantageous. After examining all of the evidence pertaining to the applications, the Board found the projects to be in the public interest and is prepared to approve the Scotford Upgrader and Scotford Refinery modifications assuming that certain prescribed conditions are met

Egg Shell and Oyster Shell Powder as Alternatives for Synthetic Phosphate: Effects on the Quality of Cooked Ground Pork Products.

Science.gov (United States)

Cho, Min Guk; Bae, Su Min; Jeong, Jong Youn

2017-01-01

This study aimed to determine the optimal ratio of natural calcium powders (oyster shell and egg shell calcium) as synthetic phosphate replacers in pork products. Ground pork samples were subjected to six treatments, as follows: control (-) (no phosphate added), control (+) (0.3% phosphate blend added), treatment 1 (0.5% oyster shell calcium powder added), treatment 2 (0.3% oyster shell calcium powder and 0.2% egg shell calcium powder added), treatment 3 (0.2% oyster shell calcium powder and 0.3% egg shell calcium powder added), and treatment 4 (0.5% egg shell calcium powder added). The addition of natural calcium powders resulted in an increase in the pH values of meat products, regardless of whether they were used individually or mixed. The highest cooking loss was observed ( p cooking loss in samples with natural calcium powder added was similar ( p >0.05) to that in the positive control samples. CIE L* values decreased as the amount of added egg shell calcium powder increased. CIE a* values were higher ( p egg shell powder (treatment 2 or 3) was effective for the improvement of textural properties of the pork products. The findings show that the combined use of 0.2% oyster shell calcium and 0.3% egg shell calcium should enable the replacement of synthetic phosphate in the production of cooked pork products with desirable qualities.

Controlled-release and preserved bioactivity of proteins from (self-assembled core-shell double-walled microspheres

Directory of Open Access Journals (Sweden)

Yuan W

2012-01-01

Full Text Available Weien Yuan1,2, Zhenguo Liu11Department of Neurology, Xinhua Hospital, affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 2School of Pharmacy, Shanghai Jiao Tong University, Shanghai, People’s Republic of ChinaAbstract: In order to address preserved protein bioactivities and protein sustained-release problems, a method for preparing double-walled microspheres with a core (protein-loaded nanoparticles with a polymer-suspended granule system-formed core and a second shell (a polymer-formed shell for controlled drug release and preserved protein bioactivities has been developed using (solid-in-oil phase-in-hydrophilic oil-in-water (S/O/Oh/W phases. The method, based on our previous microsphere preparation method (solid-in-oil phase-in-hydrophilic oil-in-water (S/O/Oh/W, employs different concentric poly(D,L-lactide-co-glycolide, poly(D,L-lactide, and protein-loaded nanoparticles to produce a suspended liquid which then self-assembles to form shell-core microspheres in the hydrophilic oil phase, which are then solidified in the water phase. Variations in the preparation parameters allowed complete encapsulation by the shell phase, including the efficient formation of a poly(D,L-lactide shell encapsulating a protein-loaded nanoparticle-based poly(D,L-lactide-co-glycolide core. This method produces core-shell double-walled microspheres that show controlled protein release and preserved protein bioactivities for 60 days. Based upon these results, we concluded that the core-shell double-walled microspheres might be applied for tissue engineering and therapy for chronic diseases, etc.Keywords: protein delivery, protein stability, core-shell microspheres, dextran nanoparticles

Core/Shell Structured TiO2/CdS Electrode to Enhance the Light Stability of Perovskite Solar Cells.

Science.gov (United States)

Hwang, Insung; Baek, Minki; Yong, Kijung

2015-12-23

In this work, enhanced light stability of perovskite solar cell (PSC) achieved by the introduction of a core/shell-structured CdS/TiO2 electrode and the related mechanism are reported. By a simple solution-based process (SILAR), a uniform CdS shell was coated onto the surface of a TiO2 layer, suppressing the activation of intrinsic trap sites originating from the oxygen vacancies of the TiO2 layer. As a result, the proposed CdS-PSC exhibited highly improved light stability, maintaining nearly 80% of the initial efficiency after 12 h of full sunlight illumination. From the X-ray diffraction analyses, it is suggested that the degradation of the efficiency of PSC during illumination occurs regardless of the decomposition of the perovskite absorber. Considering the light-soaking profiles of the encapsulated cells and the OCVD characteristics, it is likely that the CdS shell had efficiently suppressed the undesirable electron kinetics, such as trapping at the surface defects of the TiO2 and preventing the resultant charge losses by recombination. This study suggests that further complementary research on various effective methods for passivation of the TiO2 layer would be highly meaningful, leading to insight into the fabrication of PSCs stable to UV-light for a long time.

Controllable Synthesis of Gold Nanorod/Conducting Polymer Core/Shell Hybrids Toward in Vitro and in Vivo near-Infrared Photothermal Therapy.

Science.gov (United States)

Wang, Juan; Zhu, Chunhua; Han, Jie; Han, Na; Xi, Juqun; Fan, Lei; Guo, Rong

2018-04-18

Photothermal therapy (PTT) is a minimally invasive tumor treatment technology, and is regarded as a potential anticancer strategy because of its targeted destruction and low toxicity. Specifically, near-infrared light-induced PTT has attracted intriguing interest because of the high transparency of tissue, blood, and water. However, effective PTT generally requires the assistance of photothermal agents. Gold nanorods (GNRs) and conducting polymer are often used as photothermal materials because of their high absorption efficiency and photothermal conversion efficiency. Herein, we combined GNRs with poly( o-methoxyaniline) (POMA, a polyaniline derivative) to form GNRs/POMA core/shell hybrids through the surfactant-assisted chemical oxidative polymerization route and studied their photothermal conversion properties. The configuration of GNRs/POMA core/shell hybrids has been precisely controlled through adjusting the monomer concentration, and the relationship between morphology and absorption band of GNRs/POMA core/shell hybrids has been revealed. Finally, the in vitro and in vivo experiments were performed, and the results indicated that the GNRs/POMA core/shell hybrids with optimized absorbance at around 808 nm exhibited the best performance on photothermal therapy under 808 nm NIR laser irradiation.

Green Synthesis of InP/ZnS Core/Shell Quantum Dots for Application in Heavy-Metal-Free Light-Emitting Diodes

Science.gov (United States)

Kuo, Tsung-Rong; Hung, Shih-Ting; Lin, Yen-Ting; Chou, Tzu-Lin; Kuo, Ming-Cheng; Kuo, Ya-Pei; Chen, Chia-Chun

2017-09-01

Quantum dot light-emitting diodes (QD-LEDs) have been considered as potential display technologies with the characterizations of high color purity, flexibility, transparency, and cost efficiency. For the practical applications, the development of heavy-metal-free QD-LEDs from environment-friendly materials is the most important issue to reduce the impacts on human health and environmental pollution. In this work, heavy-metal-free InP/ZnS core/shell QDs with different fluorescence were prepared by green synthesis method with low cost, safe, and environment-friendly precursors. The InP/ZnS core/shell QDs with maximum fluorescence peak at 530 nm, superior fluorescence quantum yield of 60.1%, and full width at half maximum of 55 nm were applied as an emission layer to fabricate multilayered QD-LEDs. The multilayered InP/ZnS core/shell QD-LEDs showed the turn-on voltage at 5 V, the highest luminance (160 cd/m2) at 12 V, and the external quantum efficiency of 0.223% at 6.7 V. Overall, the multilayered InP/ZnS core/shell QD-LEDs reveal potential to be the heavy-metal-free QD-LEDs for future display applications.

7 CFR 983.29 - Shelled pistachios.

Science.gov (United States)

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Shelled pistachios. 983.29 Section 983.29 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE PISTACHIOS GROWN IN CALIFORNIA, ARIZONA, AND NEW MEXICO Definitions § 983.29 Shelled pistachios. Shelled pistachios means pistachio...

Vibrations of Thin Piezoelectric Shallow Shells

Indian Academy of Sciences (India)

Abstract. In this paper we consider the eigenvalue problem for piezoelectric shallow shells and we show that, as the thickness of the shell goes to zero, the eigensolutions of the three-dimensional piezoelectric shells converge to the eigensolutions of a two-dimensional eigenvalue problem.

Patterning of the turtle shell.

Science.gov (United States)

Moustakas-Verho, Jacqueline E; Cebra-Thomas, Judith; Gilbert, Scott F

2017-08-01

Interest in the origin and evolution of the turtle shell has resulted in a most unlikely clade becoming an important research group for investigating morphological diversity in developmental biology. Many turtles generate a two-component shell that nearly surrounds the body in a bony exoskeleton. The ectoderm covering the shell produces epidermal scutes that form a phylogenetically stable pattern. In some lineages, the bones of the shell and their ectodermal covering become reduced or lost, and this is generally associated with different ecological habits. The similarity and diversity of turtles allows research into how changes in development create evolutionary novelty, interacting modules, and adaptive physiology and anatomy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of solid state fermentation of peanut shell on its dye adsorption performance.

Science.gov (United States)

Liu, Jiayang; Wang, Zhixin; Li, Hongyan; Hu, Changwei; Raymer, Paul; Huang, Qingguo

2018-02-01

The effect of solid state fermentation of peanut shell to produce beneficial laccase and on its dye adsorption performance was evaluated. The resulting residues from solid fermentation were tested as sorbents (designated as SFs) in comparison to the raw peanut shell (RPS) for their ability to remove crystal violet from water. The fermentation process reduced the adsorption capacity (q m ) of SF by about 50%, and changed the sorptive behavior when compared to the RPS. The Langmuir model was more suitable for fitting adsorption by SFs. q m was positively correlated with the surface area of peanut shell, but negatively correlated with acid detergent lignin content. For all the sorbents tested, the process was spontaneous and endothermic, and the adsorption followed both the pseudo 1st and 2nd order kinetic model and the film diffusion model. Dye adsorption efficiency was greater when SFs dispersed solution than when placed in filter packets. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis of Aqueous CdTe/CdS/ZnS Core/shell/shell Quantum Dots by a Chemical Aerosol Flow Method

Directory of Open Access Journals (Sweden)

Chen Dong

2009-01-01

Full Text Available Abstract This work described a continuous method to synthesize CdTe/CdS/ZnS core/shell/shell quantum dots. In an integrated system by flawlessly combining the chemical aerosol flow system working at high temperature (200–300°C to generate CdTe/CdS intermediate products and an additional heat-up setup at relatively low temperature to overcoat the ZnS shells, the CdTe/CdS/ZnS multishell structures were realized. The as-synthesized CdTe/CdS/ZnS core/shell/shell quantum dots are characterized by photoluminescence spectra, X-ray diffraction (XRD, energy-dispersive X-ray spectra (EDS, transmission electron microscopy (TEM, and high-resolution transmission electron microscopy (HRTEM. Fluorescence and XRD results confirm that the obtained quantum dots have a core/shell/shell structure. It shows the highest quantum yield above 45% when compared to the rhodamine 6G. The core/shell/shell QDs were more stable via the oxidation experiment by H2O2.

Signatures of shell evolution in alpha decay across the N = 126 shell closure

Science.gov (United States)

Rui-Wang; Wang, Rui-Yao; Qian, Yi-Bin; Ren, Zhong-Zhou

2017-06-01

Within the alpha-cluster model, we particularly investigate the alpha decay of exotic nuclei in the vicinity of the N = 126 neutron shell plus the Z = 82 proton shell. The systematics of alpha-preformation probability (P α ), as an indicator of the shell effect, is deduced from the ratio of the experimental decay width to the calculated one. Through the comparative analysis of the P α trend in the N = 124-130 isotonic chain, the N = 126 and Z = 82 shell closures are believed to strongly affect the formation of the alpha particle before its penetration. Additionally, the P α variety in Po and Rn isotopes is presented as another proof for such an influence. More importantly, it may be concluded that the expected neutron (or proton) shell effect gradually fades away along with the increasing valence proton (or neutron) number. The odd-even staggering presented in the P α value is also discussed. Supported by National Natural Science Foundation of China (11375086, 11535004, 11605089, 11120101005), Natural Science Youth Fund of Jiangsu Province (BK20150762), Fundamental Research Funds for the Central Universities (30916011339), 973 National Major State Basic Research and Development Program of China (2013CB834400), and a Project Funded by the Priority Academic Programme Development of JiangSu Higher Education Institutions (PAPD)

Shell film- and video catalogue 1996

International Nuclear Information System (INIS)

1996-01-01

An overview is given of films and videos that are available through 'Shell Nederland Filmcentrale' (Shell Netherlands Film Center), subdivided into the subjects (1) About Shell; (2) Health, Safety and Environment; (3) Science and Technology; (4) The History of Car(racing); and (5) Historical Overview. 5 ills

7 CFR 981.6 - Shelled almonds.

Science.gov (United States)

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Shelled almonds. 981.6 Section 981.6 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE ALMONDS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 981.6 Shelled almonds. Shelled almonds mean raw or roasted almonds after...

Gold Core Mesoporous Organosilica Shell Degradable Nanoparticles for Two-Photon Imaging and Gemcitabine Monophosphate Delivery

KAUST Repository

Rhamani, Saher

2017-09-12

The synthesis of gold core degradable mesoporous organosilica shell nanoparticles is described. The nanopaticles were very efficient for two-photon luminescence imaging of cancer cells and for in vitro gemcitabine monophosphate delivery, allowing promising theranostic applications in the nanomedicine field.

Gold Core Mesoporous Organosilica Shell Degradable Nanoparticles for Two-Photon Imaging and Gemcitabine Monophosphate Delivery

KAUST Repository

Rhamani, Saher; Chaix, Arnaud; Aggad, Dina; Hoang, Phuong Mai; Moosa, Basem; Garcia, Marcel; Gary-Bobo, Magali; Charnay, Clarence; Almalik, Abdulaziz; Durand, Jean-Olivier; Khashab, Niveen M.

2017-01-01

The synthesis of gold core degradable mesoporous organosilica shell nanoparticles is described. The nanopaticles were very efficient for two-photon luminescence imaging of cancer cells and for in vitro gemcitabine monophosphate delivery, allowing promising theranostic applications in the nanomedicine field.

Indentation of Ellipsoidal and Cylindrical Elastic Shells

KAUST Repository

Vella, Dominic

2012-10-01

Thin shells are found in nature at scales ranging from viruses to hens\\' eggs; the stiffness of such shells is essential for their function. We present the results of numerical simulations and theoretical analyses for the indentation of ellipsoidal and cylindrical elastic shells, considering both pressurized and unpressurized shells. We provide a theoretical foundation for the experimental findings of Lazarus etal. [following paper, Phys. Rev. Lett. 109, 144301 (2012)PRLTAO0031-9007] and for previous work inferring the turgor pressure of bacteria from measurements of their indentation stiffness; we also identify a new regime at large indentation. We show that the indentation stiffness of convex shells is dominated by either the mean or Gaussian curvature of the shell depending on the pressurization and indentation depth. Our results reveal how geometry rules the rigidity of shells. © 2012 American Physical Society.

Double containment shell for nuclear power plants

International Nuclear Information System (INIS)

Sykora, D.

1977-01-01

A double containment shell is proposed for nuclear power plants, especially those equipped with pressurized water reactors. The shell offers increased environmental protection from primary circuit accidents. The inner shell is built of steel or concrete while the outer shell is always built of concrete. The space between the two shells is filled with water and is provided with several manholes and with stiffeners designed for compensation for load due to the water hydrostatic pressure. Water serves the airtight separation of the containment shell inside from the environment and the absorption of heat released in a primary circuit accident. In case the inner shell is made of concrete, it is provided with heat-removal tubes in-built in its walls ensuring rapid heat transfer from the inside of the containment to the water in the interwall space. (Z.M.)

Seismic analysis of axisymmetric shells

International Nuclear Information System (INIS)

Jospin, R.J.; Toledo, E.M.; Feijoo, R.A.

1984-01-01

Axisymmetric shells subjected to multiple support excitation are studied. The shells are spatialy discretized by the finite element method and in order to obtain estimates for the maximum values of displacements and stresses the response spectrum tecnique is used. Finally, some numerical results are presented and discussed in the case of a shell of revolution with vertical symmetry axis, subjected to seismic ground motions in the horizontal, vertical and rocking directions. (Author) [pt

Creep analysis of orthotropic shells

International Nuclear Information System (INIS)

Mehra, V.K.; Ghosh, A.

1975-01-01

A method of creep analysis of orthotropic cylindrical shells subjected to axisymmetric loads has been developed. A general study of creep behaviour of cylindrical shells subjected to a uniform internal pressure has been conducted for a wide range of values of anisotropy coefficients and creep law exponent. Analysis includes determination of stress re-distribution, strain rates, stationary state stresses. Application of reference stress technique has been extended to analysis of shells. (author)

Alkali resistant Ni-loaded yolk-shell catalysts for direct internal reforming in molten carbonate fuel cells

Science.gov (United States)

Jang, Won-Jun; Hong, Young Jun; Kim, Hak-Min; Shim, Jae-Oh; Roh, Hyun-Seog; Kang, Yun Chan

2017-06-01

A facile and scalable spray pyrolysis process is applied to synthesize multi-shelled Ni-loaded yolk-shell catalysts on various supports (Al2O3, CeO2, ZrO2, and La(OH)3). The prepared catalysts are applied to direct internal reforming (DIR) in a molten carbonate fuel cell (MCFC). Even on exposure to alkali hydroxide vapors, the Ni-loaded yolk-shell catalysts remain highly active for DIR-MCFCs. The Ni@Al2O3 microspheres show the highest conversion (92%) of CH4 and the best stability among the prepared Ni-loaded yolk-shell catalysts. Although the initial CH4 conversion of the Ni@ZrO2 microspheres is higher than that of the Ni@CeO2 microspheres, the Ni@CeO2 microspheres are more stable. The catalytic performance is strongly dependent on the surface area and acidity and also partly dependent on the reducibility. The acidic nature of Al2O3 combined with its high surface area and yolk-shell structure enhances the adsorption of CH4 and resistance against alkali poisoning, resulting in efficient DIR-MCFC reactions.

Synthesis, Characterization and Drug Loading of Multiresponsive p[NIPAm-co-PEGMA] (core/p[NIPAm-co-AAc] (Shell Nanogels with Monodisperse Size Distributions

Directory of Open Access Journals (Sweden)

Rajesh Raju

2018-03-01

Full Text Available We report the synthesis and properties of temperature- and pH-responsive p([NIPAm-co-PEGMA] (core/[NIPAm-co-AAc] (shell nanogels with narrow size distributions, tunable sizes and increased drug loading efficiencies. The core-shell nanogels were synthesized using an optimized two-stage seeded polymerization methodology. The core-shell nanogels show a narrow size distribution and controllable physico-chemical properties. The hydrodynamic sizes, charge distributions, temperature-induced volume phase transition behaviors, pH-responsive behaviors and drug loading capabilities of the core-shell nanogels were investigated using transmission electron microscopy, zeta potential measurements, dynamic light scattering and UV-Vis spectroscopy. The size of the core-shell nanogels was controlled by polymerizing NIPAm with crosslinker poly(ethylene glycol dimethacrylate (PEGDMA of different molecular weights (Mn-200, 400, 550 and 750 g/mol during the core synthesis. It was found that the swelling/deswelling kinetics of the nanogels was sharp and reversible; with its volume phase transition temperature in the range of 40–42 °C. Furthermore, the nanogels loaded with l-3,4-dihydroxyphenylalanine (L-DOPA, using a modified breathing-in mechanism, showed high loading and encapsulation efficiencies, providing potential possibilities of such nanogels for biomedical applications.

Faraday Wave Turbulence on a Spherical Liquid Shell

Science.gov (United States)

Holt, R. Glynn; Trinh, Eugene H.

1996-01-01

Millimeter-radius liquid shells are acoustically levitated in an ultrasonic field. Capillary waves are observed on the shells. At low energies (minimal acoustic amplitude, thick shell) a resonance is observed between the symmetric and antisymmetric thin film oscillation modes. At high energies (high acoustic pressure, thin shell) the shell becomes fully covered with high-amplitude waves. Temporal spectra of scattered light from the shell in this regime exhibit a power-law decay indicative of turbulence.

Tuning upconversion through energy migration in core-shell nanoparticles

KAUST Repository

Wang, Feng; Deng, Renren; Wang, Juan; Wang, Qingxiao; Han, Yu; Zhu, Haomiao; Chen, Xueyuan; Liu, Xiaogang

2011-01-01

Photon upconversion is promising for applications such as biological imaging, data storage or solar cells. Here, we have investigated upconversion processes in a broad range of gadolinium-based nanoparticles of varying composition. We show that by rational design of a core-shell structure with a set of lanthanide ions incorporated into separated layers at precisely defined concentrations, efficient upconversion emission can be realized through gadolinium sublattice-mediated energy migration for a wide range of lanthanide activators without long-lived intermediary energy states. Furthermore, the use of the core-shell structure allows the elimination of deleterious cross-relaxation. This effect enables fine-tuning of upconversion emission through trapping of the migrating energy by the activators. Indeed, the findings described here suggest a general approach to constructing a new class of luminescent materials with tunable upconversion emissions by controlled manipulation of energy transfer within a nanoscopic region. © 2011 Macmillan Publishers Limited. All rights reserved.

Tuning upconversion through energy migration in core-shell nanoparticles

KAUST Repository

Wang, Feng

2011-10-23

Photon upconversion is promising for applications such as biological imaging, data storage or solar cells. Here, we have investigated upconversion processes in a broad range of gadolinium-based nanoparticles of varying composition. We show that by rational design of a core-shell structure with a set of lanthanide ions incorporated into separated layers at precisely defined concentrations, efficient upconversion emission can be realized through gadolinium sublattice-mediated energy migration for a wide range of lanthanide activators without long-lived intermediary energy states. Furthermore, the use of the core-shell structure allows the elimination of deleterious cross-relaxation. This effect enables fine-tuning of upconversion emission through trapping of the migrating energy by the activators. Indeed, the findings described here suggest a general approach to constructing a new class of luminescent materials with tunable upconversion emissions by controlled manipulation of energy transfer within a nanoscopic region. © 2011 Macmillan Publishers Limited. All rights reserved.

Heat transfer in a compact tubular heat exchanger with application to the engine struts of the national aerospace plane

International Nuclear Information System (INIS)

Olsen, D.A.

1991-01-01

The authors constructed an apparatus to measure heat transfer coefficients in compact heat exchangers which are candidate cooling jackets for the engine struts of the National Aerospace Plane. This paper reports measurements on a tube specimen heat exchanger. The heat exchanger consisted of 20 nickel tubes (2 mm OD, 1 mm ID, 15.2 cm heated length), brazed to a 3 mm thick nickel plate. The tubes lay parallel to one another, 3.8 mm on-center separation. The heat exchanger was heated on one side in a radiative furnace at heat fluxes of 3.4 to 54 W/cm 2 over a normal area of 7.8 cm by 15.2 cm. The coolant fluid was helium gas at Reynolds numbers of 3000 to 35 000 and 3.50 MPa pressure. For high heat flux and low

Ab Initio Study of 40Ca with an Importance Truncated No-Core Shell Model

Energy Technology Data Exchange (ETDEWEB)

Roth, R; Navratil, P

2007-05-22

We propose an importance truncation scheme for the no-core shell model, which enables converged calculations for nuclei well beyond the p-shell. It is based on an a priori measure for the importance of individual basis states constructed by means of many-body perturbation theory. Only the physically relevant states of the no-core model space are considered, which leads to a dramatic reduction of the basis dimension. We analyze the validity and efficiency of this truncation scheme using different realistic nucleon-nucleon interactions and compare to conventional no-core shell model calculations for {sup 4}He and {sup 16}O. Then, we present the first converged calculations for the ground state of {sup 40}Ca within no-core model spaces including up to 16{h_bar}{Omega}-excitations using realistic low-momentum interactions. The scheme is universal and can be easily applied to other quantum many-body problems.

Study of characterization of trace elements in marine shells of Sambaqui: correlation between recent and old shells

International Nuclear Information System (INIS)

Gomez, Mauro Roger Batista Pousada; Rocha, Flavio Roberto; Silva, Paulo Sergio Cardoso da

2013-01-01

Calcium carbonate of recent and ancient C. rhizophorae oyster shells was analyzed for the determination of trace elements by instrumental neutron activation analysis. The ancient shells belong to a Sambaqui located in Cananeia region, South of Sao Paulo state and the recent ones are from an oyster production farm in the same region Studies related to the element concentrations in molluscs shell has been done as a tentative of establishing the element concentrations with palio-environmental factor. In this study it was aimed to verify differences in the elemental constitution of recent and ancient oyster shells that present potential for being used as indicator of marine changes. Results indicated that the elements Br, Ce, La, Na, Sm and An are higher in recent shells and the elements Cr, Fe Sc and Th are higher in ancient shells. Statistical analyses performed indicated that the enrichment of the light rare earth elements related to Ca are possibly good candidates for these palio-environmental studies. (author)

Nonuniform Effect of Carrier Separation Efficiency and Light Absorption in Type-II Perovskite Nanowire Solar Cells

Science.gov (United States)

Wang, Weiping; He, Jialun; Cao, Yiyan; Kong, Lijing; Zheng, Xuanli; Wu, Yaping; Chen, Xiaohong; Li, Shuping; Wu, Zhiming; Kang, Junyong

2017-03-01

Coaxial structures exhibit great potential for the application of high-efficiency solar cells due to the novel mechanism of radial charge separation. Here, we intensively investigate the nonuniform effect of carrier separation efficiency (CSE) and light absorption in perovskite-based type-II coaxial nanowire solar cells (ZnO/CH3NH3PbI3). Results show that the CSE rapidly decreases along the radial direction in the shell, and the value at the outer side becomes extremely low for the thick shell. Besides, the position of the main light absorption gradually moves to the outer side with the increase of the shell thickness. As a result, the external quantum efficiency shows a positional dependence with a maximal value close to the border of the nanowire. Eventually, in our case, it is found that the maximal power conversion efficiency of the solar cells reduces from 19.5 to 17.9% under the effect of the nonuniformity of CSE and light absorption. This work provides a basis for the design of high-efficiency solar cells, especially type-II nanowire solar cells.

A novel core–shell nanocomposite Ni–Ca@mSiO_2 for benzophenone selective hydrogenation

International Nuclear Information System (INIS)

Han, Xue; Feng, Wenhui; Chu, Xiaoning; Chu, Hailong; Niu, Libo; Bai, Guoyi

2017-01-01

A novel core–shell nanocomposite Ni–Ca@mSiO_2 was first prepared by a modified Stöber method in this paper. It has a core–shell structure with Ni (about 8 nm in diameter) and Ca as the cores and mesoporous silica as the outer shell, as proven by the transmission electron microscopy. This nanocomposite exhibited good catalytic performance in the selective hydrogenation of benzophenone, with 96.1% conversion and 94.9% selectivity for benzhydrol under relatively mild reaction conditions. It was demonstrated that addition of small amounts of alkaline Ca can not only markedly improve the dispersion of the active species but also tune the acid–base property of this nanocomposite, resulting in the efficient suppression of benzhydrol dehydration to achieve a high selectivity. Furthermore, the core–shell nanocomposite Ni–Ca@mSiO_2 can be recycled four runs without appreciable loss of its initial activity, more stable than the traditional supported nanocatalyst Ni–Ca/mSiO_2. It was suggested that the outer mesoporous silica shell of Ni–Ca@mSiO_2 can prevent both the aggregation and the leaching of the active Ni species, accounting for its relatively good stability.

Viscoelastic damped response of cross-ply laminated shallow spherical shells subjected to various impulsive loads

Science.gov (United States)

Şahan, Mehmet Fatih

2017-11-01

In this paper, the viscoelastic damped response of cross-ply laminated shallow spherical shells is investigated numerically in a transformed Laplace space. In the proposed approach, the governing differential equations of cross-ply laminated shallow spherical shell are derived using the dynamic version of the principle of virtual displacements. Following this, the Laplace transform is employed in the transient analysis of viscoelastic laminated shell problem. Also, damping can be incorporated with ease in the transformed domain. The transformed time-independent equations in spatial coordinate are solved numerically by Gauss elimination. Numerical inverse transformation of the results into the real domain are operated by the modified Durbin transform method. Verification of the presented method is carried out by comparing the results with those obtained by the Newmark method and ANSYS finite element software. Furthermore, the developed solution approach is applied to problems with several impulsive loads. The novelty of the present study lies in the fact that a combination of the Navier method and Laplace transform is employed in the analysis of cross-ply laminated shallow spherical viscoelastic shells. The numerical sample results have proved that the presented method constitutes a highly accurate and efficient solution, which can be easily applied to the laminated viscoelastic shell problems.

Optimal design of geometrically nonlinear shells of revolution with using the mixed finite element method

Science.gov (United States)

Stupishin, L. U.; Nikitin, K. E.; Kolesnikov, A. G.

2018-02-01

The article is concerned with a methodology of optimal design of geometrically nonlinear (flexible) shells of revolution of minimum weight with strength, stability and strain constraints. The problem of optimal design with constraints is reduced to the problem of unconstrained minimization using the penalty functions method. Stress-strain state of shell is determined within the geometrically nonlinear deformation theory. A special feature of the methodology is the use of a mixed finite-element formulation based on the Galerkin method. Test problems for determining the optimal form and thickness distribution of a shell of minimum weight are considered. The validity of the results obtained using the developed methodology is analyzed, and the efficiency of various optimization algorithms is compared to solve the set problem. The developed methodology has demonstrated the possibility and accuracy of finding the optimal solution.