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Sample records for acid core-double shell

  1. Facile synthesis of mercaptosuccinic acid-capped CdTe/CdS/ZnS core/double shell quantum dots with improved cell viability on different cancer cells and normal cells

    NASA Astrophysics Data System (ADS)

    Parani, Sundararajan; Bupesh, Giridharan; Manikandan, Elayaperumal; Pandian, Kannaiyan; Oluwafemi, Oluwatobi Samuel

    2016-11-01

    Water-soluble, mercaptosuccinic acid (MSA)-capped CdTe/CdS/ZnS core/double shell quantum dots (QDs) were prepared by successive growth of CdS and ZnS shells on the as-synthesized CdTe/CdSthin core/shell quantum dots. The formation of core/double shell structured QDs was investigated by ultraviolet-visible (UV-Vis) absorption and photoluminescence (PL) spectroscopy, PL decay studies, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The core/double shell QDs exhibited good photoluminescence quantum yield (PLQY) which is 70% higher than that of the parent core/shell QDs, and they are stable for months. The average particle size of the core/double shell QDs was ˜3 nm as calculated from the transmission electron microscope (TEM) images. The cytotoxicity of the QDs was evaluated on a variety of cancer cells such as HeLa, MCF-7, A549, and normal Vero cells by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) cell viability assay. The results showed that core/double shell QDs were less toxic to the cells when compared to the parent core/shell QDs. MCF-7 cells showed proliferation on incubation with QDs, and this is attributed to the metalloestrogenic activity of cadmium ions released from QDs. The core/double shell CdTe/CdS/ZnS (CSS) QDs were conjugated with transferrin and successfully employed for the biolabeling and fluorescent imaging of HeLa cells. These core/double shell QDs are highly promising fluorescent probe for cancer cell labeling and imaging applications.

  2. Core@Double-Shell Structured Nanocomposites: A Route to High Dielectric Constant and Low Loss Material.

    PubMed

    Huang, Yanhui; Huang, Xingyi; Schadler, Linda S; He, Jinliang; Jiang, Pingkai

    2016-09-28

    This work reports the advances of utilizing a core@double-shell nanostructure to enhance the electrical energy storage capability and suppress the dielectric loss of polymer nanocomposites. Two types of core@double-shell barium titanate (BaTiO3) matrix-free nanocomposites were prepared using a surface initiated atom transfer radical polymerization (ATRP) method to graft a poly(2-hydroxylethyle methacrylate)-block-poly(methyl methacrylate) and sodium polyacrylate-block-poly(2-hydroxylethyle methacrylate) block copolymer from BaTiO3 nanoparticles. The inner shell polymer is chosen to have either high dielectric constant or high electrical conductivity to provide large polarization, while the encapsulating outer shell polymer is chosen to be more insulating as to maintain a large resistivity and low loss. Finite element modeling was conducted to investigate the dielectric properties of the fabricated nanocomposites and the relaxation behavior of the grafted polymer. It demonstrates that confinement of the more conductive (lossy) phase in this multishell nanostructure is the key to achieving a high dielectric constant and maintaining a low loss. This promising multishell strategy could be generalized to a variety of polymers to develop novel nanocomposites.

  3. Enzyme-free hydrogen peroxide sensor based on Au@Ag@C core-double shell nanocomposites

    NASA Astrophysics Data System (ADS)

    Li, Yancai; Zhang, Yayun; Zhong, Yanmei; Li, Shunxing

    2015-08-01

    The well-designed Au@Ag@C core-double shell nanocomposites were synthesized via a facile method, and were used to fabricate an enzyme-free amperometric hydrogen peroxide (H2O2) sensor. The size, shape, elementary composition and structure of the nanocomposites were characterized by transmission electron microscope (TEM), energy-dispersed spectrum (EDS) and X-ray diffraction (XRD). The outermost layer of the nanocomposites was amorphous carbon, the second layer was Ag and the core was Au. The Au@Ag@C core-double shell nanocomposites exhibit attractive activity for electrocatalytic reduction of H2O2 according to the electrochemical experiments. It also demonstrates the H2O2 sensor possess well performance with a wide linear range of 5.0 μM to 4.75 mM and a limit of detection (LOD) as low as 0.14 μM (S/N = 3). Furthermore, the interference from the common interfering species, such as glucose, ascorbic acid, dopamine and uric acid can be effectively avoided. In a word, the Au@Ag@C nanocomposites are promising candidates for enzyme-free H2O2 sensor.

  4. Non-conductive ferromagnets based on core double-shell nanoparticles for radio-electric applications.

    PubMed

    Takacs, Hélène; Viala, Bernard; Hermán, Vanessa; Tortai, Jean-Hervé; Duclairoir, Florence; Alarcon Ramos, Juvenal; Jouneau, Pierre-Henri; Okuno, Hanako; Tallec, Gwenolé

    2016-01-01

    Two fabrication schemes of magnetic metal-polymer nanocomposites films are described. The nanocomposites are made of graphene-coated cobalt nanoparticles embedded in a polystyrene matrix. Scheme 1 uses non-covalent chemistry while scheme 2 involves covalent bonding with radicals. Preservation of the net-moment of cobalt and electrical insulation are achieved by means of a core double-shell structure of cobalt-graphene-polystyrene. The graphene shell has two functions: it is a protective layer against metal core oxidation and it serves as the functionalization surface for polymer grafting as well. The polystyrene shell is used as an insulating layer between nanoparticles and improves nanoparticles dispersion inside the polystyrene matrix. The theoretical maximum volume filling ratio estimated at ~30 % is almost reached. The nanocomposites are shown to undergo percolation behavior but retain low conductivity (<1 S/m) at the highest filling ratio reached ~25 % leading to extremely low losses (10(-3)) at high frequency. Such low conductivity values are combined with large magnetization, as high as 0.9 T. Ability for radiofrequency applications is discussed in regards to the obtained magnetization.

  5. The synthesis of Au@C@Pt core-double shell nanocomposite and its application in enzyme-free hydrogen peroxide sensing

    NASA Astrophysics Data System (ADS)

    Zhang, Yayun; Li, Yuhui; Jiang, Yingying; Li, Yancai; Li, Shunxing

    2016-08-01

    A novel Au@C@Pt core-double shell nanocomposite was synthesized and used to fabricate enzyme-free electrochemical sensor for rapid and sensitive detection of hydrogen peroxide (H2O2). The well-designed Au@C@Pt core-double shell nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM) and energy-dispersed spectrum (EDS). The Au@C@Pt core-double shell nanocomposite modified glassy carbon electrode (Au@C@Pt/GCE) exhibits good electrocatalytic activity towards H2O2 reduction at 0.0 V and can be used as H2O2 sensor. The sensor displays two wide linear ranges towards H2O2 detection. The one is 9.0 μM-1.86 mM with high sensitivity of 144.7 μA mM-1 cm-2, and the other is 1.86 mM-7.11 mM with sensitivity of 80.1 μA mM-1 cm-2. When signal to noise (S/N) is 3, the calculated detection limit (LOD) is 0.13 μM. Furthermore, the interference from the common interfering species such as glucose, ascorbic acid, dopamine and uric acid can be effectively avoided to H2O2 detection. Additionally, the H2O2 sensor also displays good stability and reproducibility.

  6. One-pot synthesis of magnetic graphene nanocomposites decorated with core@double-shell nanoparticles for fast chromium removal.

    PubMed

    Zhu, Jiahua; Wei, Suying; Gu, Hongbo; Rapole, Sowjanya B; Wang, Qiang; Luo, Zhiping; Haldolaarachchige, Neel; Young, David P; Guo, Zhanhu

    2012-01-17

    A facile thermodecomposition process to synthesize magnetic graphene nanocomposites (MGNCs) is reported. High-resolution transmission electron microscopy and energy filtered elemental mapping revealed a core@double-shell structure of the nanoparticles with crystalline iron as the core, iron oxide as the inner shell and amorphous Si-S-O compound as the outer shell. The MGNCs demonstrate an extremely fast Cr(VI) removal from the wastewater with a high removal efficiency and with an almost complete removal of Cr(VI) within 5 min. The adsorption kinetics follows the pseudo-second-order model and the novel MGNC adsorbent exhibits better Cr(VI) removal efficiency in solutions with low pH. The large saturation magnetization (96.3 emu/g) of the synthesized nanoparticles allows fast separation of the MGNCs from liquid suspension. By using a permanent magnet, the recycling process of both the MGNC adsorbents and the adsorbed Cr(VI) is more energetically and economically sustainable. The significantly reduced treatment time required to remove the Cr(VI) and the applicability in treating the solutions with low pH make MGNCs promising for the efficient removal of heavy metals from the wastewater.

  7. Direct observation of the core/double-shell architecture of intense dual-mode luminescent tetragonal bipyramidal nanophosphors.

    PubMed

    Kim, Su Yeon; Jeong, Jong Seok; Mkhoyan, K Andre; Jang, Ho Seong

    2016-05-21

    Highly efficient downconversion (DC) green-emitting LiYF4:Ce,Tb nanophosphors have been synthesized for bright dual-mode upconversion (UC) and DC green-emitting core/double-shell (C/D-S) nanophosphors-Li(Gd,Y)F4:Yb(18%),Er(2%)/LiYF4:Ce(15%),Tb(15%)/LiYF4-and the C/D-S structure has been proved by extensive scanning transmission electron microscopy (STEM) analysis. Colloidal LiYF4:Ce,Tb nanophosphors with a tetragonal bipyramidal shape are synthesized for the first time and they show intense DC green light via energy transfer from Ce(3+) to Tb(3+) under illumination with ultraviolet (UV) light. The LiYF4:Ce,Tb nanophosphors show 65 times higher photoluminescence intensity than LiYF4:Tb nanophosphors under illumination with UV light and the LiYF4:Ce,Tb is adapted into a luminescent shell of the tetragonal bipyramidal C/D-S nanophosphors. The formation of the DC shell on the core significantly enhances UC luminescence from the UC core under irradiation of near infrared light and concurrently generates DC luminescence from the core/shell nanophosphors under UV light. Coating with an inert inorganic shell further enhances the UC-DC dual-mode luminescence by suppressing the surface quenching effect. The C/D-S nanophosphors show 3.8% UC quantum efficiency (QE) at 239 W cm(-2) and 73.0 ± 0.1% DC QE. The designed C/D-S architecture in tetragonal bipyramidal nanophosphors is rigorously verified by an energy dispersive X-ray spectroscopy (EDX) analysis, with the assistance of line profile simulation, using an aberration-corrected scanning transmission electron microscope equipped with a high-efficiency EDX. The feasibility of these C/D-S nanophosphors for transparent display devices is also considered.

  8. Direct observation of the core/double-shell architecture of intense dual-mode luminescent tetragonal bipyramidal nanophosphors

    NASA Astrophysics Data System (ADS)

    Kim, Su Yeon; Jeong, Jong Seok; Mkhoyan, K. Andre; Jang, Ho Seong

    2016-05-01

    Highly efficient downconversion (DC) green-emitting LiYF4:Ce,Tb nanophosphors have been synthesized for bright dual-mode upconversion (UC) and DC green-emitting core/double-shell (C/D-S) nanophosphors--Li(Gd,Y)F4:Yb(18%),Er(2%)/LiYF4:Ce(15%),Tb(15%)/LiYF4--and the C/D-S structure has been proved by extensive scanning transmission electron microscopy (STEM) analysis. Colloidal LiYF4:Ce,Tb nanophosphors with a tetragonal bipyramidal shape are synthesized for the first time and they show intense DC green light via energy transfer from Ce3+ to Tb3+ under illumination with ultraviolet (UV) light. The LiYF4:Ce,Tb nanophosphors show 65 times higher photoluminescence intensity than LiYF4:Tb nanophosphors under illumination with UV light and the LiYF4:Ce,Tb is adapted into a luminescent shell of the tetragonal bipyramidal C/D-S nanophosphors. The formation of the DC shell on the core significantly enhances UC luminescence from the UC core under irradiation of near infrared light and concurrently generates DC luminescence from the core/shell nanophosphors under UV light. Coating with an inert inorganic shell further enhances the UC-DC dual-mode luminescence by suppressing the surface quenching effect. The C/D-S nanophosphors show 3.8% UC quantum efficiency (QE) at 239 W cm-2 and 73.0 +/- 0.1% DC QE. The designed C/D-S architecture in tetragonal bipyramidal nanophosphors is rigorously verified by an energy dispersive X-ray spectroscopy (EDX) analysis, with the assistance of line profile simulation, using an aberration-corrected scanning transmission electron microscope equipped with a high-efficiency EDX. The feasibility of these C/D-S nanophosphors for transparent display devices is also considered.Highly efficient downconversion (DC) green-emitting LiYF4:Ce,Tb nanophosphors have been synthesized for bright dual-mode upconversion (UC) and DC green-emitting core/double-shell (C/D-S) nanophosphors--Li(Gd,Y)F4:Yb(18%),Er(2%)/LiYF4:Ce(15%),Tb(15%)/LiYF4--and the C/D-S structure

  9. Freestanding one-dimensional manganese dioxide nanoflakes-titanium cabide/carbon core/double shell arrays as ultra-high performance supercapacitor electrode

    NASA Astrophysics Data System (ADS)

    Kong, Shuying; Cheng, Kui; Ouyang, Tian; Ye, Ke; Gao, Yinyi; Wang, Guiling; Cao, Dianxue

    2015-10-01

    In this paper, freestanding one-dimensional MnO2 nanoflakes are successful prepared through a simple hydrothermal reaction by using the carbon shell of TiC/C core/shell arrays as the sacrificial template. Its structure and morphology are characterized by X-ray diffractometer, X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, energy dispersive X-ray spectrometer and transmission electron microscopy. Results show that the thickness of the carbon shell decreased but also remained and the ultrathin MnO2 nanoflakes with thickness less than 5 nm uniformly grow on the surfaces of the TiC/C nanowire to form a core/double shell structure after the hydrothermal reaction. The electrochemical performance of the as-prepared electrode is evaluated by cyclic voltammetrys, galvanostatic charging-discharging tests and electrochemical impedance spectroscopy, and high capacities, excellent rate capabilities and exemplary cycling performance is obtained. The as-prepared electrode shows a high specific capacitance of 598.8 F g-1 and 85.8% of its initial capacitance is retained after 10,000 cycles at a high discharge current density of 10 A g-1, suggesting that this structure has a promising future as high-performance supercapacitor electrode.

  10. Multi-functional integration of pore P25@C@MoS2 core-double shell nanostructures as robust ternary anodes with enhanced lithium storage properties

    NASA Astrophysics Data System (ADS)

    Chen, Biao; Zhao, Naiqin; Wei, Chaopeng; Zhou, Jingwen; He, Fang; Shi, Chunsheng; He, Chunnian; Liu, Enzuo

    2017-04-01

    Ternary anodes have attracted more and more attention due to the characteristic advantages resulting from the effect integration of three different materials on the lithium storage mechanism with functional interfaces interaction. However, clarifying the distribution and interaction of carbon, MoS2 and TiO2 in the MoS2/C/TiO2 composite, which is helpful for the understanding of the formation and lithium storage mechanism of the ternary anodes, is a well-known challenge. Herein, a novel pore core-double shell nanostructure of P25@carbon network supported few-layer MoS2 nanosheet (P25@C@FL-MoS2) is successfully synthesized by a one-pot hydrothermal approach. The distribution and interaction of the carbon, MoS2 and TiO2 in the obtained P25@C@FL-MoS2 hybrid are systematically characterized by transmission electron microscopy, Raman spectra and X-ray photoelectron spectroscopy analysis et al. It is found that the carbon serves as binder, which supports few-layer MoS2 shell and coats the P25 core via Tisbnd Osbnd C bonds at the same time. Such multi-functional integration with smart structure and strong interfacial contact generates favorable structure stability and interfacial pseudocapacity-like storage mechanism. As a consequence, superior cycling and rate capacity of the muti-functional integration ternary P25@C@FL-MoS2 anode are achieved.

  11. Chitosan mediated synthesis of core/double shell ternary polyaniline/Chitosan/cobalt oxide nano composite-as high energy storage electrode material in supercapacitors

    NASA Astrophysics Data System (ADS)

    Vellakkat, Mini; Hundekkal, Devendrappa

    2016-01-01

    Nanostructured ternary composite of polyaniline (PANI), Co3O4 nanoparticles, and Chitosan (CS) has been prepared by an in situ chemical oxidation method, and the nanocomposites (CPAESCO) were used as supercapacitor electrodes. The Co3O4 nanoparticles are uniformly coated with CS and PANI layers in it. Different techniques (Fourier transform infrared spectrophotometry, x-ray diffraction, thermal gravimetric analysis, UV-visible spectroscopy, scanning electron microscopy, transmission electron microscopy and electro chemical analysis-cyclic voltammetry, galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy) were used to analyse the optical, structural, thermal, chemical and supercapacitive aspects of the nanocomposites. Core/double shell ternary composite electrode exhibits significantly increased specific capacitance than PANI/Co3O4 or PANI/CS binary composites in supercapacitors. The ternary nanocomposite with 40% nanoparticle exhibits a highest specific capacitance reaching 687 F g-1, Energy density of (95.42 Wh kg-1 at 1 A g-1) and power density of (1549 W kg-1 at 3 A g-1) and outstanding cycling performance, with, 91% capacitance retained over 5000 cycles. It is found that this unique bio compatible nano composite with synergy is a new multifunctional material which will be useful in the design of supercapacitor electrodes and other energy conversion devices too.

  12. Core/Double-Shell Structured Na3V2(PO4)2F3@C Nanocomposite as the High Power and Long Lifespan Cathode for Sodium-Ion Batteries.

    PubMed

    Liu, Qiang; Meng, Xing; Wei, Zhixuan; Wang, Dongxue; Gao, Yu; Wei, Yingjin; Du, Fei; Chen, Gang

    2016-11-23

    NASICON-structured Na3V2(PO4)2F3 is considered as a potentially high-capacity cathode material for Na-ion batteries; however, its poor rate capability and insufficient cyclability remain a challenge for battery applications. To address this issue, we designed and successfully synthesized a core/double-shell structured Na3V2(PO4)2F3@C nanocomposite (Na3V2(PO4)2F3@CD) by in situ carbon coating and embedding the Na3V2(PO4)2F3 nanoparticles in ordered mesoporous carbon framework. Benefiting from the sufficient electrochemically available interfaces and abundant electronic/ionic pathways, this Na3V2(PO4)2F3@CD material demonstrated superior Na(+)-storage performance with a high reversible capacity of 120 mA h g(-1) at a moderate current of 1 C, a strong high-rate capability with 63 mA h g(-1) at an extremely high rate of 100 C, and a long-cycle lifespan with 65% capacity retention over 5000 cycles. These superior electrochemical performances remained stable when the Na3V2(PO4)2F3@CD cathode was used in a full cell, suggesting a promising application of the material for high rate and long lifespan sodium-ion batteries. Moreover, the architectural design and synthetic method developed in this work may provide a new avenue to create high performance Na(+)-host materials for a wide range of electric energy storage applications.

  13. Core-double-shell Fe3O4@carbon@poly(In(III)-carboxylate) microspheres: cycloaddition of CO2 and epoxides on coordination polymer shells constituted by imidazolium-derived Al(III)-Salen bifunctional catalysts.

    PubMed

    An, Qiao; Li, Zifeng; Graff, Robert; Guo, Jia; Gao, Haifeng; Wang, Changchun

    2015-03-04

    A hydrid microsphere Fe3O4@carbon@poly(In(III)-carboxylate) consisting of a cluster of Fe3O4 nanoparticles as the core, a carbon layer as the inner shell and a porous In(III)-carboxylate coordination polymer as the outer shell was prepared and applied as a recyclable catalyst for the cycloaddition reaction of CO2 and epoxides. Construction of this hybrid microsphere was achieved in the two steps, including (1) the one-pot solvothermal synthesis of Fe3O4@C particles with the abundant carboxylic groups on the carbon surface and (2) the subsequent growth of the outer shell polymers based on the precipitation coordination polymerization. Imidazolium-substituted Salen ligands were synthesized and chelated with the In(III) ions using the terminal carboxylic groups. The coordination polymer shell was formed on the Fe3O4@C particles, and the structures including shell thickness, surface area and porosity could be varied by tuning the feeding ratios of the In(III) ions and the ligands. The optimal structure of the coordination polymers showed a shell thickness of ca. 45 nm with ∼5 nm of mesopore, 174.7 m(2)/g of surface area and 0.2175 cm(3)/g of pore volume. In light of gas uptake capability, catalytic activity and magnetic susceptibility, cycloaddition of CO2 with a series of epoxides were studied by using Al-complexed Fe3O4@C@In(III)-[IL-Salen] microspheres. The results validated that the self-supporting catalytic layer with high surface area was of remarkable advantages, which were attributed from great increment of effective active sites and combination of nucleophilic/electrophilic synergistic property and CO2 uptake capability. Therefore, these hybrid microspheres provided excellent catalytic activity, prominent selectivity to cyclic carbonates and outstanding recyclability with the assistance of an applied magnetic field.

  14. Geochemistry of amino acids in shells of the clam Saxidomus

    USGS Publications Warehouse

    Kvenvolden, K.A.; Blunt, D.J.; McMenamin, M.A.; Straham, S.E.

    1980-01-01

    Concentrations of amino acids and their corresponding d l enantiomeric ratios have been measured in shells of the bivalve mollusk Saxidomus from eleven localities, ranging in age from modern to probably more than 500,000 yr, along the Pacific coast of North America. Natural logarithms of amino acid concentrations correlate well with d l ratios, and the relationship provides a possible guide to the selection of fossils for use in amino acid dating. The relative order of the extents of racemization of amino acids at any given time appears to change with increasing sample age. Application of the amino acid dating method to shells from Whidbey Island, Washington, yields an age of about 80,000 yr, in contrast to the previously determined radiocarbon age of 36,000 yr which was measured on some shell carbonate and considered a minimum age. The amino acid age is compatible with the geologic record in the area. ?? 1980.

  15. Cocoa shells for heavy metal removal from acidic solutions.

    PubMed

    Meunier, N; Laroulandie, J; Blais, J F; Tyagi, R D

    2003-12-01

    The development of economic and efficient processes for the removal of heavy metals present in acidic effluents from industrial sources or decontamination technologies has become a priority. The purpose of this work was to study the efficiency with which cocoa shells remove heavy metals from acidic solutions (pH 2) and to investigate how the composition of these solutions influences heavy metal uptake efficiency. Adsorption tests were conducted in agitated flasks with single-metal solutions (0.25 mM Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn), multi-metal solution (comprised of 0.25 mM of each of the cations above) and an effluent obtained from chemical leaching of metal-contaminated soil, in the presence of different cocoa shell concentrations (5-40 g/l). Results from the single-metal solution assays indicated that the fixation capacity of heavy metals by cocoa shells followed a specific order: Pb>Cr>Cd=Cu=Fe>Zn=Co>Mn=Ni=Al. Cocoa shells are particularly efficient in the removal of lead from very acidic solutions (q(max)=6.2 mg Pb/g, pH(i)=2.0 and T=22 degrees C). The presence of other metals and cations in solution did not seem to affect the recovery of lead. It was also observed that the maximum metal uptake was reached in less than 2 h. This research has also demonstrated that the removal of metals caused a decline in solution proton concentration (pH increase) and release of calcium, magnesium, potassium and sodium from the cocoa shells.

  16. Anacardic acid: molluscicide in cashew nut shell liquid.

    PubMed

    Sullivan, J T; Richards, C S; Lloyd, H A; Krishna, G

    1982-03-01

    The components of anacardic acid, (a mixture of 6-n-C (15) alkylsalicylic acids whose side chains vary in degrees of unsaturation) have been isolated by high pressure liquid chromatography from a crude extract of cashew nut shell, Anacardium occidentale, and tested for toxicity to fresh water snails, Biomphalaria glabrata. The triene component is the most toxic form (LC (50) 0.35 ppm), the diene and monoene components are less toxic (LC (50) 0.9 and 1.4 ppm), and the saturated component is relatively nontoxic (LC (50) > 5 ppm). Since decarboxylated anacardic acid (cardanol) and salicylic acid do not kill snails at concentrations up to 5 ppm, it appears that both, carboxyl group and unsaturated side chain are absolutely required for molluscicidal activity. The mechanism of toxicity of anacardic acid to snails is unknown.

  17. Introduction of biotin or folic acid into polypyrrole magnetite core-shell nanoparticles

    SciTech Connect

    Nan, Alexandrina; Turcu, Rodica; Liebscher, Jürgen

    2013-11-13

    In order to contribute to the trend in contemporary research to develop magnetic core shell nanoparticles with better properties (reduced toxicity, high colloidal and chemical stability, wide scope of application) in straightforward and reproducible methods new core shell magnetic nanoparticles were developed based on polypyrrole shells functionalized with biotin and folic acid. Magnetite nanoparticles stabilized by sebacic acid were used as magnetic cores. The morphology of magnetite was determined by transmission electron microscopy TEM, while the chemical structure investigated by FT-IR.

  18. Closed-system behaviour of the intra-crystalline fraction of amino acids in mollusc shells

    PubMed Central

    Penkman, K.E.H.; Kaufman, D.S.; Maddy, D.; Collins, M.J.

    2008-01-01

    When mollusc shells are analysed conventionally for amino acid geochronology, the entire population of amino acids is included, both inter- and intra-crystalline. This study investigates the utility of removing the amino acids that are most susceptible to environmental effects by isolating the fraction of amino acids encapsulated within mineral crystals of mollusc shells (intra-crystalline fraction). Bleaching, heating and leaching (diffusive loss) experiments were undertaken on modern and fossil Corbicula fluminalis, Margaritifera falcata, Bithynia tentaculata and Valvata piscinalis shells. Exposure of powdered mollusc shells to concentrated NaOCl for 48 h effectively reduced the amino acid content of the four taxa to a residual level, assumed to represent the intra-crystalline fraction. When heated in water at 140 °C for 24 h, only 1% of amino acids were leached from the intra-crystalline fraction of modern shells compared with 40% from whole shell. Free amino acids were more effectively retained in the intra-crystalline fraction, comprising 55% (compared with 18%) of the whole shell after 24 h at 140 °C. For fossil gastropods, the inter-shell variability in D/L values for the intra-crystalline fraction of a single-age population was reduced by 50% compared with conventionally analysed shells. In contrast, analysis of the intra-crystalline fraction of C. fluminalis does not appear to improve the results for this taxon, possibly due to variability in shell ultrastructure. Nonetheless, the intra-crystalline fraction in gastropods approximates a closed system of amino acids and appears to provide a superior subset of amino acids for geochronological applications. PMID:19684879

  19. Ontogenetic trends in aspartic acid racemization and amino acid composition within modern and fossil shells of the bivalve Arctica

    NASA Astrophysics Data System (ADS)

    Goodfriend, Glenn A.; Weidman, Christopher R.

    2001-06-01

    Ontogenetic trends (umbo to growth edge of shell) in aspartic acid (Asp) racemization and amino acid composition and their evolution over time are examined in serial samples of annual growth bands from a time-series of three live-collected and two fossil (ca. 500 and 1000 y BP) shells of the long-lived bivalve Arctica islandica. The rate of Asp racemization is shown to be higher in the umbonal portion of the shells (laid down when the clams are young) but constant from a biological age of 10 to 20 y to more than 100 y. Corresponding changes are also seen in amino acid composition and concentration: with increasing biological age of the clam: total amino acid concentration increases substantially, the acidic amino acids Asp, glutamic acid, and alanine decrease in relative concentration (mole-percent) and more basic amino acids including tyrosine, phenylalanine, and lysine increase in relative concentration. These ontogenetic trends are generally retained in the fossil shells. These trends may reflect changing protein composition related to changes in growth rate. Clams grow considerably faster in their youth than when they are older, as indicated by changes in the annual growth increments. Production of more acidic proteins, which play a role in crystal growth, may be favored during the phase of faster growth, whereas more structural proteins, perhaps enhancing structural strength of the shell, may be favored during later growth. These ontogenetic differences in protein composition affect the observed rates of racemization of the protein pool. Some weak diagenetic trends in amino acid composition and abundance may be represented in the time series of shells. These results emphasize the importance of standardization of the location from which samples are taken from shells for dating by amino acid racemization analysis.

  20. Facile fabrication of siloxane @ poly (methylacrylic acid) core-shell microparticles with different functional groups

    NASA Astrophysics Data System (ADS)

    Zhao, Zheng-Bai; Tai, Li; Zhang, Da-Ming; Jiang, Yong

    2017-02-01

    Siloxane @ poly (methylacrylic acid) core-shell microparticles with functional groups were prepared by a facile hydrolysis-condensation method in this work. Three different silane coupling agents 3-methacryloxypropyltrimethoxysilane (MPS), 3-triethoxysilylpropylamine (APTES), and 3-glycidoxypropyltrimethoxysilane (GPTMS) were added along with tetraethoxysilane (TEOS) into the polymethylacrylic acid (PMAA) microparticle ethanol dispersion to form the Si@PMAA core-shell microparticles with different functional groups. The core-shell structure and the surface special functional groups of the resulting microparticles were measured by transmission electron microscopy and FTIR. The sizes of these core-shell microparticles were about 350-400 nm. The corresponding preparation conditions and mechanism were discussed in detail. This hydrolysis-condensation method also could be used to functionalize other microparticles which contain active groups on the surface. Meanwhile, the Si@PMAA core-shell microparticles with carbon-carbon double bonds and amino groups have further been applied to prepare hydrophobic coatings.

  1. Equation of state and critical point behavior of hard-core double-Yukawa fluids

    NASA Astrophysics Data System (ADS)

    Montes, J.; Robles, M.; López de Haro, M.

    2016-02-01

    A theoretical study on the equation of state and the critical point behavior of hard-core double-Yukawa fluids is presented. Thermodynamic perturbation theory, restricted to first order in the inverse temperature and having the hard-sphere fluid as the reference system, is used to derive a relatively simple analytical equation of state of hard-core multi-Yukawa fluids. Using such an equation of state, the compressibility factor and phase behavior of six representative hard-core double-Yukawa fluids are examined and compared with available simulation results. The effect of varying the parameters of the hard-core double-Yukawa intermolecular potential on the location of the critical point is also analyzed using different perspectives. The relevance of this analysis for fluids whose molecules interact with realistic potentials is also pointed out.

  2. Equation of state and critical point behavior of hard-core double-Yukawa fluids.

    PubMed

    Montes, J; Robles, M; López de Haro, M

    2016-02-28

    A theoretical study on the equation of state and the critical point behavior of hard-core double-Yukawa fluids is presented. Thermodynamic perturbation theory, restricted to first order in the inverse temperature and having the hard-sphere fluid as the reference system, is used to derive a relatively simple analytical equation of state of hard-core multi-Yukawa fluids. Using such an equation of state, the compressibility factor and phase behavior of six representative hard-core double-Yukawa fluids are examined and compared with available simulation results. The effect of varying the parameters of the hard-core double-Yukawa intermolecular potential on the location of the critical point is also analyzed using different perspectives. The relevance of this analysis for fluids whose molecules interact with realistic potentials is also pointed out.

  3. Boronic acid shell-crosslinked dextran-b-PLA micelles for acid-responsive drug delivery.

    PubMed

    Zhao, Ziwei; Yao, Xuemei; Zhang, Zhe; Chen, Li; He, Chaoliang; Chen, Xuesi

    2014-11-01

    Herein, 3-carboxy-5-nitrophenylboronic acid (CNPBA) shell-crosslinked micelles based on amphiphilic dextran-block-polylactide (Dex-b-PLA) are prepared and used for efficient intracellular drug deliveries. Due to the reversible pH-dependent binding with diols to form boronate esters, CNPBA modified Dex-b-PLA shows excellent pH-sensitivity. In neutral aqueous conditions, CNPBA-Dex-b-PLA forms shell-crosslinked micelles to enable DOX loading, while in acid conditions, the boronate esters hydrolyze and the micelles de-crosslink to release loaded DOX. In vitro release studies indicate that the release of the DOX cargo is minimized at physiological conditions, while there is a burst release in response to low pHs. The cell viability of CNPBA-Dex-b-PLA investigated by MTT assay was more than 90%, indicating that, as a drug delivery system, CNPBA-Dex-b-PLA has good cytocompatibility. These features suggest that the pH-responsive biodegradable CNPBA-Dex-b-PLA can efficiently load and deliver DOX into tumor cells and enhance the inhibition of cellular proliferation in vitro, providing a favorable platform as a drug delivery system for cancer therapy. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Fluctuations of sulfate, S-bearing amino acids and magnesium in a giant clam shell

    NASA Astrophysics Data System (ADS)

    Yoshimura, T.; Tamenori, Y.; Kawahata, H.; Suzuki, A.

    2014-07-01

    We used micro-X-ray fluorescence combined with X-ray photoabsorption spectroscopy to investigate speciation-specific sulfur profiles in the inner shell layer of a giant clam (Hippopus hippopus). The sulfate, S-bearing amino acids, and total sulfur profiles indicated that inorganic sulfate was the dominant component in the shell of this bivalve. Sulfur profiles in the inner shell layer showed clear annual fluctuations that varied by more than one order of magnitude, from < 50 to 1420 ppm, and sulfate and total sulfur maxima became higher with age, whereas no ontogenetic trend was noticeable in the profile of S-bearing amino acids. A change in the carbonate ion concentration in the calcifying fluid would suggest that an ontogenetic increase in the relative activity of sulfate ions to carbonate ions in the calcifying fluid affects sulfate concentrations in the shells. These results suggest that trace sulfur profiles in the shell of the giant clam may reflect both cyclic shell growth related to environmental factors such as insolation and temperature and ontogenetic changes of the calcifying fluid chemistry mediated by physiological processes. The observed S profile implies a clear change in calcifying fluid chemistry towards less alkaline condition with age. Magnesium fluctuations suggested that Mg was incorporated into the shells at high growth rates during warm seasons. The spectrum of Mg K-edge X-ray absorption near edge structure (XANES) and comparison of Mg and S-bearing amino acids profiles indicated that a pronounced effect of the organic fraction or disordered phases were observed in aragonitic shell of H. hippopus rather than regulated substitution into the aragonite crystal lattice.

  5. Fluctuations of sulfate, S-bearing amino acids and magnesium in a giant clam shell

    NASA Astrophysics Data System (ADS)

    Yoshimura, T.; Tamenori, Y.; Kawahata, H.; Suzuki, A.

    2014-01-01

    We used micro-X-ray fluorescence combined with X-ray photoabsorption spectroscopy to investigate speciation-specific sulfur profiles in the inner shell layer of a giant clam (Hippopus hippopus). The sulfate, S-bearing amino acids, and total sulfur profiles indicated that inorganic sulfate was the dominant component in the shell of this bivalve. Sulfur profiles in the inner shell layer showed clear annual fluctuations that varied by more than one order of magnitude, from < 50 to 1420 ppm, and sulfate and total sulfur maxima became higher with age, whereas no ontogenetic trend was noticeable in the profile of S-bearing amino acids. A changes in the carbonate ion concentration in the calcifying fluid would suggest that an ontogenetic increase in the relative activity of sulfate ions to carbonate ions in the calcifying fluid affects sulfate concentrations in the shells. These results suggest that trace sulfur profiles in the shell of the giant clam may reflect both cyclic shell growth related to environmental factors such as insolation and temperature and ontogenetic changes of the calcifying fluid chemistry mediated by physiological processes. The observed S profile implies a clear change in calcifying fluid chemistry towards less alkaline condition with age. Magnesium fluctuations suggested that Mg was incorporated into the shells at high growth rates during warm seasons. The spectrum of Mg K-edge XANES and comparison of Mg and S-bearing amino acids profiles indicated that a pronounced effect of the organic fraction or disordered phases were observed in aragonitic shell of H. hippopus rather than regulated substitution into the aragonite crystal lattice.

  6. Amino-acid racemizarion in Quaternary shell deposits at Willapa Bay, Washington

    USGS Publications Warehouse

    Kvenvolden, K.A.; Blunt, D.J.; Clifton, H.E.

    1979-01-01

    Extents of racemization ( d l ratios) of amino acids in fossil Saxidomus giganteus (Deshayes) and Ostrea lurida Carpenter were measured on shell deposits exposed at 21 sites on the east side of Willapa Bay, Washington. Amino acids from Saxidomus show less variability in d Spl ratios and, therefore, are of greater use in correlation and age estimation than are amino acids from Ostrea. Shells of two different ages, about 120,000 ?? 40,000 yr old and about 190,000 ?? 40,000 yr old, are present. These ages correspond to Stages 5 and 7 of the marine isotope record defined by Shackleton and Opdyke in 1973 and hence the shell deposits likely formed during two different high stands of sea level. The stratigraphic record at Willapa Bay is consistent with this interpretation. ?? 1979.

  7. Use of free amino acid composition of shell to estimate age since death of recent molluscs

    SciTech Connect

    Logan, A.M.; Powell, E.N.; Stanton, R.J. Jr.

    1985-01-01

    An understanding of death assemblage formation requires a measurement of time since death of constituent individuals. A new dating technique based on the measurement of the free amino acid content of mollusc shells has been developed which is inexpensive, rapid, and effective in dating time scales of a few decades to a few centuries. Since the breakdown of proteins of the matrix of mollusc shells begins soon after deposition, free amino acids gradually increase with shell age. The measurement of these can be used to determine the relative age among a group of shells. The future use of this technique depends on a clearer understanding of how free amino acid accumulation rate varies with age and species and developing effective calibration methods so that absolute rather than relative ages can be readily obtained. Three species were distributed widely enough for use - Rangia cuneata, Tagelus plebeius, and Phacoides pectinatus. A good relationship between free amino acids and relative age was present in all three species over the entire core; however some species and some amino acid were superior to others. Rangia cuneata produced the best correlation because it is epifaunal and thus died at the sediment surface rather than over an extended depth range and, also perhaps, because amino acid accumulation rates were more linear.

  8. Megranate-like nanoreactor with multiple cores and an acidic mesoporous shell for a cascade reaction

    NASA Astrophysics Data System (ADS)

    Wang, Xue; Guan, Buyuan; He, Yapeng; An, Dong; Zhang, Ye; Cao, Yu; Li, Xiang; Liu, Yunling; Huo, Qisheng

    2015-02-01

    Megranate-like nanoparticles possess a unique structure that is composed of multiple cores and shells, which is different from simple yolk-shell nanoparticles. Megranate-like nanoparticles can combine the properties of each component and be used as nanoreactors. This study describes the preparation of bifunctional megranate-like nanoreactors, consisting of multiple metal cores and thiol modified mesoporous SiO2 shells. Different metal nanoparticles (Pd, Pt, Au) can be incorporated into the structure as cores, and the thiol group in the shells can be oxidized to acidic -SO3H. The megranate-like nanoparticles show good bifunctional catalytic properties and recyclability in a cascade catalytic reaction for the desired benzimidazole derivative. Moreover, the individual components of the megranate-like nanoparticles also show good catalytic activities in the hydrogenation reduction of nitro-aromatics and the deprotection reaction of benzaldehyde dimethyl acetal.Megranate-like nanoparticles possess a unique structure that is composed of multiple cores and shells, which is different from simple yolk-shell nanoparticles. Megranate-like nanoparticles can combine the properties of each component and be used as nanoreactors. This study describes the preparation of bifunctional megranate-like nanoreactors, consisting of multiple metal cores and thiol modified mesoporous SiO2 shells. Different metal nanoparticles (Pd, Pt, Au) can be incorporated into the structure as cores, and the thiol group in the shells can be oxidized to acidic -SO3H. The megranate-like nanoparticles show good bifunctional catalytic properties and recyclability in a cascade catalytic reaction for the desired benzimidazole derivative. Moreover, the individual components of the megranate-like nanoparticles also show good catalytic activities in the hydrogenation reduction of nitro-aromatics and the deprotection reaction of benzaldehyde dimethyl acetal. Electronic supplementary information (ESI) available

  9. Reaction kinetics of free fatty acids esterification in palm fatty acid distillate using coconut shell biochar sulfonated catalyst

    NASA Astrophysics Data System (ADS)

    Hidayat, Arif; Rochmadi, Wijaya, Karna; Budiman, Arief

    2015-12-01

    Recently, a new strategy of preparing novel carbon-based solid acids has been developed. In this research, the esterification reactions of Palm Fatty Acid Distillate (PFAD) with methanol, using coconut shell biochar sulfonated catalyst from biomass wastes as catalyst, were studied. In this study, the coconut shell biochar sulfonated catalysts were synthesized by sulfonating the coconut shell biochar using concentrated H2SO4. The kinetics of free fatty acid (FFA) esterification in PFAD using a coconut shell biochar sulfonated catalyst was also studied. The effects of the mass ratio of catalyst to oil (1-10%), the molar ratio of methanol to oil (6:1-12:1), and the reaction temperature (40-60°C) were studied for the conversion of PFAD to optimize the reaction conditions. The results showed that the optimal conditions were an methanol to PFAD molar ratio of 12:1, the amount of catalyst of 10%w, and reaction temperature of 60°C. The proposed kinetic model shows a reversible second order reaction and represents all the experimental data satisfactorily, providing deeper insight into the kinetics of the reaction.

  10. Amino acid racemization dating of marine shells: A mound of possibilities

    PubMed Central

    Demarchi, Beatrice; Williams, Matt G.; Milner, Nicky; Russell, Nicola; Bailey, Geoff; Penkman, Kirsty

    2011-01-01

    Shell middens are one of the most important and widespread indicators for human exploitation of marine resources and occupation of coastal environments. Establishing an accurate and reliable chronology for these deposits has fundamental implications for understanding the patterns of human evolution and dispersal. This paper explores the potential application of a new methodology of amino acid racemization (AAR) dating of shell middens and describes a simple protocol to test the suitability of different molluscan species. This protocol provides a preliminary test for the presence of an intracrystalline fraction of proteins (by bleaching experiments and subsequent heating at high temperature), checking the closed system behaviour of this fraction during diagenesis. Only species which pass both tests can be considered suitable for further studies to obtain reliable age information. This amino acid geochronological technique is also applied to midden deposits at two latitudinal extremes: Northern Scotland and the Southern Red Sea. Results obtained in this study indicate that the application of this new method of AAR dating of shells has the potential to aid the geochronological investigation of shell mounds in different areas of the world. PMID:21776187

  11. Facile production of chitin from crab shells using ionic liquid and citric acid.

    PubMed

    Setoguchi, Tatsuya; Kato, Takeshi; Yamamoto, Kazuya; Kadokawa, Jun-ichi

    2012-04-01

    Facile production of chitin from crab shells was performed by direct extraction using an ionic liquid, 1-allyl-3-methylimidazolium bromide (AMIMBr), followed by demineralization using citric acid. First, dried crab shells were treated with AMIMBr at elevated temperatures to extract chitin. Supernatants separated by centrifugation were then subjected to a chelating treatment with an aqueous solution of citric acid to achieve demineralization. The precipitated extracts were filtered and dried. The isolated material was subjected to X-ray diffraction, IR, (1)H NMR, and energy-dispersive X-ray spectroscopy, and thermal gravimetric analysis; the results indicated the structure of chitin. On the basis of the IR spectra, the degree of deacetylation in the samples obtained was calculated to be <7%. Furthermore, the protein content was <0.1% and the M(w) values were 0.7-2.2×10(5).

  12. Multi-shell model of ion-induced nucleic acid condensation

    PubMed Central

    Tolokh, Igor S.; Drozdetski, Aleksander V.; Pollack, Lois; Onufriev, Alexey V.

    2016-01-01

    We present a semi-quantitative model of condensation of short nucleic acid (NA) duplexes induced by trivalent cobalt(iii) hexammine (CoHex) ions. The model is based on partitioning of bound counterion distribution around single NA duplex into “external” and “internal” ion binding shells distinguished by the proximity to duplex helical axis. In the aggregated phase the shells overlap, which leads to significantly increased attraction of CoHex ions in these overlaps with the neighboring duplexes. The duplex aggregation free energy is decomposed into attractive and repulsive components in such a way that they can be represented by simple analytical expressions with parameters derived from molecular dynamic simulations and numerical solutions of Poisson equation. The attractive term depends on the fractions of bound ions in the overlapping shells and affinity of CoHex to the “external” shell of nearly neutralized duplex. The repulsive components of the free energy are duplex configurational entropy loss upon the aggregation and the electrostatic repulsion of the duplexes that remains after neutralization by bound CoHex ions. The estimates of the aggregation free energy are consistent with the experimental range of NA duplex condensation propensities, including the unusually poor condensation of RNA structures and subtle sequence effects upon DNA condensation. The model predicts that, in contrast to DNA, RNA duplexes may condense into tighter packed aggregates with a higher degree of duplex neutralization. An appreciable CoHex mediated RNA-RNA attraction requires closer inter-duplex separation to engage CoHex ions (bound mostly in the “internal” shell of RNA) into short-range attractive interactions. The model also predicts that longer NA fragments will condense more readily than shorter ones. The ability of this model to explain experimentally observed trends in NA condensation lends support to proposed NA condensation picture based on the multivalent

  13. Multi-shell model of ion-induced nucleic acid condensation

    NASA Astrophysics Data System (ADS)

    Tolokh, Igor S.; Drozdetski, Aleksander V.; Pollack, Lois; Baker, Nathan A.; Onufriev, Alexey V.

    2016-04-01

    We present a semi-quantitative model of condensation of short nucleic acid (NA) duplexes induced by trivalent cobalt(iii) hexammine (CoHex) ions. The model is based on partitioning of bound counterion distribution around single NA duplex into "external" and "internal" ion binding shells distinguished by the proximity to duplex helical axis. In the aggregated phase the shells overlap, which leads to significantly increased attraction of CoHex ions in these overlaps with the neighboring duplexes. The duplex aggregation free energy is decomposed into attractive and repulsive components in such a way that they can be represented by simple analytical expressions with parameters derived from molecular dynamic simulations and numerical solutions of Poisson equation. The attractive term depends on the fractions of bound ions in the overlapping shells and affinity of CoHex to the "external" shell of nearly neutralized duplex. The repulsive components of the free energy are duplex configurational entropy loss upon the aggregation and the electrostatic repulsion of the duplexes that remains after neutralization by bound CoHex ions. The estimates of the aggregation free energy are consistent with the experimental range of NA duplex condensation propensities, including the unusually poor condensation of RNA structures and subtle sequence effects upon DNA condensation. The model predicts that, in contrast to DNA, RNA duplexes may condense into tighter packed aggregates with a higher degree of duplex neutralization. An appreciable CoHex mediated RNA-RNA attraction requires closer inter-duplex separation to engage CoHex ions (bound mostly in the "internal" shell of RNA) into short-range attractive interactions. The model also predicts that longer NA fragments will condense more readily than shorter ones. The ability of this model to explain experimentally observed trends in NA condensation lends support to proposed NA condensation picture based on the multivalent "ion binding

  14. Adsorption of naphthalene from aqueous solution onto fatty acid modified walnut shells.

    PubMed

    Zhu, Mijia; Yao, Jun; Dong, Lifu; Sun, Jingjing

    2016-02-01

    The removal of polycyclic aromatic hydrocarbons (PAHs) from aqueous solution is challenging to environmental technologists. Agricultural waste is apparently the most attractive materials in removing PAHs because of its abundance, renewability, and economic advantage. The adsorption of PAHs (e.g., naphthalene) onto walnut shell (WNS) and its fatty acid (e.g., capric acid, lauric acid, palmitic acid, and oleic acid)-modified equivalent were investigated in this work to develop low-cost biosorbents for hydrophobic organic compounds. Compared with other modified sorbents, oleic acid graftted walnut shell (OWNS) showed the maximum partition coefficient (4330 ± 8.8 L kg(-1)) because of its lowest polarity and highest aromaticity. The adsorption capacity (7210 μg g(-1)) of OWNS at the temperature of 298 K was observed for an initial naphthalene concentration of 25 mg L(-1) with contact time of 40 h, sorbent dosage of 1 g L(-1), and in neutral condition. Furthermore, the regeneration capability of OWNS implied that it was a promising biosorbent for naphthalene removal. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. SAFETY EVALUATION OF OXALIC ACID WASTE RETRIEVAL IN SINGLE SHELL TANK (SST) 241-C-106

    SciTech Connect

    GOETZ, T.G.

    2003-07-21

    This report documents the safety evaluation of the process of retrieving sludge waste from single-shell tank 241-C-106 using oxalic acid. The results of the HAZOP, safety evaluation, and control allocation/decision are part of the report. This safety evaluation considers the use of oxalic acid to recover residual waste in single-shell tank (SST) 241-C-106. This is an activity not addressed in the current tank farm safety basis. This evaluation has five specific purposes: (1) Identifying the key configuration and operating assumptions needed to evaluate oxalic acid dissolution in SST 241-C-106. (2) Documenting the hazardous conditions identified during the oxalic acid dissolution hazard and operability study (HAZOP). (3) Documenting the comparison of the HAZOP results to the hazardous conditions and associated analyzed accident currently included in the safety basis, as documented in HNF-SD-WM-TI-764, ''Hazard Analysis Database Report''. (4) Documenting the evaluation of the oxalic acid dissolution activity with respect to Accident analyses described in HNF-SD-WM-SAR-067, ''Tank Farms Final Safety Analysis Report'' (FSAR). (5)Controls specified in HNF-SD-WM-TSR-006, ''Tank Farms Technical Safety Requirements'' (TSR). Documenting the process and results of control decisions as well as the applicability of preventive and/or mitigative controls to each oxalic acid addition hazardous condition.

  16. Efficiency of slightly acidic electrolyzed water for inactivation of Salmonella enteritidis and its contaminated shell eggs.

    PubMed

    Cao, Wei; Zhu, Zhi Wei; Shi, Zheng Xiang; Wang, Chao Yuan; Li, Bao Ming

    2009-03-31

    The efficiency of slightly acidic electrolyzed water (SAEW) at different temperatures (4, 20 and 45 degrees C) for inactivation of Salmonella enteritidis and it on the surface of shell eggs was evaluated. The bactericidal activity of SAEW, sodium hypochlorite solution (NaClO) and acidic electrolyzed water (AEW) to inactivate S. enteritidis was also compared. SAEW with a pH value of 6.0-6.5 used was generated by the electrolysis of a dilute hydrochloric acid (2.4 mM) in a chamber without a membrane. Although the pH value of SAEW was greatly higher than that of AEW (pH2.6-2.7), SAEW had a comparative powerful bactericidal activity at the same available chlorine concentrations. The efficiency of SAEW for inactivation of pure S. enteritidis cultures increased with increasing the available chlorine concentration and treatment time at the three different temperatures. The S. enteritidis counts decreased to less than 1.0 log(10) CFU/ml at available chlorine of 2 mg/l and 100% inactivation (reduction of 8.2 log(10) CFU/ml) was resulted in using SAEW with available chlorine more than 4 mg/l at 4, 20 and 45 degrees C after 2 min treatment, whereas no reduction was observed in the control samples. Moreover, SAEW was also effective for inactivating the S. enteritidis inoculated on the surface of shell eggs. A reduction of 6.5 log(10) CFU/g of S. enteritidis on shell eggs was achieved by SAEW containing 15 mg/l available chlorine for 3 min, but only a reduction of 0.9-1.2 log(10) CFU/g for the control samples. No survival of S. enteritidis was recovered in waste wash SAEW after treatment. The findings of this study indicate that SAEW may be a promising disinfectant agent for the shell egg washing processing without environmental pollution.

  17. Natural Product Anacardic Acid from Cashew Nut Shells Stimulates Neutrophil Extracellular Trap Production and Bactericidal Activity.

    PubMed

    Hollands, Andrew; Corriden, Ross; Gysler, Gabriela; Dahesh, Samira; Olson, Joshua; Raza Ali, Syed; Kunkel, Maya T; Lin, Ann E; Forli, Stefano; Newton, Alexandra C; Kumar, Geetha B; Nair, Bipin G; Perry, J Jefferson P; Nizet, Victor

    2016-07-01

    Emerging antibiotic resistance among pathogenic bacteria is an issue of great clinical importance, and new approaches to therapy are urgently needed. Anacardic acid, the primary active component of cashew nut shell extract, is a natural product used in the treatment of a variety of medical conditions, including infectious abscesses. Here, we investigate the effects of this natural product on the function of human neutrophils. We find that anacardic acid stimulates the production of reactive oxygen species and neutrophil extracellular traps, two mechanisms utilized by neutrophils to kill invading bacteria. Molecular modeling and pharmacological inhibitor studies suggest anacardic acid stimulation of neutrophils occurs in a PI3K-dependent manner through activation of surface-expressed G protein-coupled sphingosine-1-phosphate receptors. Neutrophil extracellular traps produced in response to anacardic acid are bactericidal and complement select direct antimicrobial activities of the compound.

  18. Natural Product Anacardic Acid from Cashew Nut Shells Stimulates Neutrophil Extracellular Trap Production and Bactericidal Activity*

    PubMed Central

    Hollands, Andrew; Corriden, Ross; Gysler, Gabriela; Dahesh, Samira; Olson, Joshua; Raza Ali, Syed; Kunkel, Maya T.; Lin, Ann E.; Forli, Stefano; Newton, Alexandra C.; Kumar, Geetha B.; Nair, Bipin G.; Perry, J. Jefferson P.; Nizet, Victor

    2016-01-01

    Emerging antibiotic resistance among pathogenic bacteria is an issue of great clinical importance, and new approaches to therapy are urgently needed. Anacardic acid, the primary active component of cashew nut shell extract, is a natural product used in the treatment of a variety of medical conditions, including infectious abscesses. Here, we investigate the effects of this natural product on the function of human neutrophils. We find that anacardic acid stimulates the production of reactive oxygen species and neutrophil extracellular traps, two mechanisms utilized by neutrophils to kill invading bacteria. Molecular modeling and pharmacological inhibitor studies suggest anacardic acid stimulation of neutrophils occurs in a PI3K-dependent manner through activation of surface-expressed G protein-coupled sphingosine-1-phosphate receptors. Neutrophil extracellular traps produced in response to anacardic acid are bactericidal and complement select direct antimicrobial activities of the compound. PMID:27226531

  19. Shell and core cross-linked poly(L-lysine)/poly(acrylic acid) complex micelles.

    PubMed

    Hsieh, Yi-Hsuan; Hsiao, Yung-Tse; Jan, Jeng-Shiung

    2014-12-21

    We report the versatility of polyion complex (PIC) micelles for the preparation of shell and core cross-linked (SCL and CCL) micelles with their surface properties determined by the constituent polymer composition and cross-linking agent. The negatively and positively charged PIC micelles with their molecular structure and properties depending on the mixing weight percentage and polymer molecular weight were first prepared by mixing the negatively and positively charged polyions, poly(acrylic acid) (PAA) and poly(L-lysine) (PLL). The feasibility of preparing SCL micelles was demonstrated by cross-linking the shell of the negatively and positively charged micelles using cystamine and genipin, respectively. The core of the micelles can be cross-linked by silica deposition to stabilize the assemblies. The shell and/or core cross-linked micelles exhibited excellent colloid stability upon changing solution pH. The drug release from the drug-loaded SCL micelles revealed that the controllable permeability of the SCL micelles can be achieved by tuning the cross-linking degree and the SCL micelles exhibited noticeable pH-responsive behavior with accelerated release under acidic conditions. With the versatility of cross-linking strategies, it is possible to prepare a variety of SCL and CCL micelles from PIC micelles.

  20. Green synthesis and characterization of Au@Pt core-shell bimetallic nanoparticles using gallic acid

    NASA Astrophysics Data System (ADS)

    Zhang, Guojun; Zheng, Hongmei; Shen, Ming; Wang, Lei; Wang, Xiaosan

    2015-06-01

    In this study, we developed a facile and benign green synthesis approach for the successful fabrication of well-dispersed urchin-like Au@Pt core-shell nanoparticles (NPs) using gallic acid (GA) as both a reducing and protecting agent. The proposed one-step synthesis exploits the differences in the reduction potentials of AuCl4- and PtCl62-, where the AuCl4- ions are preferentially reduced to Au cores and the PtCl62- ions are then deposited continuously onto the Au core surface as a Pt shell. The as-prepared Au@Pt NPs were characterized by transmission electron microscope (TEM); high-resolution transmission electron microscope (HR-TEM); scanning electron microscope (SEM); UV-vis absorption spectra (UV-vis); X-ray diffraction (XRD); Fourier transmission infrared spectra (FT-IR). We systematically investigated the effects of some experimental parameters on the formation of the Au@Pt NPs, i.e., the reaction temperature, the molar ratios of HAuCl4/H2PtCl6, and the amount of GA. When polyvinylpyrrolidone K-30 (PVP) was used as a protecting agent, the Au@Pt core-shell NPs obtained using this green synthesis method were better dispersed and smaller in size. The as-prepared Au@Pt NPs exhibited better catalytic activity in the reaction where NaBH4 reduced p-nitrophenol to p-aminophenol. However, the results showed that the Au@Pt bimetallic NPs had a lower catalytic activity than the pure Au NPs obtained by the same method, which confirmed the formation of Au@Pt core-shell nanostructures because the active sites on the surfaces of the Au NPs were covered with a Pt shell.

  1. Effect of nitric acid treatment on activated carbon derived from oil palm shell

    NASA Astrophysics Data System (ADS)

    Allwar, Allwar; Hartati, Retno; Fatimah, Is

    2017-03-01

    The primary object of this work is to study the effect of nitric acid on the porous and morphology structure of activated carbon. Production of activated carbon from oil palm shell was prepared with pyrolysis process at temperature 900°C and by introduction of 10 M nitric acid. Determination of surface area, pore volume and pore size distribution of activated carbon was conducted by the N2 adsorption-desorption isotherm at 77 K. Morphology structure and elemental micro-analysis of activated carbon were estimated by Scanning Electron Microscopy (SEM) and energy dispersive X-ray (EDX), respectively. The result shows that activated carbon after treating with nitric acid proved an increasing porous characteristics involving surface area, pore volume and pore size distribution. It also could remove the contaminants including metals and exhibit an increasing of pores and crevices all over the surface.

  2. SAFETY EVALUATION OF OXALIC ACID WASTE RETRIEVAL IN SINGLE SHELL TANK (SST) 241-C-106

    SciTech Connect

    SHULTZ, M.V.

    2003-06-11

    This report documents the safety evaluation of the process of retrieving sludge waste from single-shell tank 241-C-106 using oxalic acid. The results of the HAZOP, safety evaluation, and control allocation/decision are part of the report. This safety evaluation considers the use of oxalic acid to recover residual waste in single-shell tank (SST) 241-C-106. This is an activity not addressed in the current tank farm safety basis. This evaluation has five specific purposes: (1) Identifying the key configuration and operating assumptions needed to evaluate oxalic acid dissolution in SST 241-C-106. (2) Documenting the hazardous conditions identified during the oxalic acid dissolution hazard and operability study (HAZOP). (3) Documenting the comparison of the HAZOP results to the hazardous conditions and associated analyzed accident currently included in the safety basis, as documented in HNF-SD-WM-TI-764, Hazard Analysis Database Report. (4) Documenting the evaluation of the oxalic acid dissolution activity with respect to: (A) Accident analyses described in HNF-SD-WM-SAR-067, Tank Farms Final Safety Analysis Report (FSAR), and (B) Controls specified in HNF-SD-WM-TSR-006, Tank Farms Technical Safety Requirements (TSR). (5) Documenting the process and results of control decisions as well as the applicability of preventive and/or mitigative controls to each oxalic acid addition hazardous condition. This safety evaluation is not intended to be a request to authorize the activity. Authorization issues are addressed by the unreviewed safety question (USQ) evaluation process. This report constitutes an accident analysis.

  3. Isolation of anacardic acid from natural cashew nut shell liquid (CNSL) using supercritical carbon dioxide.

    PubMed

    Philip, Joseph Y N; Da Cruz Francisco, José; Dey, Estera S; Buchweishaija, Joseph; Mkayula, Lupituko L; Ye, Lei

    2008-10-22

    Solvent extracted cashew nut shell liquid (CNSL), conventionally known as natural CNSL, is a mixture of several alkenyl phenols. One of these alkenyl phenols is anacardic acid, which is present at the highest concentration. In view of anticipated industrial applications of anacardic acid, the objective of this work was to isolate anacardic acid from natural CNSL by supercritical carbon dioxide (scCO 2). In this study, the solubility data for natural CNSL in scCO 2 under a range of operating conditions of pressure (100, 200, and 300 bar), temperature (40 and 50 degrees C), and CO 2 flow rate (5, 10, and 15 g min (-1)) were established. The best scCO 2 working conditions were found to be 50 degrees C and 300 bar at a flow rate of 5 g min (-1) CO 2. Using 3 g of sample (CNSL/solid adsorbent = 1/2) under these scCO 2 conditions, it was possible to quantitatively isolate high purity anacardic acid from crude natural CNSL (82% of total anacardic acid) within 150 min. The anacardic acid isolated by scCO 2 was analyzed by different spectroscopic techniques (UV-vis, FT-IR, and (1)H NMR) and HPLC analysis, indicating that the anacardic acid isolated by scCO 2 has better quality than that obtained through a conventional method involving several chemical conversion steps.

  4. An efficient room temperature core-shell AgPd@MOF catalyst for hydrogen production from formic acid

    NASA Astrophysics Data System (ADS)

    Ke, Fei; Wang, Luhuan; Zhu, Junfa

    2015-04-01

    Novel core-shell AgPd@MIL-100(Fe) NPs were fabricated by a facile one-pot method. Significantly, the as-prepared core-shell NPs exhibit much higher catalytic activity than the pure AgPd NPs toward hydrogen production from formic acid without using any additive at room temperature.Novel core-shell AgPd@MIL-100(Fe) NPs were fabricated by a facile one-pot method. Significantly, the as-prepared core-shell NPs exhibit much higher catalytic activity than the pure AgPd NPs toward hydrogen production from formic acid without using any additive at room temperature. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07582j

  5. Multi-shell model of ion-induced nucleic acid condensation

    SciTech Connect

    Tolokh, Igor S.; Drozdetski, Aleksander V.; Pollack, Lois; Baker, Nathan A.; Onufriev, Alexey V.

    2016-04-21

    We present a semi-quantitative model of condensation of short nucleic acid (NA) duplexes in- duced by tri-valent cobalt hexammine (CoHex) ions. The model is based on partitioning of bound counterion distribution around single NA duplex into “external” and “internal” ion binding shells distinguished by the proximity to duplex helical axis. The duplex aggregation free energy is de- composed into attraction and repulsion components represented by simple analytic expressions. The source of the short-range attraction between NA duplexes in the aggregated phase is the in- teraction of CoHex ions in the overlapping regions of the “external” shells with the oppositely charged duplexes. The attraction depends on CoHex binding affinity to the “external” shell of nearly neutralized duplex and the number of ions in the shell overlapping volume. For a given NA duplex sequence and structure, these parameters are estimated from molecular dynamics simula- tion. The attraction is opposed by the residual repulsion of nearly neutralized duplexes as well as duplex configurational entropy loss upon aggregation. The estimates of the aggregation free energy are consistent with the experimental range of NA duplex condensation propensities, including the unusually poor condensation of RNA structures and subtle sequence effects upon DNA conden- sation. The model predicts that, in contrast to DNA, RNA duplexes may condense into tighter packed aggregates with a higher degree of duplex neutralization. The model also predicts that longer NA fragments will condense easier than shorter ones. The ability of this model to explain experimentally observed trends in NA condensation, lends support to proposed NA condensation picture based on the multivalent “ion binding shells”.

  6. Highly active Pt3Pb and core-shell Pt3Pb-Pt electrocatalysts for formic acid oxidation.

    PubMed

    Kang, Yijin; Qi, Liang; Li, Meng; Diaz, Rosa E; Su, Dong; Adzic, Radoslav R; Stach, Eric; Li, Ju; Murray, Christopher B

    2012-03-27

    Formic acid is a promising chemical fuel for fuel cell applications. However, due to the dominance of the indirect reaction pathway and strong poisoning effects, the development of direct formic acid fuel cells has been impeded by the low activity of existing electrocatalysts at desirable operating voltage. We report the first synthesis of Pt(3)Pb nanocrystals through solution phase synthesis and show they are highly efficient formic acid oxidation electrocatalysts. The activity can be further improved by manipulating the Pt(3)Pb-Pt core-shell structure. Combined experimental and theoretical studies suggest that the high activity from Pt(3)Pb and the Pt-Pb core-shell nanocrystals results from the elimination of CO poisoning and decreased barriers for the dehydrogenation steps. Therefore, the Pt(3)Pb and Pt-Pb core-shell nanocrystals can improve the performance of direct formic acid fuel cells at desired operating voltage to enable their practical application. © 2012 American Chemical Society

  7. A dual-core double emulsion platform for osmolarity-controlled microreactor triggered by coalescence of encapsulated droplets

    PubMed Central

    Guan, Xuewei; Hou, Likai; Ren, Yukun; Deng, Xiaokang; Lang, Qi; Jia, Yankai; Hu, Qingming; Tao, Ye; Liu, Jiangwei; Jiang, Hongyuan

    2016-01-01

    Droplet-based microfluidics has provided a means to generate multi-core double emulsions, which are versatile platforms for microreactors in materials science, synthetic biology, and chemical engineering. To provide new opportunities for double emulsion platforms, here, we report a glass capillary microfluidic approach to first fabricate osmolarity-responsive Water-in-Oil-in-Water (W/O/W) double emulsion containing two different inner droplets/cores and to then trigger the coalescence between the encapsulated droplets precisely. To achieve this, we independently control the swelling speed and size of each droplet in the dual-core double emulsion by controlling the osmotic pressure between the inner droplets and the collection solutions. When the inner two droplets in one W/O/W double emulsion swell to the same size and reach the instability of the oil film interface between the inner droplets, core-coalescence happens and this coalescence process can be controlled precisely. This microfluidic methodology enables the generation of highly monodisperse dual-core double emulsions and the osmolarity-controlled swelling behavior provides new stimuli to trigger the coalescence between the encapsulated droplets. Such swelling-caused core-coalescence behavior in dual-core double emulsion establishes a novel microreactor for nanoliter-scale reactions, which can protect reaction materials and products from being contaminated or released. PMID:27279935

  8. A dual-core double emulsion platform for osmolarity-controlled microreactor triggered by coalescence of encapsulated droplets.

    PubMed

    Guan, Xuewei; Hou, Likai; Ren, Yukun; Deng, Xiaokang; Lang, Qi; Jia, Yankai; Hu, Qingming; Tao, Ye; Liu, Jiangwei; Jiang, Hongyuan

    2016-05-01

    Droplet-based microfluidics has provided a means to generate multi-core double emulsions, which are versatile platforms for microreactors in materials science, synthetic biology, and chemical engineering. To provide new opportunities for double emulsion platforms, here, we report a glass capillary microfluidic approach to first fabricate osmolarity-responsive Water-in-Oil-in-Water (W/O/W) double emulsion containing two different inner droplets/cores and to then trigger the coalescence between the encapsulated droplets precisely. To achieve this, we independently control the swelling speed and size of each droplet in the dual-core double emulsion by controlling the osmotic pressure between the inner droplets and the collection solutions. When the inner two droplets in one W/O/W double emulsion swell to the same size and reach the instability of the oil film interface between the inner droplets, core-coalescence happens and this coalescence process can be controlled precisely. This microfluidic methodology enables the generation of highly monodisperse dual-core double emulsions and the osmolarity-controlled swelling behavior provides new stimuli to trigger the coalescence between the encapsulated droplets. Such swelling-caused core-coalescence behavior in dual-core double emulsion establishes a novel microreactor for nanoliter-scale reactions, which can protect reaction materials and products from being contaminated or released.

  9. Shell-crosslinked hyaluronic acid nanogels for live monitoring of hyaluronidase activity in vivo.

    PubMed

    Kim, Jihyun; Chong, Youhoon; Mok, Hyejung

    2014-06-01

    A hyaluronidase (HAdase) has been noticed as a potential drug target as well as prognostic marker because of its close associations with tumor invasion, metastasis, and angiogenesis. Accordingly, precise monitoring of HAdase activity in vivo seems to be crucial not only for the evaluation of HAdase activity but also for non-invasive molecular imaging. In our study, we propose a new organic, near-infrared fluorescence imaging probe, indocyanine green (ICG)-based stimuli-responsive fluorescence probe for selective imaging of HAdases with appreciable signal-to-noise (S/N) ratios in serum and in vivo. Shell-crosslinked hyaluronic acid (HA) nanogels (sc-nanogels) are generated via a reducible covalent linkage which incorporate ICG derivatives. The ICG-embeded HA nanogels via shell-crosslinking have preferable properties for ideal selective imaging and detection of HAdase activity in vivo. The sc-nanogels exhibit prominent chemical stability against external light, greatly control background signals in serum, and small size compared to use of self-assembled ICG-based carriers. Collapsed ICG in the hydrogel core is selectively disentangled by HAdase treatment for selective near-infrared imaging without unwanted background signal. The newly designed sc-nanogels may have great potential to serve as probes for improved selective imaging of HAdase-associated diseases in clinics as well as HAdase-activity screening in vivo.

  10. Potentiality of uranium biosorption from nitric acid solutions using shrimp shells.

    PubMed

    Ahmed, S H; El Sheikh, E M; Morsy, A M A

    2014-08-01

    Biosorption has gained important credibility during recent years because of its good performance and low cost. This work is concerned with studying the potentiality of the chitin component of the shrimp shells for uranium biosorption from nitric acid liquid solutions. The structural characteristics of the working chitin have been determined via Fourier Transform Infrared Spectroscopy (FTIR). The surface morphology was examined using Scanning Electron Microscopy (SEM). The adsorption capacity of biomass was investigated experimentally. The influence of contact time, pH, metal ion concentration, solution volume to mass ratio and temperature were evaluated and the results were fitted using adsorption isotherm models. The kinetic of uranium biosorption was also investigated as well as biosorption thermodynamic.

  11. Physicochemical properties of carbons prepared from pecan shell by phosphoric acid activation.

    PubMed

    Guo, Yanping; Rockstraw, David A

    2007-05-01

    Activated carbons were prepared from pecan shell by phosphoric acid activation. The pore structure and acidic surface groups of these carbons were characterized by nitrogen adsorption, Boehm titration and transmittance Fourier infrared spectroscopy (FTIR) techniques. The characterization results demonstrated that the development of pore structure was apparent at temperatures 250 degrees C, and reached 1130m(2)/g and 0.34cm(3)/g, respectively, at 500 degrees C. Impregnation ratio and soaking time at activation temperature also affected the pore development and pore size distribution of final carbon products. At an impregnation ratio of 1.5, activated carbon with BET surface area and micropore volume as high as 861m(2)/g and 0.289cm(3)/g was obtained at 400 degrees C. Microporous activated carbons were obtained in this study. Low impregnation ratio (less than 1.5) and activation temperature (less than 300 degrees C) are favorable to the formation of acidic surface functional groups, which consist of temperature-sensitive (unstable at high temperature) and temperature-insensitive (stable at high temperature) two parts. The disappearance of temperature-sensitive groups was significant at temperature 300 degrees C; while the temperature-insensitive groups are stable even at 500 degrees C. FTIR results showed that the temperature-insensitive part was mostly phosphorus-containing groups as well as some carbonyl-containing groups, while carbonyl-containing groups were the main contributor of temperature-sensitive part.

  12. A GREEN CHEMISTRY APPROACH TO PREPARATION OF CORE (FE OR CU)-SHELL (NOBLE METALS) NANOCOMPOSITES USING AQUEOUS ASCORBIC ACID

    EPA Science Inventory

    A greener method to fabricate novel core (Fe or Cu)-shell (noble metals) nanocomposites of transition metals such as Fe and Cu and noble metals such as Au, Pt, Pd, and Ag using aqueous ascorbic acid is described. Transition metal salts such as Cu and Fe were reduced using ascor...

  13. A GREEN CHEMISTRY APPROACH TO PREPARATION OF CORE (FE OR CU)-SHELL (NOBLE METALS) NANOCOMPOSITES USING AQUEOUS ASCORBIC ACID

    EPA Science Inventory

    A greener method to fabricate novel core (Fe or Cu)-shell (noble metals) nanocomposites of transition metals such as Fe and Cu and noble metals such as Au, Pt, Pd, and Ag using aqueous ascorbic acid is described. Transition metal salts such as Cu and Fe were reduced using ascor...

  14. In-depth proteomic analysis of a mollusc shell: acid-soluble and acid-insoluble matrix of the limpet Lottia gigantea

    PubMed Central

    2012-01-01

    Background Invertebrate biominerals are characterized by their extraordinary functionality and physical properties, such as strength, stiffness and toughness that by far exceed those of the pure mineral component of such composites. This is attributed to the organic matrix, secreted by specialized cells, which pervades and envelops the mineral crystals. Despite the obvious importance of the protein fraction of the organic matrix, only few in-depth proteomic studies have been performed due to the lack of comprehensive protein sequence databases. The recent public release of the gastropod Lottia gigantea genome sequence and the associated protein sequence database provides for the first time the opportunity to do a state-of-the-art proteomic in-depth analysis of the organic matrix of a mollusc shell. Results Using three different sodium hypochlorite washing protocols before shell demineralization, a total of 569 proteins were identified in Lottia gigantea shell matrix. Of these, 311 were assembled in a consensus proteome comprising identifications contained in all proteomes irrespective of shell cleaning procedure. Some of these proteins were similar in amino acid sequence, amino acid composition, or domain structure to proteins identified previously in different bivalve or gastropod shells, such as BMSP, dermatopontin, nacrein, perlustrin, perlucin, or Pif. In addition there were dozens of previously uncharacterized proteins, many containing repeated short linear motifs or homorepeats. Such proteins may play a role in shell matrix construction or control of mineralization processes. Conclusions The organic matrix of Lottia gigantea shells is a complex mixture of proteins comprising possible homologs of some previously characterized mollusc shell proteins, but also many novel proteins with a possible function in biomineralization as framework building blocks or as regulatory components. We hope that this data set, the most comprehensive available at present, will

  15. Palladium-platinum core-shell electrocatalysts for oxygen reduction reaction prepared with the assistance of citric acid

    SciTech Connect

    Zhang, Lulu; Su, Dong; Zhu, Shangqian; Chang, Qiaowan; Yue, Jeffrey; Du, Zheng; Shao, Minhua

    2016-04-26

    Core–shell structure is a promising alternative to solid platinum (Pt) nanoparticles as electrocatalyst for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). A simple method of preparing palladium (Pd)–platinum (Pt) core–shell catalysts (Pd@Pt/C) in a gram-batch was developed with the assistance of citric acid. The Pt shell deposition involves three different pathways: galvanic displacement reaction between Pd atoms and Pt cations, chemical reduction by citric acid, and reduction by negative charges on Pd surfaces. The uniform ultrathin (~0.4 nm) Pt shell was characterized by in situ X-ray diffraction (XRD) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images combined with electron energy loss spectroscopy (EELS). Compared with state-of-the-art Pt/C, the Pd@Pt/C core–shell catalyst showed 4 times higher Pt mass activity and much better durability upon potential cycling. As a result, both the mass activity and durability were comparable to that of Pd@Pt/C synthesized by a Cu-mediated-Pt-displacement method, which is more complicated and difficult for mass production.

  16. Palladium-platinum core-shell electrocatalysts for oxygen reduction reaction prepared with the assistance of citric acid

    SciTech Connect

    Zhang, Lulu; Su, Dong; Zhu, Shangqian; Chang, Qiaowan; Yue, Jeffrey; Du, Zheng; Shao, Minhua

    2016-04-26

    Core–shell structure is a promising alternative to solid platinum (Pt) nanoparticles as electrocatalyst for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). A simple method of preparing palladium (Pd)–platinum (Pt) core–shell catalysts (Pd@Pt/C) in a gram-batch was developed with the assistance of citric acid. The Pt shell deposition involves three different pathways: galvanic displacement reaction between Pd atoms and Pt cations, chemical reduction by citric acid, and reduction by negative charges on Pd surfaces. The uniform ultrathin (~0.4 nm) Pt shell was characterized by in situ X-ray diffraction (XRD) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images combined with electron energy loss spectroscopy (EELS). Compared with state-of-the-art Pt/C, the Pd@Pt/C core–shell catalyst showed 4 times higher Pt mass activity and much better durability upon potential cycling. As a result, both the mass activity and durability were comparable to that of Pd@Pt/C synthesized by a Cu-mediated-Pt-displacement method, which is more complicated and difficult for mass production.

  17. Palladium-platinum core-shell electrocatalysts for oxygen reduction reaction prepared with the assistance of citric acid

    DOE PAGES

    Zhang, Lulu; Su, Dong; Zhu, Shangqian; ...

    2016-04-26

    Core–shell structure is a promising alternative to solid platinum (Pt) nanoparticles as electrocatalyst for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). A simple method of preparing palladium (Pd)–platinum (Pt) core–shell catalysts (Pd@Pt/C) in a gram-batch was developed with the assistance of citric acid. The Pt shell deposition involves three different pathways: galvanic displacement reaction between Pd atoms and Pt cations, chemical reduction by citric acid, and reduction by negative charges on Pd surfaces. The uniform ultrathin (~0.4 nm) Pt shell was characterized by in situ X-ray diffraction (XRD) and high-angle annular dark-field scanning transmission electron microscopymore » (HAADF-STEM) images combined with electron energy loss spectroscopy (EELS). Compared with state-of-the-art Pt/C, the Pd@Pt/C core–shell catalyst showed 4 times higher Pt mass activity and much better durability upon potential cycling. As a result, both the mass activity and durability were comparable to that of Pd@Pt/C synthesized by a Cu-mediated-Pt-displacement method, which is more complicated and difficult for mass production.« less

  18. Mesoporous core–shell Fenton nanocatalyst: a mild, operationally simple approach to the synthesis of adipic acid.

    PubMed

    Patra, Astam K; Dutta, Arghya; Bhaumik, Asim

    2013-09-09

    Mesoporous nanoparticles composed of γ-Al2O3 cores and α-Fe2O3 shells were synthesized in aqueous medium. The surface charge of γ-Al2O3 helps to form the core–shell nanocrystals. The core–shell structure and formation mechanism have been investigated by wide-angle XRD, energy-dispersive X-ray spectroscopy, and elemental mapping by ultrahigh-resolution (UHR) TEM and X-ray photoelectron spectroscopy. The N2 adsorption–desorption isotherm of this core–shell materials, which is of type IV, is characteristic of a mesoporous material having a BET surface area of 385 m2 g(−1) and an average pore size of about 3.2 nm. The SEM images revealed that the mesoporosity in this core–shell material is due to self-aggregation of tiny spherical nanocrystals with sizes of about 15–20 nm. Diffuse-reflectance UV/Vis spectra, elemental mapping by UHRTEM, and wide-angle XRD patterns indicate that the materials are composed of aluminum oxide cores and iron oxide shells. These Al2O3@Fe2O3 core–shell nanoparticles act as a heterogeneous Fenton nanocatalyst in the presence of hydrogen peroxide, and show high catalytic efficiency for the one-pot conversion of cyclohexanone to adipic acid in water. The heterogeneous nature of the catalyst was confirmed by a hot filtration test and analysis of the reaction mixture by atomic absorption spectroscopy. The kinetics of the reaction was monitored by gas chromatography and 1H NMR spectroscopy. The new core–shell catalyst remained in a separate solid phase, which could easily be removed from the reaction mixture by simple filtration and the catalyst reused efficiently.

  19. Synthesis of walnut shell modified with titanium dioxide and zinc oxide nanoparticles for efficient removal of humic acid from aqueous solutions.

    PubMed

    Naghizadeh, Ali; Shahabi, Habibeh; Ghasemi, Fatemeh; Zarei, Ahmad

    2016-12-01

    The main aim of this research was to study the efficiency of modified walnut shell with titanium dioxide (TiO2) and zinc oxide (ZnO) in the adsorption of humic acid from aqueous solutions. This experimental study was carried out in a batch condition to determine the effects of factors such as contact time, pH, humic acid concentration, dose of adsorbents (raw walnut shell, modified walnut shell with TiO2 and ZnO) on the removal efficiency of humic acid. pHzpc of raw walnut shell, walnut shell modified with TiO2 and walnut shell modified with ZnO were 7.6, 7.5, and 8, respectively. The maximum adsorption capacity of humic acid at concentration of 30 mg/L, contact time of 30 min at pH = 3 in an adsorbent dose of 0.02 g of walnut shell and ZnO and TiO2 modified walnut shell were found to be 35.2, 37.9, and 40.2 mg/g, respectively. The results showed that the studied adsorbents tended to fit with the Langmuir model. Walnut shell, due to its availability, cost-effectiveness, and also its high adsorption efficiency, can be proposed as a promising natural adsorbent in the removal of humic acid from aqueous solutions.

  20. Removal of Se(IV) from aqueous solution using sulphuric acid-treated peanut shell.

    PubMed

    El-Shafey, E I

    2007-09-01

    A carbonaceous sorbent was prepared from peanut shell via sulphuric acid treatment. Se(IV) removal from aqueous solution on the sorbent was studied varying time, pH, Se(IV) concentration, temperature and sorbent status (wet and dry). Se(IV) removal was faster using the wet sorbent than the dry sorbent following a pseudo-first-order model. Se(IV) removal increases at low pH values, and decreases as pH increases until pH 7. Sorption was found to fit the Langmuir equation and sorption capacity for the wet sorbent was higher than that for the dry one. Both sorbents showed an increased selenium sorption by rising the temperature. Redox processes between Se(IV) and the carbon sorbent are involved. Analysis by scanning electron microscope and X-ray powder diffraction for the sorbent after the reaction with acidified Se(IV) confirmed the availability of elemental selenium as particles on the sorbent surface as a result of Se(IV) reduction. Physicochemical tests showed an increase in sorbent acidity, cation exchange capacity (CEC) and surface functionality after the reaction with acidified Se(IV), indicating the oxidation processes occurring on the sorbent surface. Due to its reduction properties, the sorbent seems efficient for Se(IV) removal from aqueous solution.

  1. Hollow palladium nanospheres with porous shells supported on graphene as enhanced electrocatalysts for formic acid oxidation.

    PubMed

    Wang, Bo; Yang, Jun; Wang, Lei; Wang, Ruihong; Tian, Chungui; Jiang, Baojiang; Tian, Mei; Fu, Honggang

    2013-11-28

    The hollow palladium nanospheres with the porous shell comprised of uniform 5 nm Pd nanoparticles (Pd NS-HP) have been synthesized successfully by employing a simple replacement process between PdCl4(2-) ions and Co with the assistance of a structure-directing agent, polyvinyl pyrrolidone (PVP). Then, the obtained Pd NS-HP is supported on graphene nanosheets (GN) to prepare Pd NS-HP/GN composites by a wet-impregnation method. As the catalyst towards formic acid electrooxidation, the Pd NS-HP/GN composite exhibits a larger electrochemically active surface area, better electrocatalytic activity and better stability compared with Pd nanoparticles/graphene (Pd NP/GN) and commercial Pd/C catalysts. The enhancement in electrocatalytic performance of Pd NS-HP/GN is attributed to the abundant connected pore channels in the inner and exterior surfaces of Pd nanospheres, which could provide a large contact surface for adsorption and transmission of reactants, facilitating the oxidation of formic acid molecules on its surface and also improving the utilization of Pd metal. Moreover, the support of graphene could enhance the stability of the catalyst.

  2. Design and characterization of antimicrobial usnic acid loaded-core/shell magnetic nanoparticles.

    PubMed

    Taresco, Vincenzo; Francolini, Iolanda; Padella, Franco; Bellusci, Mariangela; Boni, Adriano; Innocenti, Claudia; Martinelli, Andrea; D'Ilario, Lucio; Piozzi, Antonella

    2015-01-01

    The application of magnetic nanoparticles (MNPs) in medicine is considered much promising especially because they can be handled and directed to specific body sites by external magnetic fields. MNPs have been investigated in magnetic resonance imaging, hyperthermia and drug targeting. In this study, properly functionalized core/shell MNPs with antimicrobial properties were developed to be used for the prevention and treatment of medical device-related infections. Particularly, surface-engineered manganese iron oxide MNPs, produced by a micro-emulsion method, were coated with two different polymers and loaded with usnic acid (UA), a dibenzofuran natural extract possessing antimicrobial activity. Between the two polymer coatings, the one based on an intrinsically antimicrobial cationic polyacrylamide (pAcDED) resulted to be able to provide MNPs with proper magnetic properties and basic groups for UA loading. Thanks to the establishment of acid-base interactions, pAcDED-coated MNPs were able to load and release significant drug amounts resulting in good antimicrobial properties versus Staphylococcus epidermidis (MIC = 0.1 mg/mL). The use of pAcDED having intrinsic antimicrobial activity as MNP coating in combination with UA likely contributed to obtain an enhanced antimicrobial effect. The developed drug-loaded MNPs could be injected in the patient soon after device implantation to prevent biofilm formation, or, later, in presence of signs of infection to treat the biofilm grown on the device surfaces.

  3. Anoxic and oxic removal of humic acids with Fe@Fe2O3 core-shell nanowires: a comparative study.

    PubMed

    Wu, Hao; Ai, Zhihui; Zhang, Lizhi

    2014-04-01

    In this study we comparatively investigate the removal of humic acids with Fe@Fe2O3 core-shell nanowires under anoxic and oxic conditions. The products of humic acids after reacting with Fe@Fe2O3 core-shell nanowires under anoxic and oxic conditions were carefully examined with three-dimensional excitation emission matrix fluorescence spectroscopy and gas chromatography mass spectrometry. It was found that humic acids were removed by Fe@Fe2O3 core-shell nanowires via adsorption under anoxic condition. Langmuir adsorption isotherm was applicable to describe the adsorption processes. Kinetics of humic acids adsorption onto Fe@Fe2O3 core-shell nanowires was found to follow pseudo-second-order rate equation. By contrast, the oxic removal of humic acids with Fe@Fe2O3 core-shell nanowires involved adsorption and subsequent oxidation of humic acids because Fe@Fe2O3 core-shell nanowires could activate molecular oxygen to produce reactive oxygen species to oxidize humic acids. This subsequent oxidation of humic acids could improve the oxic removal rate to 2.5 times that of anoxic removal, accompanying with about 8.4% of mineralization. This study provides a new method for humic acids removal and also sheds light on the effects of humic acids on the pollutant removal by nano zero-valent iron.

  4. Novel cost effective full scale mussel shell bioreactors for metal removal and acid neutralization.

    PubMed

    DiLoreto, Z A; Weber, P A; Olds, W; Pope, J; Trumm, D; Chaganti, S R; Heath, D D; Weisener, C G

    2016-12-01

    Acid mine drainage (AMD) impacted waters are a worldwide concern for the mining industry and countries dealing with this issue; both active and passive technologies are employed for the treatment of such waters. Mussel shell bioreactors (MSB) represent a passive technology that utilizes waste from the shellfish industry as a novel substrate. The aim of this study is to provide insight into the biogeochemical dynamics of a novel full scale MSB for AMD treatment. A combination of water quality data, targeted geochemical extractions, and metagenomic analyses were used to evaluate MSB performance. The MSB raised the effluent pH from 3.4 to 8.3 while removing up to ∼99% of the dissolved Al, and Fe and >90% Ni, Tl, and Zn. A geochemical gradient was observed progressing from oxidized to reduced conditions with depth. The redox conditions helped define the microbial consortium that consists of a specialized niche of organisms that influence elemental cycling (i.e. complex Fe and S cycling). MSB technology represents an economic and effective means of full scale, passive AMD treatment that is an attractive alternative for developing economies due to its low cost and ease of implementation.

  5. Kinetics and thermodynamic studies for removal of acid blue 129 from aqueous solution by almond shell

    PubMed Central

    2014-01-01

    Efficiency and performance of Almond shell (AS) adsorbent for the removal and recovery of Acid Blue 129 (AB129) from wastewater is presented in this report. The influence of variables including pH, initial dye concentration, adsorbent dosage, particle size, contact time and temperature on the dye removal have been investigated in batch method by one at a time optimization method. The experimental equilibrium data were tested by four widely used isotherm models namely, Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich (D–R). It was found that adsorption of AB129 on AS well with the Langmuir isotherm model, implying monolayer coverage of dye molecules onto the surface of the adsorbent. More than 98% removal efficiency was obtained within 14 min at adsorbent dose of 0.4 g for initial dye concentration of 40 mg/L at pH 2. Kinetics of the adsorption process was tested by pseudo-first-order and pseudo-second-order kinetics, and intraparticle diffusion mechanism. Pseudo-second-order kinetic model provided a better correlation for the experimental data studied in comparison to the pseudo-first-order model. Calculation of various thermodynamic parameters such as, Gibb’s free energy, entropy and enthalpy of the on-going adsorption process indicate feasibility and endothermic nature of AB129 adsorption on all adsorbents. This work can be used in design of adsorption columns for dyes removal. PMID:24620822

  6. Multifunctional antitumor magnetite/chitosan- l-glutamic acid (core/shell) nanocomposites

    NASA Astrophysics Data System (ADS)

    Santos, Daniela P.; Ruiz, M. Adolfina; Gallardo, Visitación; Zanoni, Maria Valnice B.; Arias, José L.

    2011-09-01

    The development of anticancer drug delivery systems based on biodegradable nanoparticles has been intended to maximize the localization of chemotherapy agents within tumor interstitium, along with negligible drug distribution into healthy tissues. Interestingly, passive and active drug targeting strategies to cancer have led to improved nanomedicines with great tumor specificity and efficient chemotherapy effect. One of the most promising areas in the formulation of such nanoplatforms is the engineering of magnetically responsive nanoparticles. In this way, we have followed a chemical modification method for the synthesis of magnetite/chitosan- l-glutamic acid (core/shell) nanostructures. These magnetic nanocomposites (average size ≈340 nm) exhibited multifunctional properties based on its capability to load the antitumor drug doxorubicin (along with an adequate sustained release) and its potential for hyperthermia applications. Compared to drug surface adsorption, doxorubicin entrapment into the nanocomposites matrix yielded a higher drug loading and a slower drug release profile. Heating characteristics of the magnetic nanocomposites were investigated in a high-frequency alternating magnetic gradient: a stable maximum temperature of 46 °C was successfully achieved within 40 min. To our knowledge, this is the first time that such kind of stimuli-sensitive nanoformulation with very important properties (i.e., magnetic targeting capabilities, hyperthermia, high drug loading, and little burst drug release) has been formulated for combined antitumor therapy against cancer.

  7. Influence of low levels of ochratoxin A on egg production, egg-shell stains, and serum uric-acid levels in Leghorn-type hens.

    PubMed

    Page, R K; Stewart, G; Wyatt, R; Bush, P; Fletcher, O J; Brown, J

    1980-01-01

    Ochratoxin A, when fed at 0.0, 0.5, or 1.0 PPM to adult white Leghorn chickens, produced significant reduction in egg production and an increase in serum uric-acid levels, with a concomitant increase in egg-shell stains. These egg-shell stains were clinically similar to those described in the case report.

  8. Hollow Ag@Pd core-shell nanotubes as highly active catalysts for the electro-oxidation of formic acid.

    PubMed

    Jiang, Yuanyuan; Lu, Yizhong; Han, Dongxue; Zhang, Qixian; Niu, Li

    2012-03-16

    Ag nanowires are prepared as templates by a polyol reduction process. Then Ag nanotubes coated with a thin layer of Pd are synthesized through sequential reduction accompanied with the galvanic displacement reaction. The products show a hollow core-shell nanotubular structure, as demonstrated by detailed characterizations. The Ag@Pd can significantly improve the electrocatalytic activity towards the electro-oxidation of formic acid and enhance the stability of the Pd component. It is proposed that the enhanced electrochemically active surface area and modulated electron structure of Pd by Ag are responsible for the improvement of electrocatalytic activity and durability. The results obtained in this work are different from those previous reports, in which alloy walls with hollow interiors are usually formed. This work provides a new and simple method for synthesizing novel bimetallic core-shell structure with a hollow interior, which can be applied as high-performance catalysts for the electro-oxidation of formic acid.

  9. Effect of the solvatation shell exchange on the formation of malvidin-3-O-glucoside-ellagic acid complexes.

    PubMed

    Kunsagi-Maté, Sandor; Ortmann, Erika; Kollar, Laszló; Nikfardjam, Martin Pour

    2007-10-11

    The interaction of malvidin-3-O-glucoside with ellagic acid was studied in aqueous solutions in dependence of the ethanol content of the samples. The results show significant changes of the thermodynamic parameters when the ethanol content exceeds 8%vol. The quantum chemical calculations and the solvent relaxation measurements validate that the solvatation shell of the malvidin-ellagic acid complexes changes from water to ethanol around this critical alcoholic concentration. The change of the solvate shell is accompanied by increasing copigmentation; i.e., higher "multi-sandwich" complexes are formed. According to the considerable role of this interaction (namely copigmentation) in the formation of color in red wines, our results have several consequences for the winemaking process with regard to the stabilization of wine color.

  10. Hollow Ag@Pd core-shell nanotubes as highly active catalysts for the electro-oxidation of formic acid

    NASA Astrophysics Data System (ADS)

    Jiang, Yuanyuan; Lu, Yizhong; Han, Dongxue; Zhang, Qixian; Niu, Li

    2012-03-01

    Ag nanowires are prepared as templates by a polyol reduction process. Then Ag nanotubes coated with a thin layer of Pd are synthesized through sequential reduction accompanied with the galvanic displacement reaction. The products show a hollow core-shell nanotubular structure, as demonstrated by detailed characterizations. The Ag@Pd can significantly improve the electrocatalytic activity towards the electro-oxidation of formic acid and enhance the stability of the Pd component. It is proposed that the enhanced electrochemically active surface area and modulated electron structure of Pd by Ag are responsible for the improvement of electrocatalytic activity and durability. The results obtained in this work are different from those previous reports, in which alloy walls with hollow interiors are usually formed. This work provides a new and simple method for synthesizing novel bimetallic core-shell structure with a hollow interior, which can be applied as high-performance catalysts for the electro-oxidation of formic acid.

  11. Preparation of core-shell PAN nanofibers encapsulated α-tocopherol acetate and ascorbic acid 2-phosphate for photoprotection.

    PubMed

    Wu, Xiao-Mei; Branford-White, Christopher J; Yu, Deng-Guang; Chatterton, Nicholas P; Zhu, Li-Min

    2011-01-01

    Magnesium l-ascorbic acid 2-phosphate (MAAP) and α-tocopherol acetate (α-TAc), as the stable vitamin C and vitamin E derivative, respectively, are often applied to skin care products for reducing UV damage. The encapsulation of MAAP (0.5%, g/mL) and α-TAc (5%, g/mL) together within the polyacrylonitrile (PAN) nanofibers was demonstrated using a coaxial electrospinning technique. The structure and morphology characterizations of the core-shell fibers MAAP/α-TAc-PAN were investigated by SEM, FTIR and XRD. As a negative control, the blend nanofibers MAAP/α-TAc/PAN were prepared from a normal electrospinning method. The results from SEM indicated that the morphology and diameter of the nanofibers were influenced by concentration of spinning solution, the polymer component of the shell, the carrying agent of the core and the fabricating methods, and the core-shell nanofibers obtained at the concentration of 8% had finer and uniform structure with the average diameters of 200 ± 15nm. From in vitro release studies it could be seen that both different fiber specimens showed a gradual increase in the amount of α-TAc or MAAP released from the nanofibers. Furthermore, α-TAc and MAAP released from the blend nanofibers showed the burst release at the maximum release of ∼15% and ∼40% during the first 6h, respectively, but their release amount from the core-shell nanofibers was only 10-12% during the initial part of the process. These results showed that core-shell nanofibers alleviated the initial burst release and gave better sustainability compared to that of the blend nanofibers. The present study would provide a basis for further optimization of processing conditions to obtain desired structured core-shell nanofibers and release kinetics for practical applications in dermal tissue.

  12. A comparative study of the kinetics of amino acid racemization/epimerization in fossil and modern mollusk shells

    SciTech Connect

    Goodfriend, G.A. Carnegie Inst. of Washington, Washington DC ); Meyer, V.R. )

    1991-11-01

    The present study examines the question of whether heating experiments on modern shell material accurately model the pattern of kinetics of racemization/epimerization in fossils. Using one modern sample and four fossil samples (dating to 9700-1700 yr B.P.) of a species of land snail from the Negev Desert, the kinetic behavior of the samples in laboratory heating experiments are compared. Results are then compared to the Holocene trend in kinetic patterns observed in a large series of radio-carbon-dated shells. For most amino acids (alanine, alloisoleucine/isoleucine, phenylalanine, and glutamic acid), the fossil material displays the same pattern of kinetics in relation to time as the modern shells; deviant patterns are observed for aspartic acid, proline, and methionine. Adherence to a first order kinetic pattern in heated shells occurs only in alloisoleucine/isoleucine (within the range of D/L ratios studied). Differences in the temperature dependence of racemization/epimerization rates are found between modern and fossil samples. In most cases this relationship when extrapolated to natural temperatures, does not agree well with observed rates of racemization/epimerization in the fossil series. However the pattern of change in rate of racemization/epimerization with time in heating experiments generally follows the trend observed in the fossil series rather well. The experiments indicate that heating experiment results for certain amino acids, such as the widely used alloisoleucine/isoleucine, do give good predictions of kinetic patterns in relation to time in fossils but that predictions of the temperature dependence of rates are less accurate.

  13. Anacardic Acid Constituents from Cashew Nut Shell Liquid: NMR Characterization and the Effect of Unsaturation on Its Biological Activities.

    PubMed

    Morais, Selene M; Silva, Katherine A; Araujo, Halisson; Vieira, Icaro G P; Alves, Daniela R; Fontenelle, Raquel O S; Silva, Artur M S

    2017-03-16

    Anacardic acids are the main constituents of natural cashew nut shell liquid (CNSL), obtained via the extraction of cashew shells with hexane at room temperature. This raw material presents high technological potential due to its various biological properties. The main components of CNSL are the anacardic acids, salicylic acid derivatives presenting a side chain of fifteen carbon atoms with different degrees of unsaturation (monoene-15:1, diene-15:2, and triene-15:3). Each constituent was isolated by column chromatography using silica gel impregnated with silver nitrate. The structures of the compounds were characterized by nuclear magnetic resonance through complete and unequivocal proton and carbon assignments. The effect of the side chain unsaturation was also evaluated in relation to antioxidant, antifungal and anticholinesterase activities, and toxicity against Artemia salina. The triene anacardic acid provided better results in antioxidant activity assessed by the inhibition of the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH), higher cytotoxicity against A. salina, and acetylcholinesterase (AChE) inhibition. Thus, increasing the unsaturation of the side chain of anacardic acid increases its action against free radicals, AChE enzyme, and A. salina nauplii. In relation to antifungal activity, an inverse result was obtained, and the linearity of the molecule plays an important role, with monoene being the most active. In conclusion, the changes in structure of anacardic acids, which cause differences in polarity, contribute to the increase or decrease in the biological activity assessed.

  14. Anacardic Acid Constituents from Cashew Nut Shell Liquid: NMR Characterization and the Effect of Unsaturation on Its Biological Activities

    PubMed Central

    Morais, Selene M.; Silva, Katherine A.; Araujo, Halisson; Vieira, Icaro G.P.; Alves, Daniela R.; Fontenelle, Raquel O.S.; Silva, Artur M.S.

    2017-01-01

    Anacardic acids are the main constituents of natural cashew nut shell liquid (CNSL), obtained via the extraction of cashew shells with hexane at room temperature. This raw material presents high technological potential due to its various biological properties. The main components of CNSL are the anacardic acids, salicylic acid derivatives presenting a side chain of fifteen carbon atoms with different degrees of unsaturation (monoene–15:1, diene–15:2, and triene–15:3). Each constituent was isolated by column chromatography using silica gel impregnated with silver nitrate. The structures of the compounds were characterized by nuclear magnetic resonance through complete and unequivocal proton and carbon assignments. The effect of the side chain unsaturation was also evaluated in relation to antioxidant, antifungal and anticholinesterase activities, and toxicity against Artemia salina. The triene anacardic acid provided better results in antioxidant activity assessed by the inhibition of the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH), higher cytotoxicity against A. salina, and acetylcholinesterase (AChE) inhibition. Thus, increasing the unsaturation of the side chain of anacardic acid increases its action against free radicals, AChE enzyme, and A. salina nauplii. In relation to antifungal activity, an inverse result was obtained, and the linearity of the molecule plays an important role, with monoene being the most active. In conclusion, the changes in structure of anacardic acids, which cause differences in polarity, contribute to the increase or decrease in the biological activity assessed. PMID:28300791

  15. Hydrogen production from formic acid decomposition at room temperature using a Ag-Pd core-shell nanocatalyst.

    PubMed

    Tedsree, Karaked; Li, Tong; Jones, Simon; Chan, Chun Wong Aaron; Yu, Kai Man Kerry; Bagot, Paul A J; Marquis, Emmanuelle A; Smith, George D W; Tsang, Shik Chi Edman

    2011-05-01

    Formic acid (HCOOH) has great potential as an in situ source of hydrogen for fuel cells, because it offers high energy density, is non-toxic and can be safely handled in aqueous solution. So far, there has been a lack of solid catalysts that are sufficiently active and/or selective for hydrogen production from formic acid at room temperature. Here, we report that Ag nanoparticles coated with a thin layer of Pd atoms can significantly enhance the production of H₂ from formic acid at ambient temperature. Atom probe tomography confirmed that the nanoparticles have a core-shell configuration, with the shell containing between 1 and 10 layers of Pd atoms. The Pd shell contains terrace sites and is electronically promoted by the Ag core, leading to significantly enhanced catalytic properties. Our nanocatalysts could be used in the development of micro polymer electrolyte membrane fuel cells for portable devices and could also be applied in the promotion of other catalytic reactions under mild conditions.

  16. Pulse electrodeposition to prepare core-shell structured AuPt@Pd/C catalyst for formic acid fuel cell application

    NASA Astrophysics Data System (ADS)

    Lu, Xueyi; Luo, Fan; Song, Huiyu; Liao, Shijun; Li, Hualing

    2014-01-01

    A novel core-shell structured AuPt@Pd/C catalyst for the electrooxidation of formic acid is synthesized by a pulse electrodeposition process, and the AuPt core nanoparticles are obtained by a NaBH4 reduction method. The catalyst is characterized with X-ray powder diffraction and transmission electron microscopy, thermogravimetric analysis, cyclic voltammetry, CO stripping and X-ray photoelectron spectroscopy. The core-shell structure of the catalyst is revealed by the increase in particle size resulting from a Pd layer covering the AuPt core, and by a negative shift in the CO stripping peaks. The addition of a small amount of Pt improves the dispersion of Au and results in smaller core particles. The catalyst's activity is evaluated by cyclic voltammetry in formic acid solution. The catalyst shows excellent activity towards the anodic oxidation of formic acid, the mass activity reaches 4.4 A mg-1Pd and 0.83 A mg-1metal, which are 8.5 and 1.6 times that of commercial Pd/C. This enhanced electrocatalytic activity could be ascribed to the good dispersion of Au core particles resulting from the addition of Pt, as well as to the interaction between the Pd shell layer and the Au and Pt in the core nanoparticles.

  17. Acidic Electrolyzed Water as a Novel Transmitting Medium for High Hydrostatic Pressure Reduction of Bacterial Loads on Shelled Fresh Shrimp

    PubMed Central

    Du, Suping; Zhang, Zhaohuan; Xiao, Lili; Lou, Yang; Pan, Yingjie; Zhao, Yong

    2016-01-01

    Acidic electrolyzed water (AEW), a novel non-thermal sterilization technology, is widely used in the food industry. In this study, we firstly investigated the effect of AEW as a new pressure transmitting medium for high hydrostatic pressure (AEW-HHP) processing on microorganisms inactivation on shelled fresh shrimp. The optimal conditions of AEW-HHP for Vibrio parahaemolyticus inactivation on sterile shelled fresh shrimp were obtained using response surface methodology: NaCl concentration to electrolysis 1.5 g/L, treatment pressure 400 MPa, treatment time 10 min. Under the optimal conditions mentioned above, AEW dramatically enhanced the efficiency of HHP for inactivating V. parahaemolyticus and Listeria monocytogenes on artificially contaminated shelled fresh shrimp, and the log reductions were up to 6.08 and 5.71 log10 CFU/g respectively, while the common HHP could only inactivate the two pathogens up to 4.74 and 4.31 log10 CFU/g respectively. Meanwhile, scanning electron microscopy (SEM) showed the same phenomenon. For the naturally contaminated shelled fresh shrimp, AEW-HHP could also significantly reduce the micro flora when examined using plate count and PCR-DGGE. There were also no significant changes, histologically, in the muscle tissues of shrimps undergoing the AEW-HHP treatment. In summary, using AEW as a new transmitting medium for HHP processing is an innovative non thermal technology for improving the food safety of shrimp and other aquatic products. PMID:27014228

  18. Acidic Electrolyzed Water as a Novel Transmitting Medium for High Hydrostatic Pressure Reduction of Bacterial Loads on Shelled Fresh Shrimp.

    PubMed

    Du, Suping; Zhang, Zhaohuan; Xiao, Lili; Lou, Yang; Pan, Yingjie; Zhao, Yong

    2016-01-01

    Acidic electrolyzed water (AEW), a novel non-thermal sterilization technology, is widely used in the food industry. In this study, we firstly investigated the effect of AEW as a new pressure transmitting medium for high hydrostatic pressure (AEW-HHP) processing on microorganisms inactivation on shelled fresh shrimp. The optimal conditions of AEW-HHP for Vibrio parahaemolyticus inactivation on sterile shelled fresh shrimp were obtained using response surface methodology: NaCl concentration to electrolysis 1.5 g/L, treatment pressure 400 MPa, treatment time 10 min. Under the optimal conditions mentioned above, AEW dramatically enhanced the efficiency of HHP for inactivating V. parahaemolyticus and Listeria monocytogenes on artificially contaminated shelled fresh shrimp, and the log reductions were up to 6.08 and 5.71 log10 CFU/g respectively, while the common HHP could only inactivate the two pathogens up to 4.74 and 4.31 log10 CFU/g respectively. Meanwhile, scanning electron microscopy (SEM) showed the same phenomenon. For the naturally contaminated shelled fresh shrimp, AEW-HHP could also significantly reduce the micro flora when examined using plate count and PCR-DGGE. There were also no significant changes, histologically, in the muscle tissues of shrimps undergoing the AEW-HHP treatment. In summary, using AEW as a new transmitting medium for HHP processing is an innovative non thermal technology for improving the food safety of shrimp and other aquatic products.

  19. Compound-Specific Amino Acid δ(15) N Values in Archaeological Shell: Assessing Diagenetic Integrity and Potential for Isotopic Baseline Reconstruction.

    PubMed

    Misarti, Nicole; Gier, Elizabeth; Finney, Bruce; Barnes, Kelli; McCarthy, Matthew

    2017-08-22

    Reconstructing stable isotope (SI) ratios at the base of paleo-food webs is often challenging. For coastal systems, the SI ratios of organic matter in archeological shell represent a possible solution, providing a direct record of primary consumer SI ratios in the littoral zone. However, shell is often porous, with organic compounds being susceptible to diagenetic alteration or contamination. If molecular isotopic information is well preserved, compound-specific amino acid isotope analysis (CSI-AA) has the potential to provide direct proxies for baseline SI ratios, bypass many contamination issues, and allow assessment of the diagenetic state. We collected shell from both archeological middens and nearby littoral zones in coastal Alaska, and used a simple organic extraction approach based on decalcification with sequential weak HCL additions to liberate organic material. We measured CSI-AA patterns, molar AA distributions, and the CSI-AA degradation parameter (ΣV), in the context of bulk SI ratios in fossil shell, modern shell, and soft tissue from five common taxa (urchin, limpet, mussel, periwinkle, chiton). CSI-AA patterns in both soft tissue and shell were consistent with primary consumers, and were indistinguishable in most modern and fossil shell pairs, showing that amino acid δ(15) N values can be well preserved in archeological shell. AA molar distributions were also similar, although most fossil shell was enriched in Asx and Gly. Comparison between CSI-AA results from modern specimens confirmed that source AA groups (tracking isotopic baselines) are transferred without substantial modification into the shell record. In contrast, the trophic AA group had elevated δ(15) N values in shell versus soft tissue for all taxa examined, suggesting that a correction will be required for any CSI-AA proxies using these AAs. Overall, this new data indicates that the CSI-AA analysis of fossil shell represents a promising new approach to determining isotopic baselines

  20. Promising new applications of Castanea sativa shell: nutritional composition, antioxidant activity, amino acids and vitamin E profile.

    PubMed

    Rodrigues, Francisca; Santos, Joana; Pimentel, Filipa B; Braga, Nair; Palmeira-de-Oliveira, Ana; Oliveira, M Beatriz P P

    2015-08-01

    The present study was aimed to assess the macronutrient composition and the amino acid and vitamin E profiles of Castanea sativa shell from different production regions of Portugal (Minho, Trás-os-Montes and Beira-Alta). The nutritional composition was similar for all samples, with a high moisture content and low fat amounts. Arginine and leucine were the predominant essential amino acids (EAA) accounting for 3.55-7.21% and 1.59-2.08%, respectively, for samples of the different production zones. All the shells presented high contents of vitamin E (481.5 mg per 100 g sample, 962.8 mg per 100 g sample and 567.5 mg per 100 g sample, respectively, for Minho, Trás-os-Montes and Beira-Alta). The predominant vitamer was γ-tocopherol (670 mg per 100 g sample for Trás-os-Montes). The antimicrobial and antioxidant activities of C. sativa shell were also determined. Trás-os-Montes extracts displayed the highest antioxidant activity (EC50 = 31.8 ± 1.3 μg mL(-1) for DPPH; 8083.5 ± 164.8 μmol per mg db for FRAP). The total phenolic content (TPC) varied from 241.9 mg to 796.8 mg gallic acid equivalents (GAE) per g db sample, the highest TPC being obtained for Trás-os-Montes. The total flavonoid content (TFC) varied from 31.4 to 43.3 mg of catechin equivalents (CEQ) per g db sample. No antimicrobial activity was observed. The results showed the potentialities of C. sativa shell extracts.

  1. Hyaluronic acid embedded cellulose acetate phthlate core/shell nanoparticulate carrier of 5-fluorouracil.

    PubMed

    Garg, Ashish; Rai, Gopal; Lodhi, Santram; Jain, Alok Pal; Yadav, Awesh K

    2016-06-01

    Aim of this research was to prepare hyaluronic acid-modified-cellulose acetate phthalate (HAC) core shell nanoparticles (NPs) of 5-fluorouracil (5-FU). HAC copolymer was synthesized and confirmed by fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. HAC NPs with 5-FU were prepared using HAC copolymer and compared with 5-FU loaded cellulose acetate phthalate (CAP) NPs. NPs were characterized by atomic force microscopy (AFM), particle size, zeta potential, polydispersity index, entrapment efficiency, in-vitro release, differential scanning calorimetry (DSC) and X-ray diffraction (XRD). HAC NPs were found slower release (97.30% in 48h) than (99.25% in 8h) CAP NPs. In cytotoxicity studies, showed great cytotoxic potential of 5-FU loaded HAC NPs in A549, MDA-MD-435 and SK-OV-3 cancer cellline. HAC NPs showing least hemolytic than CAP NPs and 5-FU. Area under curve (AUC), maximum plasma concentration (Cmax), mean residence time (MRT) and time to reach maximum plasma concentration Tmax), were observed 4398.1±7.90μgh/mL, 145.45±2.25μg/L, 45.74±0.25h, 72±0.50h, respectively of HAC NPs and 119.92±1.78μgh/mL, 46.38±3.42μg/L, 1.2±0.25h, 0.5±0.02h were observed in plain 5-FU solution. In conclusion, HAC NPs is effective deliver carrier of 5-FU for lung cancer.

  2. Hyaluronic Acid/PLGA Core/Shell Fiber Matrices Loaded with EGCG Beneficial to Diabetic Wound Healing.

    PubMed

    Shin, Yong Cheol; Shin, Dong-Myeong; Lee, Eun Ji; Lee, Jong Ho; Kim, Ji Eun; Song, Sung Hwa; Hwang, Dae-Youn; Lee, Jun Jae; Kim, Bongju; Lim, Dohyung; Hyon, Suong-Hyu; Lim, Young-Jun; Han, Dong-Wook

    2016-12-01

    During the last few decades, considerable research on diabetic wound healing strategies has been performed, but complete diabetic wound healing remains an unsolved problem, which constitutes an enormous biomedical burden. Herein, hyaluronic acid (HA)/poly(lactic-co-glycolic acid, PLGA) core/shell fiber matrices loaded with epigallocatechin-3-O-gallate (EGCG) (HA/PLGA-E) are fabricated by coaxial electrospinning. HA/PLGA-E core/shell fiber matrices are composed of randomly-oriented sub-micrometer fibers and have a 3D porous network structure. EGCG is uniformly dispersed in the shell and sustainedly released from the matrices in a stepwise manner by controlled diffusion and PLGA degradation over four weeks. EGCG does not adversely affect the thermomechanical properties of HA/PLGA-E matrices. The number of human dermal fibroblasts attached on HA/PLGA-E matrices is appreciably higher than that on HA/PLGA counterparts, while their proliferation is steadily retained on HA/PLGA-E matrices. The wound healing activity of HA/PLGA-E matrices is evaluated in streptozotocin-induced diabetic rats. After two weeks of surgical treatment, the wound areas are significantly reduced by the coverage with HA/PLGA-E matrices resulting from enhanced re-epithelialization/neovascularization and increased collagen deposition, compared with no treatment or HA/PLGA. In conclusion, the HA/PLGA-E matrices can be potentially exploited to craft strategies for the acceleration of diabetic wound healing and skin regeneration.

  3. Preparation of Porous Core-Shell Poly L-Lactic Acid/Polyethylene Glycol Superfine Fibres Containing Drug.

    PubMed

    Yang, Wenjing; He, Nongyue; Fu, Juan; Li, Zhiyang; Ji, Xuyuan

    2015-12-01

    In this paper, poly L-lactic acid (PLLA) blended with polyethylene glycol (PEG) was dissolved in methylene dichloride solution as the shell solution, and rapamycin (RAPA), was encapsulated inside the core of PLLA micro/nano fibres as a model drug. The effects of the blending ratio of PLLA to PEG, the concentration of the electrospinning solution, the voltage, the flow rate, and the encapsulation efficiency were studied. Uniform and porous RAPA-Loading PLLA fibres were obtained when the ratio of PLLA to PEG was 7/3, the concentration of PLLA was 3%, the applied voltage was 7.5 kV, and the pump speed was V(core) = 0.1 mL/h, V(shell) = 1 mL/h, repectively. The average diameter of PLLA fibres increased with the gradual increase in PLLA concentration. FTIR results showed that RAPA was successfully encapsulated into the core-co-shell PLLA fibres. Meanwhile, the RAPA-loading of coaxial electrospun PLLA fibres was significantly higher than that of the blending electrospun fibres. It was also found that the porous core-shell PLLA/PEG blending superfine fibres could regulate the appearance of pore on the surface of superfine fibres by adjusting the electrospinning parameters. The porous PLLA/PEG blending fibres can be used as drug carriers and, to improve the single way of drug release depending on the degradation of shell material to meet different need. It will be a remarkable breakthrough in the area for sustained and controlled release drug delivery system.

  4. Acid-Base-Triggered Structural Transformation of a Polyoxometalate Core Inside a Dodecahedrane-like Silver Thiolate Shell.

    PubMed

    Liu, Hong; Song, Chao-Yu; Huang, Ren-Wu; Zhang, Yu; Xu, Hong; Li, Mei-Jia; Zang, Shuang-Quan; Gao, Guang-Gang

    2016-03-07

    Self-assembly of metavanadate and organosilver(I) salts leads to a novel dodecahedrane-like [Ag30 ((t) BuS)20 ](10+) silver(I) thiolate nanocage that tightly wraps an unusual C2h polyoxovanadate anion. The polyoxovanadate core undergoes transformation to a D3d configuration upon acidification, and reverts back to its original C2h structure upon addition of base. Chromism was observed for the silver(I) thiolate cluster during the configurational change of the central polyoxovanadate core; the color of the solution changes reversibly from green to dark yellow. This work represents the first reported example of chromic polyoxometalate-templated silver(I) thiolate shells that respond to external acid-base stimuli. It also represents an important advance in providing crystallographic proof that structural transformations occur in a nanoscale core-shell cluster. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Dietary lipid level influences fatty acid profiles, tissue composition, and lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis.

    PubMed

    Huang, Chen-Huei; Lin, Way-Yee; Chu, Jen-Hong

    2005-11-01

    Dietary lipids containing equal portions of soybean oil and fish oil were fed to juvenile Chinese soft-shelled turtle, Pelodiscus sinensis, at supplementation level of 0 to 15% for 8 weeks. Tissue fat contents of turtles increased when dietary lipid concentration increased. Fatty acid profiles for turtles fed diets supplemented with 6% or higher levels of lipids were similar to those in dietary lipids. On absolute value basis, fatty acids of 14-, 16-, and 18-carbons in muscle of turtles fed diet without lipid supplementation were higher than those in the initial turtle muscle. Among them, C16:1 and C18:1 was approximately 4 and 2 fold higher, respectively, than that of the initial turtles. By contrast, absolute amounts of C20:5 and C22:6 in muscle of turtles fed diet without lipid supplementation were slightly less than those in the initial turtles. For turtles fed lipid supplemented diets, tissue C20:5 and C22:6, however, increased when dietary lipid level increased. These results suggest that soft-shelled turtles are capable of synthesizing fatty acids up to 18 carbons from other nutrients and that they may have limited or no ability to synthesize highly unsaturated fatty acids. Lipid peroxidation measured by thiobarbituric acid-reactive substances in tissues of turtles fed 12% and 15% lipids was greater (p<0.05) than that in turtles fed 3% to 9% lipids. This could be due to high lipid and unsaturated fatty acid content in these tissues. On lipid basis, lipid peroxidation in turtles fed diet without lipid supplementation was the highest among all groups suggesting the existence of antioxidant factors in the dietary lipids.

  6. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation.

    PubMed

    Hsu, Chiajen; Huang, Chienwen; Hao, Yaowu; Liu, Fuqiang

    2013-03-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies.

  7. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Hsu, Chiajen; Huang, Chienwen; Hao, Yaowu; Liu, Fuqiang

    2013-03-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies.

  8. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation

    PubMed Central

    2013-01-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet–visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies. PMID:23452438

  9. Synthesis and characterization of a poly(lactic-co-glycolic acid) core + poly(N-isopropylacrylamide) shell nanoparticle system.

    PubMed

    Kosinski, Aaron M; Brugnano, Jamie L; Seal, Brandon L; Knight, Frances C; Panitch, Alyssa

    2012-01-01

    Poly(lactic-co-glycolic acid) (PLGA) is a popular material used to prepare nanoparticles for drug delivery. However, PLGA nanoparticles lack desirable attributes including active targeting abilities, resistance to aggregation during lyophilization, and the ability to respond to dynamic environmental stimuli. To overcome these issues, we fabricated a nanoparticle consisting of a PLGA core encapsulated within a shell of poly(N-isopropylacrylamide). Dynamic light scattering and transmission electron microscope imaging were used to characterize the nanoparticles, while an MTT assay and ELISA suggested biocompatibility in THP1 cells. Finally, a collagen type II binding assay showed successful modification of these nanoparticles with an active targeting moiety.

  10. Highly catalytic hollow palladium nanoparticles derived from silver@silver-palladium core-shell nanostructures for the oxidation of formic acid

    NASA Astrophysics Data System (ADS)

    Chen, Dong; Cui, Penglei; He, Hongyan; Liu, Hui; Yang, Jun

    2014-12-01

    Hollow Palladium (hPd) nanoparticles (NPs) are prepared via a simple and mild successive method. Firstly, core-shell NPs with silver (Ag) cores and silver-palladium (Ag-Pd) alloy shells are synthesized in aqueous phase by galvanic replacement reaction (GRR) between Ag NPs and Pd2+ ion precursors. Saturated aqueous sodium chloride (NaCl) solution was then employed to remove the Ag component from the core and shell regions of core-shell Ag@Ag-Pd NPs, resulting in the formation of hPd NPs with shrunk sizes in comparison with their core-shell parents. Specifically, the hPd NPs exhibit superior catalytic activity and durability for catalyzing the oxidation of formic acid, compared with the Pd NPs reduced by NaBH4 in aqueous solution and commercial Pd/C catalyst from Johnson Matthey, mainly due to the large electrochemically active surface areas of the hollow particles. In addition, The Ag component in core-shell Ag@Ag-Pd NPs has an unfavorable influence on catalytic activity of NPs for formic acid oxidation. However, the durability could be improved due to the electron donating effect from Ag to Pd atoms in the core-shell NPs.

  11. Inhibitory activity of Fe(3) O(4)/oleic acid/usnic acid-core/shell/extra-shell nanofluid on S. aureus biofilm development.

    PubMed

    Grumezescu, Alexandru Mihai; Saviuc, Crina; Chifiriuc, Mariana Carmen; Hristu, Radu; Mihaiescu, Dan Eduard; Balaure, Paul; Stanciu, Gheorghe; Lazar, Veronica

    2011-12-01

    Undesired biofilm development is a major concern in many areas, especially in the medical field. The purpose of the present study was to comparatively investigate the antibiofilm efficacy of usnic acid, in soluble versus nanofluid formulation, in order to highlight the potential use of Fe(3) O(4)/oleic acid (FeOA) nanofluid as potential controlled release vehicle of this antibiofilm agent. The (+) -UA loaded into nanofluid exhibited an improved antibiofilm effect on S. aureus biofilm formation, revealed by the drastic decrease of the viable cell counts as well as by confocal laser scanning microscopy images. Our results demonstrate that FeOA nanoparticles could be used as successful coating agents for obtaining antibiofilm pellicles on different medical devices, opening a new perspective for obtaining new antimicrobial and antibiofilm surfaces, based on hybrid functionalized nanostructured biomaterials.

  12. Treatment of zinc-rich acid mine water in low residence time bioreactors incorporating waste shells and methanol dosing.

    PubMed

    Mayes, W M; Davis, J; Silva, V; Jarvis, A P

    2011-10-15

    Bioreactors utilising bacterially mediated sulphate reduction (BSR) have been widely tested for treating metal-rich waters, but sustained treatment of mobile metals (e.g. Zn) can be difficult to achieve in short residence time systems. Data are presented providing an assessment of alkalinity generating media (shells or limestone) and modes of metal removal in bioreactors receiving a synthetic acidic metal mine discharge (pH 2.7, Zn 15 mg/L, SO(4)(2-) 200mg/L, net acidity 103 mg/L as CaCO(3)) subject to methanol dosing. In addition to alkalinity generating media (50%, v.v.), the columns comprised an organic matrix of softwood chippings (30%), manure (10%) and anaerobic digested sludge (10%). The column tests showed sustained alkalinity generation, which was significantly better in shell treatments. The first column in each treatment was effective throughout the 422 days in removing >99% of the dissolved Pb and Cu, and effective for four months in removing 99% of the dissolved Zn (residence time: 12-14 h). Methanol was added to the feedstock after Zn breakthrough and prompted almost complete removal of dissolved Zn alongside improved alkalinity generation and sulphate attenuation. While there was geochemical evidence for BSR, sequential extraction of substrates suggests that the bulk (67-80%) of removed Zn was associated with Fe-Mn oxide fractions.

  13. Fatty acid composition and lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis, fed different dietary lipid sources.

    PubMed

    Lin, Way-Yee; Huang, Chen-Huei

    2007-01-01

    Juvenile soft-shelled turtles (Pelodiscus sinensis) were fed 7 diets containing 8% of lard, soybean oil, olive oil, menhaden fish oil, or mixtures of 1 to 1 ratio of fish oil and lard, soybean oil, olive oil for 10 weeks. Growth and muscle proximate compositions of the turtles were not affected by different dietary treatments (p>0.05). Fatty acid profiles in muscle polar lipids, muscle non-polar lipids, and liver polar lipids reflected the fatty acid composition of dietary lipid source. Turtles fed diets containing fish oil generally contained significantly higher (p<0.05) proportion of highly unsaturated fatty acids (HUFA) in both polar and non-polar lipids of muscle and polar fraction of liver lipids than those fed other oils. Non-polar fraction of liver lipids from all groups of turtles contained less than 1% of HUFA. All turtles contained relatively high proportions of oleic acid in their lipids regardless of the dietary lipid source. Further, lipid peroxidation in both muscle tissue and liver microsomes of turtles fed fish oil as the sole lipid source was greater (p<0.05) than those fed fish oil-free diets. Turtles fed olive oil as the sole lipid source had the lowest lipid peroxidation rate among all dietary groups. The results indicate that dietary n-3 HUFA may not be crucial for optimal growth of soft-shelled turtles although they may be used for metabolic purpose. Further, high level of dietary HUFA not only increases the HUFA content in turtle tissues, but also enhances the susceptibility of these tissues to lipid peroxidation.

  14. Using a Macroporous Silver Shell to Coat Sulfonic Acid Group-Functionalized Silica Spheres and Their Applications in Catalysis and Surface-Enhanced Raman Scattering.

    PubMed

    Ren, Guohong; Wang, Wenqin; Shang, Mengying; Zou, Hanzhi; Cheng, Shengwei

    2015-09-29

    In this paper, novel organic sulfonic acid group-functionalized silica spheres (SiO2-SO3H) were chosen as a template for fabricating core-shell SiO2-SO3H@Ag composite spheres by the seed-mediated growth method. The SiO2-SO3H spheres could be obtained easily by oxidation of the thiol group-terminated silica spheres (SiO2-SH) with H2O2. Due to the presence of sulfonic acid groups, the [Ag(NH3)2](+) ions were captured on the surface of the silica spheres, followed by in-site reduction to silver nanoseeds for further growth of the silver shell. By this strategy, the complete silver shell could be obtained, and the surface morphologies and structures of the silver shell could be controlled by adjusting the number of sulfonic acid groups on the silica spheres. A large number of sulfonic acid groups on the SiO2-SO3H spheres favored the formation of the macroporous silver shell, which was unique and exhibited good catalytic performance and a high surface-enhanced Raman scattering (SERS) enhancement ability.

  15. Electrochemical biosensor with ceria-polyaniline core shell nano-interface for the detection of carbonic acid in blood.

    PubMed

    Singh, Mudit; Nesakumar, Noel; Sethuraman, Swaminathan; Krishnan, Uma Maheswari; Rayappan, John Bosco Balaguru

    2014-07-01

    The normal physiological concentration of carbonic acid in human blood is in the range of 1.08-1.32 mM. However, if the concentration of carbonic acid rises above 3.45 mM, it may lead to respiratory acidosis. In this context, an electrochemical biosensor with CeO2-PANI (polyaniline) core-shell nano-interface was developed for sensing carbonic acid using carbonic anhydrase (CA). CA was immobilized on CeO2-PANI via chitosan on a glassy carbon electrode (GCE/CeO2-PANI/CA/chitosan). The X-ray diffraction (XRD) patterns confirmed the polycrystalline nature of CeO2 and CeO2-PANI nanoparticles. Field emission scanning electron microscopy (FE-SEM) studies showed the aggregation of spherical nanoparticles with size ranging from 37.6 to 47.8 nm and Field emission transmission electron microscopy (FE-TEM) study confirmed the presence of core-shell structure of CeO2-PANI. Immobilization of CA on CeO2-PANI was confirmed by Fourier transform infrared (FT-IR) spectra. Electrochemical studies were carried out with the help of GCE/CeO2-PANI/CA as a working electrode, Ag/AgCl saturated with 0.1 M KCl as a reference electrode and Pt wire as a counter electrode. This biosensor exhibited sensitivity of 696.49 μA cm(-2) mM(-1) with a linear range of 1.32-2.32 mM. It also showed a fast response time of less than 1s, lowest detection limit of 19.4 μM, Michaelis-Menten constant (KM) of 1.8191 mM and dry stability of 96% up to 18 days. The observed results revealed the potential of the modified working electrode with CeO2-PANI core-shell nano-interface for carbonic acid sensing. The developed biosensor can be applied for the real time clinical diagnosis of diseases such as obstructive pulmonary diseases (COPD). Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Preparation of Acid-Resistant Microcapsules with Shell-Matrix Structure to Enhance Stability of Streptococcus Thermophilus IFFI 6038.

    PubMed

    Zhou, Huan Bin; Chen, Jiashu; Li, Shunyi; Zhang, Jianpan; Zhu, Chun E; Ran, Hao; Luo, Meihua; Pan, Xin; Hu, Haiyan; Wu, Chuanbin

    2017-08-01

    Microencapsulation is an effective technology used to protect probiotics against harsh conditions. Extrusion is a commonly used microencapsulation method utilized to prepare probiotics microcapsules that is regarded as economical and simple to operate. This research aims to prepare acid-resistant probiotic microcapsules with high viability after freeze-drying and optimized storage stability. Streptococcus thermophilus IFFI 6038 (IFFI 6038) cells were mixed with trehalose and alginate to fabricate microcapsules using extrusion. These capsules were subsequently coated with chitosan to obtain chitosan-trehalose-alginate microcapsules with shell-matrix structure. Chitosan-alginate microcapsules (without trehalose) were also prepared using the same method. The characteristics of the microcapsules were observed by measuring the freeze-dried viability, acid resistance, and long-term storage stability of the cells. The viable count of IFFI 6038 in the chitosan-trehalose-alginate microcapsules was 8.34 ± 0.30 log CFU g(-1) after freeze-drying (lyophilization), which was nearly 1 log units g(-1) greater than the chitosan-alginate microcapsules. The viability of IFFI 6038 in the chitosan-trehalose-alginate microcapsules was 6.45 ± 0.09 log CFU g(-1) after 120 min of treatment in simulated gastric juices, while the chitosan-alginate microcapsules only measured 4.82 ± 0.22 log CFU g(-1) . The results of the long-term storage stability assay indicated that the viability of IFFI 6038 in chitosan-trehalose-alginate microcapsules was higher than in chitosan-alginate microcapsules after storage at 25 °C. Trehalose played an important role in the stability of IFFI 6038 during storage. The novel shell-matrix chitosan-trehalose-alginate microcapsules showed optimal stability and acid resistance, demonstrating their potential as a delivery vehicle to transport probiotics. © 2017 Institute of Food Technologists®.

  17. On the importance of thermodynamic self-consistency for calculating clusterlike pair correlations in hard-core double Yukawa fluids

    NASA Astrophysics Data System (ADS)

    Kim, Jung Min; Castañeda-Priego, Ramón; Liu, Yun; Wagner, Norman J.

    2011-02-01

    Understanding the mechanisms of clustering in colloids, nanoparticles, and proteins is of significant interest in material science and both chemical and pharmaceutical industries. Recently, using an integral equation theory formalism, Bomont et al. [J. Chem. Phys. 132, 184508 (2010)] studied theoretically the temperature dependence, at a fixed density, of the cluster formation in systems where particles interact with a hard-core double Yukawa potential composed of a short-range attraction and a long-range repulsion. In this paper, we provide evidence that the low-q peak in the static structure factor, frequently associated with the formation of clusters, is a common behavior in systems with competing interactions. In particular, we demonstrate that, based on a thermodynamic self-consistency criterion, accurate structural functions are obtained for different choices of closure relations. Moreover, we explore the dependence of the low-q peak on the particle number density, temperature, and potential parameters. Our findings indicate that enforcing thermodynamic self-consistency is the key factor to calculate both thermodynamic properties and static structure factors, including the low-q behavior, for colloidal dispersions with both attractive and repulsive interactions. Additionally, a simple analysis of the mean number of neighboring particles provides a qualitative description of some of the cluster features.

  18. Investigation of cutaneous penetration properties of stearic acid loaded to dendritic core-multi-shell (CMS) nanocarriers.

    PubMed

    Lohan, S B; Icken, N; Teutloff, C; Saeidpour, S; Bittl, R; Lademann, J; Fleige, E; Haag, R; Haag, S F; Meinke, M C

    2016-03-30

    Dendritic core-multi shell (CMS) particles are polymer based systems consisting of a dendritic polar polyglycerol polymer core surrounded by a two-layer shell of nonpolar C18 alkyl chains and hydrophilic polyethylene glycol. Belonging to nanotransport systems (NTS) they allow the transport and storage of molecules with different chemical characters. Their amphipihilic character CMS-NTS permits good solubility in aqueous and organic solutions. We showed by multifrequency electron paramagnetic resonance (EPR) spectroscopy that spin-labeled 5-doxyl stearic acid (5DSA) can be loaded into the CMS-NTS. Furthermore, the release of 5DSA from the carrier into the stratum corneum of porcine skin was monitored ex vivo by EPR spectroscopy. Additionally, the penetration of the CMS-NTS into the skin was analyzed by fluorescence microscopy using indocarbocyanine (ICC) covalently bound to the nanocarrier. Thereby, no transport into the viable skin was observed, whereas the CMS-NTS had penetrated into the hair follicles down to a depth of 340 μm ± 82 μm. Thus, it could be shown that the combined application of fluorescence microscopy and multi-frequency EPR spectroscopy can be an efficient tool for investigating the loading of spin labeled drugs to nanocarrier systems, drug release and penetration into the skin as well as the localization of the NTS in the skin.

  19. Synthesization and characterization of poly(lactic-co-glycolic acid) / calcium phosphate bone cement from crab shells

    NASA Astrophysics Data System (ADS)

    Hanan, M. R. Abdul; Daud, N. M.; Ismail, L. H.; Saidin, S.

    2017-05-01

    An injectable calcium phosphate (CaP) bone cement has been widely used for musculoskeletal and bone disorder due to its biocompatible and osteoconductive properties. In this study, CaP was successfully synthesized from crab shells by a wet chemical route. Poly(lactic-co-glycolic acid) (PLGA) microspheres which have been produced through a double emulsion technique were incorporated into the CaP mixture for the purpose of bone cement solidification. The ratio of both compounds, CaP and PLGA, were set at 8:2. The CaP and PLGA/CaP bone cement were analyzed by ATR-FTIR, FESEM-EDX and contact angle analyses. The bone cement was composed of CaP and PLGA where the micro-powders of CaP were agglomerated on the PLGA microspheres. Addition of the PLGA has increased the hydrophilicity of the bone cement which will be beneficial for materials degradation and bone integration.

  20. Phosphoproteomes of Strongylocentrotus purpuratus shell and tooth matrix: identification of a major acidic sea urchin tooth phosphoprotein, phosphodontin

    PubMed Central

    2010-01-01

    Background Sea urchin is a major model organism for developmental biology and biomineralization research. However, identification of proteins involved in larval skeleton formation and mineralization processes in the embryo and adult, and the molecular characterization of such proteins, has just gained momentum with the sequencing of the Strongylocentrotus purpuratus genome and the introduction of high-throughput proteomics into the field. Results The present report contains the determination of test (shell) and tooth organic matrix phosphoproteomes. Altogether 34 phosphoproteins were identified in the biomineral organic matrices. Most phosphoproteins were specific for one compartment, only two were identified in both matrices. The sea urchin phosphoproteomes contained several obvious orthologs of mammalian proteins, such as a Src family tyrosine kinase, protein kinase C-delta 1, Dickkopf-1 and other signal transduction components, or nucleobindin. In most cases phosphorylation sites were conserved between sea urchin and mammalian proteins. However, the majority of phosphoproteins had no mammalian counterpart. The most interesting of the sea urchin-specific phosphoproteins, from the perspective of biomineralization research, was an abundant highly phosphorylated and very acidic tooth matrix protein composed of 35 very similar short sequence repeats, a predicted N-terminal secretion signal sequence, and an Asp-rich C-terminal motif, contained in [Glean3:18919]. Conclusions The 64 phosphorylation sites determined represent the most comprehensive list of experimentally identified sea urchin protein phosphorylation sites at present and are an important addition to the recently analyzed Strongylocentrotus purpuratus shell and tooth proteomes. The identified phosphoproteins included a major, highly phosphorylated protein, [Glean3:18919], for which we suggest the name phosphodontin. Although not sequence-related to such highly phosphorylated acidic mammalian dental

  1. Ternary Pd-Ni-P hybrid electrocatalysts derived from Pd-Ni core-shell nanoparticles with enhanced formic acid oxidation activity.

    PubMed

    Liang, Xin; Liu, Bo; Zhang, Juntao; Lu, Siqi; Zhuang, Zhongbin

    2016-09-25

    Ternary Pd-Ni-P hybrid electrocatalysts were synthesized through low temperature phosphidation of Pd-Ni core-shell nanoparticles. They show enhanced formic acid electro-oxidation activity compared to Pd, Pd-Ni and Pd-P nanoparticles, which is ascribed to the synergistic effect of the Ni and P components with Pd.

  2. The use of raw and acid-pretreated bivalve mollusk shells to remove metals from aqueous solutions.

    PubMed

    Liu, Yang; Sun, Changbin; Xu, Jin; Li, Youzhi

    2009-08-30

    Heavy metal removal from industrial wastewater is not only to protect living organisms in the environment but also to conserve resources such as metals and water by enabling their reuse. To overcome the disadvantage of high cost and secondary pollution by the conventional physico-chemical treatment techniques, environmentally benign and low-cost adsorbents are in demand. In this study, the use of raw and acid-pretreated bivalve mollusk shells (BMSs) to remove metals from aqueous solutions with single or mixed metal was evaluated at different BMSs doses, pH and temperatures in batch shaking experiments in laboratory conditions. When the BMSs were used to treat CuSO(4)x5H(2)O solution, the copper sorption capacities of the raw and acid-pretreated BMSs were approximately 38.93 mg/g and 138.95 mg/g, respectively. The copper removal efficiency (CRE) of the raw BMSs became greatly enhanced with increasing initial pH, reaching 99.51% at the initial pH 5. Conversely, the CRE of the acid-pretreated BMSs was maintained at 99.48-99.52% throughout the pH range of 1-5. Furthermore, the CRE values of the raw and acid-pretreated BMSs were not greatly changed when the temperature was varied from 15 degrees C to 40 degrees C. In addition, the CRE value of the raw BMSs was maintained for 12 cycles of sorption-desorption with a CRE of 98.4% being observed in the final cycle. Finally, when the BMSs were used to treat electroplating wastewater, the removal efficiencies (REs) of the raw BMSs were 99.97%, 98.99% and 87% for Fe, Zn and Cu, respectively, whereas the REs of the acid-pretreated BMSs were 99.98%, 99.43% and 92.13%, respectively. Ion exchange experiments revealed that one of mechanisms for metal sorption by the BMSs from aqueous solution is related to ion exchange, especially between the metal ions in the treated solution and Ca(2+) from BMSs. Infrared absorbance spectra analysis indicated that the acid pretreatment led to occurrence of the groups (i.e. -OH, -NH, C=O and S

  3. Biosorption of formic and acetic acids from aqueous solution using activated carbon from shea butter seed shells

    NASA Astrophysics Data System (ADS)

    Adekola, Folahan A.; Oba, Ismaila A.

    2016-10-01

    The efficiency of prepared activated carbon from shea butter seed shells (SB-AC) for the adsorption of formic acid (FA) and acetic acid (AA) from aqueous solution was investigated. The effect of optimization parameters including initial concentration, agitation time, adsorbent dosage and temperature of adsorbate solution on the sorption capacity were studied. The SB-AC was characterized for the following parameters: bulk density, moisture content, ash content, pH, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The optimal conditions for the adsorption were established and the adsorption data for AA fitted Dubinin-Radushkevich (D-R) isotherm well, whereas FA followed Langmuir isotherm. The kinetic data were examined. It was found that pseudo-second-order kinetic model was found to adequately explain the sorption kinetic of AA and FA from aqueous solution. It was again found that intraparticle diffusion was found to explain the adsorption mechanism. Adsorption thermodynamic parameters were estimated and the negative values of ∆G showed that the adsorption process was feasible and spontaneous in nature, while the negative values of ∆H indicate that the adsorption process was exothermic. It is therefore established that SB-AC has good potential for the removal of AA and FA from aqueous solution. Hence, it should find application in the regular treatment of polluted water in aquaculture and fish breeding system.

  4. [Vitro study on gene transfection efficiency of hyaluronic acid modified core-shell liponanoparticles in human retinal pigment epithelium cells].

    PubMed

    Zhao, Ya-Nan; Gan, Li; Wang, Jing; Chen, Xi; Jia, Zheng; Gan, Yong; Liu, Jian-Ping

    2014-05-01

    The aim of this study is to prepare hyaluronic acid (HA) modified core-shell liponanoparticles (pHA-LCS-NPs) as gene delivery system and investigate its gene transfection efficiency in human retinal pigment epithelium (ARPE-19) cells in vitro. The pHA-LCS-NPs was prepared by firstly hydrating dry lipid film with CS-NPs suspension to get LCS-NPs, then modifying the lipid bilayer with HA by amidation reaction between HA and dioleoyl phosphatidylethanolamine (DOPE). Its morphology, particle size and zeta potential were investigated. XTT assay was used to evaluate the cell safety of different vectors in vitro. The gene transfection efficiency of pHA-LCS-NPs modified with different contents of HA was investigated in ARPE-19 cells with green fluorescent protein (pEGFP) as the reporter gene. The results showed that the obtained pHA-LCS-NPs exhibited a clear core-shell structure with the average particles size of (214.9 +/- 7.2) nm and zeta potential of (-35 +/- 3.7) mV. The 24 h cumulative release of gene from pHA-LCS-NPs was less than 30%. After 48 h incubation, gene transfection efficiency of pHA-LCS-NPs/pEGFP was 1.81 times and 3.75 times higher than that of CS-NPs/pEGFP and naked pEGFP, respectively. Also no obvious cytotoxicity was observed on pHA-LCS-NPs. It suggested that the pHA-LCS-NPs might be promising non-viral gene delivery systems with high efficiency and low cytotoxicity.

  5. Folic acid-conjugated core/shell ZnS:Mn/ZnS quantum dots as targeted probes for two photon fluorescence imaging of cancer cells.

    PubMed

    Geszke, Malgorzata; Murias, Marek; Balan, Lavinia; Medjahdi, Ghouti; Korczynski, Jaroslaw; Moritz, Michal; Lulek, Janina; Schneider, Raphaël

    2011-03-01

    This work presents a novel approach to producing water soluble manganese-doped core/shell ZnS/ZnS quantum dots (ZnS:Mn/ZnS). The Mn-doped ZnS core was prepared through a nucleation doping strategy and a ZnS shell was grown on ZnS:Mn d-dots by decomposition of Zn(2+)-3-mercaptopropionic acid (MPA) complexes at 100 °C. It was found that the Mn2+(4)T1→6A1 fluorescence emission at ∼590 nm significantly increased after growth of the shell when the Mn2+ doping content was 4.0 at.%. A photoluminescence quantum yield of ∼22% was obtained for core/shell nanocrystals. The nanoparticles were structurally and compositionally characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and dynamic light scattering. The surface MPA molecules favor the dispersion of ZnS:Mn/ZnS QDs in aqueous media and make possible conjugation with targeting folic acid molecules. The folate receptor-mediated delivery of folic acid-conjugated ZnS:Mn/ZnS QDs was demonstrated using confocal microscopy with biphotonic excitation. Bare and folate-conjugated QDs exhibit only weak cytotoxicity towards folate receptor-positive T47D cancer cells and MCF-7 cells, used as a reference, at high concentrations (mmolar range) after 72h incubation.

  6. Direct evidence for modified solvent structure within the hydration shell of a hydrophobic amino acid.

    PubMed Central

    Pertsemlidis, A; Saxena, A M; Soper, A K; Head-Gordon, T; Glaeser, R M

    1996-01-01

    Neutron scattering experiments are used to determine scattering profiles for aqueous solutions of hydrophobic and hydrophilic amino acid analogs. Solutions of hydrophobic solutes show a shift in the main diffraction peak to smaller angle as compared with pure water, whereas solutions of hydrophilic solutes do not. The same difference for solutions of hydrophobic and hydrophilic side chains is also predicted by molecular dynamics simulations. The neutron scattering curves of aqueous solutions of hydrophobic amino acids at room temperature are qualitatively similar to differences between the liquid molecular structure functions measured for ambient and supercooled water. The nonpolar solute-induced expansion of water structure reported here is also complementary to recent neutron experiments where compression of aqueous solvent structure has been observed at high salt concentration. PMID:8855255

  7. Direct evidence for modified solvent structure within the hydration shell of a hydrophobic amino acid.

    PubMed

    Pertsemlidis, A; Saxena, A M; Soper, A K; Head-Gordon, T; Glaeser, R M

    1996-10-01

    Neutron scattering experiments are used to determine scattering profiles for aqueous solutions of hydrophobic and hydrophilic amino acid analogs. Solutions of hydrophobic solutes show a shift in the main diffraction peak to smaller angle as compared with pure water, whereas solutions of hydrophilic solutes do not. The same difference for solutions of hydrophobic and hydrophilic side chains is also predicted by molecular dynamics simulations. The neutron scattering curves of aqueous solutions of hydrophobic amino acids at room temperature are qualitatively similar to differences between the liquid molecular structure functions measured for ambient and supercooled water. The nonpolar solute-induced expansion of water structure reported here is also complementary to recent neutron experiments where compression of aqueous solvent structure has been observed at high salt concentration.

  8. Microwave-assisted synthesis of a core-shell MWCNT/GONR heterostructure for the electrochemical detection of ascorbic acid, dopamine, and uric acid.

    PubMed

    Sun, Chia-Liang; Chang, Ching-Tang; Lee, Hsin-Hsien; Zhou, Jigang; Wang, Jian; Sham, Tsun-Kong; Pong, Way-Faung

    2011-10-25

    In this study, graphene oxide nanoribbons (GONRs) were synthesized from the facile unzipping of multiwalled carbon nanotubes (MWCNTs) with the help of microwave energy. A core-shell MWCNT/GONR-modified glassy carbon (MWCNT/GONR/GC) electrode was used to electrochemically detect ascorbic acid (AA), dopamine (DA), and uric acid (UA). In cyclic voltammograms, the MWCNT/GONR/GC electrode was found to outperform the MWCNT- and graphene-modified GC electrodes in terms of peak current. For the simultaneous sensing of three analytes, well-separated voltammetric peaks were obtained using a MWCNT/GONR/GC electrode in differential pulse voltammetry measurements. The corresponding peak separations were 229.9 mV (AA to DA), 126.7 mV (DA to UA), and 356.6 mV (AA to UA). This excellent electrochemical performance can be attributed to the unique electronic structure of MWCNTs/GONRs: a high density of unoccupied electronic states above the Fermi level and enriched oxygen-based functionality at the edge of the graphene-like structures, as revealed by X-ray absorption near-edge structure spectroscopy, obtained using scanning transmission X-ray microscopy.

  9. Spontaneous arrangement of a tumor targeting hyaluronic acid shell on irinotecan loaded PLGA nanoparticles.

    PubMed

    Giarra, Simona; Serri, Carla; Russo, Luisa; Zeppetelli, Stefania; De Rosa, Giuseppe; Borzacchiello, Assunta; Biondi, Marco; Ambrosio, Luigi; Mayol, Laura

    2016-04-20

    The arrangement of tumor targeting hyaluronic acid (HA) moieties on irinotecan (IRIN)-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) has been directed by means of a gradient of lipophilicity between the oil and water phases of the emulsion used to produce the NPs. PLGA constitutes the NP bulk while HA is superficially exposed, with amphiphilic poloxamers acting as a bridge between PLGA and HA. Differential scanning calorimetry, zeta potential analyses and ELISA tests were employed to support the hypothesis of polymer assembly in NP formulations. The presence of flexible HA chains on NP surface enhances NP size stability over time due to an increased electrostatic repulsion between NPs and a higher degree of hydration of the device surface. IRIN in vitro release kinetics can be sustained up to 7-13 days. In vitro biologic studies indicated that HA-containing NPs were more toxic than bare PLGA NPs against CD44-overexpressing breast carcinoma cells (HS578T), therefore indicating their ability to target CD44 receptor.

  10. Chitosan-functionalised poly(2-hydroxyethyl methacrylate) core-shell microgels as drug delivery carriers: salicylic acid loading and release.

    PubMed

    Mahattanadul, Natshisa; Sunintaboon, Panya; Sirithip, Piyawan; Tuchinda, Patoomratana

    2016-09-01

    This work presents the evaluation of chitosan-functionalised poly(2-hydroxyethyl methacrylate) (CS/PHEMA) core-shell microgels as drug delivery carriers. CS/PHEMA microgels were prepared by emulsifier-free emulsion polymerisation with N,N '-methylenebisacrylamide (MBA) as a crosslinker. The study on drug loading, using salicylic acid (SA) as a model drug, was performed. The results showed that the encapsulation efficiency (EE) increased as drug-to-microgel ratio was increased. Higher EE can be achieved with the increase in degree of crosslinking, by increasing the amount of MBA from 0.01 g to 0.03 g. In addition, the highest EE (61.1%) was observed at pH 3. The highest release of SA (60%) was noticed at pH 2.4, while the lowest one (49.4%) was obtained at pH 7.4. Moreover, the highest release of SA was enhanced by the presence of 0.2 M NaCl. The pH- and ionic-sensitivity of CS/PHEMA could be useful as a sustained release delivery device, especially for oral delivery.

  11. Characterization of the first core sample of neutralized current acid waste from double-shell tank 101-AZ

    SciTech Connect

    Peterson, M E; Scheele, R D; Tingey, J M

    1989-09-01

    In FY 1989, Westinghouse Hanford Company (WHC) successfully obtained four core samples (totaling seven segments) of neutralized current acid waste (NCAW) from double-shell tanks (DSTs) 101-AZ and 102-AZ. A segment was a 19-in.-long and 1-in.-diameter cylindrical sample of waste. A core sample consisted of enough 19-in.-long segments to obtain the waste of interest. Three core samples were obtained from DST 101-AZ and one core sample from DST 102-AZ. Two DST 101-AZ core samples consisted of two segments per core, and the third core sample consisted of only one segment. The third core consisted of the solids from the bottom of the tank and was used to determine the relative abrasiveness of this NCAW. The DST 102-AZ core sample consisted of two segments. The core samples were transported to the Pacific Northwest Laboratory (PNL), where the waste was extruded from its sampler and extensively characterized. A characterization plan was followed that simulated the processing of the NCAW samples through retrieval, pretreatment and vitrification process steps. Physical, rheological, chemical and radiochemical properties were measured throughout the process steps. The characterization of the first core sample from DST 101-AZ was completed, and the results are provided in this report. The results for the other core characterizations will be reported in future reports. 3 refs., 13 figs., 10 tabs.

  12. Core-shell nanofibers of curcumin/cyclodextrin inclusion complex and polylactic acid: Enhanced water solubility and slow release of curcumin.

    PubMed

    Aytac, Zeynep; Uyar, Tamer

    2017-02-25

    Core-shell nanofibers were designed via electrospinning using inclusion complex (IC) of model hydrophobic drug (curcumin, CUR) with cyclodextrin (CD) in the core and polymer (polylactic acid, PLA) in the shell (cCUR/HPβCD-IC-sPLA-NF). CD-IC of CUR and HPβCD was formed at 1:2 molar ratio. The successful formation of core-shell nanofibers was revealed by TEM and CLSM images. cCUR/HPβCD-IC-sPLA-NF released CUR slowly but much more in total than PLA-CUR-NF at pH 1 and pH 7.4 due to the restriction of CUR in the core of nanofibers and solubility improvement shown in phase solubility diagram, respectively. Improved antioxidant activity of cCUR/HPβCD-IC-sPLA-NF in methanol:water (1:1) is related with the solubility enhancement achieved in water based system. The slow reaction of cCUR/HPβCD-IC-sPLA-NF in methanol is associated with the shell inhibiting the quick release of CUR. On the other hand, cCUR/HPβCD-IC-sPLA-NF exhibited slightly higher rate of antioxidant activity than PLA-CUR-NF in methanol:water (1:1) owing to the enhanced solubility. To conclude, slow release of CUR was achieved by core-shell nanofiber structure and inclusion complexation of CUR with HPβCD provides high solubility. Briefly, electrospinning of core-shell nanofibers with CD-IC core could offer slow release of drugs as well as solubility enhancement for hydrophobic drugs.

  13. Material characterization of poly-lactic acid shelled ultrasound contrast agent and their dynamics

    NASA Astrophysics Data System (ADS)

    Paul, Shirshendu; Russakow, Daniel; Rodgers, Tyler; Sarkar, Kausik; Cochran, Michael; Wheatley, Margaret

    2011-11-01

    Micron-size gas bubbles encapsulated with lipids and proteins are used as contrast enhancing agents for ultrasound imaging. Biodegradable polymer poly-lactic acid (PLA) has recently been suggested as a possible means of encapsulation. Here, we report in vitro measurement of attenuation and scattering of ultrasound through an emulsion of PLA agent as well as theoretical modeling of the encapsulated bubble dynamics. The attenuation measured with three different transducers of central frequencies 2.25, 3.5 and 5 MHz, shows a peak around 2-3 MHz. These bubbles also show themselves to possess excellent scattering characteristics including strong non-linear response that can be used for harmonic and sub-harmonic contrast imaging. Our recently developed interfacial rheological models are applied to describe the dynamics of these bubbles; rheological model properties are estimated using measured attenuation data. The model is then applied to predict nonlinear scattered response, and the prediction is compared against experimental observation. Partially supported by NSF and NIH.

  14. Dissociation of a strong acid in neat solvents: diffusion is observed after reversible proton ejection inside the solvent shell.

    PubMed

    Veiga-Gutiérrez, Manoel; Brenlla, Alfonso; Carreira Blanco, Carlos; Fernández, Berta; Kovalenko, Sergey A; Rodríguez-Prieto, Flor; Mosquera, Manuel; Lustres, J Luis Pérez

    2013-11-14

    Strong-acid dissociation was studied in alcohols. Optical excitation of the cationic photoacid N-methyl-6-hydroxyquinolinium triggers proton transfer to the solvent, which was probed by spectral reconstruction of picosecond fluorescence traces. The process fulfills the classical Eigen-Weller mechanism in two stages: (a) solvent-controlled reversible dissociation inside the solvent shell and (b) barrierless splitting of the encounter complex. This can be appreciated only when fluorescence band integrals are used to monitor the time evolution of the reactant and product concentrations. Band integrals are insensitive to solvent dynamics and report relative concentrations directly. This was demonstrated by first measuring the fluorescence decay of the conjugate base across the full emission band, independently of the proton-transfer reaction. Multiexponential decay curves at single wavelengths result from a dynamic red shift of fluorescence in the course of solvent relaxation, whereas clean single exponential decays are obtained if the band integral is monitored instead. The extent of the shift is consistent with previously reported femtosecond transient absorption measurements, continuum theory of solvatochromism, and molecular properties derived from quantum chemical calculations. In turn, band integrals show clean biexponential decay of the photoacid and triexponential evolution of the conjugate base in the course of the proton transfer to solvent reaction. The dissociation step follows the slowest stage of solvation, which was measured here independently by picosecond fluorescence spectroscopy in five aliphatic alcohols. Also, the rate constant of the encounter-complex splitting stage is compatible with proton diffusion. Thus, for this photoacid, both stages reach the highest possible rates: solvation and diffusion control. Under these conditions, the concentration of the encounter complex is substantial during the earliest nanosecond.

  15. Elucidating hydrogen oxidation/evolution kinetics in base and acid by enhanced activities at the optimized Pt shell thickness on the Ru core

    DOE PAGES

    Elbert, Katherine; Hu, Jue; Ma, Zhong; ...

    2015-10-05

    Hydrogen oxidation and evolution on Pt in acid are facile processes, while in alkaline electrolytes, they are 2 orders of magnitude slower. Thus, developing catalysts that are more active than Pt for these two reactions is important for advancing the performance of anion exchange membrane fuel cells and water electrolyzers. Herein, we detail a 4-fold enhancement of Pt mass activity that we achieved using single-crystalline Ru@Pt core–shell nanoparticles with two-monolayer-thick Pt shells, which doubles the activity on Pt–Ru alloy nanocatalysts. For Pt specific activity, the two- and one-monolayer-thick Pt shells exhibited enhancement factors of 3.1 and 2.3, respectively, compared tomore » the Pt nanocatalysts in base, differing considerably from the values of 1 and 0.4, respectively, in acid. To explain such behavior and the orders of magnitude difference in activity on going from acid to base, we performed kinetic analyses of polarization curves over a wide range of potential from –250 to 250 mV using the dual-pathway kinetic equation. From acid to base, the activation free energies increase the most for the Volmer reaction, resulting in a switch of the rate-determining step from the Tafel to the Volmer reaction, and a shift to a weaker optimal hydrogen binding energy. Furthermore, the much higher activation barrier for the Volmer reaction in base than in acid is ascribed to one or both of the two catalyst-insensitive factors: slower transport of OH– than H+ in water and a stronger O–H bond in water molecules (HO–H) than in hydrated protons (H2O–H+).« less

  16. Fabrication and characterization of heparin-grafted poly-L-lactic acid-chitosan core-shell nanofibers scaffold for vascular gasket.

    PubMed

    Wang, Ting; Ji, Xuyuan; Jin, Lin; Feng, Zhangqi; Wu, Jinghang; Zheng, Jie; Wang, Hongyin; Xu, Zhe-Wu; Guo, Lingling; He, Nongyue

    2013-05-01

    Electrospun nanofibers were widely studied to be applied as potential materials for tissue engineering. A new technology to make poly-l-lactic acid/chitosan core/shell nanofibers from heterologous solution by coaxial electrospinning technique was designed for vascular gasket. Chitosan surface was cross-linked by genipin and modified by heparin. Different ratios of PLA/CS in heterologous solution were studied to optimize the surface morphology of fibers. Clean core-shell structures formed with a PLA/CS ratio at 1:3. Superior biocompatibility and mechanical properties were obtained by optimizing the core-shell structure morphology and surface cross-linking of chitosan. UE7T-13 cells grew well on the core-shell structure fibers as indicated by methylthiazolyldiphenyl-tetrazolium bromide (MTT) results and scanning electron microscopy (SEM) images. Compared with the pure PLA fiber meshes and commercial vascular patch, PLA/CS core-shell fibers had better mechanical strength. The elastic modulus was as high as 117.18 MPa, even though the yield stress of the fibers was lower than that of the commercial vascular patch. Attachment of red blood cell on the fibers was evaluated by blood anticoagulation experiments and in vitro blood flow experiments. The activated partial thromboplastin time (APTT) and prothrombin time (PT) value from PLA/CS nanofibers were significantly longer than that of pure PLA fibers. SEM images indicated there were hardly any red blood cells attached to the fibers with chitosan coating and heparin modification. This type of fiber mesh could potentially be used as vascular gasket.

  17. A new N-hydroxyethyliminodiacetic acid modified core-shell silica phase for chelation ion chromatography of alkaline earth, transition and rare earth elements.

    PubMed

    McGillicuddy, Nicola; Nesterenko, Ekaterina P; Nesterenko, Pavel N; Stack, Elaine M; Omamogho, Jesse O; Glennon, Jeremy D; Paull, Brett

    2013-12-20

    Bare core-shell silica (1.7μm) has been modified with iminodiacetic acid functional groups via standard silane chemistry, forming a new N-hydroxyethyliminodiacetic acid (HEIDA) functionalised core-shell stationary phase. The column was applied in high-performance chelation ion chromatography and evaluated for the retention of alkaline earth, transition and heavy metal cations. The influence of nitric acid eluent concentration, addition of complexing agent dipicolinic acid, eluent pH and column temperature on the column performance was investigated. The efficiencies obtained for transition and heavy metal cations (and resultant separations) were comparable or better than those previously obtained for alternative fully porous silica based chelation stationary phases, and a similarly modified monolithic silica column, ranging from ∼15 to 56μm HETP. Increasing the ionic strength of the eluent with the addition of KNO3 (0.75M) and increasing the column temperature (70°C) facilitated the isocratic separation of a mixture of 14 lanthanides and yttrium in under 12min, with HETP averaging 18μm (7μm for Ce(III)).

  18. Fatty acid compositions and trophic relationships of shelled molluscs from the Kuril-Kamchatka Trench and the adjacent abyssal plain

    NASA Astrophysics Data System (ADS)

    Kharlamenko, Vladimir I.; Würzberg, Laura; Peters, Janna; Borisovets, Evgeny E.

    2015-01-01

    Fatty acid (FA) compositions of 12 species of shelled molluscs (gastropods, bivalves, and scaphopods) from the Kuril-Kamchatka Trench and the adjacent abyssal plain were studied. According to the results of multivariate statistical analysis, molluscs were divided into three groups. Group I consisted of three scaphopod species, the bivalve Nucula profundorum and the gastropod Solariella delicata. FA compositions of this group were characterized by high levels of 20:4(n-6). We suggest that the FA pattern found in scaphopods with high values of 20:4(n-6) is most likely typical for that of benthic organisms feeding preferentially on foraminiferans. Group II included the bivalves Neilonella politissima, Bentharca asperula, and Rhinoclama filatovae. Bivalves from the second group had elevated concentrations of 22:6(n-3), and the ratio of 20:4(n-6) to 20:5(n-3) was lower than 1. Bivalves from the second group had elevated concentrations of 22:6(n-3). We propose that high concentrations of this FA can be used as a specific marker for a carnivorous feeding mode of deep-sea benthic invertebrates. The bivalve Bathyspinula calcarella as well as the scaphopod Polyschides sakuraii could not unambiguously be assigned to one group. Within the similarity analysis they rather clustered together with the foraminiferans feeders (group I), but forming an own subgroup. In the PCA on the other hand, P. sakuraii showed a position close to the other bivalves, while B. calcarella had an intermediate position between all three groups. Group III consisted of the gastropods Tacita holoserica and Paracteocina sp., which contained high concentrations of 20:5(n-3) and 22:5(n-3). Both are known to exhibit a carnivorous/scavenging feeding strategy. The very low content of DHA in both species is on first sight not consistent with the suggested carnivorous feeding behavior. A characteristic feature of Paracteocina sp. and T. holoserica was a high level of 22:5(n-3), and HUFA ratios indicate that DHA

  19. Slurry analysis of cadmium and copper collected on 11-mercaptoundecanoic acid modified TiO2 core-Au shell nanoparticles by flame atomic absorption spectrometry.

    PubMed

    Gunduz, S; Akman, S; Kahraman, M

    2011-02-15

    Separation/preconcentration of copper and cadmium using TiO(2) core-Au shell nanoparticles modified with 11-mercaptoundecanoic acid and their slurry analysis by flame atomic absorption spectrometry were described. For this purpose, at first, titanium dioxide nanoparticles were coated with gold shell by reducing the chloroauric acid with sodium borohydride and then modified with 11-mercaptoundecanoic acid. The characterization of modified nanoparticles was performed using ultra-violet spectroscopy and dynamic light scattering. Copper and cadmium were then collected on the prepared sorbent by batch method. The solid phase loaded with the analytes was separated by centrifugation and the supernatant was removed. Finally, the precipitate was slurried and directly aspirated into the flame for the determination of analytes. Thus, elution step and its all drawbacks were eliminated. The effects of pH, amount of sorbent, slurry volume, sample volume and diverse ions on the recovery were investigated. After optimization of experimental parameters, the analytes in different certified reference materials and spiked water samples were quantitatively recovered with 5% RSD. The analytes were enriched up to 20-fold. Limits of detection (N=10, 3σ) for copper and cadmium were 0.28 and 0.15 ng mL(-1), respectively. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. New core@shell nanogel based 2-acrylamido-2-methyl-1-propane sulfonic acid for preconcentration of Pb(II) from various water samples

    NASA Astrophysics Data System (ADS)

    Shoueir, Kamel Rizq; Akl, Magda Ali; Sarhan, Ali Ali; Atta, Ayman Mohamdy

    2016-12-01

    Poly(vinyl alcohol) core coated with poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-N-isopropylacrylamide) shell to produce well-define PVA@P(AMPS-co-NIPAm) core shell nanogels with a core of 25 ± 0.5 nm and shell of 5 ± 0.5 nm. The synthetic approach was produced by a surfactant free emulsion polymerization (SFEP). The specific area was found to be 1685.8 m2/g. The nanogels were studied in a batch adsorption for removal of Pb(II) ions and characterized by SEM, TEM, TGA and BET measurements. The results showed that the adsorption equilibrium data fitted the Langmuir isotherm and the kinetic studies are well described by the pseudo-second-order kinetic model. The Pb(II) maximum adsorption was 510.2 (mg/g) for PVA@P(90AMPS-co-10NIPAm) (wt.: wt%). The PVA@P(AMPS-co-NIPAm) nanogels were applied for extracting of Pb(II) in real different environmental water samples successfully with high recoveries reaches 104.4%.

  1. Acid-degradable core-shell nanoparticles for reversed tamoxifen-resistance in breast cancer by silencing manganese superoxide dismutase (MnSOD).

    PubMed

    Cho, Soo Kyung; Pedram, Ali; Levin, Ellis R; Kwon, Young Jik

    2013-12-01

    Drug resistance acquired by cancer cells is a significant challenge in the clinic and requires impairing the responsible pathological pathway. Administering chemotherapeutics along with silencing resistance-basis activity using RNA interference (RNAi) is expected to restore the activity of the chemotherapeutic and generate synergistic cancer eradication. This study attempted to reverse tamoxifen (TAM)-resistance in breast cancer by silencing a mitochondrial enzyme, manganese superoxide dismutase (MnSOD), which dismutates TAM-induced reactive oxygen species (ROS) (i.e., superoxide) to less harmful hydrogen peroxide and hampers therapeutic effects. Breast cancer cells were co-treated with TAM and MnSOD siRNA-delivering nanoparticles (NPs) made of a siRNA/poly(amidoamine) (PAMAM) dendriplex core and an acid-degradable polyketal (PK) shell. The (siRNA/PAMAM)-PK NPs were designed for the PK shell to shield siRNA from nucleases, minimize detrimental aggregation in serum, and facilitate cytosolic release of siRNA from endosomal compartments. This method of forming the PK shell around the siRNA/PAMAM core via surface-initiated photo-polymerization enables ease of tuning NPs' size for readily controlled siRNA release kinetics. The resulting NPs were notably homogenous in size, resistant to aggregation in serum, and invulnerable to heparan sulfate-mediated disassembly, compared to siRNA/PAMAM dendriplexes. Gel electrophoresis and confocal microscopy confirmed efficient siRNA release from the (siRNA/PAMAM)-PK NPs upon stimuli-responsive hydrolysis of the PK shell. Sensitization of TAM-resistant MCF7-BK-TR breast cancer cells with (MnSOD siRNA/PAMAM)-PK NPs restored TAM-induced cellular apoptosis in vitro and significantly suppressed tumor growth in vivo, as confirmed by biochemical assays and histological observations. This study implies that combined gene silencing and chemotherapy is a promising strategy to overcoming a significant challenge in cancer therapy. Copyright

  2. Acid-degradable Core-shell Nanoparticles for Reversed Tamoxifen-resistance in Breast Cancer by Silencing Manganese Superoxide Dismutase (MnSOD)

    PubMed Central

    Cho, Soo Kyung; Pedram, Ali; Levin, Ellis R.; Kwon, Young Jik

    2013-01-01

    Drug resistance acquired by cancer cells is a significant challenge in the clinic and requires impairing the responsible pathological pathway. Administering chemotherapeutics along with silencing resistance-basis activity using RNA interference (RNAi) is expected to restore the activity of the chemotherapeutic. generate synergistic cancer eradication. This study attempted to reverse tamoxifen (TAM)-resistance in breast cancer by silencing a mitochondrial enzyme, manganese superoxide dismutase (MnSOD), which dismutates TAM-induced reactive oxygen species (ROS) (i.e., superoxide) to less harmful hydrogen peroxide and hampers therapeutic effects. Breast cancer cells were co-treated with TAM and MnSOD siRNA-delivering nanoparticles (NPs) made of a siRNA/poly(amidoamine) (PAMAM) dendriplex core and an acid-degradable polyketal (PK) shell. The (siRNA/PAMAM)-PK NPs were designed for the PK shell to shield siRNA from nucleases, minimize detrimental aggregation in serum, and facilitate cytosolic release of siRNA from endosomal compartments. This method of forming the PK shell around the siRNA/PAMAM core via surface-initiated photo-polymerization enables ease of tuning NPs’ size for readily controlled siRNA release kinetics. The resulting NPs were notably homogenous in size, resistant to aggregation in serum, and invulnerable to heparan sulfate-mediated disassembly, compared to siRNA/PAMAM dendriplexes. Gel electrophoresis and confocal microscopy confirmed efficient siRNA release from the (siRNA/PAMAM)-PK NPs upon stimuli-responsive hydrolysis of the PK shell. Sensitization of TAM-resistant MCF7-BK-TR breast cancer cells with (MnSOD siRNA/PAMAM)-PK NPs restored TAM-induced cellular apoptosis in vitro and significantly suppressed tumor growth in vivo, as confirmed by biochemical assays and histological observations. This study implies that combined gene silencing and chemotherapy is a promising strategy to overcoming a significant challenge in cancer therapy. PMID:24055523

  3. Adsorption of chiral aromatic amino acids onto carboxymethyl-β-cyclodextrin bonded Fe(3)O(4)/SiO(2) core-shell nanoparticles.

    PubMed

    Ghosh, Sudipa; Badruddoza, A Z M; Uddin, M S; Hidajat, K

    2011-02-15

    Surface of magnetic silica nanoparticles is modified by grafting with carboxymethyl-β-cyclodextrin (CM-β-CD) via carbodiimide activation. The functionalized magnetic core-shell nanoparticles (MNPs) are characterized by Transmission Electron Microscopy (TEM), Fourier Transform Infra Red (FTIR) spectroscopy, X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Vibrating Sample Magnetometer (VSM). These nano-sized particles are scrutinized for adsorption of certain chiral aromatic amino acid enantiomers namely, d- and l-tryptophan (Trp), d- and l-phenylalanine (Phe) and d- and l-tyrosine (Tyr) from phosphate buffer solutions. Adsorption capacities of the coated magnetic nanoparticles toward amino acid enantiomers are in the order: l-Trp>l-Phe>l-Tyr and under the same condition, adsorption capacities are higher for l-enantiomers than the corresponding d-enantiomers. All the equilibrium adsorption isotherms are fitted well to Freundlich model. FTIR studies depict significant changes after adsorption of amino acids onto nanoparticles. The stretching vibration frequencies of NH bonds of the amino acid molecules are changed with complex formation through host-guest interaction. The structure and hydrophobicity of amino acid molecules emphasize the interactions between amino acid molecules and the nano-adsorbents bearing cyclodextrin, thus play important roles in the difference of their adsorption behaviors. Copyright © 2010 Elsevier Inc. All rights reserved.

  4. Fabrication and spectroscopic studies of folic acid-conjugated Fe3O4@Au core-shell for targeted drug delivery application

    NASA Astrophysics Data System (ADS)

    Karamipour, Sh.; Sadjadi, M. S.; Farhadyar, N.

    2015-09-01

    Gold coated magnetite core shell is a kind of nanoparticle that include magnetic iron oxide core with a thin layer nanogold. Fe3O4-gold core-shell nanostructure can be used in biomedical applications such as magnetic bioseparation, bioimaging, targeting drug delivery and cancer treatment. In this study, the synthesis and characterization of gold coated magnetite nanoparticles were discussed. Magnetite nanoparticles with an average size of 6 nm in diameter were synthesized by the chemical co-precipitation method and gold-coated Fe3O4 core-shell nanostructures were produced with an average size of 11.5 nm in diameter by reduction of Au3+ with citrate ion in the presence of Fe3O4. Folate-conjugated gold coated magnetite nanoparticles were synthesized to targeting folate receptor that is overexpressed on the surface of cancerous cells. For this purpose, we used L-cysteine, as a bi-functional linker for attachment to gold surface and it was linked to the gold nanoparticles surface through its thiol group. Then, we conjugated amino-terminated nanoparticles to folic acid with an amide-linkage formation. These gold magnetic nanoparticles were characterized by various techniques such as X-ray powder diffraction (XRD) analysis, Fourier transform infrared spectrometer (FT-IR), UV-visible spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), dispersive analysis of X-ray (EDAX) and vibrating sample magnetometer (VSM) analysis. The magnetic and optical properties of Fe3O4 nanostructure were changed by gold coating and attachment of L-cysteine and folic acid to Fe3O4@Au nanoparticles.

  5. Microspheres Assembled from Chitosan-Graft-Poly(lactic acid) Micelle-Like Core-Shell Nanospheres for Distinctly Controlled Release of Hydrophobic and Hydrophilic Biomolecules.

    PubMed

    Niu, Xufeng; Liu, Zhongning; Hu, Jiang; Rambhia, Kunal J; Fan, Yubo; Ma, Peter X

    2016-07-01

    To simultaneously control inflammation and facilitate dentin regeneration, a copolymeric micelle-in-microsphere platform is developed in this study, aiming to simultaneously release a hydrophobic drug to suppress inflammation and a hydrophilic biomolecule to enhance odontogenic differentiation of dental pulp stem cells in a distinctly controlled fashion. A series of chitosan-graft-poly(lactic acid) copolymers is synthesized with varying lactic acid and chitosan weight ratios, self-assembled into nanoscale micelle-like core-shell structures in an aqueous system, and subsequently crosslinked into microspheres through electrostatic interaction with sodium tripolyphosphate. A hydrophobic biomolecule either coumarin-6 or fluocinolone acetonide (FA) is encapsulated into the hydrophobic cores of the micelles, while a hydrophilic biomolecule either bovine serum albumin or bone morphogenetic protein 2 (BMP-2) is entrapped in the hydrophilic shells and the interspaces among the micelles. Both hydrophobic and hydrophilic biomolecules are delivered with distinct and tunable release patterns. Delivery of FA and BMP-2 simultaneously suppresses inflammation and enhances odontogenesis, resulting in significantly enhanced mineralized tissue regeneration. This result also demonstrates the potential for this novel delivery system to deliver multiple therapeutics and to achieve synergistic effects.

  6. One-pot controlled synthesis of AuPd@Pd core-shell nanocrystals with enhanced electrocatalytic performances for formic acid oxidation and glycerol oxidation.

    PubMed

    Liu, Meng-Ting; Chen, Li-Xian; Li, Dong-Ning; Wang, Ai-Jun; Zhang, Qian-Li; Feng, Jiu-Ju

    2017-12-15

    In this work, AuPd@Pd core-shell nanocrystals (AuPd@Pd NCs) were fabricated by a one-pot co-reduction approach, where theophylline-7-acetic acid (TAA) acted asa new structure-directing agent. The crystal structure and composition were mainly characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray diffraction (XRD), together with X-ray photoelectron spectroscopy (XPS). The growth mechanism of AuPd@Pd NCs was investigated in detail. The obtained AuPd@Pd NCs exhibited superior catalytic characters for formic acid oxidation reaction (FAOR) and glycerol oxidation reaction (GOR) in contrast with commercial Pd black in alkaline media. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Highly active dealloyed Cu@Pt core-shell electrocatalyst towards 2-propanol electrooxidation in acidic solution

    NASA Astrophysics Data System (ADS)

    Poochai, Chatwarin

    2017-02-01

    Dealloyed Cu@Pt core-shell electrocatalyst was fabricated by cyclic co-electrodeposition and selective Cu dealloying (CCEd-sCuD) on carbon paper (CP), namely Cu@Pt/CP. The Cu@Pt/CP exhibited a core-shell structure comprising with a Cu-rich core and a Pt-rich shell. The crystalline phases of Pt/CP and Cu@Pt/CP were a face-centered cubic (fcc). The compressive lattice strain approximately 0.85% was found in the Cu@Pt/CP owing to a lattice mismatch between a core and a shell region. In the core-region, Cu was formed Pt-Cu alloy as major and copper oxide and also metallic copper as minor. The morphology and grain size of the Cu@Pt/CP displayed a porous spherical shape with 100 nm in diameter, while those of Pt/CP seemed to be a cubic shape with smaller diameter of 40 nm. In electrochemical and catalytic activity, the surface of Cu@Pt/CP had a larger electrochemical active surface area (ECSA) than that of Pt/CP due to a porous formation caused by Cu dealloying. It is not surprising that the Cu@Pt/CP showed higher catalytic activity and greater stability towards 0.5 M 2-propanol electrooxidation in 0.5 M H2SO4 in terms of peak current density (jp), peak potential (Ep), onset potential (Eonset), diffusion coefficient (D), and charge transfer resistance (Rct) which were caused by electronic structure modification, higher compressive lattice strain, and larger ECSA, compared with Pt/CP.

  8. Piezo-phototronic effect enhanced UV photodetector based on CuI/ZnO double-shell grown on flexible copper microwire.

    PubMed

    Liu, Jingyu; Zhang, Yang; Liu, Caihong; Peng, Mingzeng; Yu, Aifang; Kou, Jinzong; Liu, Wei; Zhai, Junyi; Liu, Juan

    2016-12-01

    In this work, we present a facile, low-cost, and effective approach to fabricate the UV photodetector with a CuI/ZnO double-shell nanostructure which was grown on common copper microwire. The enhanced performances of Cu/CuI/ZnO core/double-shell microwire photodetector resulted from the formation of heterojunction. Benefiting from the piezo-phototronic effect, the presentation of piezocharges can lower the barrier height and facilitate the charge transport across heterojunction. The photosensing abilities of the Cu/CuI/ZnO core/double-shell microwire detector are investigated under different UV light densities and strain conditions. We demonstrate the I-V characteristic of the as-prepared core/double-shell device; it is quite sensitive to applied strain, which indicates that the piezo-phototronic effect plays an essential role in facilitating charge carrier transport across the CuI/ZnO heterojunction, then the performance of the device is further boosted under external strain.

  9. Piezo-phototronic effect enhanced UV photodetector based on CuI/ZnO double-shell grown on flexible copper microwire

    NASA Astrophysics Data System (ADS)

    Liu, Jingyu; Zhang, Yang; Liu, Caihong; Peng, Mingzeng; Yu, Aifang; Kou, Jinzong; Liu, Wei; Zhai, Junyi; Liu, Juan

    2016-06-01

    In this work, we present a facile, low-cost, and effective approach to fabricate the UV photodetector with a CuI/ZnO double-shell nanostructure which was grown on common copper microwire. The enhanced performances of Cu/CuI/ZnO core/double-shell microwire photodetector resulted from the formation of heterojunction. Benefiting from the piezo-phototronic effect, the presentation of piezocharges can lower the barrier height and facilitate the charge transport across heterojunction. The photosensing abilities of the Cu/CuI/ZnO core/double-shell microwire detector are investigated under different UV light densities and strain conditions. We demonstrate the I- V characteristic of the as-prepared core/double-shell device; it is quite sensitive to applied strain, which indicates that the piezo-phototronic effect plays an essential role in facilitating charge carrier transport across the CuI/ZnO heterojunction, then the performance of the device is further boosted under external strain.

  10. Dual peptide nucleic acid- and peptide-functionalized shell cross-linked nanoparticles designed to target mRNA toward the diagnosis and treatment of acute lung injury.

    PubMed

    Shrestha, Ritu; Shen, Yuefei; Pollack, Kevin A; Taylor, John-Stephen A; Wooley, Karen L

    2012-03-21

    In this work, multifunctional biosynthetic hybrid nanostructures were prepared and studied for their potential utility in the recognition and inhibition of mRNA sequences for inducible nitric oxide synthase (iNOS), which are overexpressed at sites of inflammation, such as in cases of acute lung injury. Shell cross-linked knedel-like polymer nanoparticles (SCKs) that present peptide nucleic acids, for binding to complementary mRNAs, and cell penetrating peptides (CPPs), to gain cell entry, along with fluorescent labels and sites for radiolabeling, were prepared by a series of robust, efficient, and versatile synthetic steps that proceeded from monomers to polymers to functional nanoparticles. Amphiphilic block graft copolymers having combinations of methoxy- and thioacetyl-terminated poly(ethylene glycol) (PEG) and DOTA-lysine units grafted from the backbone of poly(acrylic acid) (PAA) and extending with a backbone segment of poly(octadecyl acrylate-co-decyl acrylate) (P(ODA-co-DA)) were prepared by a combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and chemical modification reactions, which were then used as the building blocks for the formation of well-defined SCKs decorated with reactive thiols accessible to the surface. Fluorescent labeling with Alexa Fluor 633 hydrazide was then accomplished by amidation with residual acrylic acid residues within the SCK shells. Finally, the PNAs and CPP units were covalently conjugated to the SCKs via Michael addition of thiols on the SCKs to maleimide units on the termini of PNAs and CPPs. Confirmation of the ability of the PNAs to bind selectively to the target iNOS mRNAs when tethered to the SCK nanoparticles was determined by in vitro competition experiments. When attached to the SCKs having a hydrodynamic diameter of 60 ± 16 nm, the K(d) values of the PNAs were ca. an order of magnitude greater than the free PNAs, while the mismatched PNA showed no significant binding.

  11. Core-shell H-ZSM-5/silicalite-1 composites: Brønsted acidity and catalyst deactivation at the individual particle level.

    PubMed

    Mores, Davide; Stavitski, Eli; Verkleij, Suzanna P; Lombard, Antoinette; Cabiac, Amandine; Rouleau, Loïc; Patarin, Joël; Simon-Masseron, Angélique; Weckhuysen, Bert M

    2011-09-21

    A combination of in situ UV-Vis and confocal fluorescence micro-spectroscopy is applied to investigate the influence of an external silicalite-1 shell on the Brønsted acidity and coke formation process of individual H-ZSM-5 zeolite crystals. Three probe reactions were used: oligomerization of styrene, methanol-to-olefin (MTO) conversion and aromatization of light naphtha (LNA) derivatives. Oligomerization of styrene leads to the formation of optically active carbocationic oligomers. Different styrene substitutions indicate the conversion ability of the catalyst acid core, a preferred alignment of the oligomers within the straight zeolite channels and a Brønsted acidity gradient throughout the zeolite crystal. Both the MTO conversion and the LNA process lead to limited carbonaceous deposition within the external silicalite-1 layer. This outer shell furthermore prevents the growth of extended coke species at the zeolite external surface. During MTO, the formation of carbonaceous compounds initiates at the center of the H-ZSM-5 zeolite core and expands towards the zeolite exterior. This coke build-up starts with a 420 nm UV-Vis absorption band, assigned to methyl-substituted aromatic carbocations, and a second band around 550 nm, which is indicative of their growth towards larger conjugated systems. Aromatization of linear and branched C5 paraffins causes negligible darkening of the zeolite crystals though it forms fluorescent coke deposits and their precursors within the H-ZSM-5 catalyst. Olefin homologues on the contrary cause pronounced darkening of the zeolite composite. Methyl-branching of these reactants slows down the coke formation rate and produces carbonaceous species that are more restricted in their molecular size.

  12. Enhanced photodegradation of 2,4-dichlorophenoxyacetic acid using a novel TiO2@MgFe2O4 core@shell structure.

    PubMed

    Huy, Bui The; Jung, Da-Som; Kim Phuong, Nguyen Thi; Lee, Yong-Ill

    2017-10-01

    A novel TiO2@MgO-Fe2O3 core-shell structure has been synthesized via a hydrolysis and co-precipitation method followed by calcination at 500 °C and has proven to be an efficient photocatalyst. The obtained TiO2@MgO-Fe2O3 core-shell was characterized by scanning electron microscopy, X-ray diffraction, and UV-Vis diffused reflectance techniques. Its photocatalytic activity toward 2,4-dichlorophenoxyacetic acid (2,4-D) was investigated in aqueous solutions with and without visible light irradiation in the presence and absence of hydrogen peroxide. It was revealed that a strong electronic coupling exists between two components within the TiO2@MgO-Fe2O3 core-shell structure. The present findings clearly highlight that TiO2@MgO-Fe2O3 exhibits excellent photocatalytic activity under visible light irradiation in the presence of H2O2. More than 83% degradation of 2,4-D was observed within 240 min, at an initial concentration of 100 mg L(-1) with 0.5 g of catalyst per liter. Moreover, the material showed high chemical stability after four consecutive experiments with no significant difference in the rate of photocatalytic degradation. Therefore, the results reported herein offer a green, low cost and highly efficient photocatalyst for environmental remediation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. ZnSe core and ZnSe@ZnS core-shell quantum dots as platform for folic acid sensing

    NASA Astrophysics Data System (ADS)

    Mir, Irshad Ahmad; Rawat, Kamla; Solanki, Pratima R.; Bohidar, H. B.

    2017-07-01

    This report demonstrates a quantum dot (QD)-based selective and fast sensor platform for detection of folic acid (FA). This electrochemical platform provides a good linear relation between the anodic and cathodic peak currents ( i pa and i pc ) in the FA concentration range of 12 to 96 nM, and the minimum detection limit (MDL) achieved was 10 nM. As an extension, absorbance and fluorescence methods were also used for the detection of FA in solutions. Core-shell QDs provided better binding than core-only ZnSe quantum dots, and showed twofold increment in binding constant. A detailed comparative evaluation of the three methods (absorbance, fluorescence, and electrochemical) is presented vis-a-vis real samples. Therefore, in principle absorbance and fluorescence spectroscopy can also be used for detecting folic acid with high selectivity and sensitivity. The MDL can be extended to be 4-7 nM level by using fluorescence and absorbance spectroscopy. FA metabolism occurs in the intestine, where the pH conditions are basic. Hence, sensing of FA under physiological conditions is relevant, which was achieved in our case. Earlier methods have reported sensing under acidic or neutral pH conditions. Considering the importance of folic acid in physiology, the significance of the present study can be hardly stressed. [Figure not available: see fulltext.

  14. Patterns of racemization and epimerization of amino acids in land snail shells over the course of the Holocene

    SciTech Connect

    Goodfriend, G.A. )

    1991-01-01

    The patterns of racemization of six amino acids and of epimerization of isoleucine over the course of the Holocene were studied in a series of 38 radiocarbon-dated samples of the land snail Trochoidea seetzeni from the Negev Desert in southern Israel. The D/L ratios of each of the amino acids show a strong correlation with age (r = 0.84-0.94) and thus good age predictive ability. The patterns in faster-racemizing amino acids do not conform to first-order kinetics. Transformation to parabolic kinetics linearizes these faster-racemizing amino acids, except for aspartic acid (which shows a very high initial rate of racemization). After transformation, each amino acid shows an equally good correlation with age (r = 0.91-0.93). The D/L ratios of the various amino acids covary very strongly, even after the covariation due to sample age is removed from the data set. Thus, analysis of more than one amino acid provides largely redundant information on sample age. Nevertheless, because of differences in racemization rates, some amino acids provide better time resolution in different time ranges - aspartic acid is especially useful for very young samples, and glutamic acid and isoleucine for older samples. Neither the depth of burial of the samples nor the burial mode appears to affect the rate of racemization or epimerization.

  15. Gas chromatographic determination and mechanism of formation of D-amino acids occurring in fermented and roasted cocoa beans, cocoa powder, chocolate and cocoa shell.

    PubMed

    Pätzold, R; Brückner, H

    2006-07-01

    Fermented cocoa beans of various countries of origin (Ivory Coast, Ghana, Sulawesi), cocoa beans roasted under defined conditions (100-150 degrees C; 30-120 min), low and high fat cocoa powder, various brands of chocolate, and cocoa shells were analyzed for their contents of free L-and D-amino acids. Amino acids were isolated from defatted products using a cation exchanger and converted into volatile N(O)-pentafluoropropionyl amino acid 2-propyl esters which were analyzed by enantioselective gas chromatography mass spectrometry on a Chirasil-L-Val capillary column. Besides common protein L-amino acids low amounts of D-amino acids were detected in fermented cocoa beans. Quantities of D-amino acids increased on heating. On roasting cocoa beans of the Forastero type from the Ivory Coast at 150 degrees C for 2 h, relative quantities of D-amino acids approached 17.0% D-Ala, 11.7% D-Ile, 11.1% D-Asx (Asp + Asn), 7.9% D-Tyr, 5.8% D-Ser, 4.8% D-Leu, 4.3% D-Phe, 37.0% D-Pro, and 1.2% D-Val. In cocoa powder and chocolate relative quantities amounted to 14.5% D-Ala, 10.6% D-Tyr, 9.8% D-Phe, 8.1% L-Asx, and 7.2% D-Ile. Lower quantities of other D-amino acids were also detected. In order to corroborate our hypothesis that D-amino acids are generated from Amadori compounds (fructose amino acids) formed in the course of the Maillard reaction, fructose-L-phenylalanine and fructose-D-phenylalanine were synthesized and heated at 200 degrees C for 5-60 min. Already after 5 min release of 11.7% D-Phe and 11.8% L-Phe in the free form could be analyzed. Based on the data a racemization mechanism is presented founded on the intermediate and reversible formation of an amino acid carbanion in the Amadori compounds.

  16. Poly(ethylene glycol)-poly(lactic-co-glycolic acid) core-shell microspheres with enhanced controllability of drug encapsulation and release rate.

    PubMed

    Cha, Chaenyung; Jeong, Jae Hyun; Kong, Hyunjoon

    2015-01-01

    Poly(lactic-co-glycolic acid) (PLGA) microspheres have been widely used as drug carriers for minimally invasive, local, and sustained drug delivery. However, their use is often plagued by limited controllability of encapsulation efficiency, initial burst, and release rate of drug molecules, which cause unsatisfactory outcomes and several side effects including inflammation. This study presents a new strategy of tuning the encapsulation efficiency and the release rate of protein drugs from a PLGA microsphere by filling the hollow core of the microsphere with poly(ethylene glycol) (PEG) hydrogels of varying cross-linking density. The PEG gel cores were prepared by inducing in situ cross-linking reactions of PEG monoacrylate solution within the PLGA microspheres. The resulting PEG-PLGA core-shell microspheres exhibited (1) increased encapsulation efficiency, (2) decreased initial burst, and (3) a more sustained release of protein drugs, as the cross-linking density of the PEG gel core was increased. In addition, implantation of PEG-PLGA core-shell microspheres encapsulated with vascular endothelial growth factor (VEGF) onto a chicken chorioallantoic membrane resulted in a significant increase in the number of new blood vessels at an implantation site, while minimizing inflammation. Overall, this strategy of introducing PEG gel into PLGA microspheres will be highly useful in tuning release rates and ultimately in improving the therapeutic efficacy of a wide array of protein drugs.

  17. Binary release of ascorbic acid and lecithin from core-shell nanofibers on blood-contacting surface for reducing long-term hemolysis of erythrocyte.

    PubMed

    Shi, Qiang; Fan, Qunfu; Ye, Wei; Hou, Jianwen; Wong, Shing-Chung; Xu, Xiaodong; Yin, Jinghua

    2015-01-01

    There is an urgent need to develop blood-contacting biomaterials with long-term anti-hemolytic capability. To obtain such biomaterials, we coaxially electrospin [ascorbic acid (AA) and lecithin]/poly (ethylene oxide) (PEO) core-shell nanofibers onto the surface of styrene-b-(ethylene-co-butylene)-b-styrene elastomer (SEBS) that has been grafted with poly (ethylene glycol) (PEG) chains. Our strategy is based on that the grafted layers of PEG render the surface hydrophilic to reduce the mechanical injure to red blood cells (RBCs) while the AA and lecithin released from nanofibers on blood-contacting surface can actively interact with RBCs to decrease the oxidative damage to RBCs. We demonstrate that (AA and lecithin)/PEO core-shell structured nanofibers have been fabricated on the PEG grafted surface. The binary release of AA and lecithin in the distilled water is in a controlled manner and lasts for almost 5 days; during RBCs preservation, AA acts as an antioxidant and lecithin as a lipid supplier to the membrane of erythrocytes, resulting in low mechanical fragility and hemolysis of RBCs, as well as high deformability of stored RBCs. Our work thus makes a new approach to fabricate blood-contacting biomaterials with the capability of long-term anti-hemolysis.

  18. Preparation of monodispersed macroporous core-shell molecularly imprinted particles and their application in the determination of 2,4-dichlorophenoxyacetic acid.

    PubMed

    Liu, Yongliang; He, Yonghuan; Jin, Yulong; Huang, Yanyan; Liu, Guoquan; Zhao, Rui

    2014-01-03

    Porous polymers have aroused extensive attention due to their controllable porous structure in favor of mass transfer and binding capacity. In this work, the novel macroporous core-shell molecularly imprinted polymers (MIP) for selective recognition of 2,4-dichlorophenoxyacetic acid (2,4-D) were prepared by surface initiated atom transfer radical polymerization (si-ATRP). By using one-step swelling and polymerization method, the monodispersed macroporous poly(glycidyl methacrylate) (PGMA) particles were synthesized and used as supporting matrix for preparing surface MIP particles (PGMA@MIP). Thanks to the inner and outer surface-located binding cavities and the macroporous structure, the PGMA@MIPs revealed desirable efficiency for template removal and mass transfer, and thus excellent accessibility and affinity toward template 2,4-D. Moreover, PGMA@MIPs exhibited much higher selectivity toward 2,4-D than PGMA@NIPs. PGMA@MIP particles were directly used to selectively enrich 2,4-D from tap water and the recoveries of 2,4-D were obtained as 90.0-93.4% with relative standard division of 3.1-3.4% (n=3). The macroporous PGMA@MIPs also possessed steady and excellent reusable performance for 2,4-D in four extraction/stripping cycles. This novel macroporous core-shell imprinted material may become a powerful tool for rapid and efficient enrichment and separation of target compounds from the complicated samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Effects of water, sodium hypochlorite, peroxyacetic acid, and acidified sodium chlorite on in-shell hazelnuts inoculated with Salmonella enterica serovar Panama.

    PubMed

    Weller, Lisa D; Daeschel, Mark A; Durham, Catherine A; Morrissey, Michael T

    2013-12-01

    Recent foodborne disease outbreaks involving minimally processed tree nuts have generated a need for improved sanitation procedures. Chemical sprays and dips have shown promise for reducing pathogens on fresh produce, but little research has been conducted for in-shell hazelnuts. This study analyzed the effectiveness of 3 chemical sanitizers for reducing Salmonella on in-shell hazelnuts. Treatments of water, sodium hypochlorite (NaOCl; 25 and 50 ppm), peroxyacetic acid (PAA; 80 and 120 ppm), and acidified sodium chlorite (ASC; 450, 830, and 1013 ppm) were sprayed onto hazelnut samples inoculated with Salmonella enterica serovar Panama. Hazelnut samples were immersed in liquid cultures of S. Panama for 24 h, air-dried, and then sprayed with water and chemical treatments. Inoculation achieved S. Panama populations of approximately 8.04 log CFU/hazelnut. Surviving S. panama populations were evaluated using a nonselective medium (tryptic soy agar), incubated 3 h, and then overlaid with selective media (xylose lysine deoxycholate agar). All of the chemical treatments significantly reduced S. Panama populations (P ≤ 0.0001). The most effective concentrations of ASC, PAA, and NaOCl treatments reduced populations by 2.65, 1.46, and 0.66 log units, respectively. ASC showed the greatest potential for use as a postharvest sanitation treatment.

  20. Preparation, Characterization, and Optimization of Folic Acid-Chitosan-Methotrexate Core-Shell Nanoparticles by Box-Behnken Design for Tumor-Targeted Drug Delivery.

    PubMed

    Naghibi Beidokhti, Hamid Reza; Ghaffarzadegan, Reza; Mirzakhanlouei, Sasan; Ghazizadeh, Leila; Dorkoosh, Farid Abedin

    2017-01-01

    The objective of this study was to investigate the combined influence of independent variables in the preparation of folic acid-chitosan-methotrexate nanoparticles (FA-Chi-MTX NPs). These NPs were designed and prepared for targeted drug delivery in tumor. The NPs of each batch were prepared by coaxial electrospray atomization method and evaluated for particle size (PS) and particle size distribution (PSD). The independent variables were selected to be concentration of FA-chitosan, ratio of shell solution flow rate to core solution flow rate, and applied voltage. The process design of experiments (DOE) was obtained with three factors in three levels by Design expert software. Box-Behnken design was used to select 15 batches of experiments randomly. The chemical structure of FA-chitosan was examined by FTIR. The NPs of each batch were collected separately, and morphologies of NPs were investigated by field emission scanning electron microscope (FE-SEM). The captured pictures of all batches were analyzed by ImageJ software. Mean PS and PSD were calculated for each batch. Polynomial equation was produced for each response. The FE-SEM results showed the mean diameter of the core-shell NPs was around 304 nm, and nearly 30% of the produced NPs are in the desirable range. Optimum formulations were selected. The validation of DOE optimization results showed errors around 2.5 and 2.3% for PS and PSD, respectively. Moreover, the feasibility of using prepared NPs to target tumor extracellular pH was shown, as drug release was greater in the pH of endosome (acidic medium). Finally, our results proved that FA-Chi-MTX NPs were active against the human epithelial cervical cancer (HeLa) cells.

  1. pH-dependent permeation of amino acids through isolated ivy cuticles is affected by cuticular water sorption and hydration shell size of the solute

    PubMed Central

    Arand, Katja; Stock, David; Burghardt, Markus; Riederer, Markus

    2010-01-01

    The permeabilities of amino acids for isolated cuticular membranes of ivy (Hedera helix L.) were measured at different pH. Cuticular permeances were lowest for the zwitterionic form at pH 6, followed by the cationic form at pH 1. Highest permeances were obtained for the anionic form at pH 11. Permeances were not correlated with octanol/water partition coefficients and decreased at a given pH with increasing molar volume of the solute. This finding suggests that permeation takes place in the polar cuticular pathways. The effect of pH on the cuticular transport properties was analysed according to the porous membrane model considering the polyelectrolytic character of the cuticle in terms of porosity, tortuosity, and size selectivity of the aqueous cuticular pathway which is altered by pH. An increase of water content and permeability of the cuticular membrane was caused by the dissociation of weak acidic groups with increasing pH leading to a swelling of the cuticle induced by fixed negative charges. In addition, the pH-dependent size of the hydration shell of the amino acids was identified as a secondary factor explaining the variability of cuticular permeances. PMID:20631051

  2. Mechanism of in situ surface polymerization of gallic acid in an environmental-inspired preparation of carboxylated core-shell magnetite nanoparticles.

    PubMed

    Tóth, Ildikó Y; Szekeres, Márta; Turcu, Rodica; Sáringer, Szilárd; Illés, Erzsébet; Nesztor, Dániel; Tombácz, Etelka

    2014-12-30

    Magnetite nanoparticles (MNPs) with biocompatible coatings are good candidates for MRI (magnetic resonance imaging) contrasting, magnetic hyperthermia treatments, and drug delivery systems. The spontaneous surface induced polymerization of dissolved organic matter on environmental mineral particles inspired us to prepare carboxylated core-shell MNPs by using a ubiquitous polyphenolic precursor. Through the adsorption and in situ surface polymerization of gallic acid (GA), a polygallate (PGA) coating is formed on the nanoparticles (PGA@MNP) with possible antioxidant capacity. The present work explores the mechanism of polymerization with the help of potentiometric acid-base titration, dynamic light scattering (for particle size and zeta potential determination), UV-vis (UV-visible light spectroscopy), FTIR-ATR (Fourier-transformed infrared spectroscopy by attenuated total reflection), and XPS (X-ray photoelectron spectroscopy) techniques. We observed the formation of ester and ether linkages between gallate monomers both in solution and in the adsorbed state. Higher polymers were formed in the course of several weeks both on the surface of nanoparticles and in the dispersion medium. The ratio of the absorbances of PGA supernatants at 400 and 600 nm (i.e., the E4/E6 ratio commonly used to characterize the degree of polymerization of humic materials) was determined to be 4.3, similar to that of humic acids. Combined XPS, dynamic light scattering, and FTIR-ATR results revealed that, prior to polymerization, the GA monomers became oxidized to poly(carboxylic acid)s due to ring opening while Fe(3+) ions reduced to Fe(2+). Our published results on the colloidal and chemical stability of PGA@MNPs are referenced thoroughly in the present work. Detailed studies on biocompatibility, antioxidant property, and biomedical applicability of the particles will be published.

  3. A novel acid-base bifunctional catalyst (ZSM-5@Mg3Si4O9(OH)4) with core/shell hierarchical structure and superior activities in tandem reactions.

    PubMed

    Wang, Darui; Wang, Bo; Ding, Yu; Wu, Haihong; Wu, Peng

    2016-10-25

    A hierarchically core/shell structured base-acid bifunctional catalyst, ZSM-5@Mg3Si4O9(OH)4, was successfully prepared through a simple hydrothermal reaction between the silica species on the ZSM-5 crystal surface and the Mg(2+) source in basic solution. The obtained catalyst showed superior activity and stability in one-pot deacetalization-Knoevenagel condensation reaction.

  4. Shelled opisthobranchs.

    PubMed

    Mikkelsen, Paula M

    2002-01-01

    In his contributions to the monographic series "Manual of Conchology", Henry Pilsbry reviewed the subgroup Tectibranchiata, comprising those opisthobranch snails that (at least primitively) still possess a shell (Pilsbry, 1894-1896). Exemplified by the Cephalaspidea (bubble shells), others included in this group at Pilsbry's time and since were Anaspidea (sea hares) and the shelled members of Notaspidea (side-gilled slugs) and Sacoglossa (leaf slugs). Pilsbry (and others since his time) considered tectibranchs to be the "root stock" from which more advanced gastropods such as Nudibranchia and Pulmonata were derived. Tectibranch systematics is firmly based on conchology and most species were originally described from empty shells. However, soft-anatomical characters were acknowledged quite early on as equally important in tectibranchs, due to the reduction of their shells and their evolutionary proximity to unshelled gastropods. Today, Tectibranchiata is not recognized as a natural taxon although the word "tectibranch" (like "prosobranch" and "mesogastropod") continues in vernacular use. Shelled opisthobranchs have been redistributed among various taxa, including several new ones--the unresolved basal opisthobranchs (Architectibranchia) and the "lower Heterobranchia", an enigmatic and currently much-studied group of families considered basal to all of Euthyneura (Opisthobranchia and landsnails (Pulmonata)). Despite their polyphyletic status, shelled opisthobranchs remain important subjects in evolutionary studies of gastropods--as the most basal members of nearly every opisthobranch clade and as organisms with mosaic combinations of primitive and derived features within evolutionary "trends" (e.g., loss of the shell, detorsion, concentration of the nervous system, ecological specialization, etc.). Although they play a pivotal role, the shelled opisthobranchs have received minimal attention in more comprehensive gastropod studies, often relegated to token

  5. Synthesis and drug-loading properties of folic acid-modified superparamagnetic Fe3O4 hollow microsphere core/mesoporous SiO2 shell composite particles

    NASA Astrophysics Data System (ADS)

    Yang, Yong; Guo, Xue; Wei, Kaiwei; Wang, Lijuan; Yang, Dandan; Lai, Lifang; Cheng, Meiling; Liu, Qi

    2014-01-01

    A drug delivery system, which not only has superparamagnetic property, higher surface area but also has targeting function, has been developed. The core/shell structural magnetic magnetite mesoporous silica microspheres with amine groups (Fe3O4-SiO2-NH2) were first fabricated by a one-pot direct co-condensation method, then folic acid-modified magnetic mesoporous silica composite microspheres (Fe3O4-SiO2-NHFA) were obtained by the bonding of the Fe3O4-SiO2-NH2 with folic acid as targeted molecule. The resultant composite microspheres were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, low temperature nitrogen adsorption-desorption, and vibrating sample magnetometer. A well-known inflammational drug ibuprofen was used as a model drug to assess the loading and releasing behavior of the composite microspheres. Fe3O4-SiO2-NHFA system exhibits magnetic properties typical for superparamagnetic material with a higher saturation magnetization value of about 41.2 emu/g and has better capacity of drug storage (32.0 %) and sustained drug-release property. So this system has potential applications in biomedical field.

  6. Degradation characteristics of humic acid over iron oxides/Fe 0 core-shell nanoparticles with UVA/H2O2.

    PubMed

    Nie, Yulun; Hu, Chun; Zhou, Lei; Qu, Jiuhui; Wei, Qunshan; Wang, Dongsheng

    2010-01-15

    Iron oxides coated on Fe(0) core-shell nanospheres (nIOCI) were synthesized through the reduction of ferrous sulfate aqueous solution by sodium borohydride at ambient atmosphere. The catalyst was highly effective for the degradation of humic acid (HA) in the presence of H(2)O(2) and UVA at neutral pH. Under deoxygenated conditions in the dark, the generation of hydroxyl radicals in aqueous nIOCI dispersion verified its galvanic cell-like performance, which enhanced the interfacial electron transfer and led to its higher reactivity. By the total organic carbon, the absorbance of UV(254), FTIR, the molecular weight distribution and the chemical fractional character analysis, the degradation process of HA was shown to proceed by the disappearance of aromaticity, the increase of hydrophilic fraction and aromatic ring openings into CO(2) and small organic acid. The treated HA showed much lower reactivity toward chlorine and the disinfection byproduct (DBP) formation potential was also greatly reduced. Moreover, it was found that the DBP formation potential more depended on the structure of the intermediates of HA degradation than TOC removal.

  7. Ascorbic acid regulation in stress responses during acute cold exposure and following recovery in juvenile Chinese soft-shelled turtle (Pelodiscus sinensis).

    PubMed

    Chen, Bo-jian; Niu, Cui-juan; Yuan, Lin

    2015-06-01

    Intense temperature change often leads to increased oxidative stress in many animals with a few exceptions, including the turtle. To date, little is known about the mechanism of protective antioxidative defenses in turtles during acute temperature change, specifically the role that the antioxidant ascorbic acid (AA) plays. In this study, Chinese soft-shelled turtles (Pelodiscus sinensis) were initially acclimated at 28°C (3 wks), exposed to acute cold condition (8°C, 8 h) and finally placed in recovery (28°C, 24 h). L-Gulonolactone oxidase (GLO) mRNA exhibited a stable transcription pattern during the intense thermal fluctuation. GLO activity also remained stable, which validated the mRNA expression pattern. The similar Q10 values for GLO activity in the different treatment groups at incubation temperatures of 28°C and 8°C indicated that the GLO activity response to thermal change exhibited a temperature-dependent enzymatic kinetic characteristic. The AA storage was tissue-specific as well as the AA re-supply in the recovery period, with brain as the priority. Despite the insufficient transport during cold exposure, the plasma AA reservoir greatly contributed to the redistribution of AA during recovery. Depending on the prominent GLO activity, the high level of tissue-specific AA storage and the extraordinary plasma AA transport potential, the Chinese soft-shelled turtle endured severe thermal fluctuations with no apparent oxidative stress. However, the significant decrease in AA concentration in the brain tissue during acute cold exposure suggested that such a strategy may not be sufficient for prolonged cold exposure. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Preparation and application of L-cysteine-modified CdSe/CdS core/shell nanocrystals as a novel fluorescence probe for detection of nucleic acid

    NASA Astrophysics Data System (ADS)

    Huang, Fenghua; Chen, Guonan

    2008-07-01

    The water-soluble L-cysteine-modified CdSe/CdS core/shell nanocrystals (expressed as CdSe/CdS/Cys nanocrystals) have been synthesized in aqueous by using L-cysteine as stabilizer. The size, shape, component and spectral property of CdSe/CdS/Cys nanocrystals were characterized by high-resolution transmission electron microscope (HRTEM), energy dispersive X-ray fluorescence (EDX), infrared spectrum (IR) and photoluminescence (PL). The results showed that the spherical CdSe/CdS/Cys nanocrystals with an average diameter of 2.3 nm have favorable fluorescent property, theirs photostability and fluorescence intensity are enhanced greatly after overcoating with CdS. The cysteine modified on the surface of core/shell CdSe/CdS nanocrystals renders the nanocrystals water-soluble and biocompatible. Based on the fluorescence quenching of the nanocrystals in the presence of calf thymus deoxyribonucleic acid (ct-DNA), a fluorescence quenching method has been developed for the determination of ct-DNA by using the nanocrystals as a novel fluorescence probe. The pH value of the system was selected at pH 7.4, with excitation and emission wavelength at 380 and 522 nm, respectively. Under the optimal conditions, the fluorescence quenching intensity of the system is linear with the concentration of ct-DNA in the range of 0.1-3.5 μg/mL ( r = 0.9987). The detection limit is 0.06 μg/mL. And two synthetic samples were analyzed satisfactorily.

  9. Micelles Based on Biodegradable Poly(L-glutamic acid)-b-Polylactide with Paramagnetic Gd Ions Chelated to the Shell Layer as a Potential Nanoscale MRI-Visible Delivery System

    PubMed Central

    Zhang, Guodong; Zhang, Rui; Wen, Xiaoxia; Li, Li; Li, Chun

    2008-01-01

    There is much interest in the development of nanoscale drug delivery system with MRI visibility to optimize the delivery efficiency and therapeutic efficacy under image guidance. Here we report on the successful fabrication of nanoscale micelles based on biodegradable poly(L-glutamic acid)-b-polylactide (PG-b-PLA) block copolymer with paramagnetic Gd3+ ions chelated to their shell. (PG-b-PLA) was synthesized by sequential polymerization reactions: anionic polymerization of L-lactide followed by ring opening polymerization of benzyl glutamate N-carboxylic anhydride. The metal chelator p-aminobenzyldiethylenetriaminepenta(acetic acid) (DTPA) was readily conjugated to the side chain carboxylic acids of poly(L-glutamic acid). The resulting copolymer formed spherical micelles in aqueous solution with an average diameter of 230 nm at pH 7.4. The size of PG(DTPA)-b-PLA micelles decreased with increasing pH value. DTPA-Gd chelated to the shell layer of the micelles exhibited significantly higher spin-lattice relaxivity (r1) than a small-molecular-weight MRI contrast agent, indicating that water molecules could readily access the Gd ions in the micelles. Because of the presence of multiple carboxylic acid functional groups in the shell layer, polymeric micelles based on biodegradable PG(DTPA-Gd)-b-PLA may be a suitable platform for the development of MRI-visible, targeted nanoscale drug delivery systems. PMID:18047289

  10. Shell Games.

    ERIC Educational Resources Information Center

    Atkinson, Bill

    1982-01-01

    The author critiques the program design and educational aspects of the Shell Games, a program developed by Apple Computer, Inc., which can be used by the teacher to design objective tests for adaptation to specific assessment needs. (For related articles, see EC 142 959-962.) (Author)

  11. Shell Games.

    ERIC Educational Resources Information Center

    Atkinson, Bill

    1982-01-01

    The author critiques the program design and educational aspects of the Shell Games, a program developed by Apple Computer, Inc., which can be used by the teacher to design objective tests for adaptation to specific assessment needs. (For related articles, see EC 142 959-962.) (Author)

  12. Peanut Shell-Derived Carbon Solid Acid with Large Surface Area and Its Application for the Catalytic Hydrolysis of Cyclohexyl Acetate

    PubMed Central

    Xue, Wei; Sun, Lijun; Yang, Fang; Wang, Zhimiao; Li, Fang

    2016-01-01

    A carbon solid acid with large surface area (CSALA) was prepared by partial carbonization of H3PO4 pre-treated peanut shells followed by sulfonation with concentrated H2SO4. The structure and acidity of CSALA were characterized by N2 adsorption–desorption, scanning electron microscopy (SEM), X-ray powder diffraction (XRD), 13C cross polarization (CP)/magic angle spinning (MAS) nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), Fourier transform-infrared spectroscopy (FT-IR), titration, and elemental analysis. The results demonstrated that the CSALA was an amorphous carbon material with a surface area of 387.4 m2/g. SO3H groups formed on the surface with a density of 0.46 mmol/g, with 1.11 mmol/g of COOH and 0.39 mmol/g of phenolic OH. Densities of the latter two groups were notably greater than those observed on a carbon solid acid (CSA) with a surface area of 10.1 m2/g. The CSALA catalyst showed better performance than the CSA for the hydrolysis of cyclohexyl acetate to cyclohexanol. Under optimal reaction conditions, cyclohexyl acetate conversion was 86.6% with 97.3% selectivity for cyclohexanol, while the results were 25.0% and 99.4%, respectively, catalyzed by CSA. The high activity of the CSALA could be attributed to its high density of COOH and large surface area. Moreover, the CSALA showed good reusability. Its catalytic activity decreased slightly during the first two cycles due to the leaching of polycyclic aromatic hydrocarbon-containing SO3H groups, and then remained constant during following uses. PMID:28773954

  13. Peanut Shell-Derived Carbon Solid Acid with Large Surface Area and Its Application for the Catalytic Hydrolysis of Cyclohexyl Acetate.

    PubMed

    Xue, Wei; Sun, Lijun; Yang, Fang; Wang, Zhimiao; Li, Fang

    2016-10-15

    A carbon solid acid with large surface area (CSALA) was prepared by partial carbonization of H₃PO₄ pre-treated peanut shells followed by sulfonation with concentrated H₂SO₄. The structure and acidity of CSALA were characterized by N₂ adsorption-desorption, scanning electron microscopy (SEM), X-ray powder diffraction (XRD), (13)C cross polarization (CP)/magic angle spinning (MAS) nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), Fourier transform-infrared spectroscopy (FT-IR), titration, and elemental analysis. The results demonstrated that the CSALA was an amorphous carbon material with a surface area of 387.4 m²/g. SO₃H groups formed on the surface with a density of 0.46 mmol/g, with 1.11 mmol/g of COOH and 0.39 mmol/g of phenolic OH. Densities of the latter two groups were notably greater than those observed on a carbon solid acid (CSA) with a surface area of 10.1 m²/g. The CSALA catalyst showed better performance than the CSA for the hydrolysis of cyclohexyl acetate to cyclohexanol. Under optimal reaction conditions, cyclohexyl acetate conversion was 86.6% with 97.3% selectivity for cyclohexanol, while the results were 25.0% and 99.4%, respectively, catalyzed by CSA. The high activity of the CSALA could be attributed to its high density of COOH and large surface area. Moreover, the CSALA showed good reusability. Its catalytic activity decreased slightly during the first two cycles due to the leaching of polycyclic aromatic hydrocarbon-containing SO₃H groups, and then remained constant during following uses.

  14. Preparation and unique electrical behaviors of monodispersed hybrid nanorattles of metal nanocores with hairy electroactive polymer shells.

    PubMed

    Cai, Tao; Zhang, Bin; Chen, Yu; Wang, Cheng; Zhu, Chun Xiang; Neoh, Koon-Gee; Kang, En-Tang

    2014-03-03

    A versatile template-assisted strategy for the preparation of monodispersed rattle-type hybrid nanospheres, encapsulating a movable Au nanocore in the hollow cavity of a hairy electroactive polymer shell (Au@air@PTEMA-g-P3HT hybrid nanorattles; PTEMA: poly(2-(thiophen-3-yl)ethyl methacrylate; P3HT: poly(3-hexylthiophene), was reported. The Au@silica core-shell nanoparticles, prepared by the modified Stöber sol-gel process on Au nanoparticle seeds, were used as templates for the synthesis of Au@silica@PTEMA core-double shell nanospheres. Subsequent oxidative graft polymerization of 3-hexylthiophene from the exterior surface of the Au@silica@PTEMA core-double shell nanospheres allowed the tailoring of surface functionality with electroactive P3HT brushes (Au@silica@PTEMA-g-P3HT nanospheres). The Au@air@ PTEMA-g-P3HT hybrid nanorattles were obtained after etching of the silica interlayer by HF. The as-prepared nanorattles were dispersed into an electrically insulating polystyrene matrix and for the first time used to fabricate nonvolatile memory devices. As a result, unique electrical behaviors, including insulator behavior, write-once-read-many-times and rewritable memory effects, and conductor behavior as well, were observed in the Al/Au@air@PTEMA-g-P3HT+PS/ITO (ITO: indium-tin oxide) sandwich thin-film devices.

  15. Vibration of Shells

    NASA Technical Reports Server (NTRS)

    Leissa, A. W.

    1973-01-01

    The vibrational characteristics and mechanical properties of shell structures are discussed. The subjects presented are: (1) fundamental equations of thin shell theory, (2) characteristics of thin circular cylindrical shells, (3) complicating effects in circular cylindrical shells, (4) noncircular cylindrical shell properties, (5) characteristics of spherical shells, and (6) solution of three-dimensional equations of motion for cylinders.

  16. Building Atoms Shell by Shell.

    ERIC Educational Resources Information Center

    Sussman, Beverly

    1993-01-01

    Describes an atom-building activity where students construct three-dimensional models of atoms using a styrofoam ball as the nucleus and pom-poms, gum drops, minimarshmallows, or other small items of two different colors to represent protons and neutrons attached. Rings of various sizes with pom-poms attached represent electron shells and…

  17. Building Atoms Shell by Shell.

    ERIC Educational Resources Information Center

    Sussman, Beverly

    1993-01-01

    Describes an atom-building activity where students construct three-dimensional models of atoms using a styrofoam ball as the nucleus and pom-poms, gum drops, minimarshmallows, or other small items of two different colors to represent protons and neutrons attached. Rings of various sizes with pom-poms attached represent electron shells and…

  18. Equilibrium and kinetic studies on the removal of Acid Red 114 from aqueous solutions using activated carbons prepared from seed shells.

    PubMed

    Thinakaran, N; Panneerselvam, P; Baskaralingam, P; Elango, D; Sivanesan, S

    2008-10-01

    The use of low-cost and ecofriendly adsorbents has been investigated as an ideal alternative to the current expensive methods of removing dyes from wastewater. This paper deals with the removal of Acid Red 114 (AR 114) from aqueous solutions using activated carbons prepared from agricultural waste materials such as gingelly (sesame) (Sp), cotton (Cp) and pongam (Pp) seed shells. Optimum conditions for AR 114 removal were found to be pH 3, adsorbent dosage=3g/L of solution and equilibrium time=4h. Higher removal percentages were observed at lower concentrations of AR 114. The adsorption isotherm data were fitted to Langmuir and Freundlich equation, and the adsorption capacity of the studied adsorbents was in the order Sp>Cp>Pp. Kinetic studies showed that the adsorption followed both pseudo-second-order and Elovich equation. The thermodynamics parameters such as DeltaG degrees, DeltaH degrees, DeltaS degrees were also evaluated. The activated carbons prepared were characterized by FT-IR, SEM and BET analysis.

  19. Magnetic core-shell Fe₃O₄@SiO₂/MWCNT nanocomposite modified carbon paste electrode for amplified electrochemical sensing of uric acid.

    PubMed

    Arvand, Majid; Hassannezhad, Morassa

    2014-03-01

    A new type of nanocomposite based on multi-walled carbon nanotubes decorated with magnetic core-shell Fe3O4@SiO2 nanoparticles (Fe3O4@SiO2/MWCNTs) was prepared and used to fabricate a modified carbon paste electrode (CPE). The nanocomposite was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FT-IR) techniques. Electrochemical behavior of uric acid (UA) was investigated on Fe3O4@SiO2/MWCNTs-CPE by cyclic voltammetry (CV) and square wave voltammetry (SWV) in phosphate buffer solution (pH6.0). Under the optimized conditions, the peak currents increased linearly with the concentration of UA in the range from 0.60 to 100.0 μM, with a detection limit of 0.13 μM. The proposed sensor was successfully applied for the determination of UA in biological fluids.

  20. Impact of surface roughness of Au core in Au/Pd core-shell nanoparticles toward formic acid oxidation - Experiment and simulation

    NASA Astrophysics Data System (ADS)

    Hsu, Chiajen; Huang, Chienwen; Hao, Yaowu; Liu, Fuqiang

    2013-12-01

    The Au/Pd core-shell nanoparticles (NPs) were synthesized via galvanic replacement of Cu by Pd on hollow Au cores by adding different concentrations of Na2SO3 solution. It was found that the higher concentration of Na2SO3 that was used, the rougher the Au nanospheres became. However, the rougher Au surface may cause more defects in the Pd layers and decrease the catalytic abilities. The Au/Pd NPs synthesized using 0 M Na2SO3 (denoted as 0 M-Au/Pd NPs) have the smoothest Pd surface and demonstrate higher formic acid oxidation (FAO) activity (0.714 mA cm-2, normalized to the surface area of Pd) than other Au/Pd NPs and commercial Pd black (0.47 mA cm-2). Additional electrochemical characterization of the 0 M-Au/Pd NPs also demonstrated lower CO-stripping onset and peak potentials, higher stability (8× improvement in stabilized oxidation current), and superior durability (by 1.6×) than the Pd black. In addition, a simple simulation of FAO was adopted to predict the anodic curve by including reaction intermediates of formate and hydroxyl. The 0 M-Au/Pd NPs were found to show higher formate and lower hydroxyl coverage than the Pd black.

  1. Shell worlds

    NASA Astrophysics Data System (ADS)

    Roy, Kenneth I.; Kennedy, Robert G., III; Fields, David E.

    2013-02-01

    The traditional concept of terraforming assumes ready availability of candidate planets with acceptable qualities: orbiting a star in its "Goldilocks zone", liquid water, enough mass, years longer than days, magnetic field, etc. But even stipulating affordable interstellar travel, we still might never find a good candidate elsewhere. Whatever we found likely would require centuries of heavy terraforming, just as Mars or Venus would here. Our increasing appreciation of the ubiquity of life suggests that any terra nova would already possess it. We would then face the dilemma of introducing alien life forms (us, our microbes) into another living world. Instead, we propose a novel method to create habitable environments for humanity by enclosing airless, sterile, otherwise useless planets, moons, and even large asteroids within engineered shells, which avoids the conundrum. These shells are subject to two opposing internal stresses: compression due to the primary's gravity, and tension from atmospheric pressure contained inside. By careful design, these two cancel each other resulting in zero net shell stress. Beneath the shell an Earth-like environment could be created similar in almost all respects to that of Home, except for gravity, regardless of the distance to the sun or other star. Englobing a small planet, moon, or even a dwarf planet like Ceres, would require astronomical amounts of material (quadrillions of tons) and energy, plus a great deal of time. It would be a quantum leap in difficulty over building Dyson Dots or industrializing our solar system, perhaps comparable to a mission across interstellar space with a living crew within their lifetime. But when accomplished, these constructs would be complete (albeit small) worlds, not merely large habitats. They could be stable across historic timescales, possibly geologic. Each would contain a full, self-sustaining ecology, which might evolve in curious directions over time. This has interesting implications

  2. Production and characterization of functional properties of protein hydrolysates from egg shell membranes by lactic acid bacteria fermentation.

    PubMed

    Jain, Surangna; Anal, Anil Kumar

    2017-04-01

    This study aimed to ferment the chicken eggshell membrane (ESM) using the lactic acid bacteria, Lactobacillus plantarum for preparation of functional and bioactive protein hydrolysates. Cultivation at an initial pH of 8.0 for 36 h resulted in maximum protein concentration (177.3 mg/g) and degree of hydrolysis (25.1%) of the hydrolysates. Fermentation resulted in the production of hydrolysates that demonstrated excellent solubility (90.7%), good foaming capacity (36.7%) and emulsification activity (94.6 m(2)/g). Additionally, these protein hydrolysates exhibited remarkable bioactive properties for instance reducing power (2.53), protection from DPPH radical (70.5%) and angiotensin I converting enzyme inhibition (49.3%). The fermented protein hydrolysates were also found effective against various foodborne pathogens. The protein hydrolysates obtained by fermentation of ESM can be potentially incorporated in functional foods and nutraceuticals resulting in valorization of the ESM waste.

  3. Multiple-shell ZnSe core-shell spheres and their improved photocatalytic activity.

    PubMed

    Zhao, Lijuan; Sun, Chengcheng; Tian, Gang; Pang, Qi

    2017-09-15

    Multiple-shell ZnSe core-shell microspheres were synthesized on a large scale by a facile solvothermal method in ethylene glycol (EG) with ethylene diamine tetraacetic acid (EDTA) assisted. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis absorption spectroscopy and photoluminescence (PL) were used to characterize the structures and optical properties of these core-shell spheres with multiple shells. XRD and SEM analyses show that the as-grown ZnSe samples are zinc-blende core-shell structures with multiple shells. The possible growth mechanism is investigated. The results of photocatalysis of methyl red (MR) indicate that the multiple-shell ZnSe core-shell microspheres possess remarkable photocatalytic activity. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Core-shell NaGdF4@CaCO3 nanoparticles for enhanced magnetic resonance/ultrasonic dual-modal imaging via tumor acidic micro-enviroment triggering.

    PubMed

    Wei, Zuwu; Lin, Xiao; Wu, Ming; Zhao, Bixing; Lin, Ruhui; Zhang, Da; Zhang, Yun; Liu, Gang; Liu, Xiaolong; Liu, Jingfeng

    2017-07-14

    For cancer diagnosis, a paramount challenge still exists in the exploring of methods that can precisely discriminate tumor tissues from their surrounding healthy tissues with a high target-to-background signal ratio. Here, we report a NaGdF4@CaCO3-PEG core-shell nanoparticle which has the tumor acidic microenvironment enhanced imaging signals of ultrasound and magnetic resonance. Under the acidic conditions, the CaCO3 shell will gradually dissolve which then facilitate the interaction of NaGdF4 with the external aqueous environment to enhance water proton relaxation. Meanwhile, the CO2 bubbles generated by the CaCO3 dissolvement will generate strong elastic echo for US detection. The core-shell structure of NaGdF4@CaCO3-PEG can be observed by TEM, and its composition can be determined by STEM. The acid triggered generation of CO2 bubbles and the enhancement of MRI signal could be demonstrated in vitro, and the excellent dual-modal magnetic resonance/ultrasonic cancer imaging abilities of NaGdF4@CaCO3-PEG could be also proved at the tumor site in vivo. The here described proof-of-concept nanoparticles with pH triggered magnetic resonance/ultrasonic dual-modal imaging enhancement, may serve as a useful guide to develop various molecular imaging strategies for cancer diagnosis in the future.

  5. Solar photocatalysis for treatment of Acid Yellow-17 (AY-17) dye contaminated water using Ag@TiO2 core-shell structured nanoparticles.

    PubMed

    Khanna, Ankita; Shetty K, Vidya

    2013-08-01

    Wastewater released from textile industries causes water pollution, and it needs to be treated before discharge to the environment by cost effective technologies. Solar photocatalysis is a promising technology for the treatment of dye wastewater. The Ag@TiO2 nanoparticles comprising of Ag core and TiO2 shell (Ag@TiO2) have unique photocatalytic property of inhibition of electron-hole recombination and visible light absorption, which makes it a promising photocatalyst for use in solar photocatalysis and with higher photocatalytic rate. Therefore, in the present work, the Ag@TiO2 nanoparticles synthesized by one pot method with postcalcination step has been used for the degradation of Acid Yellow-17 (AY-17) dye under solar light irradiation. The Ag@TiO2 nanoparticles were characterized using thermogravimetric-differential thermal analysis, X-ray diffraction, transmission electron microscopy, selected area electron diffraction, and energy dispersive X-ray analysis. The catalyst has been found to be very effective in solar photocatalysis of AY-17, as compared to other catalysts. The effects of pH, catalyst loading, initial dye concentration, and oxidants on photocatalysis were also studied. The optimized parameters for degradation of AY-17 using Ag@TiO2 were found to be pH 3, dye/catalyst ratio of 1:10 (g/g), and 2 g/L of (NH4)2S2O8 as oxidant. Efficient decolorization and mineralization of AY-17 was achieved. The kinetics of color, total organic carbon, and chemical oxygen demand removal followed the Langmuir-Hinshelwood model. Ag@TiO2 catalyst can be reused thrice without much decline in efficiency. The catalyst exhibited its potential as economic photocatalyst for treatment of dye wastewater.

  6. NIF Double Shell outer-shell experiments

    NASA Astrophysics Data System (ADS)

    Merritt, E. C.; Montgomery, D. S.; Kline, J. L.; Daughton, W. S.; Wilson, D. C.; Dodd, E. S.; Renner, D. B.; Cardenas, T.; Batha, S. H.

    2016-10-01

    At the core of the Double Shell concept is the kinetic energy transfer from the outer shell to the inner shell via collision. This collision sets both the implosion shape of the inner shell, from imprinting of the shape of the outer shell, as well as the maximum energy available to compress the DT fuel. Therefore, it is crucial to be able to control the time-dependent shape of the outer shell, such that the outer shell is nominally round at the collision time. We present the experiment results from our sub-scale ( 1 MJ) NIF outer-shell only shape tuning campaign, where we vary shape by changing a turn-on time delay between the same pulse shape on the inner and outer cone beams. This type of shape tuning is unique to this platform and only possible since the Double Shell design uses a single-shock drive (4.5 ns reverse ramp pulse). The outer-shell only targets used a 5.75 mm diameter standard near-vacuum NIF hohlraum with 0.032 mg/cc He gas fill, and a Be capsule with 0.4% uniform Cu dopant, with 242 um thick ablator. We also present results from a third outer-shell only shot used to measure shell trajectory, which is critical in determining the shell impact time. This work conducted under the auspices of the U.S. DOE by LANL under contract DE-AC52-06NA25396.

  7. Synthesis and organic surface modification of luminescent, lanthanide-doped core/shell nanomaterials (LnF3@SiO2@NH2@organic acid) for potential bioapplications: spectroscopic, structural, and in vitro cytotoxicity evaluation.

    PubMed

    Runowski, Marcin; Ekner-Grzyb, Anna; Mrówczyńska, Lucyna; Balabhadra, Sangeetha; Grzyb, Tomasz; Paczesny, Jan; Zep, Anna; Lis, Stefan

    2014-08-12

    A facile coprecipitation reaction between Ce(3+), Gd(3+), Tb(3+), and F(-) ions, in the presence of glycerine as a capping agent, led to the formation of ultrafine, nanocrystalline CeF3:Tb(3+) 5%, Gd(3+) 5% (LnF3). The as-prepared fluoride nanoparticles were successfully coated with an amine modified silica shell. Subsequently, the obtained LnF3@SiO2@NH2 nanostructures were conjugated with 4-ethoxybenzoic acid in order to prove the possibility of organic modification and obtain a new functional nanomaterial. All of the nanophosphors synthesized exhibited intense green luminescence under UV light irradiation. Based on TEM (transmission electron microscopy) measurements, the diameters of the cores (≈12 nm) and core/shell particles (≈50 nm) were determined. To evaluate the cytotoxic activity of the nanomaterials obtained, their effect on human erythrocytes was investigated. LnF3 nanoparticles were bound to the erythrocyte membrane, without inducing any cytotoxic effects. After coating with silica, the nanoparticles revealed significant cytotoxicity. However, further functionalization of the nanomaterial with -NH2 groups as well as conjugation with 4-ethoxybenzoic acid entailed a decrease in cytotoxicity of the core/shell nanoparticles.

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

    PubMed

    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.

  9. Core-shell SiO2 -coated Fe3 O4 with a surface molecularly imprinted polymer coating of folic acid and its applicable magnetic solid-phase extraction prior to determination of folates in tomatoes.

    PubMed

    Areerob, Yonrapach; Sricharoen, Phitchan; Limchoowong, Nunticha; Chanthai, Saksit

    2016-08-01

    A novel core-shell magnetic surface molecularly imprinted polymer with folic acid as a template was successfully synthesized by the sol-gel method. To generate Lewis acid sites in the silica matrix for the interaction of the metal coordinate with the template, 3-aminopropyltriethoxysilane was used as a functional monomer, tetraethyl orthosilicate as a cross-linker, and aluminum ions as a dopant. The magnetite encapsulated by the silica shell plays an important role as a magnetic-coated polymer. The synthesized product was characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and FTIR and UV/Vis spectroscopy. The powder X-ray diffraction patterns, FTIR and UV/Vis spectra confirmed the characteristics of the as-prepared silica coated magnetite and folic acid molecularly imprinted polymer. It was successfully applied for magnetic solid-phase extraction prior to the determination of folates in tomato samples using high-performance liquid chromatography with photodiode array detection. The detection limit of the proposed method was 1.67 μg/L, and results were satisfactory, with a relative standard deviation of < 3.94%. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Macromolecular Systems with MSA-Capped CdTe and CdTe/ZnS Core/Shell Quantum Dots as Superselective and Ultrasensitive Optical Sensors for Picric Acid Explosive.

    PubMed

    Dutta, Priyanka; Saikia, Dilip; Adhikary, Nirab Chandra; Sarma, Neelotpal Sen

    2015-11-11

    This work reports the development of highly fluorescent materials for the selective and efficient detection of picric acid explosive in the nanomolar range by fluorescence quenching phenomenon. Poly(vinyl alcohol) grafted polyaniline (PPA) and its nanocomposites with 2-mercaptosuccinic acid (MSA)-capped CdTe quantum dots (PPA-Q) and with MSA-capped CdTe/ZnS core/shell quantum dots (PPA-CSQ) are synthesized in a single step free radical polymerization reaction. The thermal stability and photo stability of the polymer increases in the order of PPA < PPA-Q < PPA-CSQ. The polymers show remarkably high selectivity and efficient sensitivity toward picric acid, and the quenching efficiency for PPA-CSQ reaches up to 99%. The detection limits of PPA, PPA-Q, and PPA-CSQ for picric acid are found to be 23, 1.6, and 0.65 nM, respectively, which are remarkably low. The mechanism operating in the quenching phenomenon is proposed to be a combination of a strong inner filter effect and ground state electrostatic interaction between the polymers and picric acid. A portable and cost-effective electronic device for the visual detection of picric acid by the sensory system is successfully fabricated. The device is further employed for quantitative detection of picric acid in real water samples.

  11. Preparation of nanofiber polythiophene layered on Ba x Sr1- x Fe12O19/Fe3O4/polyacrylic acid core-shell structure and its microwave absorption investigation

    NASA Astrophysics Data System (ADS)

    Hosseini, Seyed Hossein; Moloudi, Maryam

    2015-09-01

    Ba x Sr1- x Fe12O19/Fe3O4/polyacrylic acid/polythiophene (Ba x Sr1- x Fe12O19/Fe3O4/PAA/PTh) nanocomposites with multi-core-shell structure were successfully synthesized by four steps. The samples were characterized by FTIR, X-ray diffraction (XRD), transmission electron microscope (TEM), vibrating sample magnetometer, and radar absorbing material reflectivity far-field radar cross-section method, respectively. XRD and TEM results indicated that the obtained nanoparticles have multi-core-shell morphology. The magnetic properties and microwave absorption analyses reveal that there are interphase interactions at the interface of Ba x Sr1- x Fe12O19, Fe3O4, PAA, and PTh, which can affect the magnetic properties and microwave absorption properties of the samples. The microwave-absorbing properties of nanocomposites were investigated at 8-14 GHz. A typical layer absorber exhibited an excellent microwave absorption with a -26 dB maximum absorption at 14 GHz. Compared with core material, the coercivity and saturation magnetization of multi-core-shell nanocomposites decrease obviously, but the microwave absorption properties of nanocomposites are improved greatly. The results show that these composite could be used as advancing absorption and shielding materials due to their favorable microwave-absorbing properties.

  12. Preparation and characterization of monodisperse core-shell Fe3O4@SiO2 microspheres and its application for magnetic separation of nucleic acids from E. coli BL21.

    PubMed

    Ma, Chao; Li, Chuanyan; He, Nongyue; Wang, Fang; Ma, Ningning; Zhang, Liming; Lu, Zhuoxuan; Ali, Zeeshan; Xi, Zhijiang; Li, Xiaolong; Liang, Gaofeng; Liu, Hongna; Deng, Yan; Xu, Lijian; Wang, Zhifei

    2012-12-01

    In this article, we present an easy route to prepare monodisperse core-shell Fe3O4@SiO2 microspheres with uniform size and shape. Their structures and properties were studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FT-IR), and vibrating sample magnetometer (VSM), respectively. The results showed that spherical Fe3O4 microspheres with well dispersion have a rough surface and an average diameter (about 500 nm). After the modification with silica, the particles have a well-defined core-shell structure and a much smoother surface and larger particle diameter (about 600 nm). Furthermore, VSM measurements indicated that the as-prepared Fe3O4 and Fe3O4@SiO2 microspheres were superparamagnetic at room temperature and the saturation magnetization (M(s)) were 58.110 emu/g and 33.479 emu/g, respectively. And then, the prepared monodisperse core-shell Fe3O4@SiO2 microspheres were subsequently applied to separate nucleic acids from the bacteria (E. coli BL21) and verified the great application prospects for bioseparation technology of the biomoleculars.

  13. Preparation of thermoresponsive Fe3O4/P(acrylic acid-methyl methacrylate-N-isopropylacrylamide) magnetic composite microspheres with controlled shell thickness and its releasing property for phenolphthalein.

    PubMed

    Zhang, Baoliang; Zhang, Hepeng; Fan, Xinlong; Li, Xiangjie; Yin, Dezhong; Zhang, Qiuyu

    2013-05-15

    In this work, Fe3O4/P(acrylic acid-methyl methacrylate-N-isopropylacrylamide) (Fe3O4/P(AA-MMA-NIPAm)) thermoresponsive magnetic composite microspheres have been prepared by controlled radical polymerization in the presence of 1,1-diphenylethene (DPE). The shell thickness of thermosensitive polymer (PNIPAm), which was on the surface of the microspheres, can be controlled by using DPE method. The morphology and thermosensitive properties of the composite microspheres, polymerization mechanism of the shell were characterized by TEM, FTIR, VSM, Laser Particle Sizer, TGA, NMR, and GPC. The microspheres with narrow particle size distribution show high saturation magnetization and superparamagnetism. The thermosensitive properties of the composite microspheres can be adjusted indirectly via controlling the addition amount of monomer (NIPAm) in the second step during controlled radical polymerization. Phenolphthalein was chosen as a model drug to investigate drug release behavior of the thermoresponsive magnetic composite microspheres with different shell thickness. Controlled drug release testing reveals that the release behavior depends on the thickness of polymer on the surface of the microspheres. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Multiple shells in IRC+10216: shell properties

    NASA Astrophysics Data System (ADS)

    Mauron, N.; Huggins, P. J.

    2000-07-01

    We report on the properties of the multiple shells in the circumstellar envelope of IRC+10216, using deep optical imaging, including data from the Hubble Space Telescope. The intensity profiles confirm the presence of thin ( ~ 0farcs5 -3'' ec), limb-brightened shells in the envelope, seen in stellar and ambient Galactic light scattered by dust. The shells are spaced at irregular intervals of ~ 5'' ec-20'' ec, corresponding to time scales of 200-800 yr, although intervals as short as ~ 1'' ec (40 yr) are seen close to the star. The location of the main shells shows a good correlation with high-resolution, molecular line maps of the inner envelope, indicating that the dust and gas are well coupled. The shell/intershell density contrast is typically ~ 3, and we find that the shells form the dominant mass component of the circumstellar envelope. The shells exhibit important evolutionary effects: the thickness increases with increasing radius, with an effective dispersion velocity of 0.7 km s-1 and there is evidence for shell interactions. Despite the presence of bipolar structure close to the star, the global shell pattern favors a roughly isotropic, episodic mass loss mechanism, with a range of time scales. Based on observations made with the Canada-France-Hawaii telescope, operated by CNRS, NRCC and UH, and on dearchived observations made with the NASA/ESA Hubble Space Telescope, operated by AURA Inc., under NASA contract NAS5-26555

  15. Biomineralisation in Mollusc shells

    NASA Astrophysics Data System (ADS)

    Dauphin, Y.; Cuif, J. P.; Salomé, M.; Williams, C. T.

    2009-04-01

    and polysaccharides, with a large range of molecular weights. Proteins are rich in acidic aminoacids (aspartic and glutamic acids). Sugars are usually sulphated, and very acidic. Several hundreds of proteins and sugars are present in the SOM. The compositions of IOM and SOM are characteristic for each layer present in a shell. Topographical relationships of mineral and organic components are visible at different scales of observation. SEM images of etched surfaces display the growth line rhythmicity and concordance between adjacent microstructural units. EPMA maps show similar chemical growth lines in various structures. Whatever the taxa, the average thickness of growth lines is about 2-3 µm, indicating an inner biological rhythm, not dependant on the environmental conditions. Such growth lines are observed in deep sea molluscs at depth where diurnal changes in light and temperature are absent. However, the role of the environment is shown by larger periodicities. Sulphur deserves a special interest, because it is associated with the organic matrices. Electrophoretic data have shown that acidic sulphated sugars are abundant in some layers. XANES analyses confirm these results. New microscopic techniques allow us to obtain images at a submicrometer scale. AFM images show that all the microstructural units (i.e. tablets, prisms etc.), calcite or aragonite, are composed of small sub-spherical granules with a diameter typically of about 50 nm. These granules are surrounded by a thin cortex (about 8 nm) of organic and/or amorphous material, and are organo-composite material as shown by phase images. They do not have crystalline shapes, despite the fact that the units they build are often monocrystalline. Molecular biology and genetic studies confirm that the control of the biomineralisation process is exerted at the scale of the whole organism: the expression of genes encoding major shell matrix proteins clearly indicates a regular separation of calcite and aragonite

  16. Classification Shell Game.

    ERIC Educational Resources Information Center

    Etzold, Carol

    1983-01-01

    Discusses shell classification exercises. Through keying students advanced from the "I know what a shell looks like" stage to become involved in the classification process: observing, labeling, making decisions about categories, and identifying marine animals. (Author/JN)

  17. Hierarchical inorganic-organic multi-shell nanospheres for intervention and treatment of lead-contaminated blood

    NASA Astrophysics Data System (ADS)

    Khairy, Mohamed; El-Safty, Sherif A.; Shenashen, Mohamed. A.; Elshehy, Emad A.

    2013-08-01

    The highly toxic properties, bioavailability, and adverse effects of Pb2+ species on the environment and living organisms necessitate periodic monitoring and removal whenever possible of Pb2+ concentrations in the environment. In this study, we designed a novel optical multi-shell nanosphere sensor that enables selective recognition, unrestrained accessibility, continuous monitoring, and efficient removal (on the order of minutes) of Pb2+ ions from water and human blood, i.e., red blood cells (RBCs). The consequent decoration of the mesoporous core/double-shell silica nanospheres through a chemically responsive azo-chromophore with a long hydrophobic tail enabled us to create a unique hierarchical multi-shell sensor. We examined the efficiency of the multi-shell sensor in removing lead ions from the blood to ascertain the potential use of the sensor in medical applications. The lead-induced hemolysis of RBCs in the sensing/capture assay was inhibited by the ability of the hierarchical sensor to remove lead ions from blood. The results suggest the higher flux and diffusion of Pb2+ ions into the mesopores of the core/multi-shell sensor than into the RBC membranes. These findings indicate that the sensor could be used in the prevention of health risks associated with elevated blood lead levels such as anemia.The highly toxic properties, bioavailability, and adverse effects of Pb2+ species on the environment and living organisms necessitate periodic monitoring and removal whenever possible of Pb2+ concentrations in the environment. In this study, we designed a novel optical multi-shell nanosphere sensor that enables selective recognition, unrestrained accessibility, continuous monitoring, and efficient removal (on the order of minutes) of Pb2+ ions from water and human blood, i.e., red blood cells (RBCs). The consequent decoration of the mesoporous core/double-shell silica nanospheres through a chemically responsive azo-chromophore with a long hydrophobic tail enabled

  18. Shell Worlds: The Question of Shell Stability

    NASA Astrophysics Data System (ADS)

    Roy, K. L.; Kennedy, R. G., III; Fields, D. E.

    The initial idea of shell worlds was first proposed in the January 2009 edition of JBIS. In that paper the stability of the shell around a central world was not discussed at any length except to say that it was stable due to forces induced by gravity. This paper demonstrates in a qualitative and quantitative manner that a material shell supported by atmospheric pressure around a moon or small planet is indeed stable and does not require active measures to remain centered, provided that the central body is large enough. The minimal size of the central body to provide this stability is discussed.

  19. MT1-MMP Responsive Doxorubicin Conjugated Poly(lactic-co-glycolic Acid)/Poly(styrene-alt-maleic Anhydride) Core/Shell Microparticles for Intrahepatic Arterial Chemotherapy of Hepatic Cancer.

    PubMed

    Davaa, Enkhzaya; Lee, Junghan; Jenjob, Ratchapol; Yang, Su-Geun

    2017-01-11

    In this study, we demonstrated that the MT1-MMP-responsive peptide (sequence: GPLPLRSWGLK) and doxorubicin-conjugated poly(lactic-co-glycolic acid/poly(styrene-alt-maleic anhydride) core/shell microparticles (PLGA/pSMA MPs) can be applied for intrahepatic arterial injection for hepatocellular carcinoma (HCC). PLGA/pSMA MPs were prepared with a capillary-focused microfluidic device. The particle size, observed by scanning electron microscopy (SEM), was around 22 ± 3 μm. MT1-MMP-responsive peptide and doxorubicin (DOX) were chemically conjugated with pSMA segments on the shell of MPs to form a PLGA/pSMA-peptide-DOX complex, resulting in high encapsulation efficiency (91.1%) and loading content (2.9%). DOX was released from PLGA/pSMA-peptide-DOX MPs in a pH-dependent manner (∼25% at pH 5.4 and ∼8% at pH 7.4) and accumulated significantly in an MT1-MMP-overexpressing Hep3B cell line. An in vivo intrahepatic injection study showed localization of MPs on the hepatic vessels and hepatic lobes up to 24 h after the injection without any shunting to the lung. Moreover, MPs efficiently inhibited tumor growth of Hep3B hepatic tumor xenografted mouse models. We expect that PLGA/pSMA-peptide-DOX MPs can be utilized as an effective intrahepatic drug delivery system for the treatment of HCC.

  20. Metal-organic framework UiO-66 modified magnetite@silica core-shell magnetic microspheres for magnetic solid-phase extraction of domoic acid from shellfish samples.

    PubMed

    Zhang, Wenmin; Yan, Zhiming; Gao, Jia; Tong, Ping; Liu, Wei; Zhang, Lan

    2015-06-26

    Fe3O4@SiO2@UiO-66 core-shell magnetic microspheres were synthesized and characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry, vibrating sample magnetometry, nitrogen adsorption porosimetry and zeta potential analyzer. The synthesized Fe3O4@SiO2@UiO-66 microspheres were first used for magnetic solid-phase extraction (MSPE) of domoic acid (DA) in shellfish samples. Combined with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), a fast, simple and sensitive method for the determination of DA was established successfully. Under the optimized conditions, the developed method showed short analysis time, good linearity (r(2) = 0.9990), low limit of detection (1.45 pg mL(-1); S/N = 3:1), low limit of quantification (4.82 pg mL(-1); S/N = 10:1), and good extraction repeatability (RSD ≤ 5.0%; n = 5). Real shellfish samples were processed using the developed method, and trace level of DA was detected. The results demonstrate that Fe3O4@SiO2@UiO-66 core-shell magnetic microspheres are the promising sorbents for rapid and efficient extraction of polar analytes from complex biological samples.

  1. Fluorescent spherical monodisperse silica core-shell nanoparticles with a protein-binding biofunctional shell.

    PubMed

    Weber, Achim; Herz, Marion; Tovar, Günter E M

    2013-01-01

    The production of uniform protein-binding biofunctional fluorescent spherical silica core-shell nanoparticles by a modified Stöber method is described. Fluorescent particle cores with diameters of 100 nm are synthesized in a two-step reaction. Functional shells for subsequent coupling reactions are provided by generating organic shells providing amine and carboxyl groups at the nanoparticles' shell surface. Conjugation of proteins to the nanoparticles is achieved using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) as coupling agent. The characterization of the nanoparticle systems and their surface functionalization is done by microelectrophoresis, dynamic light scattering (DLS), and a colorimetric detection of the amount of nanoparticle-attached protein via a bicinchoninic acid (BCA) assay. Fluorescently spiked nanoparticle cores with biofunctional shells for molecular recognition reactions may be used as imaging tools or reporter systems.

  2. Fluctuating shells under pressure

    PubMed Central

    Paulose, Jayson; Vliegenthart, Gerard A.; Gompper, Gerhard; Nelson, David R.

    2012-01-01

    Thermal fluctuations strongly modify the large length-scale elastic behavior of cross-linked membranes, giving rise to scale-dependent elastic moduli. Whereas thermal effects in flat membranes are well understood, many natural and artificial microstructures are modeled as thin elastic shells. Shells are distinguished from flat membranes by their nonzero curvature, which provides a size-dependent coupling between the in-plane stretching modes and the out-of-plane undulations. In addition, a shell can support a pressure difference between its interior and its exterior. Little is known about the effect of thermal fluctuations on the elastic properties of shells. Here, we study the statistical mechanics of shape fluctuations in a pressurized spherical shell, using perturbation theory and Monte Carlo computer simulations, explicitly including the effects of curvature and an inward pressure. We predict novel properties of fluctuating thin shells under point indentations and pressure-induced deformations. The contribution due to thermal fluctuations increases with increasing ratio of shell radius to thickness and dominates the response when the product of this ratio and the thermal energy becomes large compared with the bending rigidity of the shell. Thermal effects are enhanced when a large uniform inward pressure acts on the shell and diverge as this pressure approaches the classical buckling transition of the shell. Our results are relevant for the elasticity and osmotic collapse of microcapsules. PMID:23150558

  3. Conditions of Mytilus edulis extracellular body fluids and shell composition in a pH-treatment experiment: Acid-base status, trace elements and δ11B

    NASA Astrophysics Data System (ADS)

    Heinemann, Agnes; Fietzke, Jan; Melzner, Frank; BöHm, Florian; Thomsen, JöRn; Garbe-SchöNberg, Dieter; Eisenhauer, Anton

    2012-01-01

    Mytilus edulis were cultured for 3 months under six different seawater pCO2 levels ranging from 380 to 4000 μatm. Specimen were taken from Kiel Fjord (Western Baltic Sea, Germany) which is a habitat with high and variable seawater pCO2 and related shifts in carbonate system speciation (e.g., low pH and low CaCO3 saturation state). Hemolymph (HL) and extrapallial fluid (EPF) samples were analyzed for pH and total dissolved inorganic carbon (CT) to calculate pCO2 and [HCO3-]. A second experiment was conducted for 2 months with three different pCO2 levels (380, 1400 and 4000 μatm). Boron isotopes (δ11B) were investigated by LA-MC-ICP-MS (Laser Ablation-Multicollector-Inductively Coupled Plasma-Mass Spectrometry) in shell portions precipitated during experimental treatment time. Additionally, elemental ratios (B/Ca, Mg/Ca and Sr/Ca) in the EPF of specimen from the second experiment were measured via ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometry). Extracellular pH was not significantly different in HL and EPF but systematically lower than ambient water pH. This is due to high extracellular pCO2 values, a prerequisite for metabolic CO2 excretion. No accumulation of extracellular [HCO3-] was measured. Elemental ratios (B/Ca, Mg/Ca and Sr/Ca) in the EPF increased slightly with pH which is in accordance with increasing growth and calcification rates at higher seawater pH values. Boron isotope ratios were highly variable between different individuals but also within single shells. This corresponds to a high individual variability in fluid B/Ca ratios and may be due to high boron concentrations in the organic parts of the shell. The mean δ11B value shows no trend with pH but appears to represent internal pH (EPF) rather than ambient water pH.

  4. Bioinorganic magnetic core-shell nanocomposites carrying antiarthritic agents: intercalation of ibuprofen and glucuronic acid into Mg-Al-layered double hydroxides supported on magnesium ferrite.

    PubMed

    Ay, Ahmet Nedim; Zümreoglu-Karan, Birgül; Temel, Abidin; Rives, Vicente

    2009-09-21

    This paper describes the synthesis and characterization of a composite constituted by an antiarthritic agent (AA) intercalated into a layered double hydroxide (LDH) supported on magnesium ferrite. Core-shell nanocomposites were prepared by depositing Mg-Al-NO(3)-LDH on a MgFe(2)O(4) core prepared by calcination of a nonstoichiometric Mg-Fe-CO(3)-LDH. Intercalation of ibuprofen and glucuronate anions was performed by ion-exchange with nitrate ions. The structural characteristics of the obtained products were investigated by powder X-ray diffraction, element chemical analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Morphologies of the nanocomposite particles were examined by scanning electron microscopy and transmission electron microscopy. The products were shown to intercalate substantial amounts of AA with enhanced thermal stabilities. Room-temperature magnetic measurements by vibrating sample magnetometry revealed that the products show soft ferromagnetic properties suitable for potential utilization in magnetic arthritis therapy.

  5. Multiple shell fusion targets

    DOEpatents

    Lindl, J.D.; Bangerter, R.O.

    1975-10-31

    Multiple shell fusion targets for use with electron beam and ion beam implosion systems are described. The multiple shell targets are of the low-power type and use a separate relatively low Z, low density ablator at large radius for the outer shell, which reduces the focusing and power requirements of the implosion system while maintaining reasonable aspect ratios. The targets use a high Z, high density pusher shell placed at a much smaller radius in order to obtain an aspect ratio small enough to protect against fluid instability. Velocity multiplication between these shells further lowers the power requirements. Careful tuning of the power profile and intershell density results in a low entropy implosion which allows breakeven at low powers. For example, with ion beams as a power source, breakeven at 10-20 Terrawatts with 10 MeV alpha particles for imploding a multiple shell target can be accomplished.

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

    PubMed

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

    2017-10-10

    The development of new stationary phase 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 firstly 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. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  7. Imperfection Insensitive Thin Shells

    NASA Astrophysics Data System (ADS)

    Ning, Xin

    The buckling of axially compressed cylindrical shells and externally pressurized spherical shells is extremely sensitive to even very small geometric imperfections. In practice this issue is addressed by either using overly conservative knockdown factors, while keeping perfect axial or spherical symmetry, or adding closely and equally spaced stiffeners on shell surface. The influence of imperfection-sensitivity is mitigated, but the shells designed from these approaches are either too heavy or very expensive and are still sensitive to imperfections. Despite their drawbacks, these approaches have been used for more than half a century. This thesis proposes a novel method to design imperfection-insensitive cylindrical shells subject to axial compression. Instead of following the classical paths, focused on axially symmetric or high-order rotationally symmetric cross-sections, the method in this thesis adopts optimal symmetry-breaking wavy cross-sections (wavy shells). The avoidance of imperfection sensitivity is achieved by searching with an evolutionary algorithm for smooth cross-sectional shapes that maximize the minimum among the buckling loads of geometrically perfect and imperfect wavy shells. It is found that the shells designed through this approach can achieve higher critical stresses and knockdown factors than any previously known monocoque cylindrical shells. It is also found that these shells have superior mass efficiency to almost all previously reported stiffened shells. Experimental studies on a design of composite wavy shell obtained through the proposed method are presented in this thesis. A method of making composite wavy shells and a photogrametry technique of measuring full-field geometric imperfections have been developed. Numerical predictions based on the measured geometric imperfections match remarkably well with the experiments. Experimental results confirm that the wavy shells are not sensitive to imperfections and can carry axial compression

  8. Kinetic, equilibrium isotherm and thermodynamic studies of Cr(VI) adsorption onto low-cost adsorbent developed from peanut shell activated with phosphoric acid.

    PubMed

    ALOthman, Zeid A; Naushad, Mu; Ali, Rahmat

    2013-05-01

    A particular agricultural waste, peanut shell, has been used as precursor for activated carbon production by chemical activation with H₃PO₄. Unoxidized activated carbon was prepared in nitrogen atmosphere which was then heated in air at a desired temperature to get oxidized activated carbon. The prepared carbons were characterized for surface area, surface morphology, and pore volume and utilized for the removal of Cr(VI) from aqueous solution. Batch mode experiments were conducted to study the effects of pH, contact time, particle size, adsorbent dose, initial concentration of adsorbate, and temperature on the adsorption of Cr(VI). Cr(VI) adsorption was significantly dependent on solution pH, and the optimum adsorption was observed at pH 2. Pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were used to analyze the kinetic data obtained at different initial Cr(VI) concentrations. The adsorption kinetic data were described very well by the pseudo-second-order model. Equilibrium isotherm data were analyzed by the Langmuir, Freundlich, and Temkin models. The results showed that the Langmuir adsorption isotherm model fitted the data better in the temperature range studied. The adsorption capacity which was found to increase with temperature showed the endothermic nature of Cr(VI) adsorption. The thermodynamic parameters, such as Gibb's Free energy change (ΔG°), standard enthalpy change (ΔH°), and standard entropy change (ΔS°) were evaluated.

  9. A highly selective photoelectrochemical biosensor for uric acid based on core-shell Fe3O4@C nanoparticle and molecularly imprinted TiO2.

    PubMed

    Zhang, Chunjing; Si, Shihui; Yang, Zhengpeng

    2015-03-15

    Combining the surface modification and molecular imprinting technique, a novel photoelectrochemical sensing platform with excellent photochemical catalysis and molecular recognition capabilities was established for the detection of uric acid based on the magnetic immobilization of Fe3O4@C nanoparticles onto magnetic glassy carbon electrode (MGCE) and modification of molecularly imprinted TiO2 film on Fe3O4@C. The developed biosensor was highly sensitive to uric acid in solutions, with a linear range from 0.3 to 34µM and a limit of detection of 0.02μM. Furthermore, the biosensor exhibited outstanding selectivity while used in coexisting systems containing various interferents with high concentration. The practical application of the biosensor was also realized for the selective detection of uric acid in spiked samples. The study made a successful attempt in the development of highly selective and sensitive photoelectrochemical biosensor for urine monitoring.

  10. Static cylindrical matter shells

    NASA Astrophysics Data System (ADS)

    Arık, Metin; Delice, Özgür

    2005-08-01

    Static cylindrical shells composed of massive particles arising from matching of two different Levi-Civita space-times are studied for the shell satisfying either an isotropic or an anisotropic equation of state. We find that these solutions satisfy the energy conditions for certain ranges of the parameters.

  11. Iridescence color of shells

    NASA Astrophysics Data System (ADS)

    Liu, Yan

    2002-06-01

    Some shells from both salt water and fresh water show the phenomenon of iridescence color. Pearls and mother-of-pearls also display this phenomenon. In the past, the cause of the iridescence color was attributed to interference. A scanning electron microscope (SEM) was used to study the surface structure of the shell of the mollusk Pinctada Margaritifera. There is a groove structure of reflection grating on the surface area in where the iridescence color appears. An optic experiment with a laser obtained a diffraction pattern produced by the reflection grating structure of the shell. The study led to a conclusion that the iridescence color of the shell is caused by diffraction. A SEM image of the shells of an abalone Haliotis Rufescens (red abalone) showed a statistically regularly arranged tile structure that serves as a two-dimensional grating. This grating structure causes the iridescence color of the shell of red abalone. The dominant color of the iridescence of shells is caused by the uneven grating efficiency in the visible wavelength range when a shell functions as a reflection grating. The wavelength of the dominant color should be at or near the wavelength of the maximum efficiency of the grating.

  12. Decoration of gold nanoparticles with thiolated pH-responsive polymeric (PEG-b-p(2-dimethylamio ethyl methacrylate-co-itaconic acid) shell: A novel platform for targeting of anticancer agent.

    PubMed

    Ghorbani, Marjan; Hamishehkar, Hamed

    2017-12-01

    The aim of this study was to design and develop a new pH-responsive nano-platform for controlled and targeted delivery of anticancer drugs. Engineering of pH-responsive nanocarriers was prepared via decoration of gold nanoparticles (NPs) by thiolated (methoxy-poly(ethylene glycol)-b-poly((2-dimethylamino) ethyl methacrylate-co-itaconic acid) (mPEG-b-p(DMAEMA-co-IA) copolymer and fully characterized by various techniques and subsequently used for loading and targeted delivery of anticancer agent, methotrexate (MTX). By conjugation of MTX with the amino groups of polymeric shell of gold NPs (with the high loading capacity of 31%), since MTX is also the target ligand of folate receptors, the targeted performance of NPs examined through the cell uptake study. The results indicated that MTX-loaded NPs showed 1.3 times more cell internalization than MTX free NPs. Cell cytotoxicity studies pointed out ~1.5 and 3 times higher cell cytotoxicity after 24h for MTX-loaded nanoparticles than MTX in MTT assay and cell cycle arrest experiments, respectively. Additionally, mPEG was used as the outer shell of NPs which caused the long-term dispersibility of the NPs even under high ionic strength. The in-vitro pH-triggered drug release of MTX showed that MTX released more than three times in simulated cancerous tissue (40°C, pH5.3) than physiologic condition (37°C, pH7.4) during 48h. The results of various experiments determined that the developed smart nanocarrier proposed as a promising nanocarrier for active and passive targeting of anionic anti-cancer agents such as MTX. Copyright © 2017. Published by Elsevier B.V.

  13. Cohesive Elements for Shells

    NASA Technical Reports Server (NTRS)

    Davila, Carlos G.; Camanho, Pedro P.; Turon, Albert

    2007-01-01

    A cohesive element for shell analysis is presented. The element can be used to simulate the initiation and growth of delaminations between stacked, non-coincident layers of shell elements. The procedure to construct the element accounts for the thickness offset by applying the kinematic relations of shell deformation to transform the stiffness and internal force of a zero-thickness cohesive element such that interfacial continuity between the layers is enforced. The procedure is demonstrated by simulating the response and failure of the Mixed Mode Bending test and a skin-stiffener debond specimen. In addition, it is shown that stacks of shell elements can be used to create effective models to predict the inplane and delamination failure modes of thick components. The results indicate that simple shell models can retain many of the necessary predictive attributes of much more complex 3D models while providing the computational efficiency that is necessary for design.

  14. The use of land snail shells in paleoenvironmental reconstruction

    NASA Astrophysics Data System (ADS)

    Goodfriend, Glenn A.

    Fossil land snail shells constitute a valuable source of paleoenvironmental information for the Quaternary. They can be dated by a variety of methods, including radiocarbon, amino acid racemization and epimerization, and perhaps also {Th}/{U} and ESR. The vast majority of paleoenvironmental studies based on land snail shells have examined the faunal composition of fossil assemblages, from which a variety of paleoenvironmental characteristics such as biome, temperature, and moisture conditions have been reconstructed. Still, there are a number of problems involved in using this approach and these are discussed. Shell morphology has occasionally been used to reconstruct such factors as rainfall and temperature. Stable isotope studies on Quaternary land snails include: analysis of δ18O values of organic matter in the shells, to reconstruct C 4 plant distributions from which rainfall amounts can be inferred, and analysis of δ18O values of shell carbonate, from which trends in the oxygen isotope composition of rainfall can be reconstructed. Stable carbon isotopes of shell carbonate have also been studied but their interpretation is not clear. Amino acid epimerization analysis ( {dalloisoleucine }/{l-isoleucine } ratios) of land snail shells has been used for estimation of paleotemperatures. Some potential uses of land snail shells for paleoenvironmental reconstruction include the study of stable isotopes of H and N, periodic growth lines, and deposits of pedogenic carbonates on the shells.

  15. Gold decorated NaYF4:Yb,Er/NaYF4/silica (core/shell/shell) upconversion nanoparticles for photothermal destruction of BE(2)-C neuroblastoma cells

    NASA Astrophysics Data System (ADS)

    Qian, Li Peng; Zhou, Li Han; Too, Heng-Phon; Chow, Gan-Moog

    2011-02-01

    Gold decorated NaYF4:Yb,Er/NaYF4/silica (core/shell/shell) upconversion (UC) nanoparticles ( 70-80 nm) were synthesized using tetraethyl orthosilicate and chloroauric acid in a one-step reverse microemulsion method. Gold nanoparticles ( 6 nm) were deposited on the surface of silica shell of these core/shell/shell nanoparticles. The total upconversion emission intensity (green, red, and blue) of the core/shell/shell nanoparticles decreased by 31% after Au was deposited on the surface of silica shell. The upconverted green light was coupled with the surface plasmon of Au leading to rapid heat conversion. These UC/silica/Au nanoparticles were very efficient to destroy BE(2)-C cancer cells and showed strong potential in photothermal therapy.

  16. Controlling the Mesostructure Formation within the Shell of Novel Cubic/Hexagonal Phase Cetyltrimethylammonium Bromide-Poly(acrylamide-acrylic acid) Capsules for pH Stimulated Release.

    PubMed

    Tangso, Kristian J; Patel, Hetika; Lindberg, Seth; Hartley, Patrick G; Knott, Robert; Spicer, Patrick T; Boyd, Ben J

    2015-11-11

    The self-assembly of ordered structures in mixtures of oppositely charged surfactant and polymer systems has been exploited in various cleaning and pharmaceutical applications and continue to attract much interest since their discovery in the late twentieth century. The ability to control the electrostatic and hydrophobic interactions that dictate the formation of liquid crystalline phases in these systems is advantageous in manipulation of structure and rendering them responsive to external stimuli. Nanostructured capsules comprised of the cationic surfactant, cetyltrimethylammonium bromide (CTAB), and the diblock copolymer poly(acrylamide-acrylic acid) (PAAm-AA) were prepared to assess their potential as pH responsive nanomaterials. Crossed-polarizing light microscopy (CPLM) and small-angle X-ray scattering (SAXS) identified coexisting Pm3n cubic and hexagonal phases at the surfactant-polymer interface. The hydrophobic and electrostatic interactions between the oppositely charged components were studied by varying temperature and solution pH, respectively, and were found to influence the liquid crystalline nanostructure formed. The lattice parameter of the mesophases and the fraction of cubic phase in the system decreased upon heating. Acidic conditions resulted in the loss of the highly ordered structures due to protonation of the carboxylic acid group, and subsequent reduction of attractive forces previously present between the oppositely charged molecules. The rate of release of the model hydrophilic drug, Rhodamine B (RhB), from nanostructured macro-sized capsules significantly increased when the pH of the solution was adjusted from pH 7 to pH 2. This allowed for immediate release of the compound of interest "on demand", opening new options for structured materials with increased functionality over typical layer-by-layer capsules.

  17. Hollow spherical shell manufacture

    DOEpatents

    O'Holleran, Thomas P.

    1991-01-01

    A process for making a hollow spherical shell of silicate glass composition in which an aqueous suspension of silicate glass particles and an immiscible liquid blowing agent is placed within the hollow spherical cavity of a porous mold. The mold is spun to reduce effective gravity to zero and to center the blowing agent, while being heated so as to vaporize the immiscible liquid and urge the water carrier of the aqueous suspension to migrate into the body of the mold, leaving a green shell compact deposited around the mold cavity. The green shell compact is then removed from the cavity, and is sintered for a time and a temperature sufficient to form a silicate glass shell of substantially homogeneous composition and uniform geometry.

  18. Fragmentation of Shells

    NASA Astrophysics Data System (ADS)

    Wittel, F.; Kun, F.; Herrmann, H. J.; Kröplin, B. H.

    2004-07-01

    We present a theoretical and experimental study of the fragmentation of closed thin shells made of a disordered brittle material. Experiments were performed on brown and white hen egg shells under two different loading conditions: impact with a hard wall and explosion by a combustible mixture. Both give rise to power law fragment size distributions. A three-dimensional discrete element model of shells is worked out. Based on simulations of the model, we give evidence that power law fragment mass distributions arise due to an underlying phase transition which proved to be abrupt for explosion and continuous for impact. We demonstrate that the fragmentation of closed shells defines a new universality class of fragmentation phenomena.

  19. Hollow spherical shell manufacture

    DOEpatents

    O'Holleran, T.P.

    1991-11-26

    A process is disclosed for making a hollow spherical shell of silicate glass composition in which an aqueous suspension of silicate glass particles and an immiscible liquid blowing agent is placed within the hollow spherical cavity of a porous mold. The mold is spun to reduce effective gravity to zero and to center the blowing agent, while being heated so as to vaporize the immiscible liquid and urge the water carrier of the aqueous suspension to migrate into the body of the mold, leaving a green shell compact deposited around the mold cavity. The green shell compact is then removed from the cavity, and is sintered for a time and a temperature sufficient to form a silicate glass shell of substantially homogeneous composition and uniform geometry. 3 figures.

  20. Shells and Patterns

    ERIC Educational Resources Information Center

    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…

  1. Shell forming system

    NASA Technical Reports Server (NTRS)

    Kendall, Jr., James M. (Inventor); Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor)

    1990-01-01

    Hollow shells of high uniformity are formed by emitting liquid through an outer nozzle and gas through an inner nozzle, to form a hollow extrusion, by flowing the gas at a velocity between about 1.3 and 10 times the liquid velocity. The natural breakup rate of the extrusion can be increased to decrease shell size by applying periodic perturbations to one of the materials prior to exiting the nozzles, to a nozzle, or to the extrusion.

  2. Shells and Patterns

    ERIC Educational Resources Information Center

    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…

  3. Double shell liner implosions

    SciTech Connect

    Sorokin, S. A.; Chaikovsky, S. A.

    1997-05-05

    Experiments on the double shell liner (DSL) implosions with and without an initial axial magnetic were performed on the SNOP-3 pulse generator (1.1 MA, 100 ns). In implosions of a DSL without an initial axial magnetic field, high radial compressions of the inner shell were observed, as in previous experiments with an initial axial magnetic field. Possible mechanisms for the formation of the initial azimuthal magnetic field are discussed.

  4. Magnetic behavior of core shell particles

    NASA Astrophysics Data System (ADS)

    Lin, Chun-Rong; Wang, Cheng-Chien; Chen, I.-Han

    2006-09-01

    We have prepared composite magnetic core-shell particles using the process of soap-free emulsion polymerization and the co-precipitation method. The shell of the synthesized composite sphere is cobalt ferrite (CoFe 2O 4) nanoparticles and the core consists of poly(styrene-co-methacrylic acid) polymer. The mean crystallite sizes of the coated CoFe 2O 4 nanoparticles were controlled in the range of 2.4-6.7 nm by the concentration of [NH 4+] and heated temperature. The magnetic properties of the core-shell spherical particles can go from superparamagnetic to ferromagnetic behavior depending on the crystalline sizes of CoFe 2O 4.

  5. Preparation of core-shell structure Fe3 O4 @SiO2 superparamagnetic microspheres immoblized with iminodiacetic acid as immobilized metal ion affinity adsorbents for His-tag protein purification.

    PubMed

    Ni, Qian; Chen, Bing; Dong, Shaohua; Tian, Lei; Bai, Quan

    2016-04-01

    The core-shell structure Fe3 O4 /SiO2 magnetic microspheres were prepared by a sol-gel method, and immobiled with iminodiacetic acid (IDA) as metal ion affinity ligands for protein adsorption. The size, morphology, magnetic properties and surface modification of magnetic silica nanospheres were characterized by various modern analytical instruments. It was shown that the magnetic silica nanospheres exhibited superparamagnetism with saturation magnetization values of up to 58.1 emu/g. Three divalent metal ions, Cu(2+) , Ni(2+) and Zn(2+) , were chelated on the Fe3 O4 @SiO2 -IDA magnetic microspheres to adsorb lysozyme. The results indicated that Ni(2+) -chelating magnetic microspheres had the maximum adsorption capacity for lysozyme of 51.0 mg/g, adsorption equilibrium could be achieved within 60 min and the adsorbed protein could be easily eluted. Furthermore, the synthesized Fe3 O4 @SiO2 -IDA-Ni(2+) magnetic microspheres were successfully applied for selective enrichment lysozyme from egg white and His-tag recombinant Homer 1a from the inclusion extraction expressed in Escherichia coli. The result indicated that the magnetic microspheres showed unique characteristics of high selective separation behavior of protein mixture, low nonspecific adsorption, and easy handling. This demonstrates that the magnetic silica microspheres can be used efficiently in protein separation or purification and show great potential in the pretreatment of the biological sample.

  6. Influence of microgel architecture and oil polarity on stabilization of emulsions by stimuli-sensitive core-shell poly(N-isopropylacrylamide-co-methacrylic acid) microgels: Mickering versus Pickering behavior?

    PubMed

    Schmidt, Sabrina; Liu, Tingting; Rütten, Stephan; Phan, Kim-Ho; Möller, Martin; Richtering, Walter

    2011-08-16

    Charged poly(N-isopropylacrylamide-co-methacrylic acid) [P(NiPAM-co-MAA)] microgels can stabilize thermo- and pH-sensitive emulsions. By placing charged units at different locations in the microgels and comparing the emulsion properties, we demonstrate that their behaviors as emulsion stabilizers are very different from molecular surfactants and rigid Pickering stabilizers. The results show that the stabilization of the emulsions is independent of electrostatic repulsion although the presence and location of charges are relevant. Apparently, the charges facilitate emulsion stabilization via the extent of swelling and deformability of the microgels. The stabilization of these emulsions is linked to the swelling and structure of the microgels at the oil-water interface, which depends not only on the presence of charged moieties and on solvent polarity but also on the microgel (core-shell) morphology. Therefore, the internal soft and porous structure of microgels is important, and these features make microgel-stabilized emulsions characteristically different from classical, rigid-particle-stabilized Pickering emulsions, the stability of which depends on the surface properties of the particles.

  7. Achieving independent control of core diameter and carbon shell thickness in Pd-C core-shell nanoparticles by gas phase synthesis

    NASA Astrophysics Data System (ADS)

    Singh, Vinod; Mehta, B. R.; Sengar, Saurabh K.; Karakulina, Olesia M.; Hadermann, Joke; Kaushal, Akshey

    2017-07-01

    Pd-C core-shell nanoparticles with independently controllable core size and shell thickness are grown by gas phase synthesis. First, the core size is selected by electrical mobility values of charged particles, and second, the shell thickness is controlled by the concentration of carbon precursor gas. The carbon shell grows by adsorption of carbon precursor gas molecules on the surface of nanoparticles, followed by sintering. The presence of a carbon shell on Pd nanoparticles is potentially important in hydrogen-related applications operating at high temperatures or in catalytic reactions in acidic/aqueous environments.

  8. Determination of intrinsic bacterial surface acidity constants using a donnan shell model and a continuous pK(a) distribution method.

    PubMed

    Martinez, Raul E; Smith, D Scott; Kulczycki, Ezra; Ferris, F Grant

    2002-09-01

    Intrinsic acidity constants (pK(a)(int)) for Bacillus subtilis (Gram+) and Escherichia coli (Gram-) cells were calculated from potentiometric titration data at different salt concentrations. Master curves were generated by replotting charge excess data as a function of pH(S) (pH at the location of surface reactive sites) where pH(S) was determined as a function of Donnan potential, Psi(DON). This potential decreased in magnitude with increasing ionic strength, from -48.5+/-0.2 to -3.5+/-0.0 mV for B. subtilis and -47.9+/-0.3 to -3.5+/-0.0 mV for E. coli at 0.01 and 0.5 M K(+), respectively, indicating an efficient surface charge neutralization by counterions. A fully optimized continuous (FOCUS) pK(a) distribution method revealed four binding sites on B. subtilis and E. coli surfaces from the master curves with pK(a)(int) values of 3.59+/-0.38, 4.33+/-0.57, 5.94+/-0.66, and 8.64+/-0.57 for B. subtilis and 3.73+/-0.44, 4.85+/-0.71, 6.56+/-0.64, and 8.79+/-0.62 for E. coli. These were assigned to functional groups according to reported pK(a) ranges of 2.0-6.0 (carboxylic acid), 3.2-3.5 (phosphodiesters), 5.6-7.2 (phosphoric acid), and 9.0-11.0 (amine groups). Average points of zero salt effect (pH(pzse)) for B. subtilis experiments were 6.63+/-0.21 and 6.42+/-0.08 as a function of pH(bulk) and pH(S), respectively. Under the same criteria, E. coli calculations yielded 5.73+/-0.23 and 5.45+/-0.05. An understanding of metal and proton reactivity on bacterial cell surfaces can be addressed quantitatively through the use of electrostatic and chemical equilibrium modeling techniques proposed in this study. The results are consistent with those of electrical force microscopy studies used to document the intrinsic electrochemical heterogeneity of bacterial cell surfaces.

  9. Hollow Pollen Shells to Enhance Drug Delivery

    PubMed Central

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

    2014-01-01

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

  10. One-pot synthesis of Size-Controllable core-shell CdS and derivative CdS@ZnxCd1-xS structures for dramatic Photocatalytic Hydrogen Production.

    PubMed

    Kai, Shuangshuang; Xi, Baojuan; Wang, Yifeng; Xiong, Shenglin

    2017-09-18

    Chalcogenide micro/nano composite structures have been attracting world-wide attention due to the enormous prospect of applications in photocatalytic hydrogen production. Well-defined micro/nanostructures, featured with predominant properties, are of extraordinary importance. Herein, we reported a facile one-pot method on synthesis of monodispersed size-controllable CdS and CdS@ZnxCd1-xS core-shell submicrospheres, which were engineered with respect to the structural conformation and size. CdS core-shell submicrospheres with different size were selectively prepared for the first time. The growth mechanism was investigated in detail by monitoring the time-dependent morphology of intermediates via TEM technique. By introduction of zinc precursor in the synthetic system, CdS@ZnxCd1-xS core-double shell submicrospheres had been obtained by cation exchange of CdS with zinc ions, experiencing the process of diffusion of CdS towards outside and transformation of ZnxCd1-xS crystallites. The H2 evolution rate over CdS@CdxZn1-xS (5.17 mmol h-1 g -1) is 12.3 times that of CdS core-shell (0.42 mmol h- 1 g -1) under visible light, owing to the efficient charge separation demonstrated by the electrochemical impedance and transient-state time-resolved photoluminescence spectra. Furthermore, CdS@ZnxCd1-xS core-double shell structures exhibited excellent stability over 20 h hydrogen production. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Multi-Shell Hollow Nanogels with Responsive Shell Permeability

    PubMed Central

    Schmid, Andreas J.; Dubbert, Janine; Rudov, Andrey A.; Pedersen, Jan Skov; Lindner, Peter; Karg, Matthias; Potemkin, Igor I.; Richtering, Walter

    2016-01-01

    We report on hollow shell-shell nanogels with two polymer shells that have different volume phase transition temperatures. By means of small angle neutron scattering (SANS) employing contrast variation and molecular dynamics (MD) simulations we show that hollow shell-shell nanocontainers are ideal systems for controlled drug delivery: The temperature responsive swelling of the inner shell controls the uptake and release, while the thermoresponsive swelling of the outer shell controls the size of the void and the colloidal stability. At temperatures between 32 °C < T < 42 °C, the hollow nanocontainers provide a significant void, which is even larger than the initial core size of the template, and they possess a high colloidal stability due to the steric stabilization of the swollen outer shell. Computer simulations showed, that temperature induced switching of the permeability of the inner shell allows for the encapsulation in and release of molecules from the cavity. PMID:26984478

  12. Gold nanorod-based poly(lactic-co-glycolic acid) with manganese dioxide core-shell structured multifunctional nanoplatform for cancer theranostic applications.

    PubMed

    Wang, Lei; Li, Dong; Hao, Yongwei; Niu, Mengya; Hu, Yujie; Zhao, Hongjuan; Chang, Junbiao; Zhang, Zhenzhong; Zhang, Yun

    2017-01-01

    Recently, photothermal therapy has become a promising strategy in tumor treatment. However, the therapeutic effect was seriously hampered by the low tissue penetration of laser. Therefore, in this study, radiofrequency (RF) with better tissue penetration was used for tumor hyperthermia. First, one type of gold nanorods (AuNRs) suitable for RF hyperthermia was selected. Then, poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) loaded with AuNRs and docetaxel (DTX) (PLGA/AuNR/DTX) NPs were constructed. Finally, manganese dioxide (MnO2) ultrathin nanofilms were coated on the surfaces of PLGA/AuNR/DTX NPs by the reduction of KMnO4 to construct the PLGA/AuNR/DTX@MnO2 drug delivery system. This drug delivery system can not only be used for the combined therapy of chemotherapy and RF hyperthermia but can also produce Mn(2+) to enable magnetic resonance imaging. Furthermore, the RF hyperthermia and the degradation of MnO2 can significantly promote the controlled drug release in a tumor region. The in vitro and in vivo results suggested that the PLGA/AuNR/DTX@MnO2 multifunctional drug delivery system is a promising nanoplatform for effective cancer theranostic applications.

  13. Can Shells be Biomonitor of Contaminants in the Environment: an Investigation Study of Perfluorinated Compounds in Bivalve Shells of China

    NASA Astrophysics Data System (ADS)

    Wang, Lei

    2010-05-01

    To assess the feasibility of using biominerals to biomonitor the extent of persistent contaminants in the environment, concentrations of perfluorinated compounds (PFCs), including perfluorinated carboxylic acids (PFCAs) and perfluorinated alkylsulfonates (PFASs), in the bivalve shells of clams, razor clams, oysters and mussels sampled from 8 sampling sites along China coast were analyzed. Concentrations of these contaminants in the waters and sediments of the sampling sites, as well as in the soft tissues of clams were also determined. Results show that though the concentrations of most PFCs in shells were lower than in soft tissues, the amount of contaminants in shells and soft tissues of bivalves are comparable, due to the larger dry-weight of shells than soft tissues of these animals. Concentrations of some PFCs in shells primarily correlate to concentrations in sediments, while concentrations in the soft tissues seems to be more related to those in water samples. We suggested that shells uptake PFCs by adsorption or passive deposition of the target chemicals to the shell organic matrix followed by a biomineralisation process. Therefore, contaminants bound to the organic matrix in the shell microstructure are sequestrated and hard to release. Like soft tissues, biominerals, e.g. shells, might also be considered as biomonitoring matrix for some contaminants in environments, because (i) the individual differences of contaminants concentrations among shell samples were smaller than soft tissue samples; (ii) secondary pollution is less likely to affect shell samples during sampling and transportation; and (iii) the shells was hypothesized to "record" past exposure to contaminants according to their annual growth ring. (This study was supported by National Science Foundation for Natural Science, China (No. 20807024) & Research Fund for the Doctoral Program of Higher Education of China (No. 200800551051))

  14. Chemical Component and Proteomic Study of the Amphibalanus (= Balanus) amphitrite Shell.

    PubMed

    Zhang, Gen; He, Li-Sheng; Wong, Yue-Him; Xu, Ying; Zhang, Yu; Qian, Pei-Yuan

    2015-01-01

    As typical biofoulers, barnacles possess hard shells and cause serious biofouling problems. In this study, we analyzed the protein component of the barnacle Amphibalanus (= Balanus) amphitrite shell using gel-based proteomics. The results revealed 52 proteins in the A. Amphitrite shell. Among them, 40 proteins were categorized into 11 functional groups based on KOG database, and the remaining 12 proteins were unknown. Besides the known proteins in barnacle shell (SIPC, carbonic anhydrase and acidic acid matrix protein), we also identified chorion peroxidase, C-type lectin-like domains, serine proteases and proteinase inhibitor proteins in the A. Amphitrite shell. The sequences of these proteins were characterized and their potential functions were discussed. Histology and DAPI staining revealed living cells in the shell, which might secrete the shell proteins identified in this study.

  15. Chemical Component and Proteomic Study of the Amphibalanus (= Balanus) amphitrite Shell

    PubMed Central

    Zhang, Gen; He, Li-sheng; Wong, Yue-Him; Xu, Ying; Zhang, Yu; Qian, Pei-yuan

    2015-01-01

    As typical biofoulers, barnacles possess hard shells and cause serious biofouling problems. In this study, we analyzed the protein component of the barnacle Amphibalanus (= Balanus) amphitrite shell using gel-based proteomics. The results revealed 52 proteins in the A. Amphitrite shell. Among them, 40 proteins were categorized into 11 functional groups based on KOG database, and the remaining 12 proteins were unknown. Besides the known proteins in barnacle shell (SIPC, carbonic anhydrase and acidic acid matrix protein), we also identified chorion peroxidase, C-type lectin-like domains, serine proteases and proteinase inhibitor proteins in the A. Amphitrite shell. The sequences of these proteins were characterized and their potential functions were discussed. Histology and DAPI staining revealed living cells in the shell, which might secrete the shell proteins identified in this study. PMID:26222041

  16. Sensational spherical shells

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Kendall, J. M., Jr.; Bahrami, P. A.; Wang, T. G.

    1986-01-01

    Fluid-dynamic and capillary forces can be used to form nearly perfect, very small spherical shells when a liquid that can solidify is passed through an annular die to form an annular jet. Gravity and certain properties of even the most ideal materials, however, can cause slight asymmetries. The primary objective of the present work is the control of this shell formation process in earth laboratories rather than space microgravity, through the development of facilities and methods that minimize the deleterious effects of gravity, aerodynamic drag, and uncontrolled cooling. The spherical shells thus produced can be used in insulation, recyclable filter materials, fire retardants, explosives, heat transport slurries, shock-absorbing armor, and solid rocket motors.

  17. Sensational spherical shells

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Kendall, J. M., Jr.; Bahrami, P. A.; Wang, T. G.

    1986-01-01

    Fluid-dynamic and capillary forces can be used to form nearly perfect, very small spherical shells when a liquid that can solidify is passed through an annular die to form an annular jet. Gravity and certain properties of even the most ideal materials, however, can cause slight asymmetries. The primary objective of the present work is the control of this shell formation process in earth laboratories rather than space microgravity, through the development of facilities and methods that minimize the deleterious effects of gravity, aerodynamic drag, and uncontrolled cooling. The spherical shells thus produced can be used in insulation, recyclable filter materials, fire retardants, explosives, heat transport slurries, shock-absorbing armor, and solid rocket motors.

  18. Fabrication of diamond shells

    DOEpatents

    Hamza, Alex V.; Biener, Juergen; Wild, Christoph; Woerner, Eckhard

    2016-11-01

    A novel method for fabricating diamond shells is introduced. The fabrication of such shells is a multi-step process, which involves diamond chemical vapor deposition on predetermined mandrels followed by polishing, microfabrication of holes, and removal of the mandrel by an etch process. The resultant shells of the present invention can be configured with a surface roughness at the nanometer level (e.g., on the order of down to about 10 nm RMS) on a mm length scale, and exhibit excellent hardness/strength, and good transparency in the both the infra-red and visible. Specifically, a novel process is disclosed herein, which allows coating of spherical substrates with optical-quality diamond films or nanocrystalline diamond films.

  19. Oyster shell conveyor used to lift shells from the dock ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Oyster shell conveyor used to lift shells from the dock into the receiving room housed in the 1965 concrete block addition. - J.C. Lore Oyster House, 14430 Solomons Island Road, Solomons, Calvert County, MD

  20. The shell organic matrix of the crossed lamellar queen conch shell (Strombus gigas).

    PubMed

    Osuna-Mascaró, Antonio; Cruz-Bustos, Teresa; Benhamada, Sana; Guichard, Nathalie; Marie, Benjamin; Plasseraud, Laurent; Corneillat, Marion; Alcaraz, Gérard; Checa, Antonio; Marin, Frédéric

    2014-02-01

    In molluscs, the shell organic matrix comprises a large set of biomineral-occluded proteins, glycoproteins and polysaccharides that are secreted by the calcifying mantle epithelium, and are supposed to display several functions related to the synthesis of the shell. In the present paper, we have characterized biochemically the shell matrix associated to the crossed-lamellar structure of the giant queen conch Strombus gigas. The acid-soluble (ASM) and acid-insoluble (AIM) matrices represent an extremely minor fraction of the shell. Both are constituted of polydisperse and of few discrete proteins among which three fractions, obtained by preparative SDS-PAGE and named 1P3, 2P3 and 3P3, are dominant and were further characterized. Compared to other matrices, the acid-soluble matrix is weakly glycosylated (3%) and among the discrete components, only 3P3 seems noticeably glycosylated. The monosaccharide composition of the ASM shows that mannose represents the main monosaccharide. To our knowledge, this is the first report of a high ratio of this sugar in a skeletal matrix. Furthermore, the ASM interacts with the in vitro crystallization of calcium carbonate, but this interaction is moderate. It differs from that of the isolated 1P3 fraction but is similar to that of the 2P3 and 3P3 fractions. At last, antibodies developed from the 3P3 fraction were used to localize this fraction within the shell by immunogold. This study is the first one aiming at characterizing the organic matrix associated to the crossed-lamellar structure of the queen conch shell.

  1. Molecular and isotopic composition of lipids in modern and fossil bivalve shells: Records of paleoenvironmental change?

    SciTech Connect

    CoBabe, E.A.

    1995-12-31

    Suites of lipids residing in situ in modern and fossil bivalve shells offer new possibilities for the study of paleoecology and paleoclimatology. Distributions of carbon isotopic compositions of modem shell lipids suggests that many of these compounds, including alkanes, sterols, fatty acids, ketones and phytadienes, are derived from the bivalves and not directly from the surrounding environment. The occurrence of fatty acids in modem and fossil shell material opens up the possibility that saturation levels of these compounds may be used as paleothermometers. To date, the utility of fatty acids in paleoclimate studies has been limited because of the swift breakdown of these compounds in sediment. However, initial results indicate that fatty acids in bivalve shells retain their original structure for at least several million years. Comparison of modem bivalve shell fatty acids from tropical, temperate and polar nearshore marine systems will be presented, along with analogous fossil data.

  2. Peanut shell colitis.

    PubMed

    Keeffe, E B; Girard, D E

    1985-07-01

    A 40-year-old physician experienced abdominal pain, loose stools, hematochezia, and anal discomfort with defecation associated with the daily consumption of 15 to 30 whole peanuts, including the shells. Thorough evaluation revealed only nonspecific colitis of the distal portion of the sigmoid colon and inflamed hemorrhoids. Discontinuation of whole peanut ingestion was associated with symptomatic, endoscopic, and histological resolution. In this patient, undigested peanut shells seem to have caused a nonspecific colitis, perhaps as the result of mechanical abrasion of the colonic mucosa.

  3. Effects of fatty acid amide hydrolase inhibition on neuronal responses to nicotine, cocaine and morphine in the nucleus accumbens shell and ventral tegmental area: involvement of PPAR-alpha nuclear receptors.

    PubMed

    Luchicchi, Antonio; Lecca, Salvatore; Carta, Stefano; Pillolla, Giuliano; Muntoni, Anna L; Yasar, Sevil; Goldberg, Steven R; Pistis, Marco

    2010-07-01

    The endocannabinoid system regulates neurotransmission in brain regions relevant to neurobiological and behavioral actions of addicting drugs. We recently demonstrated that inhibition by URB597 of fatty acid amide hydrolase (FAAH), the main enzyme that degrades the endogenous cannabinoid N-acylethanolamine (NAE) anandamide and the endogenous non-cannabinoid NAEs oleoylethanolamide and palmitoylethanolamide, blocks nicotine-induced excitation of ventral tegmental area (VTA) dopamine (DA) neurons and DA release in the shell of the nucleus accumbens (ShNAc), as well as nicotine-induced drug self-administration, conditioned place preference and relapse in rats. Here, we studied whether effects of FAAH inhibition on nicotine-induced changes in activity of VTA DA neurons were specific for nicotine or extended to two drugs of abuse acting through different mechanisms, cocaine and morphine. We also evaluated whether FAAH inhibition affects nicotine-, cocaine- or morphine-induced actions in the ShNAc. Experiments involved single-unit electrophysiological recordings from DA neurons in the VTA and medium spiny neurons in the ShNAc in anesthetized rats. We found that URB597 blocked effects of nicotine and cocaine in the ShNAc through activation of both surface cannabinoid CB1-receptors and alpha-type peroxisome proliferator-activated nuclear receptor. URB597 did not alter the effects of either cocaine or morphine on VTA DA neurons. These results show that the blockade of nicotine-induced excitation of VTA DA neurons, which we previously described, is selective for nicotine and indicate novel mechanisms recruited to regulate the effects of addicting drugs within the ShNAc of the brain reward system.

  4. The adsorption of rare earth ions using carbonized polydopamine nano shells

    DOE PAGES

    Sun, Xiaoqi; Luo, Huimin; Mahurin, Shannon Mark; ...

    2016-01-07

    Herein we report the structure effects of nano carbon shells prepared by carbonized polydopamine for rare earth elements (REEs) adsorption for the first time. The solid carbon sphere, 60 nm carbon shell and 500 nm carbon shell were prepared and investigated for adsorption and desorption of REEs. The adsorption of carbon shells for REEs was found to be better than the solid carbon sphere. The effect of acidities on the adsorption and desorption properties was discussed in this study. The good adsorption performance of carbon shells can be attributed to their porous structure, large specific surface area, amine group andmore » carbonyl group of dopamine.« less

  5. The adsorption of rare earth ions using carbonized polydopamine nano shells

    SciTech Connect

    Sun, Xiaoqi; Luo, Huimin; Mahurin, Shannon Mark; Dai, Sheng; Liu, Rui; Hou, Xisen; Dai, Sheng

    2016-01-07

    Herein we report the structure effects of nano carbon shells prepared by carbonized polydopamine for rare earth elements (REEs) adsorption for the first time. The solid carbon sphere, 60 nm carbon shell and 500 nm carbon shell were prepared and investigated for adsorption and desorption of REEs. The adsorption of carbon shells for REEs was found to be better than the solid carbon sphere. The effect of acidities on the adsorption and desorption properties was discussed in this study. The good adsorption performance of carbon shells can be attributed to their porous structure, large specific surface area, amine group and carbonyl group of dopamine.

  6. Retention Models on Core-Shell Columns.

    PubMed

    Jandera, Pavel; Hájek, Tomáš; Růžičková, Marie

    2017-07-13

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

  7. Investigation of shell disease in map turtles (Graptemys spp.).

    PubMed

    Hernandez-Divers, Stephen J; Hensel, Patrick; Gladden, Juliet; Hernandez-Divers, Sonia M; Buhlmann, Kurt A; Hagen, Chris; Sanchez, Susan; Latimer, Kenneth S; Ard, Mary; Camus, Alvin C

    2009-07-01

    Nineteen map turtles (Graptemys spp.) maintained under natural conditions were investigated because of chronic shell abnormalities. Animals were evaluated using a novel shell scoring system that divided the 54 scutes into six regions, with each region scored for lesion extent and severity, and summated to produce a total shell disease score (TSDS). Complete blood counts and various biochemistry analytes (total protein, albumin, globulin, urea, uric acid, 25-hydroxycholecalciferol, phosphorus, and ionized and total calcium) were measured. Under ketamine-medetomidine-morphine anesthesia, cytology tape strips and full thickness shell biopsies were collected aseptically for microbiologic, histologic (including scoring of biopsy quality), and ultrastructural evaluations. The TSDSs were low and ranged from 4 to 22 (median = 9) out of a possible score of 54. There were no correlations between TSDS and any hematologic or biochemistry parameter. The histologic quality of shell biopsies was good, and normal shell structure, by both light and electron microscopy, is described. Small clefts and pitting lesions were noted in 8/19 sections. There was no evidence of erosion, ulceration, inflammation, or infectious agents, but algae and diatoms were observed. Six biopsies yielded aerobic isolates (Chryseobacterium indologenes, Aeromonas hydrophila, Ralstonia pickettii, and Morganella morganii), whereas 11 shell samples grew various clostridial anerobes. No fungal organisms were cultured. Although the etiology of the lesions described remains unknown, the use of a scoring system in conjunction with full thickness biopsies is suggested to help standardize investigations into chelonian shell disease in the future.

  8. Chemical composition of chicken eggshell and shell membranes.

    PubMed

    Nakano, T; Ikawa, N I; Ozimek, L

    2003-03-01

    This study was undertaken to determine the occurrence of uronic acid in chicken eggshell membranes and to compare chemical compositions among the inner and outer eggshell membranes and the organic matter of eggshell. We report here for the first time the occurrence of uronic acid in chicken eggshell membranes. Uronic acid concentrations were similar (P > 0.05) between the inner shell membrane and outer shell membrane but approximately fivefold higher (P < 0.05) in the organic matter of eggshell. Sialic acid concentrations were the highest (P < 0.05) in the organic matter of eggshell and higher (P < 0.05) in the inner than in the outer shell membrane. Nitrogen concentrations were the lowest (P < 0.05) in the organic matter of eggshell but relatively constant between the two shell membranes. Amino acid analysis showed that the contents of glycine and alanine were higher (P < 0.05) and those of proline and hydroxyproline were lower (P < 0.05) in the organic matter of eggshell compared to shell membranes.

  9. Snail Shell Science.

    ERIC Educational Resources Information Center

    Matthews, Catherine

    1992-01-01

    Presents three inquiry-based lessons to develop the science process skills of observation, identification, and classification. Activities use whelk eggs and snail shells as the focus of the students' inquiries. Provides a list of 19 facts about whelks and snails. (MDH)

  10. Shell Creek Summers

    ERIC Educational Resources Information Center

    Seier, Mark; Goedeken, Suzy

    2005-01-01

    In 2002 Shell Creek Watershed Improvement Group turned to the Newman Grove Public Schools' science department to help educate the public on water quality in the watershed and to establish a monitoring system that would be used to improve surface and groundwater quality in the creek's watershed. Nebraska Department of Environmental Quality provided…

  11. Shell Higher Olefins Process.

    ERIC Educational Resources Information Center

    Lutz, E. F.

    1986-01-01

    Shows how olefin isomerization and the exotic olefin metathesis reaction can be harnessed in industrial processes. Indicates that the Shell Higher Olefins Process makes use of organometallic catalysts to manufacture alpha-olefins and internal carbon-11 through carbon-14 alkenes in a flexible fashion that can be adjusted to market needs. (JN)

  12. Shell Creek Summers

    ERIC Educational Resources Information Center

    Seier, Mark; Goedeken, Suzy

    2005-01-01

    In 2002 Shell Creek Watershed Improvement Group turned to the Newman Grove Public Schools' science department to help educate the public on water quality in the watershed and to establish a monitoring system that would be used to improve surface and groundwater quality in the creek's watershed. Nebraska Department of Environmental Quality provided…

  13. Snail Shell Science.

    ERIC Educational Resources Information Center

    Matthews, Catherine

    1992-01-01

    Presents three inquiry-based lessons to develop the science process skills of observation, identification, and classification. Activities use whelk eggs and snail shells as the focus of the students' inquiries. Provides a list of 19 facts about whelks and snails. (MDH)

  14. Interventions for shell eggs

    USDA-ARS?s Scientific Manuscript database

    Eggs are the second riskiest foods regulated by the U.S. FDA. Less than 3% of shell eggs are pasteurized using a hot water process that unfortunately damages the appearance and functionality of the eggs. In addition, the current process adds more than $1.50 to the cost of a dozen eggs. Therefore, al...

  15. Shell Higher Olefins Process.

    ERIC Educational Resources Information Center

    Lutz, E. F.

    1986-01-01

    Shows how olefin isomerization and the exotic olefin metathesis reaction can be harnessed in industrial processes. Indicates that the Shell Higher Olefins Process makes use of organometallic catalysts to manufacture alpha-olefins and internal carbon-11 through carbon-14 alkenes in a flexible fashion that can be adjusted to market needs. (JN)

  16. Proteomic strategy for identifying mollusc shell proteins using mild chemical degradation and trypsin digestion of insoluble organic shell matrix: a pilot study on Haliotis tuberculata.

    PubMed

    Bédouet, Laurent; Marie, Arul; Berland, Sophie; Marie, Benjamin; Auzoux-Bordenave, Stéphanie; Marin, Frédéric; Milet, Christian

    2012-08-01

    A successful strategy for the identification of shell proteins is based on proteomic analyses where soluble and insoluble fractions isolated from organic shell matrix are digested with trypsin with the aim of generating peptides, which are used to identify novel shell proteins contained in databases. However, using trypsin as a sole degradative agent is limited by the enzyme's cleavage specificity and is dependent upon the occurrence of lysine and arginine in the shell protein sequence. To bypass this limitation, we investigated the ability of trifluoroacetic acid (TFA), a low-specificity chemical degradative agent, to generate clusters of analyzable peptides from organic shell matrix, suitable for database annotation. Acetic acid-insoluble fractions from Haliotis tuberculata shell were processed by trypsin followed by TFA digestion. The hydrolysates were used to annotate an expressed sequence tag library constructed from the mantle tissue of Haliotis asinina, a tropical abalone species. The characterization of sequences with repeat motifs featured in some of the shell matrix proteins benefited from TFA-induced serial cutting, which can result in peptide ladder series. Using the degradative specificities of TFA and trypsin, we were able to identify five novel shell proteins. This pilot study indicates that a mild chemical digestion of organic shell matrix combined with trypsin generates peptides suitable for proteomic analysis for better characterization of mollusc shell matrix proteins.

  17. Stability of thick spherical shells

    NASA Astrophysics Data System (ADS)

    Liu, I.-Shih

    1995-06-01

    The pressure-radius relation of spherical rubber balloons has been derived and its stability behavior investigated before. In this work, we show that similar results remain valid for thick spherical shells of Mooney-Rivlin materials. In addition, we show that eversion of a spherical shell is possible for any incompressible isotropic materials if the shell is not too thick.

  18. Multi-shell effective interactions

    NASA Astrophysics Data System (ADS)

    Tsunoda, Naofumi; Takayanagi, Kazuo; Hjorth-Jensen, Morten; Otsuka, Takaharu

    2014-02-01

    Background: Effective interactions, either derived from microscopic theories or based on fitting selected properties of nuclei in specific mass regions, are widely used inputs to shell-model studies of nuclei. The commonly used unperturbed basis functions are given by the harmonic oscillator. Until recently, most shell-model calculations have been confined to a single oscillator shell like the sd shell or the pf shell. Recent interest in nuclei away from the stability line requires, however, larger shell-model spaces. Because the derivation of microscopic effective interactions has been limited to degenerate models spaces, there are both conceptual and practical limits to present shell-model calculations that utilize such interactions. Purpose: The aim of this work is to present a novel microscopic method to calculate effective nucleon-nucleon interactions for the nuclear shell model. Its main difference from existing theories is that it can be applied not only to degenerate model spaces but also to nondegenerate model spaces. This has important consequences, in particular for intershell matrix elements of effective interactions. Methods: The formalism is presented in the form of a many-body perturbation theory based on the recently developed extended Kuo-Krenciglowa method. Our method enables us to microscopically construct effective interactions not only in one oscillator shell but also for several oscillator shells. Results: We present numerical results using effective interactions within (i) a single oscillator shell (a so-called degenerate model space) like the sd shell or the pf shell and (ii) two major shells (nondegenerate model space) like the sdf7p3 shell or the pfg9 shell. We also present energy levels of several nuclei that have two valence nucleons on top of a given closed-shell core. Conclusions: Our results show that the present method works excellently in shell-model spaces that comprise several oscillator shells, as well as in a single oscillator

  19. 7 CFR 51.2002 - Split shell.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Split shell. 51.2002 Section 51.2002 Agriculture... Standards for Grades of Filberts in the Shell 1 Definitions § 51.2002 Split shell. Split shell means a shell... of the shell, measured in the direction of the crack. ...

  20. 7 CFR 51.2002 - Split shell.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Split shell. 51.2002 Section 51.2002 Agriculture... Standards for Grades of Filberts in the Shell 1 Definitions § 51.2002 Split shell. Split shell means a shell... of the shell, measured in the direction of the crack. ...

  1. Arsenic, chromium and mercury removal using mussel shell ash or a sludge/ashes waste mixture.

    PubMed

    Seco-Reigosa, Natalia; Peña-Rodríguez, Susana; Nóvoa-Muñoz, Juan Carlos; Arias-Estévez, Manuel; Fernández-Sanjurjo, María J; Alvarez-Rodríguez, Esperanza; Núñez-Delgado, Avelino

    2013-04-01

    Different batches of valued mussel shell and waste mussel shell ash are characterised. Shell ash has pH > 12 and high electrical conductivities (between 16.01 and 27.27 dS m(-1)), while calcined shell shows pH values up to 10.7 and electrical conductivities between 1.19 and 3.55 dS m(-1). X-ray fluorescence, nitric acid digestion and water extractions show higher concentrations in shell ash for most parameters. Calcite is the dominant crystalline compound in this ash (95.6%), followed by aragonite. Adsorption/desorption trials were performed for mussel shell ash and for a waste mixture including shell ash, sewage sludge and wood ash, showing the following percentage adsorptions: Hg(II) >94%, As(V) >96% and Cr(VI) between 11 and 30% for shell ash; Hg(II) >98%, As(V) >88% and Cr(VI) between 30 and 88% for the waste mixture. Hg and As desorption was <5% for both shell ash and the waste mixture, while Cr desorption was between 92 and 45% for shell ash, and between 19 and 0% for the mixture. In view of that, mussel shell ash and the mixture including shell ash, sewage sludge and wood ash could be useful for Hg(II) and As(V) removal.

  2. Biomechanics of turtle shells: how whole shells fail in compression.

    PubMed

    Magwene, Paul M; Socha, John J

    2013-02-01

    Turtle shells are a form of armor that provides varying degrees of protection against predation. Although this function of the shell as armor is widely appreciated, the mechanical limits of protection and the modes of failure when subjected to breaking stresses have not been well explored. We studied the mechanical properties of whole shells and of isolated bony tissues and sutures in four species of turtles (Trachemys scripta, Malaclemys terrapin, Chrysemys picta, and Terrapene carolina) using a combination of structural and mechanical tests. Structural properties were evaluated by subjecting whole shells to compressive and point loads in order to quantify maximum load, work to failure, and relative shell deformations. The mechanical properties of bone and sutures from the plastral region of the shell were evaluated using three-point bending experiments. Analysis of whole shell structural properties suggests that small shells undergo relatively greater deformations before failure than do large shells and similar amounts of energy are required to induce failure under both point and compressive loads. Location of failures occurred far more often at sulci than at sutures (representing the margins of the epidermal scutes and the underlying bones, respectively), suggesting that the small grooves in the bone created by the sulci introduce zones of weakness in the shell. Values for bending strength, ultimate bending strain, Young's modulus, and energy absorption, calculated from the three-point bending data, indicate that sutures are relatively weaker than the surrounding bone, but are able to absorb similar amounts of energy due to higher ultimate strain values.

  3. Shell funds chair

    NASA Astrophysics Data System (ADS)

    The Shell Companies Foundation, Inc., of Houston, Tex., has given $750,000 to the University of Texas at Austin to establish the Shell Distinguished Chair in Geophysics. The 5-year, $150,000-per-year grant will support the studies of John G. Sclater. Sclater, currently a professor at the Massachusetts Institute of Technology, has accepted a joint position that begins July 1 in the geological sciences department and in the Institute for Geophysics at UT Austin.Sclater's research into the formation of ocean basins has applications for understanding the way petroleum deposits mature. He has studied the reconstruction of movements of the continents and the subsidence of ocean basins. He is considered an expert in the interpretation of geothermal and seismic data.

  4. HST/ACS observations of shell galaxies: inner shells, shell colours and dust

    NASA Astrophysics Data System (ADS)

    Sikkema, G.; Carter, D.; Peletier, R. F.; Balcells, M.; Del Burgo, C.; Valentijn, E. A.

    2007-06-01

    Context: Shells in Elliptical Galaxies are faint, sharp-edged features, believed to provide evidence for a merger event. Accurate photometry at high spatial resolution is needed to learn on presence of inner shells, population properties of shells, and dust in shell galaxies. Aims: Learn more about the origin of shells and dust in early type galaxies. Methods: V-I colours of shells and underlying galaxies are derived, using HST Advanced Camera for Surveys (ACS) data. A galaxy model is made locally in wedges and subtracted to determine shell profiles and colours. We applied Voronoi binning to our data to get smoothed colour maps of the galaxies. Comparison with N-body simulations from the literature gives more insight to the origin of the shell features. Shell positions and dust characteristics are inferred from model galaxy subtracted images. Results: The ACS images reveal shells well within the effective radius in some galaxies (at 0.24 re = 1.7 kpc in the case of NGC 5982). In some cases, strong nuclear dust patches prevent detection of inner shells. Most shells have colours which are similar to the underlying galaxy. Some inner shells are redder than the galaxy. All six shell galaxies show out of dynamical equilibrium dust features, like lanes or patches, in their central regions. Our detection rate for dust in the shell ellipticals is greater than that found from HST archive data for a sample of normal early-type galaxies, at the 95% confidence level. Conclusions: The merger model describes better the shell distributions and morphologies than the interaction model. Red shell colours are most likely due to the presence of dust and/or older stellar populations. The high prevalence and out of dynamical equilibrium morphologies of the central dust features point towards external influences being responsible for visible dust features in early type shell galaxies. Inner shells are able to manifest themselves in relatively old shell systems. Based on observations made

  5. A Technique for Calculation of Shell Thicknesses for Core-Shell-Shell Nanoparticles from XPS Data

    PubMed Central

    Cant, David J. H.; Wang, Yung-Chen; Castner, David G.; Shard, Alexander G.

    2016-01-01

    This paper extends a straightforward technique for the calculation of shell thicknesses in core-shell nanoparticles to the case of core-shell-shell nanoparticles using X-ray Photoelectron Spectroscopy (XPS) data. This method can be applied by XPS analysts and does not require any numerical simulation or advanced knowledge, although iteration is required in the case where both shell thicknesses are unknown. The standard deviation in the calculated thicknesses vs simulated values is typically less than 10%, which is the uncertainty of the electron attenuation lengths used in XPS analysis. PMID:27087712

  6. Blended Isogeometric Shells

    DTIC Science & Technology

    2012-08-01

    possibilities that heretofore have not been investigated, namely, “rigid bodies” [7]. Another need for the use of these techniques is in multi-patch NURBS meshes... techniques is completely satisfactory in all cases. Even if they can be used successfully in certain situations they can give rise to reduced critical...condition which is violated at the patch boundaries. The C0 boundaries between patches behave like piano hinges for thin shell formulations, and

  7. Thermomechanical Postbuckling of Shells

    NASA Technical Reports Server (NTRS)

    Librescu, Liviu

    1998-01-01

    A number of issues involving the postbuckling of doubly-curved panels exposed to a non-uniform temperature field and subjected to a system of mechanical loads are considered in this paper. Effects played by transverse shear, initial geometric imperfections, membrane and thickness-wise temperature gradient, tangential edge constraints, linear/non-linear elastic foundation are incorporated and their implications on the non-linear response behavior of shells are discussed. Issues related with the delay of the occurrence of the snap-through buckling, alleviation of its intensity and even with its removal are addressed and remarks on conditions rendering a curved panel insensitive to initial geometric imperfections are included. Results on small vibration of shells about sub- and post-critical ranges are provided and structural modeling issues playing a non-negligible role towards a reliable prediction of the postbuckling behavior of shells under complex loading conditions are discussed. Results on non-linear response of flat reinforced panels subjected to thermomechanical loads are also presented. Finally, problems not covered by this article are briefly indicated.

  8. Protein profiles of hatchery egg shell membrane.

    PubMed

    Rath, N C; Liyanage, R; Makkar, S K; Lay, J O

    2016-01-01

    Eggshells which consist largely of calcareous outer shell and shell membranes, constitute a significant part of poultry hatchery waste. The shell membranes (ESM) not only contain proteins that originate from egg whites but also from the developing embryos and different contaminants of microbial and environmental origins. As feed supplements, during post hatch growth, the hatchery egg shell membranes (HESM) have shown potential for imparting resistance of chickens to endotoxin stress and exert positive health effects. Considering that these effects are mediated by the bioactive proteins and peptides present in the membrane, the objective of the study was to identify the protein profiles of hatchery eggshell membranes (HESM). Hatchery egg shell membranes were extracted with acidified methanol and a guanidine hydrochloride buffer then subjected to reduction/alkylation, and trypsin digestion. The methanol extract was additionally analyzed by matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS). The tryptic digests were analyzed by liquid chromatography and tandem mass spectrometry (LC-MS-MS) to identify the proteins. Our results showed the presence of several proteins that are inherent and abundant in egg white such as, ovalbumin, ovotransferrin, ovocleidin-116, and lysozyme, and several proteins associated with cytoskeletal, cell signaling, antimicrobial, and catalytic functions involving carbohydrate, nucleic acid, and protein metabolisms. There were some blood derived proteins most likely originating from the embryos and several other proteins identified with different aerobic, anaerobic, gram positive, gram negative, soil, and marine bacterial species some commensals and others zoonotic. The variety of bioactive proteins, particularly the cell signaling and enzymatic proteins along with the diverse microbial proteins, make the HESM suitable for nutritional and biological application to improve post hatch immunity of poultry.

  9. Shell deposition of CdSe nano dots and rods

    NASA Astrophysics Data System (ADS)

    Yang, Ping; Chen, Hsueh Shin; Zhang, Qiang; Shi, Ruixia; Wang, Junpeng; Che, Quande

    2014-08-01

    To investigate the shell deposited kinetics, CdSe quantum dots (QDs) and nanorods (NRs) with a maximum length of 17 nm were fabricated via organic synthesis routes. CdSe with a hexagonal crystal structure (wurtzite) favors epitaxial growth on the {002} surfaces when well-controlled conditions were used. The morphologies and sizes of CdSe samples depended strongly on chemicals and temperature. In the case of 320 °C, CdSe NRs with adjusted length of 7-17 nm were obtained from trioctylphosphine oxide (TOPO) and tetradecylphosphonic acid (TDPA). In contrast, short CdSe NRs (less than 10 nm) were created from octadecylphosphonic acid (ODPA) and trioctylamine (TOA). Spherical CdSe QDs were further fabricated using stearic acid (SA) and TOPO at 300 °C. CdSe cores were coated with Cd0.5Zn0.5S and CdTe shells. Anisotropic growth occurred during shell deposition because CdS shells grown preferentially on the {001} facet of the CdSe core. In the case of CdSe core prepared from TOPO and TDPA, CdSe/Cd0.5Zn0.5S core/shell samples prepared from long CdSe NRs (more than 10 nm) revealed a peanut morphology while the core/shell samples created from short ones (less than 10 nm) exhibited a spherical morphology. All of the CdSe/Cd0.5Zn0.5S core/shell samples revealed a similar length to that of the CdSe cores. This phenomenon was also observed for the core/shell samples fabricated using CdSe NRs prepared by ODPA and TOA. This is ascribed to the well-developed crystal structure of CdSe NRs fabricated using an organic synthesis at high temperature. In contrast, this anisotropic growth did not occur when spherical CdSe QDs prepared from SA and TOPO and the shell (Cd0.5Zn0.5S) coating carried out using SA and TOA. To indicate the shell depositing process, CdSe NRs fabricated using TDPA and TOPO were coated with a CdTe shell. CdTe monomers were deposited on the middle and tip parts of the CdSe NRs to form a tetrapod-like morphology at 220 °C. This is ascribed to the large difference of

  10. Synthesis of triangular Au core-Ag shell nanoparticles

    SciTech Connect

    Rai, Akhilesh; Chaudhary, Minakshi; Ahmad, Absar; Bhargava, Suresh; Sastry, Murali . E-mail: msastry@tatachemicals.com

    2007-07-03

    In this paper, we demonstrate a simple and reproducible method for the synthesis of triangular Au core-Ag shell nanoparticles. The triangular gold core is obtained by the reduction of gold ions by lemongrass extract. Utilizing the negative charge on the gold nanotriangles, silver ions are bound to their surface and thereafter reduced by ascorbic acid under alkaline conditions. The thickness of the silver shell may be modulated by varying the pH of the reaction medium. The formation of the Au core-Ag shell triangular nanostructures has been followed by UV-vis-NIR Spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy (TEM) and atomic force microscopy (AFM) measurements. The sharp vertices of the triangles coupled with the core-shell structure is expected to have potential for application in surface enhanced Raman spectroscopy and in the sensitive detection of biomolecules.

  11. Shell model calculations of 109Sb in the sdgh shell

    NASA Astrophysics Data System (ADS)

    Dikmen, E.; Novoselsky, A.; Vallieres, M.

    2001-12-01

    The energy spectra of the antimony isotope 109Sb in the sdgh shell are calculated in the nuclear shell model approach by using the CD-Bonn nucleon-nucleon interaction. The modified Drexel University parallel shell model code (DUPSM) was used for the calculations with maximum Hamiltonian dimension of 762 253 of 5.14% sparsity. The energy levels are compared to the recent experimental results. The calculations were done on the Cyborg Parallel Cluster System at Drexel University.

  12. A novel silk-like shell matrix gene is expressed in the mantle edge of the Pacific oyster prior to shell regeneration.

    PubMed

    Takahashi, Jun; Takagi, Masaya; Okihana, Yumiko; Takeo, Kei; Ueda, Takahisa; Touhata, Ken; Maegawa, Shingo; Toyohara, Haruhiko

    2012-05-10

    During shell formation, little is known about the functions of organic matrices, especially about the biomineralization of shell prismatic layer. We identified a novel gene, shelk2, from the Pacific oyster presumed to be involved in the shell biosynthesis. The Pacific oyster has multiple copies of shelk2. Shelk2 mRNA is specifically expressed on the mantle edge and is induced during shell regeneration, thereby suggesting that Shelk2 is involved in shell biosynthesis. To our surprise, the database search revealed that it encodes a spider silk-like alanine-rich protein. Interestingly, most of the Shelk2 primary structure is composed of two kinds of poly-alanine motifs-GXNA(n)(S) and GSA(n)(S)-where X denotes Gln, Arg or no amino acid. Occurrence of common motifs of Shelk2 and spider silk led us to the assumption that shell and silk are constructed under similar strategies despite of their living environments.

  13. Synthesis of stiffened conical shells.

    NASA Technical Reports Server (NTRS)

    Thornton, W. A.

    1972-01-01

    The development of a method to effect the automated minimum weight design of ring and stringer stiffened shells is presented. Membrane theory is used for the shell prebuckling analysis. The buckling analysis is based upon an arbitrary shell of revolution computer program. The structural analysis includes both buckling and yielding modes of failure. The synthesis involves the coupling of an exterior penalty function with a method for the unconstrained minimization of a function comprised of a sum of squares. Results of the application of the method to the design of the Viking Aeroshell cone are presented. The least weight Viking Aeroshell appears to be an all magnesium shell with ring stiffeners of hollow circular cross section. Because the method incorporates a general shell of revolution buckling analysis, it can be readily modified and applied to the design of any axisymmetrically loaded uniformly stiffened shell of revolution for which a membrane prebuckling solution exists.

  14. Shell Biorefinery: Dream or Reality?

    PubMed

    Chen, Xi; Yang, Huiying; Yan, Ning

    2016-09-12

    Shell biorefinery, referring to the fractionation of crustacean shells into their major components and the transformation of each component into value-added chemicals and materials, has attracted growing attention in recent years. Since the large quantities of waste shells remain underexploited, their valorization can potentially bring both ecological and economic benefits. This Review provides an overview of the current status of shell biorefinery. It first describes the structural features of crustacean shells, including their composition and their interactions. Then, various fractionation methods for the shells are introduced. The last section is dedicated to the valorization of chitin and its derivatives for chemicals, porous carbon materials and functional polymers. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Ultrasonic scattering from anisotropic shells

    NASA Astrophysics Data System (ADS)

    Mittleman, John; Thompson, R. B.; Roberts, R.

    The exact differential equations for elastic wave scattering from spherical shells with spherically orthotropic properties are presently shown to be separable; the angular equations are satisfied by Legendre polynomials that are independent of material properties. The results thus obtained have been validated by exact solutions for the case with vanishing shell thickness, and that of isotropic elastic constants. Excellent agreement is thus obtained over a wide range of shell thicknesses and wave numbers.

  16. Reduced molybenum-oxide-based core-shell hybrids: "blue" electrons are delocalized on the shell.

    PubMed

    Todea, Ana Maria; Szakács, Julia; Konar, Sanjit; Bögge, Hartmut; Crans, Debbie C; Glaser, Thorsten; Rousselière, Hélène; Thouvenot, René; Gouzerh, Pierre; Müller, Achim

    2011-06-06

    The present study refers to a variety of reduced metal-oxide core-shell hybrids, which are unique with regard to their electronic structure, their geometry, and their formation. They contain spherical {Mo72Fe30} Keplerate-type shells encapsulating Keggin-type polyoxomolybdates based on very weak interactions. Studies on the encapsulation of molybdosilicate as well as on the earlier reported molybdophosphate, coupled with the use of several physical methods for the characterization led to unprecedented results (see title). Upon standing in air at room temperature, acidified aqueous solutions obtained by dissolving sodium molybdate, iron(II) chloride, acetic acid, and molybdosilicic acid led to the precipitation of monoclinic greenish crystals (1). A rhombohedral variant (2) has also been observed. Upon drying at room temperature, compound 3 with a layer structure was obtained from 1 in a solid-state reaction based on cross-linking of the shells. The compounds 1, 2, and 3 have been characterized by a combination of methods including single-crystal X-ray crystallography, magnetic studies, as well as IR, Mössbauer, (resonance) Raman, and electronic absorption spectroscopy. In connection with detailed studies of the guest-free two-electron-reduced {Mo72Fe30}-type Keplerate (4) and of the previously reported molybdophosphate-based hybrids (including 31P NMR spectroscopy results), it is unambiguously proved that 1, 2, and 3 contain non-reduced Keggin ion cores and reduced {Mo72Fe30}-type shells. The results are discussed in terms of redox considerations (the shell as well as the core can be reduced) including those related to the reduction of "molybdates" by FeII being of interdisciplinary including catalytic interest (the MoVI/MoV and FeIII/FeII couples have very close redox potentials!), while also referring to the special formation of the hybrids based on chemical Darwinism.

  17. The structure of circumstellar shells

    NASA Technical Reports Server (NTRS)

    Fix, John D.

    1993-01-01

    This document provides a report on research activities carried out with the support of NASA grant NAG 5-1174, the Structure of Circumstellar Shells, funded under the Astrophysics Data Program. The research carried out with the support of this grant is a study of the properties of circumstellar dust shells for which spectra are available through IRAS low resolution spectrometry (LRS). This research consisted of the development and application of models of axisymmetric circumstellar shells and a preliminary survey of the applicability of neural nets for analysis of the IRAS LRS spectra of circumstellar dust shells.

  18. Shell Analysis Manual

    DTIC Science & Technology

    1968-04-01

    plane strains o 0 0 el, e 2 , el2 Components of nonlinear in-plane middle surface strains; also, strains corresponding to equilibrium configuration el...plates) in the treatment of shell problems. This theory, often referred to as Love’s first approximation, has since occupied a position of prominence...Materials such as wood and synthetic fiberboard possess this property. For this case, the generalized Hooke’s Law reduces to oII = El Fl + E 2 p 2 1

  19. Automated shell theory for rotating structures (ASTROS)

    NASA Technical Reports Server (NTRS)

    Foster, B. J.; Thomas, J. M.

    1971-01-01

    A computer program for analyzing axisymmetric shells with inertial forces caused by rotation about the shell axis is developed by revising the STARS II shell program. The basic capabilities of the STARS II shell program, such as the treatment of the branched shells, stiffened wall construction, and thermal gradients, are retained.

  20. 7 CFR 51.2002 - Split shell.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Split shell. 51.2002 Section 51.2002 Agriculture..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Filberts in the Shell 1 Definitions § 51.2002 Split shell. Split shell means a shell having any crack which is open and conspicuous for a...

  1. 7 CFR 51.2289 - Shell.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Shell. 51.2289 Section 51.2289 Agriculture Regulations... Standards for Shelled English Walnuts (Juglans Regia) Definitions § 51.2289 Shell. Shell means the outer shell and/or the woody partition from between the halves of the kernel, and any fragments of either. ...

  2. 7 CFR 51.2289 - Shell.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Shell. 51.2289 Section 51.2289 Agriculture Regulations... Standards for Shelled English Walnuts (Juglans Regia) Definitions § 51.2289 Shell. Shell means the outer shell and/or the woody partition from between the halves of the kernel, and any fragments of either. ...

  3. 7 CFR 51.2002 - Split shell.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Split shell. 51.2002 Section 51.2002 Agriculture..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Filberts in the Shell 1 Definitions § 51.2002 Split shell. Split shell means a shell having any crack which is open and conspicuous for a...

  4. Rh(0)/Rh(iii) core-shell nanoparticles as heterogeneous catalysts for cyclic carbonate synthesis.

    PubMed

    Jung, Younjae; Shin, Taeil; Kim, Kiseong; Byun, Hyeeun; Cho, Sung June; Kim, Hyunwoo; Song, Hyunjoon

    2016-12-22

    Rh(0)/Rh(iii) core-shell nanoparticles were prepared by surface oxidation of Rh nanoparticles with N-bromosuccinimide. They were employed as heterogeneous catalysts for cyclic carbonate synthesis from propylene oxide and CO2, and exhibited high activity and excellent recyclability due to Lewis acidic Rh(iii) species on the shells.

  5. Development of antimicrobial coatings for improving the microbiological safety and quality of shell eggs

    USDA-ARS?s Scientific Manuscript database

    This study was conducted to develop antimicrobial coatings to decontaminate and prevent cross- contamination of shell eggs. Egg shells were inoculated with nalidixic acid resistant Salmonella enterica Enteritidis strains OB030832, OB040159, and C405, and then treated with antimicrobial coatings. Pol...

  6. Magnetic self-assembly of gold nanoparticle chains using dipolar core-shell colloids.

    PubMed

    Kim, Bo Yun; Shim, In-Bo; Monti, Oliver L A; Pyun, Jeffrey

    2011-01-21

    The preparation of gold nanoparticle (AuNP) assemblies was conducted by the synthesis and dipolar assembly of ferromagnetic core-shell nanoparticles composed of AuNP cores and cobalt NP shells. Dissolution of metallic Co phases with mineral acids afforded self-assembled AuNP chains and bracelets.

  7. Cadmium Telluride, Cadmium Telluride/Cadmium Sulfide Core/Shell, and Cadmium Telluride/Cadmium Sulfide/Zinc Sulfide Core/Shell/Shell Quantum Dots Study

    NASA Astrophysics Data System (ADS)

    Yan, Yueran

    CdTe, CdTe/CdS core/shell, and CdTe/CdS/ZnS core/shell/shell quantum dots (QDs) are potential candidates for bio-imaging and solar cell applications because of some special physical properties in these nano materials. For example, the band gap energy of the bulk CdTe is about 1.5 eV, so that principally they can emit 790 nm light, which is in the near-infrared range (also called biological window). Moreover, theoretically hot exciton generated by QDs is possible to be caught since the exciton relaxation process in QDs is slower than in bulk materials due to the large intraband energy gap in QDs. In this dissertation, we have synthesized the CdTe and CdTe/CdS core/shell QDs, characterized their structure, and analyzed their photophysical properties. We used organometallic methods to synthesize the CdTe QDs in a noncoordinating solvent. To avoid being quenched by air, ligands, solvent, or other compounds, CdS shell was successfully deposited on the CdTe QDs by different methods, including the slow injection method, the successive ion layer adsorption and reaction (SILAR) method, and thermal-cycling coupled single precursor method (TC-SP). Our final product, quasi-type- II CdTe/CdS core/shell QDs were able to emit at 770 nm with a fluorescence quantum yield as high as 70%. We also tried to deposit a second shell ZnS on CdTe/CdS core/shell QDs since some compounds can quench CdTe/CdS core/shell QDs. Even though different methods were used to deposit ZnS shell on the CdTe/CdS core/shell QDs, CdTe/CdS/ZnS core/shell/shell QDs still can be quenched. Furthermore, the CdTe/CdS core/shell and CdTe/CdS/ZnS core/shell/shell QDs were transferred into aqueous phase, phosphate buffered saline or deionized water, by switching the hydrophilic ligands (thiol or PEG ligands). The thioglycolic acid (TGA)-capped CdTe/CdS core/shell QDs can be kept in aqueous phase with high fluorescence quantum yield (60%--70%) for more than two months. However, some other compounds in organic or

  8. Testing the best method to prepare recent and fossil brachiopod shells for SEM analysis

    NASA Astrophysics Data System (ADS)

    Crippa, Gaia; Ye, Facheng

    2017-04-01

    The analysis of shell microstructures by Scanning Electron Microscope (SEM) is a method easily available to most palaeontologists and geochemists. This kind of analysis is a fundamental step in the study of the mineralised parts of marine and terrestrial organisms, and it provides invaluable information in different fields of palaeontology, from the comprehension of evolutionary taxonomy and biomineralisation processes to the screening of shell diagenetic alteration. In precipitating their low-magnesium calcite shells in isotopic equilibrium with ambient seawater, brachiopods are excellent archives of past seawater temperature and ocean chemistry. However, diagenetic processes may alter the original fabric and the original geochemical composition of the shells; the SEM analysis of the microstructure represents one of the most common method used to test fossil shell preservation and eventually exclude diagenetic alteration. Notwithstanding the importance of this analysis, only few and scattered data have been published about the preparation and cleaning of brachiopod shells for SEM analyses Here, we describe several tests performed on recent and fossil brachiopod shells, experimenting new and old methodologies in order to identify a general protocol to better highlight and analyze the shell fabric. Recent taxa include Liothyrella uva and Liothyrella neozelanica, respectively collected from Antarctica and New Zealand; fossil shells are those of Terebratula scillae collected from the lower Pleistocene Stirone River sedimentary succession in Northern Italy. We carried out several tests to check the response of the shell fabric to the resin used to embed the valves before cutting and to different times of exposure to hydrochloric acid; furthermore, as the presence of the organic matrix in recent shells represents the main obstacle to obtaining high quality SEM images, we used bleach and hydrogen peroxide with different concentrations and times of exposure to remove it

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

    SciTech Connect

    Heiles, C.

    1984-08-01

    We present photographic representations of the combination of two Hi surveys, so as to eliminate the survey boundaries at Vertical BarbVertical Bar = 10/sup 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.

  10. Microscopic Shell Model Calculations for sd-Shell Nuclei

    NASA Astrophysics Data System (ADS)

    Barrett, Bruce R.; Dikmen, Erdal; Maris, Pieter; Shirokov, Andrey M.; Smirnova, Nadya A.; Vary, James P.

    Several techniques now exist for performing detailed and accurate calculations of the structure of light nuclei, i.e., A ≤ 16. Going to heavier nuclei requires new techniques or extensions of old ones. One of these is the so-called No Core Shell Model (NCSM) with a Core approach, which involves an Okubo-Lee-Suzuki (OLS) transformation of a converged NCSM result into a single major shell, such as the sd-shell. The obtained effective two-body matrix elements can be separated into core and single-particle (s.p.) energies plus residual two-body interactions, which can be used for performing standard shell-model (SSM) calculations. As an example, an application of this procedure will be given for nuclei at the beginning ofthe sd-shell.

  11. Double-shelled tremella-like NiO@Co3O4@MnO2 as a high-performance cathode material for alkaline supercapacitors

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Ren, Qian; Brett, Dan J. L.; He, Guanjie; Wang, Rongfang; Key, Julian; Ji, Shan

    2017-03-01

    Tremella-like NiO@Co3O4@MnO2 particles of core-double-shelled structure were synthesized by a three-step hydrothermal route and thermal treatment. The hierarchical layered porous structure of the particles has a BET surface area of 179.2 m2 g-1. Galvanostatic cycling in 6.0 M KOH aqueous solution produced capacitance over an ideal cathode potential cycling range. At a high current density of 2 A g-1, NiO@Co3O4@MnO2 has a high specific capacitance of 792.5 F g-1 with > 90% capacity retention over 1000 cycles, and a high rate capability of 68.9% of its initial capacitance was also maintained over a 0.2-4 A g-1 current density increase. We conclude that NiO@Co3O4@MnO2 offers a promising high rate, high specific capacitance cathode material for alkaline supercapacitors, which owes both to its porous architecture and its synergistic mixed oxide core-shell-shell composition.

  12. Foam shell cryogenic ICF target

    DOEpatents

    Darling, Dale H.

    1987-01-01

    A uniform cryogenic layer of DT fuel is maintained in a fusion target having a low density, small pore size, low Z rigid foam shell saturated with liquid DT fuel. Capillary action prevents gravitational slumping of the fuel layer. The saturated shell may be cooled to produce a solid fuel layer.

  13. Multi-shelled Hollow Metal-Organic Frameworks.

    PubMed

    Liu, Wenxian; Huang, Jijiang; Yang, Qiu; Wang, Shiji; Sun, Xiaoming; Zhang, Weina; Liu, Junfeng; Huo, Fengwei

    2017-05-08

    Hollow metal-organic frameworks (MOFs) are promising materials with sophisticated structures, such as multiple shells, that cannot only enhance the properties of MOFs but also endow them with new functions. Herein, we show a rational strategy to fabricate multi-shelled hollow chromium (III) terephthalate MOFs (MIL-101) with single-crystalline shells through step-by-step crystal growth and subsequent etching processes. This strategy relies on the creation of inhomogeneous MOF crystals in which the outer layer is chemically more robust than the inner layer and can be selectively etched by acetic acid. The regulation of MOF nucleation and crystallization allows the tailoring of the cavity size and shell thickness of each layer. The resultant multi-shelled hollow MIL-101 crystals show significantly enhanced catalytic activity during styrene oxidation. The insight gained from this systematic study will aid in the rational design and synthesis of other multi-shelled hollow structures and the further expansion of their applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Multifunctional magnetic and fluorescent core-shell nanoparticles for bioimaging.

    PubMed

    Lu, Yanjiao; He, Bicheng; Shen, Jie; Li, Jie; Yang, Wantai; Yin, Meizhen

    2015-02-07

    Novel magnetic and fluorescent core-shell nanoparticles have been fabricated, which exhibit superparamagnetic behavior and emit strong near-infrared fluorescence. The nanoparticles are highly biocompatible and can be internalized into cells with nucleic accumulation via strong interaction with nucleic acids, implying potential applications in the biomedical field.

  15. Chemical and thermal stability of core-shelled magnetite nanoparticles and solid silica

    NASA Astrophysics Data System (ADS)

    Cendrowski, Krzysztof; Sikora, Pawel; Zielinska, Beata; Horszczaruk, Elzbieta; Mijowska, Ewa

    2017-06-01

    Pristine nanoparticles of magnetite were coated by solid silica shell forming core/shell structure. 20 nm thick silica coating significantly enhanced the chemical and thermal stability of the iron oxide. Chemical and thermal stability of this structure has been compared to the magnetite coated by mesoporous shell and pristine magnetite nanoparticles. It is assumed that six-membered silica rings in a solid silica shell limit the rate of oxygen diffusion during thermal treatment in air and prevent the access of HCl molecules to the core during chemical etching. Therefore, the core/shell structure with a solid shell requires a longer time to induce the oxidation of iron oxide to a higher oxidation state and, basically, even strong concentrated acid such as HCl is not able to dissolve it totally in one month. This leads to the desired performance of the material in potential applications such as catalysis and environmental protection.

  16. Synthesis and characterizations of Ni-Fe-spinel oxide core-shell nanoparticles

    SciTech Connect

    Zhang, H.T. Ding, J.; Chow, G.M.

    2009-05-06

    Core-shell Ni-Fe-ferrite nanoparticles with an average diameter of 14 nm and shell thickness of 3 nm were synthesized through a redox-transmetalation process. The alloy core and spinel oxide shell were verified by X-ray photoelectron spectroscopy, X-ray diffraction, and transmission electron microscopy. The hydrophobic oleylamine molecules on the surface were replaced by hydrophilic meso-2,3-Dimercaptosuccinic acid to make the nanoparticles to be water-soluble. X-ray diffraction study of the as-prepared core-shell nanoparticles indicates that they remained face centered cubic alloy core and spinel shell form in air. Magnetic measurements indicate that the core-shell nanoparticles exhibit superparamagnetic and exchange bias characteristics at 300 K and 5 K, respectively.

  17. The template-assisted synthesis of polypyrrole hollow microspheres with a double-shelled structure.

    PubMed

    Niu, Chunyu; Zou, Bingfang; Wang, Yongqiang; Chen, Lin; Zheng, Haihong; Zhou, Shaomin

    2015-03-25

    Double-shelled polypyrrole hollow microspheres were synthesized via a novel template-assisted concept, using iron oxide hollow microspheres as both the sacrificial template and initiator in acidic solution.

  18. Shell forming apparatus

    NASA Technical Reports Server (NTRS)

    Wang, Taylor G. (Inventor); Granett, Dan (Inventor); Akutagawa, Wesley M. (Inventor)

    1987-01-01

    A nozzle assembly is described for use in a system that forms small gas-filled shells, which avoids the need for holding a miniature inner nozzle precisely concentric with a miniature outer nozzle. The outer nozzle has a diameter which is less than about 0.7 millimeter, which results in fluid passing through the nozzle having a progressively greater velocity at locations progressively further from the walls of the outer nozzle across most of the nozzle. This highly variable velocity profile automatically forces gas to the center of the outer nozzle. The end of the inner nozzle, which emits gas, is spaced upstream from the tip of the outer nozzle, to provide a distance along which to center the gas. This self-centering characteristic permits the inner nozzle to be positioned so its axis is not concentric with the axis of the outer nozzle.

  19. Composite shell spacecraft seat

    NASA Technical Reports Server (NTRS)

    Barackman, Victor J. (Inventor); Pulley, John K. (Inventor); Simon, Xavier D. (Inventor); McKee, Sandra D. (Inventor)

    2008-01-01

    A two-part seat (10) providing full body support that is specific for each crew member (30) on an individual basis. The two-part construction for the seat (10) can accommodate many sizes and shapes for crewmembers (30) because it is reconfigurable and therefore reusable for subsequent flights. The first component of the two-part seat construction is a composite shell (12) that surrounds the crewmember's entire body and is generically fitted to their general size in height and weight. The second component of the two-part seat (10) is a cushion (20) that conforms exactly to the specific crewmember's entire body and gives total body support in more complex environment.

  20. Crack problems in cylindrical and spherical shells

    NASA Technical Reports Server (NTRS)

    Erdogan, F.

    1976-01-01

    Standard plate or shell theories were used as a starting point to study the fracture problems in thin-walled cylindrical and spherical shells, assuming that the plane of the crack is perpendicular to the surface of the sheet. Since recent studies have shown that local shell curvatures may have a rather considerable effect on the stress intensity factor, the crack problem was considered in conjunction with a shell rather than a plate theory. The material was assumed to be isotropic and homogeneous, so that approximate solutions may be obtained by approximating the local shell crack geometry with an ideal shell which has a solution, namely a spherical shell with a meridional crack, a cylindrical shell with a circumferential crack, or a cylindrical shell with an axial crack. A method of solution for the specially orthotropic shells containing a crack was described; symmetric and skew-symmetric problems are considered in cylindrical shells with an axial crack.

  1. Glass shell manufacturing in space

    NASA Technical Reports Server (NTRS)

    Downs, R. L.; Ebner, M. A.; Nolen, R. L., Jr.

    1981-01-01

    Highly-uniform, hollow glass spheres (shells), which are used for inertial confinement fusion targets, were formed from metal-organic gel powder feedstock in a vertical furnace. As a result of the rapid pyrolysis caused by the furnace, the gel is transformed to a shell in five distinct stages: (a) surface closure of the porous gel; (b) generation of a closed-cell foam structure in the gel; (c) spheridization of the gel and further expansion of the foam; (d) coalescence of the closed-cell foam to a single-void shell; and (e) fining of the glass shell. The heat transfer from the furnace to the falling gel particle was modeled to determine the effective heating rate of the gel. The model predicts the temperature history for a particle as a function of mass, dimensions, specific heat, and absorptance as well as furnace temperature profile and thermal conductivity of the furnace gas. A model was developed that predicts the gravity-induced degradation of shell concentricity in falling molten shells as a function of shell characteristics and time.

  2. Core/Shell semiconductor nanocrystals.

    PubMed

    Reiss, Peter; Protière, Myriam; Li, Liang

    2009-02-01

    Colloidal core/shell nanocrystals contain at least two semiconductor materials in an onionlike structure. The possibility to tune the basic optical properties of the core nanocrystals, for example, their fluorescence wavelength, quantum yield, and lifetime, by growing an epitaxial-type shell of another semiconductor has fueled significant progress on the chemical synthesis of these systems. In such core/shell nanocrystals, the shell provides a physical barrier between the optically active core and the surrounding medium, thus making the nanocrystals less sensitive to environmental changes, surface chemistry, and photo-oxidation. The shell further provides an efficient passivation of the surface trap states, giving rise to a strongly enhanced fluorescence quantum yield. This effect is a fundamental prerequisite for the use of nanocrystals in applications such as biological labeling and light-emitting devices, which rely on their emission properties. Focusing on recent advances, this Review discusses the fundamental properties and synthesis methods of core/shell and core/multiple shell structures of II-VI, IV-VI, and III-V semiconductors.

  3. Optimum rotationally symmetric shells for flywheel rotors

    DOEpatents

    Blake, Henry W.

    2000-01-01

    A flywheel rim support formed from two shell halves. Each of the shell halves has a disc connected to the central shaft. A first shell element connects to the disc at an interface. A second shell element connects to the first shell element. The second shell element has a plurality of meridional slits. A cylindrical shell element connects to the second shell element. The cylindrical shell element connects to the inner surface of the flywheel rim. A flywheel rim support having a disc connected an outer diameter of a shaft. Two optimally shaped shell elements connect to the optimally shaped disc at an interface. The interface defines a discontinuity in a meridional slope of said support. A cylindrical shell element connects to the two shell elements. The cylindrical shell element has an outer surface for connecting to the inner surface of the flywheel rim. A flywheel rim casing includes an annular shell connected to the central shaft. The annular shell connects to the flywheel rim. A composite shell surrounds the shaft, annular shell and flywheel rim.

  4. Optimum rotationally symmetric shells for flywheel rotors

    SciTech Connect

    Blake, H.W.

    2000-04-04

    A flywheel rim support formed from two shell halves. Each of the shell halves has a disc connected to the central shaft. A first shell element connects to the disc at an interface. A second shell element connects to the first shell element. The second shell element has a plurality of meridional slits. A cylindrical shell element connects to the second shell element. The cylindrical shell element connects to the inner surface of the flywheel rim. A flywheel rim support having a disc connected an outer diameter of a shaft. Two optimally shaped shell elements connect to the optimally shaped disc at an interface. The interface defines a discontinuity in a meridional slope of said support. A cylindrical shell element connects to the two shell elements. The cylindrical shell element has an outer surface for connecting to the inner surface of the flywheel rim. A flywheel rim casing includes an annular shell connected to the central shaft. The annular shell connects to the flywheel rim. A composite shell surrounds the shaft, annular shell and flywheel rim.

  5. Core-shell colloidal particles with dynamically tunable scattering properties.

    PubMed

    Meng, Guangnan; Manoharan, Vinothan N; Perro, Adeline

    2017-09-27

    We design polystyrene-poly(N'-isopropylacrylamide-co-acrylic acid) core-shell particles that exhibit dynamically tunable scattering. We show that under normal solvent conditions the shell is nearly index-matched to pure water, and the particle scattering is dominated by Rayleigh scattering from the core. As the temperature or salt concentration increases, both the scattering cross-section and the forward scattering increase, characteristic of Mie scatterers. The magnitude of the change in the scattering cross-section and scattering anisotropy can be controlled through the solvent conditions and the size of the core. Such particles may find use as optical switches or optical filters with tunable opacity.

  6. Comparative study of shell swab and shell crush methods for the recovery of Salmonella from shell eggs.

    USDA-ARS?s Scientific Manuscript database

    Swabbing (SW) is the standard methodology for the recovery of resident microorganisms from shell eggs in Japan. A comparative study of shell swab (SW) and a shell crush (CR) technique was performed to recover the laboratory-inoculated Salmonella from shell eggs. It was found that the recovery of ...

  7. Metric theory of nematoelastic shells.

    PubMed

    Pismen, L M

    2014-12-01

    We consider three-dimensional reshaping of a thin nematoelastic film upon nematic-isotropic transition in the field of a charge one topological defect, leading to either cone or anticone (d-cone) shells. The analysis is based on the relation between the shell metric and the tensor order parameter under the assumption of no elastic deformation and volume change. The shape of the shell can be modified by doping, creating cones with curved generatrices. Anticones necessarily have an even number of radial creases. The curvature singularity at the apex is resolved due to decay of the nematic order parameter at the defect core.

  8. The entropy of Black Shells

    NASA Astrophysics Data System (ADS)

    Rojas C., W. A.; Arenas S., R.

    2017-07-01

    The formalism of Darmois-Israel is used to calculate the entropy of a thin spherical shell that contracts from infinity down to near its gravitational radius. It was found that the entropy contained in the thin shell is proportional to the horizon area depending on the number of species N, the distance own above the horizon α and two constants C1 and C2 which can be measured observationally. Certain thermodynamic parameters were calculated, when thin shell it is near the horizon of events for a static space-time, this parameters are agree with reported.

  9. MicroShell Minimalist Shell for Xilinx Microprocessors

    NASA Technical Reports Server (NTRS)

    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

  10. Recovery of Salmonella from commercial shell eggs by shell rinse and shell crush methodologies.

    PubMed

    Musgrove, M T; Jones, D R; Northcutt, J K; Harrison, M A; Cox, N A; Ingram, K D; Hinton, A J

    2005-12-01

    Salmonella is the most important human pathogen associated with shell eggs. Salmonella Enteritidis is the serotype most often implicated in outbreaks, although other serotypes have been recovered from eggs and from the commercial shell egg washing environment. Many sample methods are used to recover microorganisms from eggshells and membranes. A shell rinse and modified shell-and-membrane crush method for recovery of Salmonella were compared. Eggs were collected from 3 commercial shell-washing facilities (X, Y, and Z) during 3 visits. Twelve eggs were collected from each of 10 to 12 locations along the egg processing chain. After being transported back to the laboratory, each egg was sampled first by a shell rinse method and then by a shell crush method. For each technique (rinse or crush), 2 pools of 5 eggs per location sampled were selectively enriched for the recovery of Salmonella. Presumptive samples positive for Salmonella were confirmed serologically. Overall, there were 10.1% (40/396) Salmonella-positive pooled samples. Salmonella were recovered by the shell rinse and shell crush techniques (4.8 vs. 5.3%, respectively). Plant X yielded 21.5% Salmonella positives, whereas less than 5% of samples from plants Y and Z were found to be contaminated with the organism (4.2 and 4.5%, respectively). Salmonella was recovered more often from unwashed eggs (15.8%) than from washed eggs (8.3%). For some eggs, Salmonella was only recovered by one of the methods. Use of both approaches in the same experiment increased sampling sensitivity, although in most cases, crushing provided more sensitive Salmonella recovery.

  11. Rapid microwave synthesis and photoluminescence properties of rare earth-based coordination polymer core-shell particles

    NASA Astrophysics Data System (ADS)

    Huang, Shuang; Xu, Hualan; Wang, Mengya; Zhong, Shengliang; Zeng, Chenghui

    2016-12-01

    Coordination polymer (CP) core-shell particles, with Eu-based CP as the core and La-based CP as the shell, were prepared using a facile microwave heating method. Pyridine-2, 5-dicarboxylic acid (PDA) was selected as the organic building blo, and DMF was used as the solvent. SEM and TEM images show that the resultant cores are nanospheres with diameters of 200-400 nm. Products with different shell thickness were prepared. The luminescence properties of the core-shell structures were studied and the influence of the La-based CP shell on the photoluminescence properties of the core were investigated. The fluorescence intensity and lifetime of the Eu-based CP core were varied with the addition of shell thickness. Both of them increases at first and then decreases with the increase of shell thickness.

  12. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed. ... 7 Agriculture 8 2013-01-01 2013-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture...

  13. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed. ... 7 Agriculture 8 2012-01-01 2012-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture...

  14. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed. ... 7 Agriculture 8 2011-01-01 2011-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture...

  15. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed. ... 7 Agriculture 8 2010-01-01 2010-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture...

  16. 7 CFR 996.19 - Shelled peanuts.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the kernels or portions of kernels of peanuts after the shells are removed. ... 7 Agriculture 8 2014-01-01 2014-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture...

  17. 7 CFR 51.2289 - Shell.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Shell. 51.2289 Section 51.2289 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... § 51.2289 Shell. Shell means the outer shell and/or the woody partition from between the halves of the...

  18. 7 CFR 51.2289 - Shell.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Shell. 51.2289 Section 51.2289 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... § 51.2289 Shell. Shell means the outer shell and/or the woody partition from between the halves of the...

  19. Evaluation of sanitizers for inactivating Salmonella on in-shell pecans and pecan nutmeats.

    PubMed

    Beuchat, Larry R; Mann, David A; Alali, Walid Q

    2012-11-01

    Chlorine, organic acids, and water extracts of inedible pecan components were tested for effectiveness in killing Salmonella on pecans. In-shell pecans and nutmeats (U.S. Department of Agriculture medium pieces) were immersion inoculated with a mixture of five Salmonella serotypes, dried to 3.7% moisture, and stored at 4°C for 3 to 6 weeks. In-shell nuts were immersed in chlorinated water (200, 400, and 1,000 μg/ml), lactic acid (0.5, 1, and 2%), and levulinic acid (0.5, 1, and 2%) with and without 0.05% sodium dodecyl sulfate (SDS), and a mixed peroxyacid sanitizer (Tsunami 200, 40 μg/ml) for up to 20 min at 21°C. The rate of reduction of free chlorine in conditioning water decreased as the ratio of in-shell nuts/water was increased. The rate of reduction was more rapid when nuts were not precleaned before treatment. The initial population of Salmonella on in-shell nuts (5.9 to 6.3 log CFU/g) was reduced by 2.8 log CFU/g after treating with chlorinated water (1,000 μg/ml). Treatment with 2% lactic acid plus SDS or 2% levulinic acid plus SDS reduced the pathogen by 3.7 and 3.4 log CFU/g, respectively. Lactic and levulinic acids (2%) without SDS were less effective (3.3- and 2.1-log CFU/g reductions, respectively) than acids with SDS. Treatment with Tsunami 200 resulted in a 2.4-log CFU/g reduction. In-shell nuts and nutmeats were immersed in water extracts of ground pecan shucks (hulls), shells, a mixture of shells and pith, and pith. The general order of lethality of extracts to Salmonella was shuck < shell-pith ≤ shell ≤ pith < chlorine (400 μg/ml) and shuck < shell ≤ pith = shell-pith < chlorine (400 μg/ml). Results emphasize the importance of removing soil and dust on in-shell pecans before conditioning in chlorinated water and the need for sanitizers with increased effectiveness in killing Salmonella on pecans.

  20. Shell Scores with Interactive Video.

    ERIC Educational Resources Information Center

    Zemke, Ron

    1991-01-01

    Documents Shell Oil's success with interactive video training (IVT) and identifies the costs involved in this long-term investment. Provides guidelines for judging the effectiveness of IVT programs. (SK)

  1. Core–Shell Plasmonic Nanohelices

    PubMed Central

    2017-01-01

    We introduce core–shell plasmonic nanohelices, highly tunable structures that have a different response in the visible for circularly polarized light of opposite handedness. The glass core of the helices is fabricated using electron beam induced deposition and the pure gold shell is subsequently sputter coated. Optical measurements allow us to explore the chiral nature of the nanohelices, where differences in the response to circularly polarized light of opposite handedness result in a dissymmetry factor of 0.86, more than twice of what has been previously reported. Both experiments and subsequent numerical simulations demonstrate the extreme tunability of the core–shell structures, where nanometer changes to the geometry can lead to drastic changes of the optical responses. This tunability, combined with the large differential transmission, make core–shell plasmonic nanohelices a powerful nanophotonic tool for, for example, (bio)sensing applications. PMID:28824931

  2. Shell proteome of rhynchonelliform brachiopods.

    PubMed

    Immel, Françoise; Gaspard, Danièle; Marie, Arul; Guichard, Nathalie; Cusack, Maggie; Marin, Frédéric

    2015-06-01

    Brachiopods are a phylum of marine invertebrates that have an external bivalved shell to protect their living tissues. With few exceptions, this biomineralized structure is composed of calcite, mixed together with a minor organic fraction, comprising secreted proteins that become occluded in the shell structure, once formed. This organic matrix is thought to display several functions, in particular, to control mineral deposition and to regulate crystallite shapes. Thus, identifying the primary structure of matrix proteins is a prerequisite for generating bioinspired materials with tailored properties. In this study, we employed a proteomic approach to identify numerous peptides that constitute the shell proteins, in three rhynchonellid brachiopods from different localities. Our results suggest that the shell protein repertoires identified thus far, differ from that of better known calcifying metazoans, such as molluscs. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Patterning of the turtle shell.

    PubMed

    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.

  4. Insulative laser shell coupler

    DOEpatents

    Arnold, Phillip A.; Anderson, Andrew T.; Alger, Terry W.

    1994-01-01

    A segmented coaxial laser shell assembly having at least two water jacket sections, two pairs of interconnection half rings, a dialectric break ring, and a pair of threaded ring sections. Each water jacket section with an inner tubular section that defines an inner laser cavity with water paths adjacent to at least a portion of the exterior of the inner tubular section, and mating faces at the end of the water jacket section through which the inner laser cavity opens and which defines at least one water port therethrough in communication with the water jackets. The water paths also define in their external surface a circumferential notch set back from and in close proximity to the mating face. The dielectric break ring has selected thickness and is placed between, and in coaxial alignment with, the mating faces of two of the adjacent water jacket sections. The break ring also defines an inner laser cavity of the same size and shape as the inner laser cavity of the water jacket sections and at least one water passage through the break ring to communicate with at least one water port through the mating faces of the water jacket sections.

  5. Insulative laser shell coupler

    DOEpatents

    Arnold, P.A.; Anderson, A.T.; Alger, T.W.

    1994-09-20

    A segmented coaxial laser shell assembly having at least two water jacket sections, two pairs of interconnection half rings, a dielectric break ring, and a pair of threaded ring sections is disclosed. Each water jacket section with an inner tubular section that defines an inner laser cavity with water paths adjacent to at least a portion of the exterior of the inner tubular section, and mating faces at the end of the water jacket section through which the inner laser cavity opens and which defines at least one water port therethrough in communication with the water jackets. The water paths also define in their external surface a circumferential notch set back from and in close proximity to the mating face. The dielectric break ring has selected thickness and is placed between, and in coaxial alignment with, the mating faces of two of the adjacent water jacket sections. The break ring also defines an inner laser cavity of the same size and shape as the inner laser cavity of the water jacket sections and at least one water passage through the break ring to communicate with at least one water port through the mating faces of the water jacket sections. 4 figs.

  6. Nematic textures in spherical shells

    NASA Astrophysics Data System (ADS)

    Vitelli, V.; Nelson, D. R.

    2006-08-01

    The equilibrium texture of nematic shells is studied as a function of their thickness. For ultrathin shells the ground state has four short (1)/(2) disclination lines but, as the thickness of the film increases, a three-dimensional escaped configuration composed of two pairs of half-hedgehogs becomes energetically favorable. We derive an exact solution for the nematic ground state in the one Frank constant approximation and study the stability of the corresponding texture against thermal fluctuations.

  7. Rotating thin-shell wormhole

    NASA Astrophysics Data System (ADS)

    Ovgun, A.

    2016-11-01

    We construct a rotating thin-shell wormhole using a Myers-Perry black hole in five dimensions, using the Darmois-Israel junction conditions. The stability of the wormhole is analyzed under perturbations. We find that exotic matter is required at the throat of the wormhole to keep it stable. Our analysis shows that stability of the rotating thin-shell wormhole is possible if suitable parameter values are chosen.

  8. Glycogenic effect of an alkali soluble fraction from sepia shell.

    PubMed

    Reddy, T N; Reddy, C P; Srinivas, V; Divan, P V; Reddy, P U

    1994-10-01

    The alkali soluble fraction of the sepia shell possesses both anticonvulsant and hypoglycemic effect. The investigation regarding the fate of the blood sugar during the hypoglycemia revealed that the sepia shell extract acts as a glycogenic agent by mobilising the blood sugar towards liver glycogen reserve through the modulation of the enzymes glycogen phosphorylase a and ab in normal and streptozotocin diabetic mice. The glucose tolerance test (GTT) showed a depression in the GTT curve in experimental mice. The available literature on the biochemistry of the shell reveals that it contains glucosamines and some amino acid residues. The presence of amine group may resemble the sulfonylureas like tolbutamide which also possesses both anticonvulsant and hypoglycemic effect.

  9. Red ochre and shells: clues to human evolution.

    PubMed

    Duarte, Carlos M

    2014-10-01

    The 200-kiloannus (ka) use of red ochre and shells by humans is interpreted as a simple clue of symbolic thinking. Integration of multiple lines of evidence supports the opinion that the use of red ochre and shells might have had direct significance for human evolution. Use of seafood and red ochre supplies docosahexaenoic acid (DHA), possibly iron, and other essential nutrients for brain development and reproductive health, improving human fitness and triggering brain growth. The fitness advantages to humans of using shells, and possibly red ochre, might have selected for artistic and symbolic expression, and, thereby, lead to social cohesion. Current global health syndromes show that an adequate supply of seafood and iron continues to play a fundamental role in human health. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Waste shells of mollusk and egg as biodiesel production catalysts.

    PubMed

    Viriya-Empikul, N; Krasae, P; Puttasawat, B; Yoosuk, B; Chollacoop, N; Faungnawakij, K

    2010-05-01

    The solid oxide catalysts derived from waste shells of egg, golden apple snail, and meretrix venus were employed to produce biodiesel from transesterification of palm olein oil. The shell materials were calcined in air at 800 degrees C with optimum time of 2-4h to transform calcium species in the shells into active CaO catalysts. All catalysts showed the high biodiesel production activity over 90% fatty acid methyl ester (FAME) in 2h, whilst the eggshell-derived catalyst showed comparable activity to the one derived from commercial CaCO(3). The catalytic activity was in accordance with the surface area of and the Ca content in the catalysts.

  11. Triton shells of intact erythrocytes.

    PubMed

    Sheetz, M P; Sawyer, D

    1978-01-01

    About 40% of human erythrocyte membrane protein is resistant to solubilization in 0.5% Triton X-114. These components comprise a structure called a Triton shell roughly similar in size and shape to the original erythrocyte and thus constitute a cytoskeleton. With increasing concentrations of Triton the lipid content of the Triton shell decreases dramatically, whereas the majority of the protein components remain constant. Exceptions to this rule include proteins contained in band 3, the presumed anion channel, and in band 4 which decrease with increasing Triton concentration. The Triton-insoluble complex includes spectrin (bands 1 and 2), actin (band 5), and bands 3' and 7. Component 3' has an apparent molecular weight of 88,000 daltons as does 3; but unlike 3, it is insensitive to protease treatment of the intact cell, has a low extinction coefficient at 280 nm, and is solubilized from the shells in alkaline water solutions. Component 7 also has a low extinction coefficient at 280 nm. Spectrin alone is solubilized from the Triton shells in isotonic media. The solubilized spectrin contains no bound Triton and coelectrophoreses with spectrin eluted in hypotonic solutions from ghosts. Electron micrographs of fixed Triton shells stained with uranyl acetate show the presence of numerous filaments which appear beaded and are 80--120 A in diameter. The filaments cannot be composed mainly af actin, but enough spectrin is present to form the filaments. Triton shells may provide an excellent source of material useful in the investigation of the erythrocyte cytoskeleton.

  12. Comparative shell buffering properties correlate with anoxia tolerance in freshwater turtles.

    PubMed

    Jackson, Donald C; Taylor, Sarah E; Asare, Vivian S; Villarnovo, Dania; Gall, Jonathan M; Reese, Scott A

    2007-02-01

    Freshwater turtles as a group are more resistant to anoxia than other vertebrates, but some species, such as painted turtles, for reasons not fully understood, can remain anoxic at winter temperatures far longer than others. Because buffering of lactic acid by the shell of the painted turtle is crucial to its long-term anoxic survival, we have tested the hypothesis that previously described differences in anoxia tolerance of five species of North American freshwater turtles may be explained at least in part by differences in their shell composition and buffering capacity. All species tested have large mineralized shells. Shell comparisons included 1) total shell CO2 concentration, 2) volume of titrated acid required to hold incubating shell powder at pH 7.0 for 3 h (an indication of buffer release from shell), and 3) lactate concentration of shell samples incubated to equilibrium in a standard lactate solution. For each measurement, the more anoxia-tolerant species (painted turtle, Chrysemys picta; snapping turtle, Chelydra serpentina) had higher values than the less anoxia-tolerant species (musk turtle, Sternotherus odoratus; map turtle, Graptemys geographica; red-eared slider, Trachemys scripta). We suggest that greater concentrations of accessible CO2 (as carbonate or bicarbonate) in the more tolerant species enable these species, when acidotic, to release more buffer into the extracellular fluid and to take up more lactic acid into their shells. We conclude that the interspecific differences in shell composition and buffering can contribute to, but cannot explain fully, the variations observed in anoxia tolerance among freshwater turtles.

  13. Adsorption of metal ions by pecan shell-based granular activated carbons.

    PubMed

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

    2003-09-01

    The present investigation was undertaken to evaluate the adsorption effectiveness of pecan shell-based granular activated carbons (GACs) in removing metal ions (Cu(2+), Pb(2+), Zn(2+)) commonly found in municipal and industrial wastewater. Pecan shells were activated by phosphoric acid, steam or carbon dioxide activation methods. Metal ion adsorption of shell-based GACs was compared to the metal ion adsorption of a commercial carbon, namely, Calgon's Filtrasorb 200. Adsorption experiments were conducted using solutions containing all three metal ions in order to investigate the competitive effects of the metal ions as would occur in contaminated wastewater. The results obtained from this study showed that acid-activated pecan shell carbon adsorbed more lead ion and zinc ion than any of the other carbons, especially at carbon doses of 0.2-1.0%. However, steam-activated pecan shell carbon adsorbed more copper ion than the other carbons, particularly using carbon doses above 0.2%. In general, Filtrasorb 200 and carbon dioxide-activated pecan shell carbons were poor metal ion adsorbents. The results indicate that acid- and steam-activated pecan shell-based GACs are effective metal ion adsorbents and can potentially replace typical coal-based GACs in treatment of metal contaminated wastewater.

  14. Tunable construction of multi-shelled hollow carbonate nanospheres and their potential applications

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoming; Zhang, Xiaoting; Yang, Lin; Wang, Ge; Jiang, Kai; Wu, Geoffrey; Cui, Weigang; Wei, Zipeng

    2016-04-01

    The development of multi-shelled hollow carbonate nanospheres (MHCN) for biomedical applications is challenging, and has not been reported. In this study, a facile approach is firstly reported to synthesize hierarchically porous MHCN with controllable shell numbers using a novel strategy called layer-by-layer thermal decomposition of organic acid salts and templates. The choice of organic acid salts as the reactants is innovative and crucial. The shell numbers of porous MHCN can be easily controlled and tuned through adjusting the adsorption temperature of organic acid salts and/or the adsorption ability of the template. The synthetic method can not only open a window to prepare the multi-shelled carbonates but also provide a new strategy to synthesise other multi-shelled inorganic salts. Notably, the hierarchically porous multi-shelled hollow structures empower the carbonates with not only a large specific surface area but also good porosity and permeability, showing great potential for future applications. Herein, our in vitro/vivo evaluations show that CaCO3 MHCN possess a high drug loading capacity and a sustained-release drug profile. It is highly expected that this novel synthetic strategy for MHCN and novel MHCN platform have the potential for biomedical applications in the near future.The development of multi-shelled hollow carbonate nanospheres (MHCN) for biomedical applications is challenging, and has not been reported. In this study, a facile approach is firstly reported to synthesize hierarchically porous MHCN with controllable shell numbers using a novel strategy called layer-by-layer thermal decomposition of organic acid salts and templates. The choice of organic acid salts as the reactants is innovative and crucial. The shell numbers of porous MHCN can be easily controlled and tuned through adjusting the adsorption temperature of organic acid salts and/or the adsorption ability of the template. The synthetic method can not only open a window to

  15. Phenolic compounds and antioxidant activity of kernels and shells of Mexican pecan (Carya illinoinensis).

    PubMed

    de la Rosa, Laura A; Alvarez-Parrilla, Emilio; Shahidi, Fereidoon

    2011-01-12

    The phenolic composition and antioxidant activity of pecan kernels and shells cultivated in three regions of the state of Chihuahua, Mexico, were analyzed. High concentrations of total extractable phenolics, flavonoids, and proanthocyanidins were found in kernels, and 5-20-fold higher concentrations were found in shells. Their concentrations were significantly affected by the growing region. Antioxidant activity was evaluated by ORAC, DPPH•, HO•, and ABTS•-- scavenging (TAC) methods. Antioxidant activity was strongly correlated with the concentrations of phenolic compounds. A strong correlation existed among the results obtained using these four methods. Five individual phenolic compounds were positively identified and quantified in kernels: ellagic, gallic, protocatechuic, and p-hydroxybenzoic acids and catechin. Only ellagic and gallic acids could be identified in shells. Seven phenolic compounds were tentatively identified in kernels by means of MS and UV spectral comparison, namely, protocatechuic aldehyde, (epi)gallocatechin, one gallic acid-glucose conjugate, three ellagic acid derivatives, and valoneic acid dilactone.

  16. Amphoteric core-shell microgels: contraphilic two-compartment colloidal particles.

    PubMed

    Christodoulakis, Kostas E; Vamvakaki, Maria

    2010-01-19

    pH-responsive amphoteric core-shell microgel particles were synthesized by emulsion copolymerization of the appropriate functional monomers with ethylene glycol dimethacrylate as the cross-linker. 2-(Diethylamino)ethyl methacrylate (DEA) was used as the ionizable basic monomer, and tert-butyl methacrylate served as the hydrophobic monomer precursor, which gave the methacrylic acid (MAA) moieties following acid hydrolysis of the ester groups. The core of the polyampholyte microgels comprised a cross-linked poly(2-(diethylamino)ethyl methacrylate) (PDEA) or poly(methacrylic acid) (PMAA) network surrounded by a cross-linked PMAA or PDEA shell, respectively. A polyampholyte random copolymer microgel with the DEA and MAA units randomly distributed within the gel phase was also prepared. Scanning electron microscopy studies showed spherical particles of a narrow size distribution, and transmission electron microscopy verified the core-shell topology of the particles. Potentiometric titration curves revealed two plateau regions for the polyampholyte core-shell microgels attributed to the independent ionization process of the core and the shell of the particles, in contrast to the random copolymer microgel particles that exhibited a single plateau region as a result of the simultaneous protonation/deprotonation process of the basic and acidic moieties of the microgels. The core and the shell of the particles were found to swell independently upon ionization of the DEA or MAA moieties at low or high pH, respectively, whereas collapsed latex particles were obtained in the intermediate pH range when both the core and the shell of the particles were neutral, in agreement with the potentiometric titration data. These core-shell microgels comprise novel two-compartment nanostructures that exhibit contraphilic properties in the core and the shell of the particles in response to a single external stimulus.

  17. Foam shell project: Progress report

    SciTech Connect

    Overturf, G.; Reibold, B.; Cook, B.; Schroen-Carey, D.

    1994-03-25

    The authors report on their work to produce a foam shell target for two possible applications: (1) as liquid-layered cryogenic target on Omega Upgrade, and (2) as a back-up design for the NIF. This target consists of a roughly 1 mm diameter and 100 {mu}m thick spherical low-density foam shell surrounding a central void. The foam will be slightly overfilled with liquid D{sub 2} or DT, the overfilled excess being symmetrically distributed on the inside of the shell and supported by thermal gradient techniques. The outside of the foam is overcoated with full density polymer which must be topologically smooth. The technology for manufacturing this style of foam shell involves microencapsulation techniques and has been developed by the Japanese at ILE. Their goal is to determine whether this technology can be successfully adapted to meet US ICF objectives. To this end a program of foam shell development has been initiated at LLNL in collaboration with both the General Atomics DOE Target Fabrication Contract Corporation and the Target Fabrication Group at LLE.

  18. Shell models of magnetohydrodynamic turbulence

    NASA Astrophysics Data System (ADS)

    Plunian, Franck; Stepanov, Rodion; Frick, Peter

    2013-02-01

    Shell models of hydrodynamic turbulence originated in the seventies. Their main aim was to describe the statistics of homogeneous and isotropic turbulence in spectral space, using a simple set of ordinary differential equations. In the eighties, shell models of magnetohydrodynamic (MHD) turbulence emerged based on the same principles as their hydrodynamic counter-part but also incorporating interactions between magnetic and velocity fields. In recent years, significant improvements have been made such as the inclusion of non-local interactions and appropriate definitions for helicities. Though shell models cannot account for the spatial complexity of MHD turbulence, their dynamics are not over simplified and do reflect those of real MHD turbulence including intermittency or chaotic reversals of large-scale modes. Furthermore, these models use realistic values for dimensionless parameters (high kinetic and magnetic Reynolds numbers, low or high magnetic Prandtl number) allowing extended inertial range and accurate dissipation rate. Using modern computers it is difficult to attain an inertial range of three decades with direct numerical simulations, whereas eight are possible using shell models. In this review we set up a general mathematical framework allowing the description of any MHD shell model. The variety of the latter, with their advantages and weaknesses, is introduced. Finally we consider a number of applications, dealing with free-decaying MHD turbulence, dynamo action, Alfvén waves and the Hall effect.

  19. Semiclassical environment of collapsing shells

    SciTech Connect

    Banerjee, Kinjal; Paranjape, Aseem

    2009-12-15

    We explore in detail the semiclassical environment of collapsing shells of matter, and determine the semiclassical flux measured by a variety of observers. This study is a preliminary step in a broader investigation of thermodynamic properties of the geometry of collapsing objects. Specifically, in this paper we consider spherically symmetric null and timelike collapsing shells which form an event horizon, and calculate the flux measured by observers both inside and outside the shell, and both inside and outside the event horizon, and find nontrivial results in most of the cases. Additionally, we also investigate the environment of a shell which collapses but does not form a horizon, halting at some radius larger than the Schwarzschild radius, and find that such an object generically gives rise to a pulse of radiation which is sharply peaked as it travels inwards and is reflected at the origin, and eventually emerges from the shell in a thermalized form. Our results have potential consequences in addressing questions pertaining, e.g. to black hole entropy and backreaction.

  20. Comparing Fluid and Elastic Block Copolymer Shells

    NASA Astrophysics Data System (ADS)

    Rozairo, Damith; Croll, Andrew B.

    2014-03-01

    Emulsions can be stabilized with the addition of an amphiphilic diblock copolymer, resulting in droplets surrounded and protected by a polymer monolayer. Such droplets show considerable promise as advanced cargo carriers in pharmaceuticals or cosmetics due to their strength and responsiveness. Diblock copolymer interfaces remain mostly fluid and may not be able to attain the mechanical performance desired by industry. To strengthen block copolymer emulsion droplets we have developed a novel method for creating thin elastic shells using polystyrene-b-poly(acrylic acid)-b-polystyrene (PS-PAA-PS). Characterization of the fluid filled elastic shells is difficult with traditional means which lead us to develop a new and general method of mechanical measurement. Specifically, we use laser scanning confocal microscopy to achieve a high resolution measure of the deformation of soft spheres under the influence of gravity. To prove the resilience of the technique we examine both a polystyrene-b-poly(ethylene oxide) (PS-PEO) stabilized emulsion and the PS-PAA-PS emulsion. The mechanical measurement allows the physics of the polymer at the interface to be examined, which will ultimately lead to the rational development of these technologies.

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

    EPA Science Inventory

    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 ...

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

    EPA Science Inventory

    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 ...

  3. Closed-shell and open-shell 2D nanographenes.

    PubMed

    Sun, Zhe; Wu, Jishan

    2014-01-01

    This chapter describes a series of two-dimensional (2D) expanded arene networks, also known as nanographenes, with either closed-shell or open-shell electronic structure in the ground state. These systems are further categorized into three classes on a basis of different edge structures: those with zigzag edges only, those with armchair edges only, and those possessing both. Distinctive physical properties of these 2D aromatic systems are closely related to their structural characteristics and provide great potential for them as materials for different applications.

  4. Development of antimicrobial coatings for improving the microbiological safety and quality of shell eggs.

    PubMed

    Jin, Tony Z; Gurtler, Joshua B; Li, Si-Quan

    2013-05-01

    This study was conducted to develop antimicrobial coatings to decontaminate and prevent cross-contamination of shell eggs. Egg shells were inoculated with nalidixic acid-resistant Salmonella enterica Enteritidis strains OB030832, OB040159, and C405 and treated with antimicrobial coatings. Polylactic acid served as a nonedible polymer, and chitosan served as an edible polymer carrier of natural antimicrobials, including nisin, allyl isothiocyanate (AIT), lauric arginate ester (LAE), and organic acids. Increases of AIT concentrations or addition of nisin to AIT in either the polylactic acid or chitosan coating solutions resulted in greater reductions of Salmonella. Chitosan coatings with 0.1, 0.5, and 1.0% LAE reduced Salmonella by 1.7, 2.5, and 5.2 log CFU/cm(2), respectively. Shell eggs treated with 1.0 and 0.5% LAE in chitosan coatings had nondetectable Salmonella cells (< 0.5 log CFU/cm(2)) after 3 and 7 days of storage at 7°C, respectively, and no outgrowth was observed up to 28 days. Coating treatments significantly reduced weight loss of shell eggs during 12 weeks of storage at 7 or 4°C. This study demonstrates an alternative and effective intervention technology for decontaminating shell eggs and provides an alternative approach to reduce possible recalls and outbreaks associated with pathogen contamination on shell eggs and in egg products.

  5. Design and synthesis of highly luminescent near-infrared-emitting water-soluble CdTe/CdSe/ZnS core/shell/shell quantum dots.

    PubMed

    Zhang, Wenjin; Chen, Guanjiao; Wang, Jian; Ye, Bang-Ce; Zhong, Xinhua

    2009-10-19

    Applications of water-dispersible near-infrared (NIR)-emitting quantum dots (QDs) have been hampered by their instability and low photoluminescence (PL) efficiencies. In this paper, water-soluble highly luminescent NIR-emitting QDs were developed through constructing CdTe/CdSe/ZnS core/shell/shell nanostructure. The CdTe/CdSe type-II structure yields the QDs with NIR emission. By varying the size of CdTe cores and the thickness of the CdSe shell, the emission wavelength of the obtained nanostructure can span from 540 to 825 nm. In addition, the passivation of the ZnS shell with a substantially wide bandgap confines the excitons within the CdTe/CdSe interface and isolates them from the solution environment and consequently improves the stability of the nanostructure, especially in aqueous media. An effective shell-coating route was developed for the preparation of CdTe/CdSe core/shell nanostructures by selecting capping reagents with a strong coordinating capacity and adopting a low temperature for shell deposition. An additional ZnS shell was deposited around the outer layer of CdTe/CdSe QDs to form the core/shell/shell nanostructure through the decomposition of single molecular precursor zinc diethyldithiocarbamate in the crude CdTe/CdSe reaction solution. The water solubilization of the initially oil-soluble CdTe/CdSe/ZnS QDs was achieved through ligand replacement by 3-mercaptopropionic acid. The as-prepared water-soluble CdTe/CdSe/ZnS QDs possess PL quantum yields as high as 84% in aqueous media, which is one of the best results for the luminescent semiconductor nanocrystals.

  6. Microfluidic synthesis of Ag@Cu2O core-shell nanoparticles with enhanced photocatalytic activity.

    PubMed

    Tao, Sha; Yang, Mei; Chen, Huihui; Ren, Mingyue; Chen, Guangwen

    2017-01-15

    A microfluidic-based method for the continuous synthesis of Ag@Cu2O core-shell nanoparticles (NPs) has been developed. It only took 32s to obtain Ag@Cu2O core-shell NPs, indicating a high efficiency of this microfluidic-based method. Triangular Ag nanoprisms were employed as the cores for the overgrowth of Cu2O through the reduction of Cu(OH)4(2-) with ascorbic acid. The as-synthesized samples were characterized by XRD, TEM, SEM, HAADF-STEM, EDX, HRTEM, UV-vis spectra and N2 adsorption-desorption. The characterization results revealed that the as-synthesized Ag@Cu2O core-shell NPs exhibited a well-defined core-shell nanostructure with a polycrystalline shell, which was composed of numbers of Cu2O domains epitaxially growing on the triangular Ag nanoprism. It was concluded that the synthesis parameters such as the molar ratio of trisodium citrate to AgNO3, H2O2 to AgNO3, NaOH to CuSO4, ascorbic acid to CuSO4 and AgNO3 to CuSO4 had significant effect on the synthesis of Ag@Cu2O core-shell NPs. Moreover, Ag@Cu2O core-shell NPs exhibited superior catalytic activity in comparison with pristine Cu2O NPs towards the visible light-driven degradation of methyl orange. This enhanced photocatalytic activity of Ag@Cu2O core-shell NPs was attributed to the larger BET surface area and improved charge separation efficiency. The trapping experiment indicated that holes and superoxide anion radicals were the major reactive species in the photodegradation of methyl orange over Ag@Cu2O core-shell NPs. In addition, Ag@Cu2O core-shell NPs showed no obvious deactivation in the cyclic test.

  7. Chemical Analysis Of Beryllium Shells

    SciTech Connect

    Gunther, J; Cook, R

    2005-11-17

    There is a need to understand the level of high-Z impurities in Beryllium shells prepared by sputter coating. The Ignition Point Design Requirements state the following: ''Except for allowed ingredients, as listed in the ablator composition entries, the ablator material in all layers shall contain sufficiently low impurity levels that the sum over all impurities of atom fraction*Z{sup 2} shall be less than or equal to 0.2''. This is a tight specification that requires careful materials analysis. Early in the first quarter of FY06, we undertook a study of Be shell impurities via ICP-MS{sup 2} and determined that the impurity levels in the sputtered shells are very close to the specification.

  8. Asymptotic safety goes on shell

    NASA Astrophysics Data System (ADS)

    Benedetti, Dario

    2012-01-01

    It is well known in quantum field theory that the off-shell effective action depends on the gauge choice and field parametrization used in calculating it. Nevertheless, the typical scheme in which the scenario of asymptotically safe gravity is investigated is an off-shell version of the functional renormalization group equation. Working with the Einstein-Hilbert truncation as a test bed, we develop a new scheme for the analysis of asymptotically safe gravity in which the on-shell part of the effective action is singled out and we show that the beta function for the essential coupling has no explicit gauge dependence. In order to reach our goal, we introduce several technical novelties, including a different decomposition of the metric fluctuations, a new implementation of the ghost sector and a new cut-off scheme. We find a nontrivial fixed point, with a value of the cosmological constant that is independent of the gauge-fixing parameters.

  9. Plastic buckling of cylindrical shells

    SciTech Connect

    Bandyopadhyay, K.; Xu, J.; Shteyngart, S.; Eckert, H.

    1994-05-01

    Cylindrical shells exhibit buckling under axial loads at stresses much less than the respective theoretical critical stresses. This is due primarily to the presence of geometrical imperfections even through such imperfections could be very small (e.g., comparable to thickness). Under internal pressure, the shell regains some of its buckling strength. For a relatively large radius-to-tickness ratio and low internal pressure, the effect can be reasonably estimated by an elastic analysis. However, for low radius-to-thickness ratios and greater pressures, the elastic-plastic collapse controls the failure load. In order to quantify the elastic-plastic buckling capacity of cylindrical shells, an analysis program was carried out by use of the computer code BOSOR5 developed by Bushnell of Lockheed Missiles and Space company. The analysis was performed for various radius-to- thickness ratios and imperfection amplitudes. The analysis results are presented in this paper.

  10. Prevalence of anisotropic shell growth in rare earth core-shell upconversion nanocrystals.

    PubMed

    Zhang, Chao; Lee, Jim Yang

    2013-05-28

    Through a series of carefully executed experiments, we discovered the prevalence of anisotropic shell growth in many upconversion NaREF4 systems caused by a combination of factors: selective adsorption of ligands on the core surface due to the core crystal structure, ligand etching, and the lattice mismatch between core and shell components. This could lead to incomplete shell formation in core-shell nanocrystals under certain conditions. Shell growth is always faster in the a and b crystallographic directions than in the c direction. In the case of a larger lattice mismatch between the core and shell, shell growth only occurs in the a and b directions resulting in an oblong core-shell structure. These findings are useful for rationalizing shell-dependent emission properties, understanding the emission mechanisms in complex core-shell nanostructures, and for creating accurate models of core-shell designs for multifunctionality and optimal performance in applications.

  11. Shell may expand detergent alcohols

    SciTech Connect

    1996-10-23

    Shell Chemical is studying plans to expand detergent alcohols capacity in the US, CW has learned. The company is considering adding capacity for about 80 million lbs/year. If the project is approved, it would be implemented at the company`s Geismar, LA site. Shell will make a final decision on whether to proceed with the project within six months. It has been rumored to be considering a capacity addition as a result of tightening supply of natural and synthetic detergent alcohols.

  12. On Closed Shells in Nuclei

    DOE R&D Accomplishments Database

    Mayer, M. G.

    1948-02-01

    It has been suggested in the past that special numbers of neutrons or protons in the nucleus form a particularly stable configuration.{sup1} The complete evidence for this has never been summarized, nor is it generally recognized how convincing this evidence is. That 20 neutrons or protons (Ca{sup40}) form a closed shell is predicted by the Hartree model. A number of calculations support this fact.{sup2} These considerations will not be repeated here. In this paper, the experimental facts indicating a particular stability of shells of 50 and 82 protons and of 50, 82, and 126 neutrons will be listed.

  13. Glass shell manufacturing in space

    NASA Technical Reports Server (NTRS)

    Nolen, R. L., Jr.; Ebner, M. A.; Downs, R. L.

    1980-01-01

    A heat transfer model was developed that mathematically describes the heating and calculates the thermal history of a gel particle in free-fall through the furnace. The model parameters that greatly affect the calculations were found to be gel particle mass, geometry, specific heat, and furnace gas. Empirical testing of the model has commenced. The code calculations and the initial empirical testing results both indicate that the gel-to-shell transformation occurs early and rapidly in the thermal history of the gel particle, and that for current work the heat transfer rate is not a limitation in shell production.

  14. Acid–base bifunctional shell cross-linked micelle nanoreactor for one-pot tandem reaction

    DOE PAGES

    Lee, Li -Chen; Lu, Jie; Weck, Marcus; ...

    2015-12-29

    In shell cross-linked micelles (SCMs) containing acid sites in the shell and base sites in the core are prepared from amphiphilic poly(2-oxazoline) triblock copolymers. These materials are utilized as two-chamber nanoreactors for a prototypical acid-base bifunctional tandem deacetalization-nitroaldol reaction. Furthermore, the acid and base sites are localized in different regions of the micelle, allowing the two steps in the reaction sequence to largely proceed in separate compartments, akin to the compartmentalization that occurs in biological systems.

  15. Multifunctional yolk-in-shell nanoparticles for pH-triggered drug release and imaging

    PubMed Central

    Chen, Hongyu; Qi, Bin; Moore, Thomas; Wang, Fenglin; Colvin, Daniel C.; Sanjeewa, Liurukara D.; Gore, John C.; Hwu, Shiou-Jyh; Mefford, O. Thompson; Alexis, Frank; Anker, Jeffrey N.

    2015-01-01

    Multifunctional nanoparticles are synthesized for both pH-triggered drug release and imaging with radioluminescence, upconversion luminescent, and magnetic resonance imaging (MRI). The particles have a yolk-in-shell morphology, with a radioluminescent core, an upconverting shell, and a hollow region between the core and shell for loading drugs. They are synthesized by controlled encapsulation of a radioluminescent nanophosphor yolk in a silica shell, partial etching of the yolk in acid, and encapsulation of the silica with an upconverting luminescent shell. Metroxantrone, a chemotherapy drug, was loaded into the hollow space between X-ray phosphor yolk and up-conversion phosphor shell through pores in the shell. To encapsulate the drug and control the release rate, the nanoparticles are coated with pH-responsive biocompatible polyelectrolyte layers of charged hyaluronic acid sodium salt and chitosan. The nanophosphors display bright luminescence under X-ray, blue light (480 nm), and infrared light (980 nm). They also served as T1 and T2 MRI contrast agents with relaxivities of 3.5 mM−1 s−1 (r1) and 64 mM−1s−1 (r2). These multifunctional nanocapsules have applications in controlled drug delivery and multimodal imaging. PMID:24753264

  16. Proteomic analysis of the organic matrix of the abalone Haliotis asinina calcified shell

    PubMed Central

    2010-01-01

    Background The formation of the molluscan shell is regulated to a large extent by a matrix of extracellular macromolecules that are secreted by the shell forming tissue, the mantle. This so called "calcifying matrix" is a complex mixture of proteins and glycoproteins that is assembled and occluded within the mineral phase during the calcification process. While the importance of the calcifying matrix to shell formation has long been appreciated, most of its protein components remain uncharacterised. Results Recent expressed sequence tag (EST) investigations of the mantle tissue from the tropical abalone (Haliotis asinina) provide an opportunity to further characterise the proteins in the shell by a proteomic approach. In this study, we have identified a total of 14 proteins from distinct calcified layers of the shell. Only two of these proteins have been previously characterised from abalone shells. Among the novel proteins are several glutamine- and methionine-rich motifs and hydrophobic glycine-, alanine- and acidic aspartate-rich domains. In addition, two of the new proteins contained Kunitz-like and WAP (whey acidic protein) protease inhibitor domains. Conclusion This is one of the first comprehensive proteomic study of a molluscan shell, and should provide a platform for further characterization of matrix protein functions and interactions. PMID:21050442

  17. Au/Au@polythiophene core/shell nanospheres for heterogeneous catalysis of nitroarenes.

    PubMed

    Shin, Hye-Seon; Huh, Seong

    2012-11-01

    Monodisperse Au/Au@polythiophene core/shell nanospheres were facilely prepared through the reduction of gold precursor, AuCl₄⁻, by 2-thiopheneacetonitrile in an aqueous solution. Concomitantly, 2-thiopheneacetonitrile polymerized during this redox process. As a result, Au nanoparticle was encapsulated by conductive polymer shell to afford novel core/shell nanospheres. Interestingly, the shell was composed of very tiny Au nanoparticles surrounded with thiophene polymers. Thus, the new material is best described as Au/Au@polythiophene core/shell nanospheres. FT-IR spectroscopy revealed that the Au nanoparticles were coordinated by the C≡N groups of the polythiophene shell. Some of the C≡N groups were partially hydrolyzed into COOH groups during the redox process because of the acidic reaction condition. The shell was conductive based on the typical ohmic behavior found in electrical measurement. The Au/Au@polythiophene core/shell nanospheres were found to be very active catalysts for the hydrogenation of various nitroarene compounds into corresponding aminoarene compounds in the presence of NaBH₄. Both hydrophilic and hydrophobic nitroarenes were efficiently hydrogenated under mild conditions.

  18. Facile microfluidic production of composite polymer core-shell microcapsules and crescent-shaped microparticles.

    PubMed

    Ekanem, Ekanem E; Zhang, Zilin; Vladisavljević, Goran T

    2017-07-15

    Core-shell microcapsules and crescent-shaped microparticles can be used as picolitre bioreactors for cell culture and microwells for cell trapping/immobilisation, respectively. Monodisperse polylactic acid (PLA) core-shell microcapsules with a diameter above 200μm, a shell thickness of 10μm, and 96% water entrapment efficiency were produced by solvent evaporation from microfluidically generated W/O/W emulsion drops with core-shell structure, and used to encapsulate Saccharomyces cerevisiae yeast cells in their aqueous cores. The morphological changes of the capsules stained with Nile red were studied over 14days under different osmotic pressure and pH gradients. The shell retained its integrity under isotonic conditions, but buckling and particle crumbling occurred in a hypertonic solution. When the capsules containing 5wt% aqueous Eudragit® S 100 solution in the core were incubated in 10(-4)M HCl solution, H(+) diffused through the PLA film into the core causing an ionic gelation of the inner phase and its phase separation into polymer-rich and water-rich regions, due to the transition of Eudragit from a hydrophilic to hydrophobic state. Crescent-shaped composite microparticles with Eudragit cores and PLA shells were fabricated by drying core-shell microcapsules with gelled cores, due to the collapse of PLA shells encompassing water-rich crescent regions. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Method and apparatus for an inflatable shell

    NASA Technical Reports Server (NTRS)

    Johnson, Christopher J. (Inventor)

    2012-01-01

    A method of assembling an inflatable shell of a structure comprises folding a plurality of shell sections about a set of fold lines and integrating the plurality of shell sections together with one another to form the shell. In another embodiment, an inflatable shell comprises a plurality of shell sections, each shell section having two pairs of fold lines for folding into stowage comprising a first gore section having a plurality of first gore panels layered and collectively folded about at a first set of fold lines. Each layer of the first gore panels and second gore panels are configured such that, once the first gore panel and second gore panel are attached to one another at the respective side edges of each panel, the lines of attachment forming a second set of fold lines for the shell section. A system and method for fabricating gore panels is also disclosed.

  20. Shell Games: Uncovering Periodic Properties.

    ERIC Educational Resources Information Center

    Lamb, William G.

    1983-01-01

    Describes activities (demonstrations/experiments) used to introduce history of periodic properties--without electrons, orbitals, filling shells, or any conception of atoms beyond Dalton's model. Activities supplement first chapter in a currently available chemistry text. Indicates potential danger of experiments if proper safety precautions are…

  1. Shell Games: Uncovering Periodic Properties.

    ERIC Educational Resources Information Center

    Lamb, William G.

    1983-01-01

    Describes activities (demonstrations/experiments) used to introduce history of periodic properties--without electrons, orbitals, filling shells, or any conception of atoms beyond Dalton's model. Activities supplement first chapter in a currently available chemistry text. Indicates potential danger of experiments if proper safety precautions are…

  2. Finite element shell instability analysis

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Formulation procedures and the associated computer program for finite element thin shell instability analysis are discussed. Data cover: (1) formulation of basic element relationships, (2) construction of solution algorithms on both the conceptual and algorithmic levels, and (3) conduction of numerical analyses to verify the accuracy and efficiency of the theory and related programs therein are described.

  3. Recent advances in shell theory. [application of asymptotic approach to thin walled shells

    NASA Technical Reports Server (NTRS)

    Simmonds, J. G.

    1976-01-01

    The results reviewed are divided into two categories: those that relate two-dimensional shell theory to three-dimensional elasticity theory and those concerned with shell theory per se. In the second category results for general elastic systems that carry over, by specialization or analogy, to shells and results that are unique to shell theory itself are considered.

  4. Structure of Enceladus' Ice Shell

    NASA Astrophysics Data System (ADS)

    Hemingway, D.

    2016-12-01

    Constraining the internal structure of Enceladus is essential for understanding its evolution, its highly active south polar region, and its prospects for habitability. Of particular interest is the thickness of the icy shell, which has implications for the thermal structure, the effects of tidal stresses, and the conduits feeding the jets and plume. Since Enceladus' low order gravity field was first measured [1], several studies of shape and gravity have suggested the presence of an internal ocean beneath the icy shell [1-3]. These analyses, however, involve several assumptions and approximations and yield distinct shell thickness estimates (ranging from 18-60 km), only some of which are compatible with estimates from the measured physical librations (15-25 km [4,5]). Part of the challenge is that standard approaches to interior modeling (e.g., Radau-Darwin) are not well suited to Enceladus due to its fast rotation and relatively large non-hydrostatic topography [2,6]. Because of Enceladus' small radius, results are also sensitive to the details of the compensation model [7,8]. Here we apply an analytical compensation model that accommodates the spherical geometry in a manner that is distinct from previous studies, and employ a high fidelity numerical approach to modeling the hydrostatic equilibrium figure [6]. We show that the resulting shell thickness estimates are smaller than in previous models—in agreement with the libration observations—suggesting the possibility of an extremely thin ice crust at the south pole. While a range of mean shell thicknesses are permitted within the observational constraints, the amplitude of lateral shell thickness variations is well constrained. In particular, the shell is 10 km thicker at the north pole than at the south pole, potentially helping to explain the nature of the north-south polar asymmetry in endogenic activity. 1. Iess et al., Science. 344, 78-80 (2014). 2. McKinnon, Geophys. Res. Lett.42 (2015). 3. Cadek et al

  5. Tunable construction of multi-shelled hollow carbonate nanospheres and their potential applications.

    PubMed

    Ma, Xiaoming; Zhang, Xiaoting; Yang, Lin; Wang, Ge; Jiang, Kai; Wu, Geoffrey; Cui, Weigang; Wei, Zipeng

    2016-04-28

    The development of multi-shelled hollow carbonate nanospheres (MHCN) for biomedical applications is challenging, and has not been reported. In this study, a facile approach is firstly reported to synthesize hierarchically porous MHCN with controllable shell numbers using a novel strategy called layer-by-layer thermal decomposition of organic acid salts and templates. The choice of organic acid salts as the reactants is innovative and crucial. The shell numbers of porous MHCN can be easily controlled and tuned through adjusting the adsorption temperature of organic acid salts and/or the adsorption ability of the template. The synthetic method can not only open a window to prepare the multi-shelled carbonates but also provide a new strategy to synthesise other multi-shelled inorganic salts. Notably, the hierarchically porous multi-shelled hollow structures empower the carbonates with not only a large specific surface area but also good porosity and permeability, showing great potential for future applications. Herein, our in vitro/vivo evaluations show that CaCO3 MHCN possess a high drug loading capacity and a sustained-release drug profile. It is highly expected that this novel synthetic strategy for MHCN and novel MHCN platform have the potential for biomedical applications in the near future.

  6. 7 CFR 984.10 - Shelled walnuts.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Shelled walnuts. 984.10 Section 984.10 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 984.10 Shelled walnuts. Shelled walnuts means walnut kernels after...

  7. 7 CFR 984.10 - Shelled walnuts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Shelled walnuts. 984.10 Section 984.10 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 984.10 Shelled walnuts. Shelled walnuts means walnut kernels after...

  8. 7 CFR 984.10 - Shelled walnuts.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Shelled walnuts. 984.10 Section 984.10 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 984.10 Shelled walnuts. Shelled walnuts means walnut kernels after...

  9. 7 CFR 984.10 - Shelled walnuts.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Shelled walnuts. 984.10 Section 984.10 Agriculture... and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 984.10 Shelled walnuts. Shelled walnuts means walnut kernels after...

  10. 7 CFR 984.10 - Shelled walnuts.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Shelled walnuts. 984.10 Section 984.10 Agriculture... AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 984.10 Shelled walnuts. Shelled walnuts means walnut kernels after...

  11. 7 CFR 983.29 - Shelled pistachios.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 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...

  12. 7 CFR 983.29 - Shelled pistachios.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 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...

  13. 7 CFR 983.29 - Shelled pistachios.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 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...

  14. Thin-shell wormholes in dilaton gravity

    SciTech Connect

    Eiroa, Ernesto F.; Simeone, Claudio

    2005-06-15

    In this work we construct charged thin-shell Lorentzian wormholes in dilaton gravity. The exotic matter required for the construction is localized in the shell and the energy conditions are satisfied outside the shell. The total amount of exotic matter is calculated and its dependence with the parameters of the model is analyzed.

  15. Protein profiles of hatchery egg shell membrane

    USDA-ARS?s Scientific Manuscript database

    Background: Eggshells, which consist largely of calcareous outer shell and shell membranes, constitute a significant part of poultry hatchery waste. The shell membranes (ESM) not only contain proteins that originate from egg whites but also from the developing embryos and different contaminants of m...

  16. 7 CFR 981.6 - Shelled almonds.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 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...

  17. 7 CFR 981.6 - Shelled almonds.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 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...

  18. 7 CFR 981.6 - Shelled almonds.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 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...

  19. 7 CFR 981.6 - Shelled almonds.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 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...

  20. 7 CFR 981.6 - Shelled almonds.

    Code of Federal Regulations, 2010 CFR

    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...

  1. 21 CFR 886.3800 - Scleral shell.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Scleral shell. 886.3800 Section 886.3800 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3800 Scleral shell. (a) Identification. A scleral shell is a device made of glass or plastic that is...

  2. 21 CFR 886.3800 - Scleral shell.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Scleral shell. 886.3800 Section 886.3800 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3800 Scleral shell. (a) Identification. A scleral shell is a...

  3. 21 CFR 886.3800 - Scleral shell.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Scleral shell. 886.3800 Section 886.3800 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3800 Scleral shell. (a) Identification. A scleral shell is a...

  4. 21 CFR 886.3800 - Scleral shell.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Scleral shell. 886.3800 Section 886.3800 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3800 Scleral shell. (a) Identification. A scleral shell is a...

  5. 21 CFR 886.3800 - Scleral shell.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Scleral shell. 886.3800 Section 886.3800 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3800 Scleral shell. (a) Identification. A scleral shell is a...

  6. Cacao bean shell poisoning in a dog.

    PubMed

    Drolet, R; Arendt, T D; Stowe, C M

    1984-10-15

    Cacao bean shells contain potentially toxic quantities of theobromine, a xanthine compound similar in effects to caffeine and theophylline. A dog, which ingested a lethal quantity of garden mulch made from cacao bean shells, developed severe convulsions and died 17 hours later. Analysis of the stomach contents and the ingested cacao bean shells revealed the presence of lethal amounts of theobromine.

  7. Developments in Cylindrical Shell Stability Analysis

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.; Starnes, James H., Jr.

    1998-01-01

    Today high-performance computing systems and new analytical and numerical techniques enable engineers to explore the use of advanced materials for shell design. This paper reviews some of the historical developments of shell buckling analysis and design. The paper concludes by identifying key research directions for reliable and robust methods development in shell stability analysis and design.

  8. Vibrations of cantilevered circular cylindrical shells Shallow versus deep shell theory

    NASA Technical Reports Server (NTRS)

    Lee, J. K.; Leissa, A. W.; Wang, A. J.

    1983-01-01

    Free vibrations of cantilevered circular cylindrical shells having rectangular planforms are studied in this paper by means of the Ritz method. The deep shell theory of Novozhilov and Goldenveizer is used and compared with the usual shallow shell theory for a wide range of shell parameters. A thorough convergence study is presented along with comparisons to previously published finite element solutions and experimental results. Accurately computed frequency parameters and mode shapes for various shell configurations are presented. The present paper appears to be the first comprehensive study presenting rigorous comparisons between the two shell theories in dealing with free vibrations of cantilevered cylindrical shells.

  9. Triterpenoid saponins from the shells of Argania spinosa seeds.

    PubMed

    Alaoui, Asma; Charrouf, Zoubida; Soufiaoui, Mohamed; Carbone, Virginia; Malorni, Antonio; Pizza, Cosimo; Piacente, Sonia

    2002-07-31

    Two new oleanene saponins were isolated from the MeOH extract of the shell of Argania spinosa. They possess protobassic acid and 16alpha-protobassic acid as aglycons. The disaccharide moiety linked to C-3 of the aglycon is made up of two glucose units; the pentasaccharide moiety linked to C-28 is made up of arabinose, xylose, and three rhamnose units. Their structures were elucidated by 1D and 2D NMR experiments including (1)H-(1)H (DQF-COSY, 1D TOCSY, and 2D HOHAHA) and (1)H-(13)C (HSQC and HMBC) spectroscopy along with mass spectrometry.

  10. Physical quality and composition of retail shell eggs.

    PubMed

    Jones, D R; Musgrove, M T; Anderson, K E; Thesmar, H S

    2010-03-01

    There are a number of specialty shell eggs available to consumers in the US retail market. A survey consisting of white and brown large shell eggs with various production and nutritional differences (traditional, cage-free, free-roaming, pasteurized, nutritionally enhanced, and fertile) was conducted to determine if physical quality and compositional differences exist. Identical brands of eggs were purchased from the same retail outlets on 3 occasions (replicates) in a single city. The average range of time from processing to purchase for all eggs was 7.67 to 25.33 d, with traditional white eggs in retail having the shortest time. Haugh unit values ranged from 66.67 (cage-free, docosahexaenoic acid, and n-3 enhanced) to 84.42 (traditional white). Albumen height followed a similar pattern. Egg weight was greater for brown eggs (61.12 vs. 58.85 g). Brown eggs also had greater static compression shell strength than white eggs (4,130.61 vs. 3,690.31 g force). Vitelline membrane strength was greatest for traditional brown eggs (2.24 g force). Percentage of total solids and crude fat was greatest in the cage-free, n-3-enhanced white eggs (25.07 and 11.71%, respectively). Although significant differences were found between white and brown shell eggs and production methods, average values for quality attributes varied without one egg type consistently maintaining the highest or lowest values.

  11. X-ray fluorescence microtomography of SiC shells

    SciTech Connect

    Ice, G.E.; Chung, J.S.; Nagedolfeizi, M.

    1997-04-01

    TRISCO coated fuel particles contain a small kernel of nuclear fuel encapsulated by alternating layers of C and SiC. The TRISCO coated fuel particle is used in an advanced fuel designed for passive containment of the radioactive isotopes. The SiC layer provides the primary barrier for radioactive elements in the kernel. The effectiveness of this barrier layer under adverse conditions is critical to containment. The authors have begun the study of SiC shells from TRISCO fuel. They are using the fluorescent microprobe beamline 10.3.1. The shells under evaluation include some which have been cycled through a simulated core melt-down. The C buffer layers and nuclear kernels of the coated fuel have been removed by laser drilling through the SiC and then exposing the particle to acid. Elements of interest include Ru, Sb, Cs, Ce and Eu. The radial distribution of these elements in the SiC shells can be attributed to diffusion of elements in the kernel during the melt-down. Other elements in the shells originate during the fabrication of the TRISCO particles.

  12. Optimization of Method to Extract Collagen from "Emperor" Tissue of Soft-shelled Turtles.

    PubMed

    Yamamoto, Tetsushi; Uemura, Kentaro; Sawashi, Yuki; Mitamura, Kuniko; Taga, Atsushi

    2016-01-01

    Soft-shelled turtles (Pelodiscus sinensis) are widely distributed in some Asian countries, and parts of this turtle contain abundant collagen. In this study, we optimized a method for extracting collagen from the soft-shelled turtle. We used three types of solvent and four extraction conditions to determine an effective collagen extraction method, which was extraction at 37°C with acetic acid after hydrochloric acid pretreatment. Next, we extracted collagen from three regions in the soft-shelled turtle: muscle, skin, and an area of soft tissue in the periphery of the turtle shell known in Japan and China as the "emperor." We determined that emperor tissue yielded the highest concentration and purity of collagen. We then optimized the pretreatment method for extraction from emperor tissue by using formic acid instead of hydrochloric acid, and the amount of extracted collagen increased by approximately 1.3-fold. Finally, we identified the optimal solvent out of four types of organic acid for collagen extraction from emperor tissue; the amount of extracted collagen from emperor tissue increased approximately 3-fold when citric acid was used as the extraction solvent instead of acetic acid. Emperor tissue can regenerate; thus, it is possible to obtain collagen from the emperor repeatedly without killing the turtle. Our findings suggest that the emperor tissue of softshelled turtles may be a good source of collagen for pharmaceutical and cosmetic applications.

  13. High-resolution nitrogen stable isotope sclerochronology of bivalve shell carbonate-bound organics

    NASA Astrophysics Data System (ADS)

    Gillikin, David P.; Lorrain, Anne; Jolivet, Aurélie; Kelemen, Zita; Chauvaud, Laurent; Bouillon, Steven

    2017-03-01

    Nitrogen stable isotope ratios (δ15N) of organic material have successfully been used to track food-web dynamics, nitrogen baselines, pollution, and nitrogen cycling. Extending the δ15N record back in time has not been straightforward due to a lack of suitable substrates in which δ15N records are faithfully preserved, thus sparking interest in utilizing skeletal carbonate-bound organic matter (CBOM) in mollusks, corals, and foraminifera. Here we test if calcite Pecten maximus shells from the Bay of Brest and the French continental shelf can be used as an archive of δ15N values over a large environmental gradient and at a high temporal resolution (approximately weekly). Bulk CBOM δ15N values from the growing tip of shells collected over a large nitrogen isotope gradient were strongly correlated with adductor muscle tissue δ15N values (R2 = 0.99, n = 6, p < 0.0001). We were able to achieve weekly resolution (on average) over the growing season from sclerochronological profiles of three shells, which showed large seasonal variations up to 3.4‰. However, there were also large inter-specimen differences (up to 2.5‰) between shells growing at the same time and location. Generally, high-resolution shell δ15N values follow soft-tissue δ15N values, but soft-tissues integrate more time, hence soft-tissue data are more time-averaged and smoothed. Museum-archived shells from the 1950s, 1965, and 1970s do not show a large difference in δ15N values through time despite expected increasing N loading to the Bay over this time, which could be due to anthropogenic N sources with contrasting values. Compiling shell CBOM δ15N data from several studies suggests that the offset between soft-tissue and shell δ15N values (Δtissue-shell) differs between calcite and aragonite shells. We hypothesize that this difference is caused by differences in amino acids used in constructing the different minerals, which should be specific to the CaCO3 polymorph being constructed. Future

  14. Comparison of protoporphyrin IX content and related gene expression in the tissues of chickens laying brown-shelled eggs.

    PubMed

    Li, Guangqi; Chen, Sirui; Duan, Zhongyi; Qu, Lujiang; Xu, Guiyun; Yang, Ning

    2013-12-01

    Protoporphyrin IX (PpIX), an immediate precursor of heme, is the main pigment resulting in the brown coloration of eggshell. The brownness and uniformity of the eggshell are important marketing considerations. In this study, 9 chickens laying darker brown shelled eggs and 9 chickens laying lighter brown shelled eggs were selected from 464 individually caged layers in a Rhode Island Red pureline. The PpIX contents were measured with a Microplate Reader at the wavelength of 412 nm and were compared in different tissues of the 2 groups. Although no significant difference in serum, bile, and excreta was found between the 2 groups, PpIX content in the shell gland and eggshell of the darker group was higher than in those of the lighter group, suggesting that PpIX was synthesized in the shell gland. We further determined the expression levels of 8 genes encoding enzymes involved in the heme synthesis and transport in the liver and shell gland at 6 h postoviposition by quantitative PCR. The results showed that expression of aminolevulinic acid synthase-1 (ALAS1) was higher in the liver of hens laying darker brown shelled eggs, whereas in the shell gland the expression levels of ALAS1, coproporphyrinogen oxidase (CPOX), ATP-binding cassette family members ABCB7 and ABCG2, and receptor for feline leukemia virus, subgroup C (FLVCR) were significantly higher in the hens laying darker brown shelled eggs. Our results demonstrated that hens laying darker brown shelled eggs could deposit more PpIX onto the eggshell and the brownness of the eggshell was dependent on the total quantity of PpIX in the eggshell. More heme was synthesized in the liver and shell gland of hens laying darker brown shelled eggs than those of hens laying lighter brown shelled eggs. High expression level of ABCG2 might facilitate the accumulation of PpIX in the shell gland.

  15. Activity modulation of core and shell in nanozeolite@enzyme bi-functional catalyst for dynamic kinetic resolution.

    PubMed

    Li, Xiang; Yan, Yueer; Wang, Wanlu; Zhang, Yahong; Tang, Yi

    2015-01-15

    A core-shell nanozeolite@enzyme bi-functional catalyst is prepared by using nanozeolite β as acidic core and immobilized Candida antarctica lipase B (CALB) as enzyme shell for the purpose of dynamic kinetic resolution (DKR), and polydiallyldimethylammonium chloride (PDDA) is used as interlayer to compart core and shell. The activities of core and shell in bi-functional catalyst are modulated to achieve the matching between racemization and kinetic resolution (KR) rates in DKR, i.e., a slow racemization rate on core while a fast KR rate on shell. Nanozeolite β with intermediate SiO2/Al2O3 ratio provides proper acid amount for racemization step. A relatively thick layer of PDDA not only improves the activity of CALB by its coverage for surface acidic sites but also limits the accessibility and diffusion of substrate towards the acidic core. The CALB shell with larger immobilized amount and higher enzyme activity offers enhanced driving force of DKR process, leading to higher conversion, selectivity and yield. The preparation and activity modulation of core-shell catalyst provide an ideal method to improve the catalytic performance of bi-functional catalyst. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. On chaotic behavior of gravitating stellar shells.

    PubMed

    Barkov, M V; Bisnovatyi-Kogan, G S; Neishtadt, A I; Belinski, V A

    2005-03-01

    Motion of two gravitating spherical stellar shells around a massive central body is considered. Each shell consists of point particles with the same specific angular momenta and energies. In the case when one can neglect the influence of gravitation of one ("light") shell onto another ("heavy") shell ("restricted problem") the structure of the phase space is described. The scaling laws for the measure of the domain of chaotic motion and for the minimal energy of the light shell sufficient for its escape to infinity are obtained.

  17. Shell stars in the Geneva photometric system

    NASA Astrophysics Data System (ADS)

    Hauck, B.

    1987-05-01

    The behavior of Be/Ae stars and shell stars in a d vs Delta diagram clearly shows that the majority of shell stars have a greater Balmer jump than normal stars. This result is in agreement with that of Divan (1979) for 48 Lib, a B2IV e-shell star. However, out of the 45 shell stars measured in the Geneva system, 26 are A or F stars, of which 16 have a Balmer jump that is greater than normal. This result suggests that A-F type shell stars represent the cool end of the Be-star sequence.

  18. Shell Model Depiction of Isospin Mixing in sd Shell

    SciTech Connect

    Lam, Yi Hua; Smirnova, Nadya A.; Caurier, Etienne

    2011-11-30

    We constructed a new empirical isospin-symmetry breaking (ISB) Hamiltonian in the sd(1s{sub 1/2}, 0d{sub 5/2} and 0d{sub 3/2}) shell-model space. In this contribution, we present its application to two important case studies: (i){beta}-delayed proton emission from {sup 22}Al and (ii) isospin-mixing correction to superallowed 0{sup +}{yields}0{sup +}{beta}-decay ft-values.

  19. Pressure Shell Approach to Integrated Environmental Protection

    NASA Technical Reports Server (NTRS)

    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.

  20. Shell Model Approach to Nuclear Level Density

    NASA Astrophysics Data System (ADS)

    Horoi, Mihai

    2000-04-01

    Nuclear level densities (NLD) are traditionally estimated using variations of Fermi Gas Formula (FGF) or combinatoric techniques. Recent investigations using Monte Carlo Shell Model (MCSM) techniques indicate that a shell model description of NLD may be an accurate and stable approach. Full shell model calculations of NLD are very difficult. We calculated the NLD for all nuclei in the sd shell and show that the results can be described by a single particle combinatoric model, which depends on two parameters similar to FGF. We further investigated other models and find that a sum of gaussians with means and variances given by French and Ratcliff averages (Phys. Rev. C 3, 94(1971)) is able to accurately describe shell model NLD, even when shell effects are present. The contribution of the spurious center-of-mass motion to the shell model NLD is also discussed.

  1. Turbine blade with spar and shell

    DOEpatents

    Davies, Daniel O [Palm City, FL; Peterson, Ross H [Loxahatchee, FL

    2012-04-24

    A turbine blade with a spar and shell construction in which the spar and the shell are both secured within two platform halves. The spar and the shell each include outward extending ledges on the bottom ends that fit within grooves formed on the inner sides of the platform halves to secure the spar and the shell against radial movement when the two platform halves are joined. The shell is also secured to the spar by hooks extending from the shell that slide into grooves formed on the outer surface of the spar. The hooks form a serpentine flow cooling passage between the shell and the spar. The spar includes cooling holes on the lower end in the leading edge region to discharge cooling air supplied through the platform root and into the leading edge cooling channel.

  2. Inner-shell excitation spectroscopy of peroxides

    NASA Astrophysics Data System (ADS)

    Harding, K. L.; Kalirai, S.; Hayes, R.; Ju, V.; Cooper, G.; Hitchcock, A. P.; Thompson, M. R.

    2015-11-01

    O 1s inner-shell excitation spectra of a number of vapor phase molecules containing peroxide bonds - hydrogen peroxide (H2O2), di-t-butylperoxide (tBuOtBu), benzoyl peroxide, ((C6H5(CO)O)2), luperox-F [1,3(4)-bis(tertbutylperoxyisopropyl) benzene], and analogous, non-peroxide compounds - water, t-butanol and benzoic acid have been measured. C 1s spectra are also reported. O 1s spectra of solid benzoic acid, di-t-butylperoxide and luperox-F recorded using a scanning transmission X-ray microscope, are also reported, and compared to the corresponding gaseous spectra. Spectral interpretation was aided by comparing the spectra of the peroxide and non-peroxide counterparts and with ab initio calculations. A characteristic O 1s → σ∗O-O transition at 533.0(3) eV is identified in each peroxide species, which is absent in the corresponding non-peroxide counterpart species. The energy and intensity of the 533 eV peroxide feature is stable and thus useful for analysis of peroxides in mixtures, such as tracking residual peroxide initiators, or peroxides produced in fuel cells.

  3. Glass shell manufacturing in space

    NASA Technical Reports Server (NTRS)

    Nolen, R. L.; Downs, R. L.; Ebner, M. A.

    1982-01-01

    Highly-uniform, hollow glass spheres, which are used for inertial-confinement fusion targets, are formed from metal-organic gel powder feedstock in a drop-tower furnace. The modelling of this gel-to-sphere transformation has consisted of three phases: gel thermochemistry, furnance-to-gel heat transfer, and gravity-driven degradation of the concentricity of the molten shell. The heat transfer from the furnace to the free-falling gel particle was modelled with forced convection. The gel mass, dimensions, and specific heat as well as furnace temperature profile and furnace gas conductivity, were controlled variables. This model has been experimentally verified. In the third phase, a mathematical model was developed to describe the gravity-driven degradation of concentricity in molten glass shells.

  4. The shell coal gasification process

    SciTech Connect

    Koenders, L.O.M.; Zuideveld, P.O.

    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.

  5. Buckling of spherical shells revisited

    NASA Astrophysics Data System (ADS)

    Hutchinson, John W.

    2016-11-01

    A study is presented of the post-buckling behaviour and imperfection sensitivity of complete spherical shells subject to uniform external pressure. The study builds on and extends the major contribution to spherical shell buckling by Koiter in the 1960s. Numerical results are presented for the axisymmetric large deflection behaviour of perfect spheres followed by an extensive analysis of the role axisymmetric imperfections play in reducing the buckling pressure. Several types of middle surface imperfections are considered including dimple-shaped undulations and sinusoidal-shaped equatorial undulations. Buckling occurs either as the attainment of a maximum pressure in the axisymmetric state or as a non-axisymmetric bifurcation from the axisymmetric state. Several new findings emerge: the abrupt mode localization that occurs immediately after the onset of buckling, the existence of an apparent lower limit to the buckling pressure for realistically large imperfections, and comparable reductions of the buckling pressure for dimple and sinusoidal equatorial imperfections.

  6. Density Measurements of Be Shells

    SciTech Connect

    Cook, R C

    2005-02-15

    The purpose of this memo is to lay out the uncertainties associated with the measurement of density of Be ablators by the weigh and volume method. I am counting on the readers to point out any faulty assumptions about the techniques or uncertainties associated with them. Based on the analysis presented below we should expect that 30 {micro}m thick shells will have an uncertainty in the measured density of about 2% of the value, coming more or less equally from the mass and volume measurement. The uncertainty is roughly inversely proportional to the coating thickness, thus a 60 {micro}m walled shell would result in a 1% uncertainty in the density.

  7. Glass shell manufacturing in space

    NASA Technical Reports Server (NTRS)

    Nolen, R. L.; Downs, R. L.; Ebner, M. A.

    1982-01-01

    Highly-uniform, hollow glass spheres, which are used for inertial-confinement fusion targets, are formed from metal-organic gel powder feedstock in a drop-tower furnace. The modelling of this gel-to-sphere transformation has consisted of three phases: gel thermochemistry, furnance-to-gel heat transfer, and gravity-driven degradation of the concentricity of the molten shell. The heat transfer from the furnace to the free-falling gel particle was modelled with forced convection. The gel mass, dimensions, and specific heat as well as furnace temperature profile and furnace gas conductivity, were controlled variables. This model has been experimentally verified. In the third phase, a mathematical model was developed to describe the gravity-driven degradation of concentricity in molten glass shells.

  8. Shell Evolutions and Nuclear Forces

    NASA Astrophysics Data System (ADS)

    Sorlin, O.

    2014-03-01

    During the last 30 years, and more specifically during the last 10 years, many experiments have been carried out worldwide using different techniques to study the shell evolution of nuclei far from stability. What seemed not conceivable some decades ago became rather common: all known magic numbers that are present in the valley of stability disappear far from stability and are replaced by new ones at the drip line. By gathering selected experimental results, beautifully consistent pictures emerge, that very likely take root in the properties of the nuclear forces.The present manuscript describes some of these discoveries and proposes an intuitive understanding of these shell evolutions derived from observations. Extrapolations to yet unstudied regions, as where the explosive r-process nucleosynthesis occurs, are proposed. Some remaining challenges and puzzling questions are also addressed.

  9. Corrosion inhibition property of polyester-groundnut shell biodegradable composite.

    PubMed

    Sounthari, P; Kiruthika, A; Saranya, J; Parameswari, K; Chitra, S

    2016-12-01

    The use of natural fibers as reinforcing materials in thermoplastics and thermoset matrix composites provide optimistic environmental profits with regard to ultimate disposability and better use of raw materials. The present work is focused on the corrosion inhibition property of a polymer matrix composite produced by the use of groundnut shell (GNS) waste. Polyester (PE) was synthesized by condensation polymerization of symmetrical 1,3,4-oxadiazole and pimelic acid using sodium lauryl sulfate as surfactant. The polyester-groundnut shell composite (PEGNS) was prepared by ultrasonication method. The synthesized polyester-groundnut shell composite was characterized by FT-IR, TGA and XRD analysis. The corrosion inhibitory effect of PEGNS on mild steel in 1M H2SO4 was investigated using gravimetric method, electrochemical impedance spectroscopy, potentiodynamic polarization, atomic absorption spectroscopy and scanning electron microscopy. The results showed that PEGNS inhibited mild steel corrosion in acid solution and indicated that the inhibition efficiency increased with increasing inhibitor concentration and decrease with increasing temperature. The composite inhibited the corrosion of mild steel through adsorption following the Langmuir adsorption isotherm. Changes in the impedance parameters Rt, Cdl, Icorr, Ecorr, ba and bc suggested the adsorption of PEGNS onto the mild steel surface, leading to the formation of protective film.

  10. Vibration Control of Shallow Shell Structures Using a Shell-Type Dynamic Vibration Absorber

    NASA Astrophysics Data System (ADS)

    Aida, T.; Aso, T.; Nakamoto, K.; Kawazoe, K.

    1998-11-01

    In this study, a new shell-type dynamic vibration absorber is presented for suppressing several modes of vibration of the shallow shell (main shell) under harmonic load. It consists of a shallow shell (the dynamic absorbing shell), under the same boundary condition and with the same shape as those of the main shell, with connecting springs and dampers in the vertical direction between the main and dynamic absorbing shells. Formulae for an approximate tuning method for the shell-type dynamic absorber are also presented using the optimum tuning method for a dynamic absorber in the two-degree-of-freedom system, obtained by the Den Hartog method. Subsequently, numerical calculations are presented which demonstrate the usefulness of the shell-type dynamic vibration absorbers.

  11. L -shell ionization by antiprotons

    SciTech Connect

    Sarkadi, L. , H-4001 Debrecen, Pf. 51, Hungary ); Mukoyama, T. )

    1990-10-01

    Semiclassical coupled-state model calculations have been performed for {ital L}-shell ionization of gold induced by protons and antiprotons in the energy range 0.15--3 MeV. The results of the calculations have been compared with the predictions of a simple approach suggested by Brandt and Basbas for description of antiparticle excitation of atomic inner shells. Apart from the range of very low collision velocities, a reasonable agreement has been found between the two models. In addition to the binding and Coulomb-distortion effects discussed by Brandt and Basbas (Phys. Rev. A 27, 578 (1983); 28, 3142(E) (1983)), for the {ital L} shell a further effect due to dynamical couplings between the {ital L}-substate ionization amplitudes also contributes to the particle-antiparticle differences. While the latter processes have only a negligible effect on the energy dependence of the cross sections, their inclusion has been shown to be unavoidable when ratios of the subshell ionization cross sections are analyzed for the two kinds of excitation.

  12. Atomic inner-shell transitions

    NASA Technical Reports Server (NTRS)

    Crasemann, B.; Chen, M. H.; Mark, H.

    1984-01-01

    Atomic inner-shell processes have quite different characteristics, in several important aspects, from processes in the optical regime. Energies are large, e.g., the 1s binding energy reaches 100 keV at Z = 87; relativistic and quantum-electrodynamic effects therefore are strong. Radiationless transitions vastly dominate over photon emission in most cases. Isolated inner-shell vacancies have pronounced single-particle character, with correlations generally contributing only approximately 1 eV to the 1s and 2p binding energies; the structure of such systems is thus well tractable by independent-particle self-consistent-field atomic models. For systems containing multiple deep inner-shell vacancies, or for highly stripped ions, the importance of relativistic intermediate coupling and configuration interaction becomes pronounced. Cancellation of the Coulomb interaction can lead to strong manifestations of the Breit interaction in such phenomena as multiplet splitting and hypersatellite X-ray shifts. Unique opportunities arise for the test of theory.

  13. Atomic inner-shell transitions

    NASA Technical Reports Server (NTRS)

    Crasemann, B.; Chen, M. H.; Mark, H.

    1984-01-01

    Atomic inner-shell processes have quite different characteristics, in several important aspects, from processes in the optical regime. Energies are large, e.g., the 1s binding energy reaches 100 keV at Z = 87; relativistic and quantum-electrodynamic effects therefore are strong. Radiationless transitions vastly dominate over photon emission in most cases. Isolated inner-shell vacancies have pronounced single-particle character, with correlations generally contributing only approximately 1 eV to the 1s and 2p binding energies; the structure of such systems is thus well tractable by independent-particle self-consistent-field atomic models. For systems containing multiple deep inner-shell vacancies, or for highly stripped ions, the importance of relativistic intermediate coupling and configuration interaction becomes pronounced. Cancellation of the Coulomb interaction can lead to strong manifestations of the Breit interaction in such phenomena as multiplet splitting and hypersatellite X-ray shifts. Unique opportunities arise for the test of theory.

  14. Fabrication of polyimide shells by vapor phase deposition for use as ICF targets

    SciTech Connect

    Alfonso, E.L.; Tsai, F.Y.; Chen, S.H.; Gram, R.Q.; Harding, D.R.

    1999-03-01

    Hollow polyimide shells, for use as ICF targets, were fabricated by co-depositing monomer precursors from the vapor phase onto bounced spherical mandrels. The process involved two stages: first, the deposited monomers (pyromellitic dianhydride and 4,4{prime}-oxydianiline) reacted on the mandrel surface to form polyamic acid; second, the mandrel was heated to 300 C to imidize the polyamic acid and to decompose the mandrel. During this latter process the decomposed mandrel diffused through the thermally stable coating, leaving a polyimide shell. Depositions were performed under low ({approximately}10{sup {minus}3} Torr) and high ({approximately}10{sup {minus}6} Torr) vacuum. Also, flat witness films of polyimide deposited on Si wafers and NaCl allowed the mechanical properties and chemical composition of the film during the heating cycle to be measured. Polyimide shells with diameters ranging from 700 to 950 {micro}m and wall thicknesses ranging from 2 to 13 {micro}m were produced. The shell`s sphericity was greater than 99%. Burst and buckle pressure tests on these shells yielded the estimated mechanical strength properties. The elastic modulus and tensile strength were {approximately}15 GPa and {approximately}300 MPa, respectively. The permeability of D{sub 2} through polyamic acid at 25 C was 7.4 {times} 10{sup {minus}17} mol{center_dot}m/m{sup 2}{center_dot}Pa{center_dot}s and increased to 6.4 {times} 10{sup {minus}16} mol{center_dot}m/m{sup 2}{center_dot}Pa{center_dot}s at 25 C upon curing the shell to 150 C. The permeability of D{sub 2} at 25 C through vapor-deposited polyimide flat films was measured to be 240 times greater than through the as-deposited polyamic acid, and about 7 times greater than through commercially available solution-cast Kapton.

  15. Controlled protein release from monodisperse biodegradable double-wall microspheres of controllable shell thickness

    PubMed Central

    Xia, Yujie; Ribeiro, Pedro F.; Pack, Daniel W.

    2013-01-01

    Biodegradable polymer microparticles are promising delivery depots for protein therapeutics due to their relatively simple fabrication and facile administration. Double-wall microspheres (DWMS) comprising a core and shell made of two distinct polymers may provide enhanced control of the drug release profiles. Using precision particle fabrication (PPF) technology, monodisperse DWMS were fabricated with model protein bovine serum albumin (BSA)-loaded poly(lactide-co-glycolide) (PLG) core and drug-free poly(d,l-lactic acid) (PDLL) shell of uniform thickness. Monolithic single-wall microspheres were also fabricated to mimic the BSA-loaded PLG core. Using ethyl acetate and dichloromethane as shell- and core-phase solvents, respectively, BSA was encapsulated selectively in the core region within DWMS with higher loading and encapsulation efficiency compared to using dichloromethane as core and shell solvents. BSA in vitro release rates were retarded by the presence of the drug-free PDLL shell. Moreover, increasing PDLL shell thickness resulted in decreasing BSA release rate. With a 14-µm thick PDLL shell, an extended period of constant-rate release was achieved. PMID:23954731

  16. Carbon-Supported IrNi Core-Shell Nanoparticles: Synthesis Characterization and Catalytic Activity

    SciTech Connect

    K Sasaki; K Kuttiyiel; L Barrio; D Su; A Frenkel; N Marinkovic; D Mahajan; R Adzic

    2011-12-31

    We synthesized carbon-supported IrNi core-shell nanoparticles by chemical reduction and subsequent thermal annealing in H{sub 2}, and verified the formation of Ir shells on IrNi solid solution alloy cores by various experimental methods. The EXAFS analysis is consistent with the model wherein the IrNi nanoparticles are composed of two-layer Ir shells and IrNi alloy cores. In situ XAS revealed that the Ir shells completely protect Ni atoms in the cores from oxidation or dissolution in an acid electrolyte under elevated potentials. The formation of Ir shell during annealing due to thermal segregation is monitored by time-resolved synchrotron XRD measurements, coupled with Rietveld refinement analyses. The H{sub 2} oxidation activity of the IrNi nanoparticles was found to be higher than that of a commercial Pt/C catalyst. This is predominantly due to Ni-core-induced Ir shell contraction that makes the surface less reactive for IrOH formation, and the resulting more metallic Ir surface becomes more active for H{sub 2} oxidation. This new class of core-shell nanoparticles appears promising for application as hydrogen anode fuel cell electrocatalysts.

  17. Mesopore-free silica shell with nanometer-scale thickness-controllable on cationic polystyrene core.

    PubMed

    Nandiyanto, Asep Bayu Dani; Iwaki, Toru; Ogi, Takashi; Okuyama, Kikuo

    2013-01-01

    The formation of mesopore-free silica shell with homogenous shell thickness, smooth surface, and controllable thickness in the nanometer range (from 4 to 12 nm) on core material was studied. Cationic polystyrene particles with various sizes (ranged from 80 to 300 nm) were used as a model of core material, which could be effective to support the electrostatic attraction between the core material and the negatively charged silica without any additives. Different from other reports, mesopore-free shell was produced due to the absence of additive. Basic amino acid (i.e., lysine) was used as a catalyst for forming the silica, which is harmless and able to control the silica growth and produce shell with smooth surface. Homogenous thin shell (thickness <13 nm) with nanometer-scale-controllable was reported, while in the current reports, the modification of the shell in this thickness range was typically difficult and relating to the formation of incomplete/inhomogeneous silica coating and rough surface. The relationships among the reaction parameters were also investigated in detail along with the theoretical consideration and the proposal of the silica coating formation mechanism. The present mesopore-free silica shell was efficiently used for various applications because of their tendency not to adsorb large molecules, as confirmed by the nitrogen sorption and large molecule adsorption analysis. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Development and characterization of cores-shell poly(lactide-co-glycolide)-chitosan microparticles for sustained release of GDNF.

    PubMed

    Zeng, Wen; Liu, Zhongyang; Li, Yuqian; Zhu, Shu; Ma, Jie; Li, Weixin; Gao, Guodong

    2017-08-30

    The microencapsulation of bioactive neurotrophic factors in biodegradable poly(lactide-co-glycolide) (PLGA) microspheres has been a promising tool in the treatment of various nervous system disorders. However, challenges still exist; the PLGA burst drug release and acidic degradation products often limit clinical application. In this study, cores-shell PLGA-chitosan microparticles (MPs) were fabricated with a single shell of chitosan and multi-cores of PLGA using a re-emulsification method. The glial cell line-derived neurotrophic factor (GDNF) was encapsulated at the PLGA cores of the cores-shell MPs. The cores-shell MPs prepared by different chitosan concentrations showed a rough surface, and the particle mean size varied between 32.3 and 45.2μm. The fluorescence images indicated that Nile red-stained PLGA microspheres were uniformly distributed in the cores-shell MPs. Compared with PLGA microspheres, the cores-shell MPs were able to reduce the initial burst release of GDNF and neutralize the acidity of PLGA degradation products, which could be modulated by changing the chitosan concentrations. Further differentiation of PC12 cells toward a neuronal phenotype in vitro indicated that the cores-shell MPs were capable of maintaining the bioactivity of GDNF during preparation. Taken together, these findings highlight the possibility of using cores-shell PLGA-chitosan MPs for the sustained release of GDNF, which offers potential applications in nerve injury repair. Copyright © 2017. Published by Elsevier B.V.

  19. Challenges to the Application of δ15N measurements of the organic fraction of archaeological and fossil mollusk shells to assess paleoenvironmental change.

    NASA Astrophysics Data System (ADS)

    Andrus, C. F. T.

    2015-12-01

    Nitrogen isotope analysis of the organic fraction of mollusk shells is beginning to be applied to questions of past anthropogenic and natural environmental variation using samples from archaeological and fossil deposits. Fairly extensive proxy validation research has been conducted in the past decade, documenting the relationship between the δ15N of ambient particulate organic matter, mollusk soft tissues, and shell organic matrix. However, comparatively little research has addressed the potential effects of taphonomy and diagenesis on these proxy records. Assessing archaeological samples are especially complex in that humans may have transported and/or cooked shell prior to deposition. Shell δ15N data will be presented from modern and archaeological oyster (Crassostrea virginica) and clam shell (Mercenaria spp.) of various late Holocene ages and late Cretaceous Crassatellites vadosus shells. Archaeological shells show some loss of organic matter over time, yet some Cretaceous shells retain enough matrix to permit δ15N analysis. The Cretaceous samples required concentration of the remaining organic matrix by removing carbonate via acid pretreatment prior to EA-IRMS analysis, but modern and archaeological shells had sufficient organic matrix to permit analysis without acid pretreatment. The δ15N data from the archaeological shells do not display obvious alteration from the loss of organic matrix. The results of cooking experiments performed on modern oyster shells also indicate little alteration of δ15N values, unless the shell was heated to the point of disintegration. While these experiments indicate promise for the application of δ15N analysis of shell organic matter, the results are incomplete and lack ideal control over initial δ15N values in ancient samples used for comparisons. Future research, perhaps focused on compound-specific δ15N analysis and additional controlled experiments on moderns shells, may improve this assessment.

  20. Synthesis of zirconium tungstate-zirconia core-shell composite particles

    SciTech Connect

    Khazeni, Nasser; Mavis, Bora; Guenduez, Guengoer; Colak, Uner

    2011-11-15

    Highlights: {yields} ZrW{sub 2}O{sub 8}-ZrO{sub 2} core-shell particles to offer solutions for sintering problems. {yields} Core synthesis by a precursor based on tungstic acid and zirconium acetate. {yields} Shell phase by urea hydrolysis in the presence of zirconium ions. {yields} [Urea]/[ZrOCl{sub 2}] ratio controls the rate of shell precursor precipitation. -- Abstract: In this work, ZrW{sub 2}O{sub 8}-ZrO{sub 2} core-shell composite particles were synthesized. ZrW{sub 2}O{sub 8} that was used in the core is a material with negative coefficient of thermal expansion, and it was synthesized from a high-pH precursor based on use of tungstic acid and zirconium acetate. Shell layer was composed of ZrO{sub 2} nanocrystallites and precipitated from an aqueous solution by urea hydrolysis. While volume of the shell was effectively controlled by the initial zirconium ion concentration in the solutions, the rate of precipitation was a function of the ratio of initial concentrations of urea to zirconium ions. It is hypothesized that isolation of the ZrW{sub 2}O{sub 8} within a layer of ZrO{sub 2}, will be a key element in solving problems associated with reactivity of ZrW{sub 2}O{sub 8} towards other components in sintering of ceramic-ceramic composites with tuned or zero thermal expansion coefficient.

  1. The second-shell metal ligands of human arginase affect coordination of the nucleophile and substrate.

    PubMed

    Stone, Everett M; Chantranupong, Lynne; Georgiou, George

    2010-12-14

    The active sites of eukaryotic arginase enzymes are strictly conserved, especially the first- and second-shell ligands that coordinate the two divalent metal cations that generate a hydroxide molecule for nucleophilic attack on the guanidinium carbon of l-arginine and the subsequent production of urea and l-ornithine. Here by using comprehensive pairwise saturation mutagenesis of the first- and second-shell metal ligands in human arginase I, we demonstrate that several metal binding ligands are actually quite tolerant to amino acid substitutions. Of >2800 double mutants of first- and second-shell residues analyzed, we found more than 80 unique amino acid substitutions, of which four were in first-shell residues. Remarkably, certain second-shell mutations could modulate the binding of both the nucleophilic water/hydroxide molecule and substrate or product ligands, resulting in activity greater than that of the wild-type enzyme. The data presented here constitute the first comprehensive saturation mutagenesis analysis of a metallohydrolase active site and reveal that the strict conservation of the second-shell metal binding residues in eukaryotic arginases does not reflect kinetic optimization of the enzyme during the course of evolution.

  2. Carbohydrates of the Organic Shell Matrix and the Shell-Forming Tissue of the Snail Biomphalaria glabrata (Say).

    PubMed

    Marxen, J C; Hammer, M; Gehrke, T; Becker, W

    1998-04-01

    Sulfated carbohydrates may play a role in the biomineralization of the molluscan shell. The carbohydrates of the extracted water-insoluble organic shell matrix (IM) of the freshwater snail Biomphalaria glabrata were identified as glucose, mannose, galactose, and N-acetyl-glucosamine, whereas the water-soluble organic matrix (SM) additionally contained N-acetyl-galactosamine. A specific lectin binding pattern of the matrix was obtained. One prominent protein of the SM, with a size of 19.6 kDa and a pI of 7.4, was shown to be a glycoprotein with terminal glucosyl or mannosyl moieties. The acidic constitutents of the matrix showed a variety of possible terminal sugars, indicating a heterogenous mixture of proteoglycans or glycosaminoglycans (GAGs) and glycoproteins. At the shell-forming mantle edge, an alcian-blue-positive material was observed in the periostracum groove (PG), the belt, and apically in the cells of the outer mantle epithelium (OME). With the help of lectins, all sugars in question were detected in the PG and the belt, whereas the OME was bound by glucose/mannose- and GlcNac-specific lectins only. Although the complete set of GAGs will be produced in the PG and the belt, a very acidic fraction of GAGs and the 19.6-kDa protein can also be delivered by the OME.

  3. Thermal and catalytic slow pyrolysis of Calophyllum inophyllum fruit shell.

    PubMed

    Alagu, R M; Sundaram, E Ganapathy; Natarajan, E

    2015-10-01

    Pyrolysis of Calophyllum inophyllum shell was performed in a fixed bed pyrolyser to produce pyrolytic oil. Both thermal (without catalysts) and catalytic pyrolysis process were conducted to investigate the effect of catalysts on pyrolysis yield and pyrolysis oil characteristics. The yield of pyrolytic oil through thermal pyrolysis was maximum (41% wt) at 425 °C for particle size of 1.18 mm and heating rate of 40 °C/min. In catalytic pyrolysis the pyrolytic oil yield was maximum (45% wt) with both zeolite and kaolin catalysts followed by Al2O3 catalyst (44% wt). The functional groups and chemical components present in the pyrolytic oil are identified by Fourier Transform Infrared Spectroscopy (FT-IR) and Gas Chromatography-Mass Spectrometry (GC-MS) techniques. This study found that C. inophyllum shell is a potential new green energy source and that the catalytic pyrolysis process using zeolite catalyst improves the calorific value and acidity of the pyrolytic oil.

  4. Rigid shells enhance survival of gekkotan eggs.

    PubMed

    Andrews, Robin M

    2015-11-01

    The majority of lizards and snakes produce permeable parchment-shelled eggs that require high moisture conditions for successful embryonic development. One clade of gekkotan lizards is an exception; females produce relatively impermeable rigid-shelled eggs that normally incubate successfully under low moisture conditions. I tested the hypothesis that the rigid-shell increases egg survival during incubation, but only under low moisture conditions. To test this hypothesis, I incubated rigid-shelled eggs of Chondrodactylus turneri under low and under high moisture conditions. Eggs were incubated with parchment-shelled eggs of Eublepharis macularius to insure that incubation conditions were suitable for parchment-shelled eggs. Chondrodactylus turneri eggs had very high survival (>90%) when they were incubated under low moisture conditions. In contrast, eggs incubated under high moisture conditions had low survival overall, and lower survival than those of the parchment-shelled eggs of E. macularius. Mortality of C. turneri and E. macularius eggs incubated under high moisture conditions was the result of fungal infection, a common source of egg mortality for squamates under laboratory and field conditions. These observations document high survival of rigid-shelled eggs under low moisture conditions because eggs escape from fungal infection. Highly mineralized rigid shells also make egg survival independent of moisture availability and may also provide protection from small invertebrates in nature. Enhanced egg survival could thus compensate for the low reproductive output of gekkotans that produce rigid-shelled eggs. © 2015 Wiley Periodicals, Inc.

  5. Transesterification of soybean oil using combusted oyster shell waste as a catalyst.

    PubMed

    Nakatani, Nobutake; Takamori, Hitoshi; Takeda, Kazuhiko; Sakugawa, Hiroshi

    2009-02-01

    Transesterification of soybean oil catalyzed by combusted oyster shell, which is waste material from shellfish farms, was examined. Powdered oyster shell combusted at a temperature above 700 degrees C, at which point the calcium carbonate of oyster shell transformed to calcium oxide, acted as a catalyst in the transesterification of soybean oil. On the basis of factorial design, the reaction conditions of catalyst concentration and reaction time were optimized in terms of the fatty acid methyl ester concentration expressed as biodiesel purity. Under the optimized reaction conditions of a catalyst concentration and reaction time of 25wt.%. and 5h, respectively, the biodiesel yield, expressed relative to the amount of soybean oil poured into the reaction vial, was more than 70% with high biodiesel purity. These results indicate oyster shell waste combusted at high temperature can be reused in biodiesel production as a catalyst.

  6. Synthesis of polyacrylate core-shell structure latex by radiation techniques

    NASA Astrophysics Data System (ADS)

    Minghong, Wu; Weiping, Shen; Zueteh, Ma

    1993-07-01

    A series of poly(butyl acrylate-co-methyl methacrylate)/poly (ethyl acrylate-co-acrylic acid) interpenetrating polymer network (IPN) was synthesized in latex form by emulsion polymerization. The multiphase morphology of the latex particles was studied after two-stage polymerization by using transimission electron microscope (TEM), the result indicated that the morphology of the particles comprises gradient shell structure, cellular structure and core-shell structure. The change of morphology might stem from emulsion polymerization by radiation initiation or chemical initiation and the weight composition of poly(EA-co-MMA) seed latex which formed the core. By radiation techniques, we successfully synthesized poly( BA-co-MMA)/poly(EA-co-AA) latex of core-shell structure having (42-8)/(46-4) weight compositions. The PA core-shell structure latex applied to textile as a water proofing coating showed higher water-pressure and easier handling than that with PA homogeneous phase structure latex.

  7. Zeolitic Core@Shell Adsorbents for the Selective Removal of Free Glycerol from Crude Biodiesel.

    PubMed

    Masoumifard, Nima; Arnal, Pablo M; Kaliaguine, Serge; Kleitz, Freddy

    2015-06-22

    Selective adsorption of free glycerol from crude biodiesel was investigated by using mesoporous silica spheres coated with a thin shell of microporous silicalite-1. A polycrystalline silicalite-1 shell was formed upon first covering the external surfaces of various core templates with discrete silicalite-1 nanocrystals, and this was followed by short hydrothermal treatment to ensure shell uniformity. Batch glycerol adsorption experiments were conducted to evaluate the ability of the sorbents to remove free glycerol selectively from crude biodiesel mixtures at various temperatures, also in comparison to that of conventional sorbents, for example, bare mesoporous silica gel spheres and zeolites. The silicalite-1 shell provided a microporous membrane that hindered the diffusion of fatty acid methyl esters into the mesopores of the composite sorbent, whereas the large pore volume of the mesoporous core enabled multilayer glycerol adsorption; this ultimately substantially enhanced the performance in terms of purification yield and adsorption capacity.

  8. Electrosprayed core-shell polymer-lipid nanoparticles for active component delivery

    NASA Astrophysics Data System (ADS)

    Eltayeb, Megdi; Stride, Eleanor; Edirisinghe, Mohan

    2013-11-01

    A key challenge in the production of multicomponent nanoparticles for healthcare applications is obtaining reproducible monodisperse nanoparticles with the minimum number of preparation steps. This paper focus on the use of electrohydrodynamic (EHD) techniques to produce core-shell polymer-lipid structures with a narrow size distribution in a single step process. These nanoparticles are composed of a hydrophilic core for active component encapsulation and a lipid shell. It was found that core-shell nanoparticles with a tunable size range between 30 and 90 nm and a narrow size distribution could be reproducibly manufactured. The results indicate that the lipid component (stearic acid) stabilizes the nanoparticles against collapse and aggregation and improves entrapment of active components, in this case vanillin, ethylmaltol and maltol. The overall structure of the nanoparticles produced was examined by multiple methods, including transmission electron microscopy and differential scanning calorimetry, to confirm that they were of core-shell form.

  9. Relative Contributions of Core Protein and Solvatation Shell in the Terahertz Dielectric Properties of Protein Solutions.

    PubMed

    Grognot, Marianne; Gallot, Guilhem

    2017-09-22

    The properties of the solvation shell surrounding biomolecules in solution are fundamental to understand the modifications of the dynamics of the water molecules by peptides and proteins. The dynamics of the hydrogen bonding network typically occurs at the picosecond time scale, then terahertz spectroscopy is a unique tool to investigate the solvation shell. Here, we present terahertz measurements of the refractive index and extinction coefficient of solutions of biomolecules of various molecular weights. We observe a clear correlation between the terahertz dielectric properties and the weight of the molecules. A three-component model is developed and analyzes the relative contributions from the solute and the solvation shell to the total dielectric values. We find that the amino acids and short peptides (small molecules) domain is mainly governed by the solvation shell, while the solute properties are also implied in the protein domain (big molecules).

  10. Electrosprayed core-shell polymer-lipid nanoparticles for active component delivery.

    PubMed

    Eltayeb, Megdi; Stride, Eleanor; Edirisinghe, Mohan

    2013-11-22

    A key challenge in the production of multicomponent nanoparticles for healthcare applications is obtaining reproducible monodisperse nanoparticles with the minimum number of preparation steps. This paper focus on the use of electrohydrodynamic (EHD) techniques to produce core-shell polymer-lipid structures with a narrow size distribution in a single step process. These nanoparticles are composed of a hydrophilic core for active component encapsulation and a lipid shell. It was found that core-shell nanoparticles with a tunable size range between 30 and 90 nm and a narrow size distribution could be reproducibly manufactured. The results indicate that the lipid component (stearic acid) stabilizes the nanoparticles against collapse and aggregation and improves entrapment of active components, in this case vanillin, ethylmaltol and maltol. The overall structure of the nanoparticles produced was examined by multiple methods, including transmission electron microscopy and differential scanning calorimetry, to confirm that they were of core-shell form.

  11. Electromagnetic functionalized and core-shell micro/nanostructured polypyrrole composites.

    PubMed

    Li, Xin; Wan, Meixiang; Wei, Yen; Shen, Jiaoyan; Chen, Zhaojia

    2006-08-03

    Core-shell micro/nanostructured and electromagnetic functionalized polypyrrole (PPy) composites were prepared by a self-assembly process associated with the template method in the presence of p-toluenesulfonate acid (p-TSA) as the dopant, in which the spherical hydroxyl iron (Fe[OH], 0.5-5 microm in diameter) functioned not only as the hard template, but also as the "core" of the micro/nanostructure, and the self-assembled PPy-p-TSA nanofibers (20-30 nm in diameter) acted as the "shell" (50-100 nm in thickness) of the microspheres. We found that the core-shell micro/nanostructures exhibit controllable electromagnetic properties by adjusting the mass ratio of Fe[OH] to pyrrole monomer. The micelle model was proposed to interpret the self-assembly of the core-shell micro/nanostructured composites.

  12. Preparation of C18-functionalized Fe3O4@SiO2 core-shell magnetic nanoparticles for extraction and determination of phthalic acid esters in Chinese herb preparations.

    PubMed

    Guo, Bize; Ji, Shunli; Zhang, Feifang; Yang, Bingcheng; Gu, Jiangping; Liang, Xinmiao

    2014-11-01

    The extraction and determination of phthalic acid esters (PAEs) residue in Chinese herbal preparations (CHP) by C18-functionalized magnetic nanoparticles (C18-FS-MNP) has been firstly performed. It was synthesized through coating Fe3O4 nanoparticles with sodium silicate, followed by freeze-drying technique and then modified with C18 groups. C18-FS-MNPs prepared via freeze-drying technique were superior to those particles prepared via common vacuum drying method in terms of dispersion and extraction recovery. C18-FS-MNPs demonstrated obvious enrichment effect for four model PAEs and 478-627-fold enrichment factors were obtained. The limit of detection was <1.89ng/mL and relative standard deviation was ranging from 3.7 to 5.8%. It was successfully applied for determination of trace PAEs residue in CHP with good recoveries. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Core/shell composites with polystyrene cores and meso-silica shells as abrasives for improved chemical mechanical polishing behavior

    NASA Astrophysics Data System (ADS)

    Chen, Yang; Qin, Jiawei; Wang, Yayun; Li, Zefeng

    2015-09-01

    The core/shell-structured organic/inorganic composite abrasive has an important potential application in damage-free chemical mechanical polishing (CMP) due to its non-rigid mechanical property. In this work, the PS/ M SiO2 composites, containing polystyrene (PS) sphere (211 ± 4 nm) cores and mesoporous silica shells (31 ± 3 nm in thickness) were synthesized through directed surface sol-gel process of tetraethylorthosilicate on the polymer cores in the presence of the cetyltrimethylammonium bromide surfactant. For comparison, the conventional core/shell PS/ N SiO2 composites with non-porous silica shells were also prepared via a modified Stöber procedure that involved the hydrolysis of TEOS under acidic condition. The physical properties of the samples were examined by small-angle X-ray diffraction, fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, field emission scanning electron microscopy, and nitrogen adsorption-desorption. As novel abrasives, the core/shell-structured PS/ M SiO2 composites were introduced into the CMP process for silicon oxide films. The oxide-CMP performance among conventional solid silica particles, PS/ N SiO2 composites, and novel PS/ M SiO2 composites was explored by atomic force microscopy. Polishing results indicated that the substrate revealed a comparable root-mean-square surface roughness (0.25 ± 0.03 and 0.22 ± 0.02 nm, respectively) after CMP with PS/ N SiO2 and PS/ M SiO2 abrasives under the same polishing conditions. However, the material removal rate of the PS/ M SiO2 composites (123 ± 15 nm/min) was about three times larger than that of the PS/ N SiO2 composites (47 ± 13 nm/min). The reduced surface roughness and improved removal rate might be due to the optimization of the physical and/or chemical environments in the local contacting region between abrasives and substrates. The as-synthesized core/shell PS/ M SiO2 composites with mesoporous shells are expected to

  14. Thermal stresses in thick laminated composite shells

    NASA Technical Reports Server (NTRS)

    Yuan, F. G.

    1993-01-01

    The paper provides an analytical formulation to investigate the thermomechanical behavior of thick composite shells subjected to a temperature distribution which varies arbitrarily in the radial direction. For illustrative purposes, shells under uniform temperature change are presented. It is found that thermal twist would occur even for symmetric laminated shells. Under uniform temperature rise, results for off-axis graphite/epoxy shells show that extensional-shear coupling can cause tensile radial stress throughout the shell and tensile hoop stress in the inner region. Laminated graphite/epoxy shells can exhibit negative effective thermal expansion coefficients in the longitudinal and transverse directions. Finally, the stacking sequence has a strong influence on the thermal stress distributions.

  15. SPSM and its application in cylindrical shells

    NASA Astrophysics Data System (ADS)

    Nie, Wu; Zhou, Su-Lian; Peng, Hui

    2008-03-01

    In naval architectures, the structure of prismatic shell is used widely. But there is no suitable method to analyze this kind of structure. Stiffened prismatic shell method (SPSM) presented in this paper, is one of the harmonic semi-analytic methods. Theoretically, strong stiffened structure can be analyzed economically and accurately. SPSM is based on the analytical solution of the governing differential equations for orthotropic cylindrical shells. In these differential equations, the torsional stiffness, bending stiffness and the exact position of each stiffener are taken into account with the Heaviside singular function. An algorithm is introduced, in which the actions of stiffeners on shells are replaced by external loads at each stiffener position. Stiffened shells can be computed as non-stiffened shells. Eventually, the displacement solution of the equations is acquired by the introduction of Green function. The stresses in a corrugated transverse bulkhead without pier base of an oil tanker are computed by using SPSM.

  16. Flow past a porous approximate spherical shell

    NASA Astrophysics Data System (ADS)

    Srinivasacharya, D.

    2007-07-01

    In this paper, the creeping flow of an incompressible viscous liquid past a porous approximate spherical shell is considered. The flow in the free fluid region outside the shell and in the cavity region of the shell is governed by the Navier Stokes equation. The flow within the porous annulus region of the shell is governed by Darcy’s Law. The boundary conditions used at the interface are continuity of the normal velocity, continuity of the pressure and Beavers and Joseph slip condition. An exact solution for the problem is obtained. An expression for the drag on the porous approximate spherical shell is obtained. The drag experienced by the shell is evaluated numerically for several values of the parameters governing the flow.

  17. Cracked shells under skew-symmetric loading

    NASA Technical Reports Server (NTRS)

    Lelale, F.

    1982-01-01

    A shell containing a through crack in one of the principal planes of curvature and under general skew-symmetric loading is considered. By employing a Reissner type shell theory which takes into account the effect of transverse shear strains, all boundary conditions on the crack surfaces are satisfied separately. Consequently, unlike those obtained from the classical shell theory, the angular distributions of the stress components around the crack tips are shown to be identical to the distributions obtained from the plane and antiplane elasticity solutions. Extensive results are given for axially and circumferentially cracked cylindrical shells, spherical shells, and toroidal shells under uniform inplane shearing, out of plane shearing, and torsion. The effect of orthotropy on the results is also studied.

  18. Core-shell-structured magnetic ternary nanocubes.

    PubMed

    Wang, Lingyan; Wang, Xin; Luo, Jin; Wanjala, Bridgid N; Wang, Chongmin; Chernova, Natasha A; Engelhard, Mark H; Liu, Yao; Bae, In-Tae; Zhong, Chuan-Jian

    2010-12-22

    We report a novel core-shell-structured ternary nanocube of MnZn ferrite synthesized by controlling the reaction temperature and composition in the absence of conventionally used reducing agents. The highly monodispersed core-shell structure consists of an Fe(3)O(4) core and an MnZn Ferrite shell. The observation of a Moiré pattern indicates that the core and the shell are two highly crystalline materials with slightly different lattice constants that are rotated relative to each other by a small angle. The ternary core-shell nanocubes display magnetic properties regulated by a combination of the core-shell composition and exhibit an increased coercivity and field-cooled/zero-field-cooled characteristics drastically different from those of regular MnZn ferrite nanoparticles. The ability to engineer the spatial nanostructures of ternary magnetic nanoparticles in terms of shape and composition offers atomic-level versatility in fine-tuning the nanoscale magnetic properties.

  19. Impact of pecan nut shell aqueous extract on the oxidative properties of margarines during storage.

    PubMed

    Engler Ribeiro, Paula Cristina; de Britto Policarpi, Priscila; Dal Bo, Andrea; Barbetta, Pedro Alberto; Block, Jane Mara

    2017-07-01

    The oxidative properties of margarines supplemented with pecan nut shell extract, rosemary extract and butylated hydroxytoluene (BHT) were investigated. The extracts of pecan nut shell and rosemary showed a high content of total phenolics and condensed tannins (93 and 102.9 mg GAE g(-1) and 46 and 38.9 mg CE g(-1) respectively) as well as a high antioxidant activity (1257 and 2306 µmol TEAC g(-1) and 293 and 856 mg TEAC g(-1) by ABTS and DPPH methods respectively). Gallic acid, chlorogenic acid, p-hydroxybenzoic acid, epicatechin and epicatechin gallate were identified in the pecan nut shell extract. Peroxide and p-anisidine values of 3.75-4.43 meq kg(-1) and 1.22-2.73 respectively, Totox values of 9.88-10.8 and specific extinction values of 4.38-4.59 and 0.92-0.94 at 232 and 268 nm respectively were observed after 8 months of storage in the studied samples. Margarines supplemented with pecan nut shell extract, rosemary extract or BHT during prolonged storage were found to be of equal quality within the degree of confidence limits. The extract of pecan nut shell may be considered as a natural product replacement for the synthetic antioxidant BHT. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  20. Boson shells harboring charged black holes

    SciTech Connect

    Kleihaus, Burkhard; Kunz, Jutta; Laemmerzahl, Claus; List, Meike

    2010-11-15

    We consider boson shells in scalar electrodynamics coupled to Einstein gravity. The interior of the shells can be empty space, or harbor a black hole or a naked singularity. We analyze the properties of these types of solutions and determine their domains of existence. We investigate the energy conditions and present mass formulae for the composite black hole-boson shell systems. We demonstrate that these types of solutions violate black hole uniqueness.

  1. Integrable structure in discrete shell membrane theory

    PubMed Central

    Schief, W. K.

    2014-01-01

    We present natural discrete analogues of two integrable classes of shell membranes. By construction, these discrete shell membranes are in equilibrium with respect to suitably chosen internal stresses and external forces. The integrability of the underlying equilibrium equations is proved by relating the geometry of the discrete shell membranes to discrete O surface theory. We establish connections with generalized barycentric coordinates and nine-point centres and identify a discrete version of the classical Gauss equation of surface theory. PMID:24808755

  2. Advances in shell side condensation for refrigerants

    NASA Astrophysics Data System (ADS)

    Webb, Ralph L.

    The design of shell and tube condensers used in air conditioning and refrigeration applications is discussed. The geometry of interest involves condensation on the shell side of a horizontal tube bundle. Enhanced heat transfer geometries are typically used for condensation on the shell side. The heat transfer is removed by water on the tube side, which typically have tube side enhancement. Single tube and row effect condensation data are presented. Thermal design methods for sizing of the condenser are outlined.

  3. Adaptive finite element strategies for shell structures

    NASA Technical Reports Server (NTRS)

    Stanley, G.; Levit, I.; Stehlin, B.; Hurlbut, B.

    1992-01-01

    The present paper extends existing finite element adaptive refinement (AR) techniques to shell structures, which have heretofore been neglected in the AR literature. Specific challenges in applying AR to shell structures include: (1) physical discontinuities (e.g., stiffener intersections); (2) boundary layers; (3) sensitivity to geometric imperfections; (4) the sensitivity of most shell elements to mesh distortion, constraint definition and/or thinness; and (5) intrinsic geometric nonlinearity. All of these challenges but (5) are addressed here.

  4. Theory of Viscoplastic Shells for Dynamic Response.

    DTIC Science & Technology

    1982-01-01

    experimental data representing various loading combinations ( biaxial bending and stretching) at various loading rates on plate and shell specimens. The shell...multiaxial tests on plate and shell specimens of a particular material. These experiments should consist of biaxial bending and stretching tests conducted...Jones, N., Uran, T.O. and Tekin, S.A., "The Dynamic Plastic Behavior of Fully Clamped Rectangular Plates ", Int. J. Solids and Structures, Vol. 6, pp

  5. Alternating current dielectrophoresis of core-shell nanoparticles: Experiments and comparison with theory

    NASA Astrophysics Data System (ADS)

    Yang, Chungja

    3D particle-assemblies. Chitosan (amino sugar) and poly-L-lysine (amino acid, PLL) CSnp shell materials were custom synthesized around a hollow (gas) core by utilizing a phospholipid micelle around a volatile fluid templating for the shell material; this approach proves to be novel and distinct from conventional core-shell models wherein a conductive core is coated with an insulative shell. Experiments were conducted within a 100 nl chamber housing 100 um wide Ti/Au quadrapole electrodes spaced 25 um apart. Frequencies from 100kHz to 80MHz at fixed local field of 5Vpp were tested with 10-5 and 10-3 S/m medium conductivities for 25 seconds. Dielectrophoretic responses of ~220 and 340(or ~400) nm chitosan or PLL CSnp were compiled as a function of medium conductivity, size and shell material. Experiments further examined shell thickness and particle concentration (chapter 6) dependencies on ~530 nm CSnp dielectrophoretic and electrorotational responses with ~30nm and ~80 nm shell thicknesses and at particle concentration count rates of 5000 +/- 500, 10000 +/- 500, and 15000 +/- 500 counts per second. Using similar experimental conditions, both dielectrophoretic and electrorotational CSnp responses were compiled versus frequency, shell thickness, and particle concentration. Knowledge gained from this study includes a unique resonance-like dielectrophoretic and electrorotational spectrum, which is significantly distinct from other cells and particles. CSnp dielectric properties were then calculated by parametrically fitting parameters to an existing core-shell model. The optimum conductivity and relative permittivity for the core and the shell are 1E-15 S/m, 1, 0.6 S/m, and 90, respectively. These properties can be exploited to rapidly assemble these unique core-shell particles for future structural color production in fabrics, vehicle, and wall painting.

  6. Single Shell Tank (SST) Retrieval Sequence & Double Shell Tank (DST) Space Evaluation

    SciTech Connect

    HOHL, T.M.

    2001-09-20

    This document describes the baseline single-shell tank (SST) waste retrieval sequence for the River Protection Project updated for Fiscal Year 2002. The double-shell tank (DST) space evaluation presents projected DST needs for Hanford for additional DSTs.

  7. Single Shell Tank (SST) Retrieval Sequence & Double Shell Tank (DST) Space Evaluation

    SciTech Connect

    STRODE, J.N.

    2002-09-23

    This document describes the baseline single-shell tank (SST) waste retrieval sequence for the River Protection Project updated for Fiscal Year 2002. The double-shell tank (DST) space evaluation presents projected DST needs for Hanford for additional DSTs.

  8. Single Shell Tank (SST) Retrieval Sequence and Double Shell Tank (DST) Space Evaluation

    SciTech Connect

    KIRCH, N.W.

    2003-09-23

    This document describes the baseline single-shell tank (SST) waste retrieval sequence for the River Protection Project updated for Fiscal Year 2002. The double-shell tank (DST) space evaluation presents projected DST needs for Hanford for additional DSTs.

  9. Cell-in-Shell Hybrids: Chemical Nanoencapsulation of Individual Cells.

    PubMed

    Park, Ji Hun; Hong, Daewha; Lee, Juno; Choi, Insung S

    2016-05-17

    structures found in nature, for example, bacterial endospores. Bioinspired silicification and phenolics-based coatings are, so far, the main approaches to the formation of cytoprotective cell-in-shell hybrids, because they ensure cell viability during encapsulations and also generate durable nanoshells on cell surfaces. The resulting cell-in-shell hybrids extrinsically possess enhanced resistance to external aggressors, and more intriguingly, the encapsulation alters their metabolic activity, exemplified by retarded or suppressed cell cycle progression. In addition, recent developments in the field have further advanced the synthetic tools available to the stage of chemical sporulation and germination of mammalian cells, where cytoprotective shells are formed on labile mammalian cells and broken apart on demand. For example, individual HeLa cells are coated with a metal-organic complex of ferric ion and tannic acid, and cellular adherence and proliferation are controlled by the programmed shell formation and degradation. Based on these demonstrations, the (degradable) cell-in-shell hybrids are anticipated to find their applications in various biomedical and bionanotechnological areas, such as cytotherapeutics, high-throughput screening, sensors, and biocatalysis, as well as providing a versatile research platform for single-cell biology.

  10. Shell boosts recovery at Kernridge

    SciTech Connect

    Moore, S.

    1984-01-01

    Since acquiring the Kernridge property in December 1979, Shell Oil Co. has drilled more than 1,800 wells and steadily increased production from 42,000 to 89,000 b/d of oil. Currently, the Kernridge Production Division of Shell California Production Inc. (SCPI), a newly formed subsidiary of Shell Oil Co., is operator for the property. The property covers approximately 35,000 mostly contiguous net acres, with production concentrated mainly on about 5,500 net acres. SCPI's four major fields in the area are the North and South Belridge, Lost Hills, and Antelope Hills. Most of the production comes from the North and South Belridge fields, which were previously held by the Belridge Oil Co. Productive horizons in the fields are the Tulare, Diatomite, Brown Shale, Antelope Shale, 64 Zone, and Agua sand. The Tulare and Diatomite are the two major reservoirs SCPI is developing. The Tulare, encountered between 400 and 1,300 ft, is made up of fine- to coarse-grained, unconsolidated sands with interbedded shales and silt stones and contains 13 /sup 0/ API oil. Using steam drive as the main recovery method, SCPI estimates an ultimate recovery from the Tulare formation of about 60% of the original 1 billion barrels in place. The Diatomite horizon, found between 800 and 3,500 ft and containing light, 28 /sup 0/ API oil, has high porosity (more than 60%), low permeability (less than 1 md), and natural fractures. Because of the Diatomite's low permeability, fracture stimulation is being used to increase well productivity. SCPI anticipates that approximately 5% of the almost 2 billion barrels of oil originally in place will be recovered by primary production.

  11. Shell appraising deepwater discovery off Philippines

    SciTech Connect

    Scherer, M. ); Lambers, E.J.T.; Steffens, G.S. )

    1993-05-10

    Shell International Petroleum Co. Ltd. negotiated a farmout in 1990 from Occidental International Exploration and Production Co. for Block SC-38 in the South China Sea off Palawan, Philippines, following Oxy's discovery of gas in 1989 in a Miocene Nido limestone buildup. Under the terms of the farmout agreement, Shell became operator with a 50% share. Following the disappointing well North Iloc 1, Shell was successful in finding oil and gas in Malampaya 1. Water 700-1,000 m deep, remoteness, and adverse weather conditions have imposed major challenges for offshore operations. The paper describes the tectonic setting; the Nido limestone play; the Malampaya discovery; and Shell's appraisal studies.

  12. Core/shell colloidal semiconductor nanoplatelets.

    PubMed

    Mahler, Benoit; Nadal, Brice; Bouet, Cecile; Patriarche, Gilles; Dubertret, Benoit

    2012-11-14

    We have recently synthesized atomically flat semiconductor colloidal nanoplatelets with quasi 2D geometry. Here, we show that core/shell nanoplatelets can be obtained with a 2D geometry that is conserved. The epitaxial growth of the shell semiconductor is performed at room temperature. We report the detailed synthesis of CdSe/CdS and CdSe/CdZnS structures with different shell thicknesses. The shell growth is characterized both spectroscopically and structurally. In particular, the core/shell structure appears very clearly on high-resolution, high-angle annular dark-field transmission electron microscope images, thanks to the difference of atomic density between the core and the shell. When the nanoplatelets stand on their edge, we can precisely count the number of atomic planes forming the core and the shell. This provides a direct measurement, with atomic precision, of the core nanoplatelets thickness. The constraints exerted by the shell growth on the core is analyzed using global phase analysis. The core/shell nanoplatelets we obtained have narrow emission spectra with full-width at half-maximum close to 20 nm, and quantum yield that can reach 60%.

  13. Thermal buckling of laminated composite shells

    SciTech Connect

    Thangaratnam, R.K.; Palaninathan, R.; Ramachandran, J. )

    1990-05-01

    The linear buckling analysis of laminated composite cylindrical and conical shells under thermal load using the finite element method is reported here. Critical temperatures are presented for various cases of cross-ply and angly-ply laminated shells. The effects of radius/thickness ratio, number of layers, ratio of coefficients of thermal expansion, and the angle of fiber orientation have been studied. The results indicate that the buckling behavior of laminated shell under thermal load is different from that of mechanically loaded shell with respect to the angle of fiber orientation. 6 refs.

  14. Fracture Mitigation Strategies in Gastropod Shells

    NASA Astrophysics Data System (ADS)

    Salinas, Christopher; Kisailus, David

    2013-04-01

    For hundreds of millions of years, gastropods have been evolving, modifying their external calcified shells for defense against shell-breaking and drilling predators. They have evolved primarily to use two different aragonitic microstructures: the evolutionary older Nacre (mother of pearl) structure and the more recently developed crossed-lamellar structure. By using both of these structures, gastropods are able to produce shells that are significantly tougher then geologic aragonite. However, the crossed-lamellar structure allows for a wider variety of shell morphologies, ensuring its increasing presence since the Mesozoic Marine Revolution more than 200 million years ago.

  15. Material with core-shell structure

    DOEpatents

    Luhrs, Claudia [Rio Rancho, NM; Richard, Monique N [Ann Arbor, MI; Dehne, Aaron [Maumee, OH; Phillips, Jonathan [Rio Rancho, NM; Stamm, Kimber L [Ann Arbor, MI; Fanson, Paul T [Brighton, MI

    2011-11-15

    Disclosed is a material having a composite particle, the composite particle including an outer shell and a core. The core is made from a lithium alloying material and the outer shell has an inner volume that is greater in size than the core of the lithium alloying material. In some instances, the outer mean diameter of the outer shell is less than 500 nanometers and the core occupies between 5 and 99% of the inner volume. In addition, the outer shell can have an average wall thickness of less than 100 nanometers.

  16. Carbon isotopes in mollusk shell carbonates

    NASA Astrophysics Data System (ADS)

    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.

  17. Hydrate Shell Growth Measured Using NMR.

    PubMed

    Haber, Agnes; Akhfash, Masoumeh; Loh, Charles K; Aman, Zachary M; Fridjonsson, Einar O; May, Eric F; Johns, Michael L

    2015-08-18

    Benchtop nuclear magnetic resonance (NMR) pulsed field gradient (PFG) and relaxation measurements were used to monitor the clathrate hydrate shell growth occurring in water droplets dispersed in a continuous cyclopentane phase. These techniques allowed the growth of hydrate inside the opaque exterior shell to be monitored and, hence, information about the evolution of the shell's morphology to be deduced. NMR relaxation measurements were primarily used to monitor the hydrate shell growth kinetics, while PFG NMR diffusion experiments were used to determine the nominal droplet size distribution (DSD) of the unconverted water inside the shell core. A comparison of mean droplet sizes obtained directly via PFG NMR and independently deduced from relaxation measurements showed that the assumption of the shell model-a perfect spherical core of unconverted water-for these hydrate droplet systems is correct, but only after approximately 24 h of shell growth. Initially, hydrate growth is faster and heat-transfer-limited, leading to porous shells with surface areas larger than that of spheres with equivalent volumes. Subsequently, the hydrate growth rate becomes mass-transfer-limited, and the shells become thicker, spherical, and less porous.

  18. Electron Shell as a Resonator

    NASA Astrophysics Data System (ADS)

    Karpeshin, F. F.

    2002-11-01

    Main principles of the resonance effect arising in the electron shells in interaction of the nuclei with electromagnetic radiation are analyzed and presented in the historical aspect. Principles of NEET are considered from a more general position, as compared to how this is usually presented. Characteristic features of NEET and its reverse, TEEN, as internal conversion processes are analyzed, and ways are offered of inducing them by laser radiation. The ambivalent role of the Pauli exclusion principles in NEET and TEEN processes is investigated.

  19. Generic thin-shell gravastars

    SciTech Connect

    Martin-Moruno, Prado; Visser, Matt; Garcia, Nadiezhda Montelongo; Lobo, Francisco S.N. E-mail: nmontelongo@fis.cinvestav.mx E-mail: matt.visser@msor.vuw.ac.nz

    2012-03-01

    We construct generic spherically symmetric thin-shell gravastars by using the cut-and-paste procedure. We take considerable effort to make the analysis as general and unified as practicable; investigating both the internal physics of the transition layer and its interaction with 'external forces' arising due to interactions between the transition layer and the bulk spacetime. Furthermore, we discuss both the dynamic and static situations. In particular, we consider 'bounded excursion' dynamical configurations, and probe the stability of static configurations. For gravastars there is always a particularly compelling configuration in which the surface energy density is zero, while surface tension is nonzero.

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

    PubMed

    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.

  1. Apparatus and methods for installing, removing and adjusting an inner turbine shell section relative to an outer turbine shell section

    DOEpatents

    Leach, David; Bergendahl, Peter Allen; Waldo, Stuart Forrest; Smith, Robert Leroy; Phelps, Robert Kim

    2001-01-01

    A turbine includes upper and lower inner shell sections mounting the nozzles and shrouds and which inner shell is supported by pins secured to a surrounding outer shell. To disassemble the turbine for access to the inner shell sections and rotor, an alignment fixture is secured to the lower outer shell section and has pins engaging the inner shell section. To disassemble the turbine, the inner shell weight is transferred to the lower outer shell section via the alignment fixture and cradle pins. Roller assemblies are inserted through access openings vacated by support pins to permit rotation of the lower inner shell section out of and into the lower outer shell section during disassembly and assembly. The alignment fixture includes adjusting rods for adjusting the inner shell axially, vertically, laterally and about a lateral axis. A roller over-cage is provided to rotate the inner shell and a dummy shell to facilitate assembly and disassembly in the field.

  2. Atomic inner-shell ionization

    NASA Astrophysics Data System (ADS)

    Das, J. N.; Chakraborty, S.

    1985-07-01

    Cross sections for the K-shell ionization of medium-heavy atoms by relativistic electrons have been calculated in a relativistic framework in the Coulomb gauge to order α0 (=e2/ħc) in the interaction Hamiltonian. Here exchange is neglected. The incident- and scattered-electron wave functions are described by Dirac plane waves. Only the bound- and ejected-electron wave functions are described nonrelativistically for a screened Coulomb potential, used earlier by the present authors. Thus the screening effect is taken into account in this calculation in a satisfactory manner. The calculation is a repetition of what has been published recently by the present authors with one important exception: Here, the ejected-electron continuum state wave function that is used is determined variationally for the above screened Coulomb potential. Thereby some perturbation approximation of ad hoc nature could be avoided. As a consequence, considerable improvement is noticed in the total cross-section results. Comparison with experimental results for 29Cu, 47Ag, and 79Au shows a good agreement. The calculation may easily be extended to ionization from other shells.

  3. Transitional nuclei near shell closures

    SciTech Connect

    Mukherjee, G.

    2014-08-14

    High spin states in Bismuth and Thallium nuclei near the Z = 82 shell closure and Cesium nuclei near the N = 82 shell closure in A = 190 and A = 130 regions, respectively, have been experimentally investigated using heavy-ion fusion evaporation reaction and by detecting the gamma rays using the Indian National Gamma Array (INGA). Interesting shape properties in these transitional nuclei have been observed. The results were compared with the neighboring nuclei in these two regions. The total Routhian surface (TRS) calculations have been performed for a better understanding of the observed properties. In mass region A = 190, a change in shape from spherical to deformed has been observd around neutron number N = 112 for the Bi (Z = 83) isotopes with proton number above the magic gap Z = 82, whereas, the shape of Tl (Z = 81) isotopes with proton number below the magic gap Z = 82 remains stable as a function of neutron number. An important transition from aplanar to planar configuration of angular momentum vectors leading to the occurance of nuclar chirality and magnetic rotation, respectively, has been proposed for the unique parity πh{sub 11/2}⊗νh{sub 11/2} configuration in Cs isotopes in the mass region A ∼ 130 around neutron number N = 79. These results are in commensurate with the TRS calculations.

  4. Lead behavior in abalone shell

    NASA Astrophysics Data System (ADS)

    Hirao, Yoshimitsu; Matsumoto, Akikazu; Yamakawa, Hiroshi; Maeda, Masaru; Kimura, Kan

    1994-08-01

    In order to gain information about the behavior of heavy metals in biological assimilation processes in a marine food chain and to investigate the possibility that lead pollution in a marine environment can be estimated by measurement of a small number of key materials from such a food chain, muscle and shell were analyzed from abalone ( Haliotis) from a shallow water locality in a Japanese coastal region. Lead concentrations in muscle were about 26 ppb for abalone of approximately 3 years old and decreased systematically with increasing age of animals sampled, to about 3.3 ppb for a specimen approximately 8 years old. Lead concentrations in shell material gradually decreased also, from 150 ppb to 82 ppb in the oldest specimen. The decrease of concentration in tissues with increasing age indicates that a mechanism for exclusion of lead during tissue growth becomes more efficient with age. Along the food chain in which abalone is the final stage, lead was enriched at the first stage, from seawater to algae, by a factor of 100. Lead was diminished at all subsequent stages of the chain. Tissue of artificially cultured abalone had four times higher lead values compared to abalone grown in natural conditions, and this appears to reflect the fact that lead concentration was three times higher in seawater in the cultured environment.

  5. Lead behavior in abalone shell

    SciTech Connect

    Hirao, Yoshimitsu; Matsumoto, Akikazu; Kimura, Kan ); Yamakawa, Hiroshi; Maeda, Masaru )

    1994-08-01

    In order to gain information about the behavior of heavy metals in biological assimilation processes in a marine food chain and to investigate the possibility that lead pollution in a marine environment can be estimated by measurement of a small number of key materials from such a food chain, muscle and shell were analyzed from abalone (Haliotis) from a shallow water locality in a Japanese coastal region. Lead concentrations in muscle were about 26 ppb for abalone approximately 3 years old and decreased systematically with increasing age of animals sampled, to about 3.3 ppb for a specimen approximately 8 years old. Lead concentrations in shell material gradually decreased also, from 150 ppb to 82 ppb in the oldest specimen. The decrease of concentration in tissues with increasing age indicates that a mechanism for exclusion of lead during tissue growth becomes more efficient with age. Along the food chain in which abalone is the final stage, lead was enriched at the first stage, from seawater to algae, by a factor of 100. Lead was diminished at all subsequent stages of the chain. Tissue of artificially cultured abalone had four times higher lead values compared to abalone grown in natural conditions, and this appears to reflect the fact that lead concentration was three times higher in seawater in the cultured environment.

  6. The ultimate step towards a tailored engineering of core@shell and core@shell@shell nanoparticles.

    PubMed

    Llamosa, D; Ruano, M; Martínez, L; Mayoral, A; Roman, E; García-Hernández, M; Huttel, Y

    2014-11-21

    Complex core@shell and core@shell@shell nanoparticles are systems that combine the functionalities of the inner core and outer shell materials together with new physico-chemical properties originated by their low (nano) dimensionality. Such nanoparticles are of prime importance in the fast growing field of nanotechnology as building blocks for more sophisticated systems and a plethora of applications. Here, it is shown that although conceptually simple a modified gas aggregation approach allows the one-step generation of well-controlled complex nanoparticles. In particular, it is demonstrated that the atoms of the core and the shell of the nanoparticles can be easily inverted, avoiding intrinsic constraints of chemical methods.

  7. Radiocarbon dating late Quaternary loess deposits using small terrestrial gastropod shells

    USGS Publications Warehouse

    Pigati, Jeff S.; McGeehin, John P.; Muhs, Daniel R.; Bettis, E. Arthur

    2013-01-01

    Constraining the ages and mass accumulation rates of late Quaternary loess deposits is often difficult because of the paucity of organic material typically available for 14C dating and the inherent limitations of luminescence techniques. Radiocarbon dating of small terrestrial gastropod shells may provide an alternative to these methods as fossil shells are common in loess and contain ∼12% carbon by weight. Terrestrial gastropod assemblages in loess have been used extensively to reconstruct past environmental conditions but have been largely ignored for dating purposes. Here, we present the results of a multi-faceted approach to understanding the potential for using small terrestrial gastropod shells to date loess deposits in North America. First, we compare highly resolved 14C ages of well-preserved wood and gastropod shells (Succineidae) recovered from a Holocene loess section in Alaska. Radiocarbon ages derived from the shells are nearly identical to wood and plant macrofossil ages throughout the section, which suggests that the shells behaved as closed systems with respect to carbon for at least the last 10 ka (thousands of calibrated 14C years before present). Second, we apply 14C dating of gastropod shells to late Pleistocene loess deposits in the Great Plains using stratigraphy and independent chronologies for comparison. The new shell ages require less interpretation than humic acid radiocarbon ages that are commonly used in loess studies, provide additional stratigraphic coverage to previous dating efforts, and are in correct stratigraphic order more often than their luminescence counterparts. Third, we show that Succineidae shells recovered from historic loess in the Matanuska River Valley, Alaska captured the 20th century 14C bomb spike, which suggests that the shells can be used to date late Holocene and historic-aged loess. Finally, results from Nebraska and western Iowa suggest that, similar to other materials, shell ages approaching ∼40 ka should

  8. A honeycomb composite of mollusca shell matrix and calcium alginate.

    PubMed

    You, Hua-jian; Li, Jin; Zhou, Chan; Liu, Bin; Zhang, Yao-guang

    2016-03-01

    A honeycomb composite is useful to carry cells for application in bone, cartilage, skin, and soft tissue regenerative therapies. To fabricate a composite, and expand the application of mollusca shells as well as improve preparing methods of calcium alginate in tissue engineering research, Anodonta woodiana shell powder was mixed with sodium alginate at varying mass ratios to obtain a gel mixture. The mixture was frozen and treated with dilute hydrochloric acid to generate a shell matrix/calcium alginate composite. Calcium carbonate served as the control. The composite was transplanted subcutaneously into rats. At 7, 14, 42, and 70 days after transplantation, frozen sections were stained with hematoxylin and eosin, followed by DAPI, β-actin, and collagen type-I immunofluorescence staining, and observed using laser confocal microscopy. The composite featured a honeycomb structure. The control and composite samples displayed significantly different mechanical properties. The water absorption rate of the composite and control group were respectively 205-496% and 417-586%. The composite (mass ratio of 5:5) showed good biological safety over a 70-day period; the subcutaneous structure of the samples was maintained and the degradation rate was lower than that of the control samples. Freezing the gel mixture afforded control over chemical reaction rates. Given these results, the composite is a promising honeycomb scaffold for tissue engineering. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  9. Multistage process for the production of bioethanol from almond shell.

    PubMed

    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.

  10. Cellulose nanocrystals/cellulose core-in-shell nanocomposite assemblies.

    PubMed

    Magalhães, Washington Luiz Esteves; Cao, Xiaodong; Lucia, Lucian A

    2009-11-17

    We report herein for the first time how a co-electrospinning technique can be used to overcome the issue of orienting cellulose nanocrystals within a neat cellulose matrix. A home-built co-electrospinning apparatus was fabricated that was comprised of a high-voltage power supply, two concentric capillary needles, and one screw-type pump syringe. Eucalyptus-derived cellulose was dissolved in N-methylmorpholine oxide (NMMO) at 120 degrees C and diluted with dimethyl sulfoxide (DMSO) which was used in the external concentric capillary needle as the shell solution. A cellulose nanocrystal suspension obtained by the sulfuric acid hydrolysis of bleached sisal and cotton fibers was used as the core liquid in the internal concentric capillary needle. Three flow rate ratios between the shell and core, four flow rates for the shell dope solution, and four high voltages were tested. The resultant co-electrospun composite fibers were collected onto a grounded metal screen immersed in cold water. Micrometer and submicrometer cellulose fiber assemblies were obtained which were reinforced with cellulose nanocrystals and characterized by FESEM, FTIR, TGA, and XRD. Surprisingly, it was determined that the physical properties for the cellulose controls are superior to the composites; in addition, the crystallinity of the controls was slightly greater.

  11. The ultimate step towards a tailored engineering of core@shell and core@shell@shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Llamosa, D.; Ruano, M.; Martínez, L.; Mayoral, A.; Roman, E.; García-Hernández, M.; Huttel, Y.

    2014-10-01

    Complex core@shell and core@shell@shell nanoparticles are systems that combine the functionalities of the inner core and outer shell materials together with new physico-chemical properties originated by their low (nano) dimensionality. Such nanoparticles are of prime importance in the fast growing field of nanotechnology as building blocks for more sophisticated systems and a plethora of applications. Here, it is shown that although conceptually simple a modified gas aggregation approach allows the one-step generation of well-controlled complex nanoparticles. In particular, it is demonstrated that the atoms of the core and the shell of the nanoparticles can be easily inverted, avoiding intrinsic constraints of chemical methods.Complex core@shell and core@shell@shell nanoparticles are systems that combine the functionalities of the inner core and outer shell materials together with new physico-chemical properties originated by their low (nano) dimensionality. Such nanoparticles are of prime importance in the fast growing field of nanotechnology as building blocks for more sophisticated systems and a plethora of applications. Here, it is shown that although conceptually simple a modified gas aggregation approach allows the one-step generation of well-controlled complex nanoparticles. In particular, it is demonstrated that the atoms of the core and the shell of the nanoparticles can be easily inverted, avoiding intrinsic constraints of chemical methods. Electronic supplementary information (ESI) available: 1: Scheme illustrating the different strategies to grow nanoparticles with controlled chemical composition and structure. 2: Examples of TEM results on Ag@Au nanoparticles. 3: Magnetic measurements results on Co@Au and Au@Co nanoparticles. See DOI: 10.1039/c4nr02913e

  12. Cargo-shell and cargo-cargo couplings govern the mechanics of artificially loaded virus-derived cages

    NASA Astrophysics Data System (ADS)

    Llauró, Aida; Luque, Daniel; Edwards, Ethan; Trus, Benes L.; Avera, John; Reguera, David; Douglas, Trevor; Pablo, Pedro J. De; Castón, José R.

    2016-04-01

    Nucleic acids are the natural cargo of viruses and key determinants that affect viral shell stability. In some cases the genome structurally reinforces the shell, whereas in others genome packaging causes internal pressure that can induce destabilization. Although it is possible to pack heterologous cargoes inside virus-derived shells, little is known about the physical determinants of these artificial nanocontainers' stability. Atomic force and three-dimensional cryo-electron microscopy provided mechanical and structural information about the physical mechanisms of viral cage stabilization beyond the mere presence/absence of cargos. We analyzed the effects of cargo-shell and cargo-cargo interactions on shell stability after encapsulating two types of proteinaceous payloads. While bound cargo to the inner capsid surface mechanically reinforced the capsid in a structural manner, unbound cargo diffusing freely within the shell cavity pressurized the cages up to ~30 atm due to steric effects. Strong cargo-cargo coupling reduces the resilience of these nanocompartments in ~20% when bound to the shell. Understanding the stability of artificially loaded nanocages will help to design more robust and durable molecular nanocontainers.Nucleic acids are the natural cargo of viruses and key determinants that affect viral shell stability. In some cases the genome structurally reinforces the shell, whereas in others genome packaging causes internal pressure that can induce destabilization. Although it is possible to pack heterologous cargoes inside virus-derived shells, little is known about the physical determinants of these artificial nanocontainers' stability. Atomic force and three-dimensional cryo-electron microscopy provided mechanical and structural information about the physical mechanisms of viral cage stabilization beyond the mere presence/absence of cargos. We analyzed the effects of cargo-shell and cargo-cargo interactions on shell stability after encapsulating two

  13. Isothermal Circumstellar Dust Shell Model for Teaching

    ERIC Educational Resources Information Center

    Robinson, G.; Towers, I. N.; Jovanoski, Z.

    2009-01-01

    We introduce a model of radiative transfer in circumstellar dust shells. By assuming that the shell is both isothermal and its thickness is small compared to its radius, the model is simple enough for students to grasp and yet still provides a quantitative description of the relevant physical features. The isothermal model can be used in a…

  14. A Geometric Theory of Nonlinear Morphoelastic Shells

    NASA Astrophysics Data System (ADS)

    Sadik, Souhayl; Angoshtari, Arzhang; Goriely, Alain; Yavari, Arash

    2016-08-01

    Many thin three-dimensional elastic bodies can be reduced to elastic shells: two-dimensional elastic bodies whose reference shape is not necessarily flat. More generally, morphoelastic shells are elastic shells that can remodel and grow in time. These idealized objects are suitable models for many physical, engineering, and biological systems. Here, we formulate a general geometric theory of nonlinear morphoelastic shells that describes both the evolution of the body shape, viewed as an orientable surface, as well as its intrinsic material properties such as its reference curvatures. In this geometric theory, bulk growth is modeled using an evolving referential configuration for the shell, the so-called material manifold. Geometric quantities attached to the surface, such as the first and second fundamental forms, are obtained from the metric of the three-dimensional body and its evolution. The governing dynamical equations for the body are obtained from variational consideration by assuming that both fundamental forms on the material manifold are dynamical variables in a Lagrangian field theory. In the case where growth can be modeled by a Rayleigh potential, we also obtain the governing equations for growth in the form of kinetic equations coupling the evolution of the first and the second fundamental forms with the state of stress of the shell. We apply these ideas to obtain stress-free growth fields of a planar sheet, the time evolution of a morphoelastic circular cylindrical shell subject to time-dependent internal pressure, and the residual stress of a morphoelastic planar circular shell.

  15. Alternative Storage Environments for Shelled Peanuts

    USDA-ARS?s Scientific Manuscript database

    Studies were conducted in small chambers and commercial storage facilities to evaluate the effect of storing shelled peanuts at 3, 13, and 21 C (38, 55, 70 F) for one year. Shelled medium runner peanuts from the 2014 crop were placed in the three different environments in Feb 2015, sampled at 60-d ...

  16. A Well-Defined Bipolar Outflow Shell

    NASA Astrophysics Data System (ADS)

    Xie, Taoling; Goldsmith, Paul F.; Patel, Nimesh

    1992-12-01

    A well-defined "eggplant-shaped" thin shell is revealed in the Mon R2 central core region by CO and (13) CO J=1-0 maps obtained with QUARRY. This thin shell outlines the extended blue lobe of the massive bipolar outflow. The projected length and width of the shell are about 5.7 pc and 2.5 pc respectively, and the averaged projected thickness of the shell is ~ 0.3 pc. The shape of this shell can be satisfactorily accounted for quantitatively in terms of limb-brightening within the framework of the Shu et al shell model with radially directed wind, although the model seems to be oversimplified with respect to the complexity that our data reveal. The outflow shell's symmetry axis is estimated to be inclined by ~ 70(deg) with respect to the line of sight. We suggest that the coincident blue- and red-shifted emission and the bending of the red-shifted lobe are the result of the red-shifted shell being compressed, rather than having a second bipolar outflow aligned roughly perpendicular to the axis of the first bipolar outflow.

  17. Isotopic equilibrium between shells and their environement.

    PubMed

    Mook, W G; Vogel, J C

    1968-02-23

    The carbon-isotopic composition of shell carbonate is shown to be in isotopic equilibrium with bicarbonate dissolved in the water. By measurement of both 13C and 18O in a series of brackish-water shells a mean growth temperature can be deduced.

  18. Isothermal Circumstellar Dust Shell Model for Teaching

    ERIC Educational Resources Information Center

    Robinson, G.; Towers, I. N.; Jovanoski, Z.

    2009-01-01

    We introduce a model of radiative transfer in circumstellar dust shells. By assuming that the shell is both isothermal and its thickness is small compared to its radius, the model is simple enough for students to grasp and yet still provides a quantitative description of the relevant physical features. The isothermal model can be used in a…

  19. Layzer type models for pressure driven shells

    SciTech Connect

    Hurricane, O A

    2004-09-16

    Models for the nonlinear instability of finite thickness shells driven by pressure are constructed in the style of Layzer. Equations for both Cartesian and cylindrically convergent/divergent geometries are derived. The resulting equations are appropriate for incompressible shells with unity Atwood number. Predictions from the equations compare well with two-dimensional simulations.

  20. Thick-shell nanocrystal quantum dots

    SciTech Connect

    Hollingsworth, Jennifer A; Chen, Yongfen; Klimov, Victor I; Htoon, Han; Vela, Javier

    2011-05-03

    Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, where said outer shell comprises multiple monolayers, wherein at least 30% of the quantum dots have an on-time fraction of 0.80 or greater under continuous excitation conditions for a period of time of at least 10 minutes.

  1. Biomineral repair of abalone shell apertures.

    PubMed

    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.

  2. Statistical Mechanics of Thin Spherical Shells

    NASA Astrophysics Data System (ADS)

    Košmrlj, Andrej; Nelson, David R.

    2017-01-01

    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.

  3. Layzer type models for pressure driven shells

    SciTech Connect

    Hurricane, O.A.

    2005-05-01

    Models for the nonlinear instability of finite thickness shells driven by pressure are constructed in the style of Layzer. Equations for both Cartesian and cylindrically convergent/divergent geometries are derived. The resulting equations are appropriate for incompressible shells with unity Atwood number. Predictions from the equations compare well with two-dimensional simulations.

  4. Factors affecting the yield of bio-oil from the pyrolysis of coconut shell.

    PubMed

    Gao, Yun; Yang, Yi; Qin, Zhanbin; Sun, Yi

    2016-01-01

    Coconut is a high-quality agricultural product of the Asia-Pacific region. In this paper, coconut shell which mainly composed of cellulose, hemicellulose, lignin was used as a raw material for coconut shell oil from coconut shell pyrolysis. The influence of the pyrolysis temperature, heating rate and particle size on coconut oil yield was investigated, and the effect of heating rate on coconut oil components was discussed. Experimental results show that the maximum oil yield of 75.74 wt% (including water) were obtained under the conditions that the final pyrolysis temperature 575 °C, heating rate 20 °C/min, coconut shell diameter about 5 mm. Thermal gravimetric analysis was used and it can be seen that coconut shell pyrolysis process can be divided into three stages: water loss, pyrolysis and pyrocondensation. The main components of coconut-shell oil are water (about 50 wt%), aromatic, phenolic, acid, ketone and ether containing compounds.

  5. ZnS shell growth on thiol capped CdTe quantum dots using gamma irradiation

    NASA Astrophysics Data System (ADS)

    Raju, S. P.; Hareesh, K.; Pai, S. Chethan; Dhole, S. D.; Sanjeev, Ganesh

    2017-05-01

    The formation of ZnS shell on 3-Mercaptopropionic acid (MPA) capped CdTe quantum dots (QDs) using gamma radiation has been reported in this study. Hydrothermally synthesized CdTe QDs were exposed to gamma radiation before and after introducing shell source materials (Zn+MPA complex). The gamma rays exposed samples were characterized using UV-Vis spectroscopy, Photoluminescence spectroscopy (PL) and X-Ray Diffraction (XRD) techniques. The redshift in absorption spectra for gamma irradiated samples indicates the formation of bigger nanoparticles as the shell stretched the core size. The shift in the XRD peaks (cubic zinc blade structure) towards higher angle reveals the formation of MPA capped CdTe/ZnS core/shell QDs against gamma radiation. The variation in PL spectra also followed the same redshift corroborating the UV-Vis and XRD results. The increase in PL intensity only after introducing shell source material against gamma radiation clearly confirms ZnS shell saturated the surface dangling bonds by increasing radiative decay mechanism over CdTe core surface.

  6. The Shell of the Invasive Bivalve Species Dreissena polymorpha: Biochemical, Elemental and Textural Investigations

    PubMed Central

    Broussard, Cédric; Catherinet, Bastien; Plasseraud, Laurent; Alcaraz, Gérard; Bundeleva, Irina; Marin, Frédéric

    2016-01-01

    The zebra mussel Dreissena polymorpha is a well-established invasive model organism. Although extensively used in environmental sciences, virtually nothing is known of the molecular process of its shell calcification. By describing the microstructure, geochemistry and biochemistry/proteomics of the shell, the present study aims at promoting this species as a model organism in biomineralization studies, in order to establish a bridge with ecotoxicology, while sketching evolutionary conclusions. The shell of D. polymorpha exhibits the classical crossed-lamellar/complex crossed lamellar combination found in several heterodont bivalves, in addition to an external thin layer, the characteristics of which differ from what was described in earlier publication. We show that the shell selectively concentrates some heavy metals, in particular uranium, which predisposes D. polymorpha to local bioremediation of this pollutant. We establish the biochemical signature of the shell matrix, demonstrating that it interacts with the in vitro precipitation of calcium carbonate and inhibits calcium carbonate crystal formation, but these two properties are not strongly expressed. This matrix, although overall weakly glycosylated, contains a set of putatively calcium-binding proteins and a set of acidic sulphated proteins. 2D-gels reveal more than fifty proteins, twenty of which we identify by MS-MS analysis. We tentatively link the shell protein profile of D. polymorpha and the peculiar recent evolution of this invasive species of Ponto-Caspian origin, which has spread all across Europe in the last three centuries. PMID:27213644

  7. Phenolic profile and antioxidant activity from non-toxic Mexican Jatropha curcas L. shell methanolic extracts.

    PubMed

    Perea-Domínguez, Xiomara Patricia; Espinosa-Alonso, Laura Gabriela; Hosseinian, Farah; HadiNezhad, Mehri; Valdez-Morales, Maribel; Medina-Godoy, Sergio

    2017-03-01

    Jatropha curcas seed shells are the by-product obtained during oil extraction process. Recently, its chemical composition has gained attention since its potential applications. The aim of this study was to identify phenolic compounds profile from a non-toxic J. curcas shell from Mexico, besides, evaluate J. curcas shell methanolic extract (JcSME) antioxidant activity. Free, conjugate and bound phenolics were fractionated and quantified (606.7, 193.32 and 909.59 μg/g shell, respectively) and 13 individual phenolic compounds were detected by HPLC. The radical-scavenging activity of JcSME was similar to Trolox and ascorbic acid by DPPH assay while by ABTS assay it was similar to BHT. Effective antioxidant capacity by ORAC was found (426.44 ± 53.39 μmol Trolox equivalents/g shell). The Mexican non-toxic J. curcas shell is rich in phenolic compounds with high antioxidant activity; hence, it could be considerate as a good source of natural antioxidants.

  8. Use of Walnut Shell Powder to Inhibit Expression of Fe(2+)-Oxidizing Genes of Acidithiobacillus Ferrooxidans.

    PubMed

    Li, Yuhui; Liu, Yehao; Tan, Huifang; Zhang, Yifeng; Yue, Mei

    2016-04-30

    Acidithiobacillus ferrooxidans is a Gram-negative bacterium that obtains energy by oxidizing Fe(2+) or reduced sulfur compounds. This bacterium contributes to the formation of acid mine drainage (AMD). This study determined whether walnut shell powder inhibits the growth of A. ferrooxidans. First, the effects of walnut shell powder on Fe(2+) oxidization and H⁺ production were evaluated. Second, the chemical constituents of walnut shell were isolated to determine the active ingredient(s). Third, the expression of Fe(2+)-oxidizing genes and rus operon genes was investigated using real-time polymerase chain reaction. Finally, growth curves were plotted, and a bioleaching experiment was performed to confirm the active ingredient(s) in walnut shells. The results indicated that both walnut shell powder and the phenolic fraction exert high inhibitory effects on Fe(2+) oxidation and H⁺ production by A. ferrooxidans cultured in standard 9K medium. The phenolic components exert their inhibitory effects by down-regulating the expression of Fe(2+)-oxidizing genes and rus operon genes, which significantly decreased the growth of A. ferrooxidans. This study revealed walnut shell powder to be a promising substance for controlling AMD.

  9. The Shell of the Invasive Bivalve Species Dreissena polymorpha: Biochemical, Elemental and Textural Investigations.

    PubMed

    Immel, Françoise; Broussard, Cédric; Catherinet, Bastien; Plasseraud, Laurent; Alcaraz, Gérard; Bundeleva, Irina; Marin, Frédéric

    2016-01-01

    The zebra mussel Dreissena polymorpha is a well-established invasive model organism. Although extensively used in environmental sciences, virtually nothing is known of the molecular process of its shell calcification. By describing the microstructure, geochemistry and biochemistry/proteomics of the shell, the present study aims at promoting this species as a model organism in biomineralization studies, in order to establish a bridge with ecotoxicology, while sketching evolutionary conclusions. The shell of D. polymorpha exhibits the classical crossed-lamellar/complex crossed lamellar combination found in several heterodont bivalves, in addition to an external thin layer, the characteristics of which differ from what was described in earlier publication. We show that the shell selectively concentrates some heavy metals, in particular uranium, which predisposes D. polymorpha to local bioremediation of this pollutant. We establish the biochemical signature of the shell matrix, demonstrating that it interacts with the in vitro precipitation of calcium carbonate and inhibits calcium carbonate crystal formation, but these two properties are not strongly expressed. This matrix, although overall weakly glycosylated, contains a set of putatively calcium-binding proteins and a set of acidic sulphated proteins. 2D-gels reveal more than fifty proteins, twenty of which we identify by MS-MS analysis. We tentatively link the shell protein profile of D. polymorpha and the peculiar recent evolution of this invasive species of Ponto-Caspian origin, which has spread all across Europe in the last three centuries.

  10. Evidence for Improved Encapsulated Pathway Behavior in a Bacterial Microcompartment through Shell Protein Engineering.

    PubMed

    Slininger Lee, Marilyn F; Jakobson, Christopher M; Tullman-Ercek, Danielle

    2017-06-21

    Bacterial microcompartments are a class of proteinaceous organelles comprising a characteristic protein shell enclosing a set of enzymes. Compartmentalization can prevent escape of volatile or toxic intermediates, prevent off-pathway reactions, and create private cofactor pools. Encapsulation in synthetic microcompartment organelles will enhance the function of heterologous pathways, but to do so, it is critical to understand how to control diffusion in and out of the microcompartment organelle. To this end, we explored how small differences in the shell protein structure result in changes in the diffusion of metabolites through the shell. We found that the ethanolamine utilization (Eut) protein EutM properly incorporates into the 1,2-propanediol utilization (Pdu) microcompartment, altering native metabolite accumulation and the resulting growth on 1,2-propanediol as the sole carbon source. Further, we identified a single pore-lining residue mutation that confers the same phenotype as substitution of the full EutM protein, indicating that small molecule diffusion through the shell is the cause of growth enhancement. Finally, we show that the hydropathy index and charge of pore amino acids are important indicators to predict how pore mutations will affect growth on 1,2-propanediol, likely by controlling diffusion of one or more metabolites. This study highlights the use of two strategies to engineer microcompartments to control metabolite transport: altering the existing shell protein pore via mutation of the pore-lining residues, and generating chimeras using shell proteins with the desired pores.

  11. Use of Walnut Shell Powder to Inhibit Expression of Fe2+-Oxidizing Genes of Acidithiobacillus Ferrooxidans

    PubMed Central

    Li, Yuhui; Liu, Yehao; Tan, Huifang; Zhang, Yifeng; Yue, Mei

    2016-01-01

    Acidithiobacillus ferrooxidans is a Gram-negative bacterium that obtains energy by oxidizing Fe2+ or reduced sulfur compounds. This bacterium contributes to the formation of acid mine drainage (AMD). This study determined whether walnut shell powder inhibits the growth of A. ferrooxidans. First, the effects of walnut shell powder on Fe2+ oxidization and H+ production were evaluated. Second, the chemical constituents of walnut shell were isolated to determine the active ingredient(s). Third, the expression of Fe2+-oxidizing genes and rus operon genes was investigated using real-time polymerase chain reaction. Finally, growth curves were plotted, and a bioleaching experiment was performed to confirm the active ingredient(s) in walnut shells. The results indicated that both walnut shell powder and the phenolic fraction exert high inhibitory effects on Fe2+ oxidation and H+ production by A. ferrooxidans cultured in standard 9K medium. The phenolic components exert their inhibitory effects by down-regulating the expression of Fe2+-oxidizing genes and rus operon genes, which significantly decreased the growth of A. ferrooxidans. This study revealed walnut shell powder to be a promising substance for controlling AMD. PMID:27144574

  12. In vitro release profiles of PLGA core-shell composite particles loaded with theophylline and budesonide.

    PubMed

    Yeh, Hsi-Wei; Chen, Da-Ren

    2017-08-07

    We investigated the effects of drug loading location, matrix material and shell thickness on the in vitro release of combinational drugs from core-shell PLGA (i.e., poly(lactic-co-glycolic acid)) particles. Budesonide and Theophylline were selected as highly hydrophobic and hydrophilic model drugs, respectively. The dual-capillary electrospray (ES) technique, operated at the cone-jet mode, was used to produce samples of drug-loaded core-shell composite particles with selected overall sizes, polymer materials, and shell thicknesses. Theophylline and Budesonide were loaded at different locations in a PLGA composite particle. This study illustrated how the aforementioned factors affect the release rates of Budesonide and Theophylline loaded in core-shell PLGA composites. We further identified that core-shell composite particles with both model drugs loaded in the core and with matrix PLGA polymers of low molecular weights and low LA/GA ratios are the best formulation for the sustained release of highly hydrophilic and hydrophobic active pharmaceutical ingredients from PLGA composite particles. The formulation strategy obtained in this study can be in principle generalized for biopharmaceutical applications in fixed-dose combination therapy. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. NMR and ESR characterization of activated carbons produced from pecan shells

    USDA-ARS?s Scientific Manuscript database

    A large number of solid-state NMR and ESR experiments were explored as potential tools to study chemical structure, mobility, and pore volume of activated carbon. We used a model system where pecan shells were activated with phosphoric acid, and carbonized at 450ºC for 4 h with varying amounts of ai...

  14. Production of Biodiesel from Chlorella sp. Enriched with Oyster Shell Extracts

    PubMed Central

    Choi, Woon Yong; Kang, Do Hyung; Lee, Hyeon Yong

    2014-01-01

    This study investigated the cultivation of the marine microalga Chlorella sp. without supplying an inorganic carbon source, but instead with enriching the media with extracts of oyster shells pretreated by a high-pressure homogenization process. The pretreated oyster shells were extracted by a weak acid, acetic acid, that typically has harmful effects on cell growth and also poses environmental issues. The concentration of the residual dissolved carbon dioxide in the medium was sufficient to maintain cell growth at 32 ppm and pH 6.5 by only adding 5% (v/v) of oyster shell extracts. Under this condition, the maximum cell density observed was 2.74 g dry wt./L after 27 days of cultivation. The total lipid content was also measured as 18.1 (%, w/w), and this value was lower than the 23.6 (%, w/w) observed under nitrogen deficient conditions or autotrophic conditions. The fatty acid compositions of the lipids were also measured as 10.9% of C16:1 and 16.4% of C18:1 for the major fatty acids, which indicates that the biodiesel from this culture process should be a suitable biofuel. These results suggest that oyster shells, environmental waste from the food industry, can be used as a nutrient and carbon source with seawater, and this reused material should be important for easily scaling up the process for an outdoor culture system. PMID:24696841

  15. Production of biodiesel from Chlorella sp. enriched with oyster shell extracts.

    PubMed

    Choi, Cheol Soon; Choi, Woon Yong; Kang, Do Hyung; Lee, Hyeon Yong

    2014-01-01

    This study investigated the cultivation of the marine microalga Chlorella sp. without supplying an inorganic carbon source, but instead with enriching the media with extracts of oyster shells pretreated by a high-pressure homogenization process. The pretreated oyster shells were extracted by a weak acid, acetic acid, that typically has harmful effects on cell growth and also poses environmental issues. The concentration of the residual dissolved carbon dioxide in the medium was sufficient to maintain cell growth at 32 ppm and pH 6.5 by only adding 5% (v/v) of oyster shell extracts. Under this condition, the maximum cell density observed was 2.74 g dry wt./L after 27 days of cultivation. The total lipid content was also measured as 18.1 (%, w/w), and this value was lower than the 23.6 (%, w/w) observed under nitrogen deficient conditions or autotrophic conditions. The fatty acid compositions of the lipids were also measured as 10.9% of C16:1 and 16.4% of C18:1 for the major fatty acids, which indicates that the biodiesel from this culture process should be a suitable biofuel. These results suggest that oyster shells, environmental waste from the food industry, can be used as a nutrient and carbon source with seawater, and this reused material should be important for easily scaling up the process for an outdoor culture system.

  16. 129Xe NMR studies of pecan shell-based biochar and structure-process correlations

    USDA-ARS?s Scientific Manuscript database

    Pecan shell-based biochar is being utilized as filtration medium, sequestrant for metallic ions, soil conditioner, and other applications. One process involves the use of phosphoric acid at high temperature in a partial oxygen atmosphere to produce a highly porous carbonaceous material. In this work...

  17. A GREENER SYNTHESIS OF CORE (FE, CU)-SHELL (AU, PT, PD AND AG) NANOCRYSTALS USING AQUEOUS VITAMIN C

    EPA Science Inventory

    A greener method to fabricate the novel core (Fe and Cu)-shell (noble metals) metal nanocrystals using aqueous ascorbic acid (vitamin C) is described. Transition metal salts such as Cu and Fe were reduced using ascorbic acid, a benign naturally available antioxidant, and then add...

  18. A GREENER SYNTHESIS OF CORE (FE, CU)-SHELL (AU, PT, PD AND AG) NANOCRYSTALS USING AQUEOUS VITAMIN C

    EPA Science Inventory

    A greener method to fabricate the novel core (Fe and Cu)-shell (noble metals) metal nanocrystals using aqueous ascorbic acid (vitamin C) is described. Transition metal salts such as Cu and Fe were reduced using ascorbic acid, a benign naturally available antioxidant, and then add...

  19. Surface design of core-shell superparamagnetic iron oxide nanoparticles drives record relaxivity values in functional MRI contrast agents.

    PubMed

    Maity, Dipak; Zoppellaro, Giorgio; Sedenkova, Veronika; Tucek, Jiri; Safarova, Klara; Polakova, Katerina; Tomankova, Katerina; Diwoky, Clemens; Stollberger, Rudolf; Machala, Libor; Zboril, Radek

    2012-12-04

    Core-shell hydrophilic superparamagnetic iron oxide (SPIO) nanoparticles, surface functionalized with either terephthalic acid or 2-amino terephthalic acid, showed large negative MRI contrast ability, validating the advantage of using low molecular weight and π-conjugated canopies for engineering functional nanostructures with superior performances.

  20. Faraday Wave Turbulence on a Spherical Liquid Shell

    NASA Technical Reports Server (NTRS)

    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.

  1. Variability in shell models of GRBs

    NASA Technical Reports Server (NTRS)

    Sumner, M. C.; Fenimore, E. E.

    1997-01-01

    Many cosmological models of gamma-ray bursts (GRBs) assume that a single relativistic shell carries kinetic energy away from the source and later converts it into gamma rays, perhaps by interactions with the interstellar medium or by internal shocks within the shell. Although such models are able to reproduce general trends in GRB time histories, it is difficult to reproduce the high degree of variability often seen in GRBs. The authors investigate methods of achieving this variability using a simplified external shock model. Since the model emphasizes geometric and statistical considerations, rather than the detailed physics of the shell, it is applicable to any theory that relies on relativistic shells. They find that the variability in GRBs gives strong clues to the efficiency with which the shell converts its kinetic energy into gamma rays.

  2. Shell explores a cheaper route to MMA

    SciTech Connect

    Rotman, D.

    1993-02-17

    A novel methyl methacrylate (MMA) technology developed by Shell Research (Amsterdam) could be simpler and far cheaper than existing MMA manufacturing processes, according to a recent analysis by SRI International (Menlo Park, CA). The Shell palladium-catalyzed process makes MMA from methyl acetylene, avoiding the classic acetone cyanohydrin route. And, says Robert Schwaar, a senior SRI consultant, while availability of methyl acetylene feedstock may limit plant sizes, the Shell technology could make MMA for 44 cts/lb in a 100-million lbs/yr unit. Other commercial and developmental processes, he says, produce MMA at roughly 47 cts-58cts/lb in a 250-million lbs/yr plant. Shell-which is not an MMA producer-has not yet decided the technology's fate. The key question about Shell's process is whether producers can get enough cheap methyl acetylene. The technology calls for separating the methyl acetylene from the mixed C[sub 3] by-product stream.

  3. Engineered Magnetic Core-Shell Structures.

    PubMed

    Alavi Nikje, Mir Mohammad; Vakili, Maryam

    2015-01-01

    In recent years, engineered magnetic core-shell structures are playing an important role in the wide range of various applications. These magnetic core-shell structures have attracted considerable attention because of their unique properties and various applications. Also, the synthesis of engineered magnetic core-shell structures has attracted practical interest because of potential applications in areas such as ferrofluids, medical imaging, drug targeting and delivery, cancer therapy, separations, and catalysis. So far a large number of engineered magnetic core-shell structures have been successfully synthesized. This review article focuses on the recent progress in synthesis and characterization of engineered magnetic core-shell structures. Also, this review gives a brief description of the various application of these structures. It is hoped that this review will play some small part in helping future developments in important field.

  4. Buckling of axially compressed conical shells

    NASA Technical Reports Server (NTRS)

    Chang, C.-H.; Katz, L.

    1980-01-01

    The buckling of a truncated elastic conical shell subjected to an axial compression is a classical problem in shell structures. The paper reinvestigates the buckling of an axially compressed truncated conical shell with rigid bulkheads. Two improvements are achieved. First, the condition that the total horizontal displacement must vanish due to rigid bulkhead and axisymmetry is treated as a constraint. This constraint is incorporated into the system through the use of the Lagrange multiplier; then the variational method is used to derive a complete set of boundary conditions for conical shells. Second, the stability is evaluated in the deformed state using the asymptotic solutions of the pair of Donnell-type equations for axisymmetric configuration. The results indicate that the buckling strength of conical shells depends mainly on the condition of the smaller end. In addition to the vertex angle, the distance ratio plays, at least, an equally important role.

  5. Semiclassical shell structure in rotating Fermi systems

    SciTech Connect

    Magner, A. G.; Sitdikov, A. S.; Khamzin, A. A.; Bartel, J.

    2010-06-15

    The collective moment of inertia is derived analytically within the cranking model for any rotational frequency of the harmonic-oscillator potential well and at a finite temperature. Semiclassical shell-structure components of the collective moment of inertia are obtained for any potential by using the periodic-orbit theory. We found semiclassically their relation to the free-energy shell corrections through the shell-structure components of the rigid-body moment of inertia of the statistically equilibrium rotation in terms of short periodic orbits. The shell effects in the moment of inertia exponentially disappear with increasing temperature. For the case of the harmonic-oscillator potential, one observes a perfect agreement of the semiclassical and quantum shell-structure components of the free energy and the moment of inertia for several critical bifurcation deformations and several temperatures.

  6. Ecology and shell chemistry of Loxoconcha matagordensis

    USGS Publications Warehouse

    Cronin, T. M.; Kamiya, T.; Dwyer, G.S.; Belkin, H.; Vann, C.D.; Schwede, S.; Wagner, R.

    2005-01-01

    Studies of the seasonal ecology and shell chemistry of the ostracode Loxoconcha matagordensis and related species of Loxoconcha from regions off eastern North America reveal that shell size and trace elemental (Mg/Ca ratio) composition are useful in paleothermometry using fossil populations. Seasonal sampling of populations from Chesapeake Bay, augmented by samples from Florida Bay, indicate that shell size is inversely proportional to water temperature and that Mg/Ca ratios are positively correlated with the water temperature in which the adult carapace was secreted. Microprobe analyses of sectioned valves reveal intra-shell variability in Mg/Ca ratios but this does not strongly influence the utility of whole shell Mg/Ca analyses for paleoclimate application.

  7. Variability in shell models of GRBs

    SciTech Connect

    Sumner, M.C.; Fenimore, E.E.

    1997-09-01

    Many cosmological models of gamma-ray bursts (GRBs) assume that a single relativistic shell carries kinetic energy away from the source and later converts it into gamma rays, perhaps by interactions with the interstellar medium or by internal shocks within the shell. Although such models are able to reproduce general trends in GRB time histories, it is difficult to reproduce the high degree of variability often seen in GRBs. The authors investigate methods of achieving this variability using a simplified external shock model. Since the model emphasizes geometric and statistical considerations, rather than the detailed physics of the shell, it is applicable to any theory that relies on relativistic shells. They find that the variability in GRBs gives strong clues to the efficiency with which the shell converts its kinetic energy into gamma rays.

  8. [Determination of underivatized glycine and proline in vinegar turtle shell by HPLC-ELSD].

    PubMed

    Wang, Xinyu; Tan, Xiaomei; Gao, Mingze; Peng, Jinlong

    2011-08-01

    To establish a method to determine the underivatized glycine (Gly) and proline (Pro) in vinegar turtle shell. An HPLC-ELSD method was conducted on a Prevail C18 column (4.6 mm x 250 mm, 5 microm) with the mobile phase of acetonitrile and 0.7% trifluoroacetic acid solution (containing 5.0 mmol x L(-1) heptafluorobutyric acid), and elution time was 15 min. The calibration curves were showed good linearity within the concentration range of 0.14-0.6 g x L(-1). The average recoveries were 101.2% and 102.5%, and RSD were 1.9% and 2.5%, respectively. Since this method needs neither the special amino acid analyzer nor derivation of amino acid., it is efficient, simple and accurate., which could be used for quality control of vinegar turtle shell.

  9. Taphonomic trade-offs in tropical marine death assemblages: Differential time averaging, shell loss, and probable bias in siliciclastic vs. carbonate facies

    NASA Astrophysics Data System (ADS)

    Kidwell, Susan M.; Best, Mairi M. R.; Kaufman, Darrell S.

    2005-09-01

    Radiocarbon-calibrated amino-acid racemization ages of individually dated bivalve mollusk shells from Caribbean reef, nonreefal carbonate, and siliciclastic sediments in Panama indicate that siliciclastic sands and muds contain significantly older shells (median 375 yr, range up to ˜5400 yr) than nearby carbonate seafloors (median 72 yr, range up to ˜2900 yr; maximum shell ages differ significantly at p < 0.02 using extreme-value statistics). The implied difference in shell loss rates is contrary to physicochemical expectations but is consistent with observed differences in shell condition (greater bioerosion and dissolution in carbonates). Higher rates of shell loss in carbonate sediments should lead to greater compositional bias in surviving skeletal material, resulting in taphonomic trade-offs: less time averaging but probably higher taxonomic bias in pure carbonate sediments, and lower bias but greater time averaging in siliciclastic sediments from humid-weathered accretionary arc terrains, which are a widespread setting of tropical sedimentation.

  10. Suzuki cross-coupling reactions on the surface of carbon-coated cobalt: expanding the applicability of core-shell nano-magnets.

    PubMed

    Tan, Chun Ghee; Grass, Robert N

    2008-09-28

    To develop magnetic nanomaterials applicable to organic synthesis, the Suzuki cross-coupling method was adapted to attach a range of functional groups to carbon-coated core-shell materials via commercially-available substituted arylboronic acids.

  11. In-situ Liquid Phase Epitaxy: Another Strategy to Synthesize Heterostructured Core-shell Composites

    NASA Astrophysics Data System (ADS)

    Wen, Zhongsheng; Wang, Guanqin

    2016-04-01

    Core-shell Nb2O5/TiO2 composite with hierarchical heterostructure is successfully synthesized In-situ by a facile template-free and acid-free solvothermal method based on the mechanism of liquid phase epitaxy. The chemical circumstance change induced by the alcoholysis of NbCl5 is utilized tactically to trigger core-shell assembling In-situ. The tentative mechanism for the self-assembling of core-shell structure and hierarchical structure is explored. The microstructure and morphology changes during synthesis process are investigated systematically by using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. The dramatic alcoholysis of NbCl5 has been demonstrated to be the fundamental factor for the formation of the spherical core, which changes the acid circumstance of the solution and induces the co-precipitation of TiO2. The homogeneous co-existence of Nb2O5/TiO2 in the core and the co-existence of Nb/Ti ions in the reaction solution facilitate the In-situ nucleation and epitaxial growth of the crystalline shell with the same composition as the core. In-situ liquid phase epitaxy can offer a different strategy for the core-shell assembling for oxide materials.

  12. In-situ Liquid Phase Epitaxy: Another Strategy to Synthesize Heterostructured Core-shell Composites.

    PubMed

    Wen, Zhongsheng; Wang, Guanqin

    2016-04-28

    Core-shell Nb2O5/TiO2 composite with hierarchical heterostructure is successfully synthesized In-situ by a facile template-free and acid-free solvothermal method based on the mechanism of liquid phase epitaxy. The chemical circumstance change induced by the alcoholysis of NbCl5 is utilized tactically to trigger core-shell assembling In-situ. The tentative mechanism for the self-assembling of core-shell structure and hierarchical structure is explored. The microstructure and morphology changes during synthesis process are investigated systematically by using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. The dramatic alcoholysis of NbCl5 has been demonstrated to be the fundamental factor for the formation of the spherical core, which changes the acid circumstance of the solution and induces the co-precipitation of TiO2. The homogeneous co-existence of Nb2O5/TiO2 in the core and the co-existence of Nb/Ti ions in the reaction solution facilitate the In-situ nucleation and epitaxial growth of the crystalline shell with the same composition as the core. In-situ liquid phase epitaxy can offer a different strategy for the core-shell assembling for oxide materials.

  13. In-situ Liquid Phase Epitaxy: Another Strategy to Synthesize Heterostructured Core-shell Composites

    PubMed Central

    Wen, Zhongsheng; Wang, Guanqin

    2016-01-01

    Core-shell Nb2O5/TiO2 composite with hierarchical heterostructure is successfully synthesized In-situ by a facile template-free and acid-free solvothermal method based on the mechanism of liquid phase epitaxy. The chemical circumstance change induced by the alcoholysis of NbCl5 is utilized tactically to trigger core-shell assembling In-situ. The tentative mechanism for the self-assembling of core-shell structure and hierarchical structure is explored. The microstructure and morphology changes during synthesis process are investigated systematically by using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. The dramatic alcoholysis of NbCl5 has been demonstrated to be the fundamental factor for the formation of the spherical core, which changes the acid circumstance of the solution and induces the co-precipitation of TiO2. The homogeneous co-existence of Nb2O5/TiO2 in the core and the co-existence of Nb/Ti ions in the reaction solution facilitate the In-situ nucleation and epitaxial growth of the crystalline shell with the same composition as the core. In-situ liquid phase epitaxy can offer a different strategy for the core-shell assembling for oxide materials. PMID:27121200

  14. Anisotropic syntheses of boat-shaped core shell Au Ag nanocrystals and nanowires

    NASA Astrophysics Data System (ADS)

    Yang, Zusing; Chang, Huan-Tsung

    2006-05-01

    This paper describes the syntheses of boat-shaped core-shell Au-Ag bimetallic nanoparticles (NPs) and Au-Ag bimetallic nanowires (NWs). Initially, gold nanorods (AuNRs) having lengths and widths of 70 ± 18 and 12 ± 2 nm, respectively, were prepared from gold seeds in the presence of hexadecyltrimethylammonium bromide (CTAB), benzyldimethylammonium chloride (BDAC), NaAuCl4, AgNO3, and ascorbic acid. The thus-prepared AuNRs were then used to prepare boat-shaped core-shell Au-Ag bimetallic NPs in a glycine solution (pH 8.0) containing CTAB, AgNO3, and ascorbic acid. The CTAB/BDAC molar ratio and the AgNO3 concentration were important parameters affecting the anisotropy of the products. Silver atoms were deposited at both ends of the AuNRs to form the boat-shaped core-shell Au-Ag bimetallic NPs. Upon coalescence of the NPs at 88 ± 2 °C, the boat-shaped core-shell Au-Ag bimetallic NPs assembled into the form of NWs. These NWs, which were stable in solution at room temperature for at least 3 weeks, formed nanomaterials containing AuNRs after being heated at 210 °C for 15 min, i.e. as a result of the melting of the BDAC and silver shells.

  15. Effects of pretreatment methods for hazelnut shell hydrolysate fermentation with Pichia Stipitis to ethanol.

    PubMed

    Arslan, Yeşim; Eken-Saraçoğlu, Nurdan

    2010-11-01

    In this study, we investigated the use of hazelnut shell as a renewable and low cost lignocellulosic material for bioethanol production for the first time. High lignin content of hazelnut shell is an important obstacle for such a biotransformation. Biomass hydrolysis with acids yields reducing sugar with several inhibitors which limit the fermentability of sugars. The various conditioning methods for biomass and hydrolysate were performed to overcome the toxicity and their effects on the subsequent fermentation of hazelnut shell hydrolysate by Pichia stipitis were evaluated with shaking flasks experiments. Hazelnut shells hydrolysis with 0.7M H(2)SO(4) yielded 49 gl(-1) total reducing sugars and fermentation inhibitors in untreated hydrolysate. First, it was shown that several hydrolysate detoxification methods were solely inefficient in achieving cell growth and ethanol production in the fermentation of hazelnut shell hydrolysates derived from non-delignified biomass. Next, different pretreatments of hazelnut shells were considered for delignification and employed before hydrolysis in conjunction with hydrolysate detoxification to improve alcohol fermentation. Among six delignification methods, the most effective pretreatment regarding to ethanol concentration includes the treatment of shells with 3% (w/v) NaOH at room temperature, which was integrated with sequential hydrolysate detoxification by overliming and then treatment with charcoal twice at 60 degrees C. This treatment brought about a total reduction of 97% in furans and 88.4% in phenolics. Almost all trialed treatments caused significant sugar loss. Under the best assayed conditions, ethanol concentration of 16.79gl(-1) was reached from a hazelnut shell hyrolysate containing initial 50g total reducing sugar l(-1) after partial synthetic xylose supplementation. This value is equal to 91.25% of ethanol concentration that was obtained from synthetic d-xylose under same conditions. The present study

  16. Micromechanical measurements of the effect of surfactants on cyclopentane hydrate shell properties.

    PubMed

    Brown, Erika P; Koh, Carolyn A

    2016-01-07

    Investigating the effect of surfactants on clathrate hydrate growth and morphology, especially particle shell strength and cohesion force, is critical to advancing new strategies to mitigate hydrate plug formation. In this study, dodecylbenzenesulfonic acid and polysorbate 80 surfactants were included during the growth of cyclopentane hydrates at several concentrations above and below the critical micelle concentration. A novel micromechanical method was applied to determine the force required to puncture the hydrate shell using a glass cantilever (with and without surfactants), with annealing times ranging from immediately after the hydrate nucleated to 90 minutes after formation. It was shown that the puncture force was decreased by the addition of both surfactants up to a maximum of 79%. Over the entire range of annealing times (0-90 minutes), the thickness of the hydrate shell was also measured. However, there was no clear change in shell thickness with the addition of surfactants. The growth rate of the hydrate shell was found to vary less than 15% with the addition of surfactants. The cohesive force between two hydrate particles was measured for each surfactant and found to be reduced by 28% to 78%. Interfacial tension measurements were also performed. Based on these results, microscopic changes to the hydrate shell morphology (due to the presence of surfactants) were proposed to cause the decrease in the force required to break the hydrate shell, since no macroscopic morphology changes were observed. Understanding the hydrate shell strength can be critical to reducing the capillary bridge interaction between hydrate particles or controlling the release of unconverted water from the interior of the hydrate particle, which can cause rapid hydrate conversion.

  17. Gravity on-shell diagrams

    DOE PAGES

    Herrmann, Enrico; Trnka, Jaroslav

    2016-11-22

    Here, we study on-shell diagrams for gravity theories with any number of super-symmetries and find a compact Grassmannian formula in terms of edge variables of the graphs. Unlike in gauge theory where the analogous form involves only d log-factors, in gravity there is a non-trivial numerator as well as higher degree poles in the edge variables. Based on the structure of the Grassmannian formula for N = 8 supergravity we conjecture that gravity loop amplitudes also possess similar properties. In particular, we find that there are only logarithmic singularities on cuts with finite loop momentum and that poles at infinitymore » are present, in complete agreement with the conjecture presented in.« less

  18. Gravity on-shell diagrams

    SciTech Connect

    Herrmann, Enrico; Trnka, Jaroslav

    2016-11-22

    Here, we study on-shell diagrams for gravity theories with any number of super-symmetries and find a compact Grassmannian formula in terms of edge variables of the graphs. Unlike in gauge theory where the analogous form involves only d log-factors, in gravity there is a non-trivial numerator as well as higher degree poles in the edge variables. Based on the structure of the Grassmannian formula for N = 8 supergravity we conjecture that gravity loop amplitudes also possess similar properties. In particular, we find that there are only logarithmic singularities on cuts with finite loop momentum and that poles at infinity are present, in complete agreement with the conjecture presented in.

  19. Gravity on-shell diagrams

    NASA Astrophysics Data System (ADS)

    Herrmann, Enrico; Trnka, Jaroslav

    2016-11-01

    We study on-shell diagrams for gravity theories with any number of super-symmetries and find a compact Grassmannian formula in terms of edge variables of the graphs. Unlike in gauge theory where the analogous form involves only d log-factors, in gravity there is a non-trivial numerator as well as higher degree poles in the edge variables. Based on the structure of the Grassmannian formula for {N}=8 supergravity we conjecture that gravity loop amplitudes also possess similar properties. In particular, we find that there are only logarithmic singularities on cuts with finite loop momentum and that poles at infinity are present, in complete agreement with the conjecture presented in [1].

  20. The EOS TPC analysis shell

    SciTech Connect

    Olson, D.L.

    1991-03-01

    Key features of the general purpose event-based-data analysis shell (TAS) for the EOS TPC at LBL are described including the code development/code management procedures used. The architecture is designed with a view towards a distributed and multi-processing environment. TAS is interfaced seamlessly with the CERN PAW program and provides a consistent environment for both on-line and off-line analysis. The data model used is relational tables and the data structure definitions are maintained in a commercial database (INFORMIX). The interface for analysis modules is specified and enhances group participation in the development process. The use of commercial database as a data dictionary for both the table definitions and parameters used in the TAS kernel is extremely useful and productive. 6 refs., 4 figs.