Hydrothermal synthesis of sodium titanate nanotubes; Hydrotermalna synteza nanorurok titanatu sodneho

Energy Technology Data Exchange (ETDEWEB)

Miskoci, M.; Jesenak, K. [Univerzita Komenskeho, Prirodovedecka fakulta, Katedra anorganickej chemie, 84215 Bratislava (Slovakia); Caplovicova, M. [Univerzita Komenskeho, Prirodovedecka fakulta, Katedra loziskovej geologie, 84215 Bratislava (Slovakia)

2013-04-16

From suspension of nanoparticles TiO{sub 2} in concentrated water solution of NaOH were prepared by hydrothermal synthesis sodium titanates particles with different shapes. Influence of synthesis duration under temperature 180 grad C on the change of particles shapes was observed. The result of experiment showed that one day synthesis resulted to obtained product with high content of nanotubes, but the extension of this period led to the transformation of product's shape into stripes. From the results of experiment follows that as a precursor for TiO{sub 2} nanotubes preparation may be used only products of hydrothermal synthesis, which duration of pressure synthesis was not longer than 24 hours. (authors)

Use of titanates in decontamination of defense waste

International Nuclear Information System (INIS)

Dosch, R.G.

1978-06-01

Sodium titanate, an inorganic ion exchange material, has been evaluated for use in a process to remove strontium from Defense Waste or other high-sodium, caustic solutions. Distribution coefficients on the order of 10 5 were observed at sub part per million concentrations of Sr, and the effects of other cation impurities and complexants in the waste were investigated. The preparation and general chemical properties of the exchange material are discussed. This information was used in developing a commercial source which has since supplied a 200 kg batch of the material for evaluation. In column ion exchange experiments with 85 Sr-doped simulated waste, decontamination factors of 500 or greater were observed in the first 2000 to 3500 bed volumes of effluent, depending on the impurities in the simulant. A -40 to +130 mesh range of sodium titanate powder was used as the baseline material, but a study to produce alternate forms of the titanate was carried in parallel. This has resulted in two materials which appear promising with respect to both simplification of handling and chemical properties. One of the materials is an agglomerated form of the titanate formed by extrusion pelletizing using water as a binder, and the second is a macroreticular organic anion resin which was loaded with 30 to 40% (by weight) of sodium titanate. The results of initial testing of these materials are discussed

Antibacterial Properties of Titanate Nano fiber Thin Films Formed on a Titanium Plate

International Nuclear Information System (INIS)

Yada, M.; Inoue, Y.; Morita, T.; Torikai, T.; Watari, T.; Noda, I.; Hotokebuchi, T.

2013-01-01

A sodium titanate nano fiber thin film and a silver nanoparticle/silver titanate nano fiber thin film formed on the surface of a titanium plate exhibited strong antibacterial activities against methicillin-resistant Staphylococcus aureus, which is one of the major bacteria causing in-hospital infections. Exposure of the sodium titanate nano fiber thin film to ultraviolet rays generated a high antibacterial activity due to photo catalysis and the sodium titanate nano fiber thin film immediately after its synthesis possessed a high antibacterial activity even without exposure to ultraviolet rays. Elution of silver from the silver nanoparticle/silver titanate nano fiber thin film caused by the silver ion exchange reaction was considered to contribute substantially to the strong antibacterial activity. The titanate nano fiber thin films adhered firmly to titanium. Therefore, these titanate nano fiber thin film/titanium composites will be extremely useful as implant materials that have excellent antibacterial activities.

Effects of surface passivation on α-Si_3N_4 nanobelts: A first-principles study

International Nuclear Information System (INIS)

Xiong, Li; Dai, Jianhong; Song, Yan; Wen, Guangwu; Qin, Chunlin

2016-01-01

Highlights: • The stability and electronic properties of α-Si_3N_4 nanobelts are theoretically studied. • The surface of α-Si_3N_4 nanobelts are passivated with H, OH, F and Cl atoms. • The structural stability of nanobelts decreases in the order of OH, F, Cl, and H passivations. • The surface passivation greatly changes the electronic structures of α-Si_3N_4 nanobelts. - Abstract: The energetic stability and electronic structures of H, OH, F, or Cl passivated α-Si_3N_4 nanobelts orientating along various directions are systematically investigated via first-principles calculations. The results show that the stability of nanobelts is more sensitive to the surface passivation than growth direction. It decreases in the order of (100% OH), (50% H, 50% OH), (50% H, 50% F), (100% F), (50% H, 50% Cl), (100% Cl), (100% H), and unpassivation. H atoms prefer to bond with surface N atoms of nanobelts, while OH, F and Cl prefer to bond with Si atoms of nanobelts. In addition, the surface passivation greatly changes the electronic structures of nanobelts. The OH and F passivations result in the larger band gaps than the Cl passivation. While the coverage of OH, F or Cl increases to 100%, their band gaps decrease significantly, indicating an improvement of electrical properties, which is good agreement with the experimental findings. The 100% Cl-passivated nanobelt orientating along the [011] direction possesses the smallest band gap of 1.038 eV. The band gaps are found to be affected by a competition between quantum confinement effect and the role of the surface passivated groups or atoms at the band-gap edges.

Preparation and application of potassium and sodium titanate for removal of plutonium from basic solution

International Nuclear Information System (INIS)

Patil, Prashant; Pathak, Sachin S.; Pius, I.C.; Mukerjee, S.K.

2014-01-01

In PUREX process, after extraction and stripping of uranium and plutonium, the extractant, tributyl phosphate is usually washed with sodium carbonate solution before reuse for the removal of radiolytic/hydrolytic degradation products of TBP and small amounts of HNO 3 , uranium and plutonium goes into aqueous phase during carbonate washings. Partial neutralization of carbonate by the acid converts it to bicarbonate. Removal of plutonium from such sodium carbonate/bicarbonate streams facilitates their disposal. In the present work, studies were carried out to prepare inorganic ion-exchangers such as potassium and sodium titanates for their application as ion-exchange material. It is essential to prepare these materials in granular form to obtain good liquid flow property for ion exchange column operations, however, it is also important that the final product is having good surface area and porosity so that they may exhibit good ion exchange capacity

A Raman Study of Titanate Nanotubes | Liu | South African Journal ...

African Journals Online (AJOL)

The effect of the addition of NaOH or KOH on commercial Degussa Titania P25 was investigated using TEM, Raman and in situ Raman spectroscopy. Treatment of titania with conc. NaOH generated a tubular material corresponding to a sodium titanate. An in situ Raman study on the sodium titanate nanotubes as a function ...

Novel radial vanadium pentoxide nanobelt clusters for Li-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Liu, Yanping; Zhong, Wenwu [Department of Physics and Electronic Engineering, Taizhou University, Taizhou, Zhejiang 318000 (China); Du, Yinxiao, E-mail: duyinxiao@zzia.edu.cn [Department of Mathematics and Physics, Zhengzhou Institute of Aeronautical Industry Management, Zhengzhou 450015 (China); Yuan, Q.X. [Department of Mathematics and Physics, Zhengzhou Institute of Aeronautical Industry Management, Zhengzhou 450015 (China); Wang, Xu [School of Microelectronics, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xidian University, Xi' an 710071 (China); Jia, Renxu, E-mail: rxjia@mail.xidian.edu.cn [School of Microelectronics, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xidian University, Xi' an 710071 (China)

2015-06-05

Highlights: • Radial V{sub 2}O{sub 5} nanobelt clusters were synthesized by a novel hydrothermal process. • The V{sub 2}O{sub 5} clusters are single crystallites with [0 1 0] growth direction. • Specific discharge capacity of V{sub 2}O{sub 5} is 134 mA h/g coupled with good cycle stability. - Abstract: This paper reports the synthesis, characterization and Li-ion intercalation properties of moundlily-like radial vanadium pentoxide (V{sub 2}O{sub 5}) nanobelt clusters. The V{sub 2}O{sub 5} nanobelt clusters was successfully synthesized by a novel soft template assisted hydrothermal process followed by thermal annealing. The as-prepared products were characterized by X-ray diffraction, thermogravimetric analysis, FT-IR spectrometry, scanning electron microscopy and high resolution transmission electron microscopy. The obtained V{sub 2}O{sub 5} possesses a single-crystalline structure with a preferred orientation along the [0 1 0] crystal plane. Electrochemical analysis shows that the specific discharge capacity of the V{sub 2}O{sub 5} nanobelt clusters reaches 134 mA h/g at a current density of 2 A/g coupled with good cycle stability.

Hierarchical CuCo2O4 nanobelts as a supercapacitor electrode with high areal and specific capacitance

International Nuclear Information System (INIS)

Vijayakumar, Subbukalai; Lee, Seong-Hun; Ryu, Kwang-Sun

2015-01-01

Highlights: • First time we report the synthesis of CuCo 2 O 4 nanobelts using hydrothermal method. • The spinel CuCo 2 O 4 nanobelts exhibit maximum areal capacitance of 2.42 F cm −2 . • After 1800 cycles, 127% of the initial specific capacitance was retained. - Abstract: One dimensional hierarchical CuCo 2 O 4 nanobelt like architecture was synthesized via hydrothermal method. The synthesized nanomaterial was characterized using X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The TEM image clearly shows the nanobelt like architecture of CuCo 2 O 4 . The supercapacitor properties of CuCo 2 O 4 nanobelts electrode were tested using cyclic voltammetry, charge-discharge and electrochemical impedance spectroscopy. The spinel CuCo 2 O 4 nanobelts exhibit maximum areal and specific capacitance of 2.42 F cm −2 (809 F g −1 ). After 1800 continuous charge-discharge cycles, 127% of the initial capacitance was retained. This superior electrochemical supercapacitor property is mainly due to increased surface area and ion transport of nanobelt like architecture. The charge transfer resistance (R ct ) value of CuCo 2 O 4 nanobelt electrode is 3.85 Ω. This high capacitance and cyclic stability demonstrate that the prepared CuCo 2 O 4 nanobelts are a promising candidate for supercapacitors.

Adsorptive removal of heavy metals from water using sodium titanate nanofibres loaded onto GAC in fixed-bed columns.

Science.gov (United States)

Sounthararajah, D P; Loganathan, P; Kandasamy, J; Vigneswaran, S

2015-04-28

Heavy metals are serious pollutants in aquatic environments. A study was undertaken to remove Cu, Cd, Ni, Pb and Zn individually (single metal system) and together (mixed metals system) from water by adsorption onto a sodium titanate nanofibrous material. Langmuir adsorption capacities (mg/g) at 10(-3)M NaNO3 ionic strength in the single metal system were 60, 83, 115 and 149 for Ni, Zn, Cu, and Cd, respectively, at pH 6.5 and 250 for Pb at pH 4.0. In the mixed metals system they decreased at high metals concentrations. In column experiments with 4% titanate material and 96% granular activated carbon (w/w) mixture at pH 5.0, the metals breakthrough times and adsorption capacities (for both single and mixed metals systems) decreased in the order Pb>Cd, Cu>Zn>Ni within 266 bed volumes. The amounts adsorbed were up to 82 times higher depending on the metal in the granular activated carbon+titanate column than in the granular activated carbon column. The study showed that the titanate material has high potential for removing heavy metals from polluted water when used with granular activated carbon at a very low proportion in fixed-bed columns. Copyright © 2015 Elsevier B.V. All rights reserved.

Highly flexible sub-1 nm tungsten oxide nanobelts as efficient desulfurization catalysts.

Science.gov (United States)

He, Jie; Liu, Huiling; Xu, Biao; Wang, Xun

2015-03-01

Ultrathin tungsten oxide nanobelts are successfully synthesized via a facile solvothermal method. Sub-1 nm thickness and hydrophobic surface property endow the nanobelts with flexibility, viscosity, gelation, and good catalytic performance in oxidative desulfurization. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solution-phase synthesis of single-crystalline Fe3O4 magnetic nanobelts

International Nuclear Information System (INIS)

Li Lili; Chu Ying; Liu Yang; Wang Dan

2009-01-01

Single-crystalline Fe 3 O 4 nanobelt was first synthesized on a large scale by a facile and efficient hydrothermal process. The samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The SAED pattern obtained from a typical individual nanobelt has a highly symmetrical dotted lattice, which reveals the single-crystalline nature of belt-like Fe 3 O 4 . The saturation magnetization of the Fe 3 O 4 nanobelt is higher than the wire, hollow sphere and octahedral structure. Such methods are easy and mild, and could synthesize other metal oxide in such experiment situation

Ge nanobelts with high compressive strain fabricated by secondary oxidation of self-assembly SiGe rings

DEFF Research Database (Denmark)

Lu, Weifang; Li, Cheng; Lin, Guangyang

2015-01-01

Curled Ge nanobelts were fabricated by secondary oxidation of self-assembly SiGe rings, which were exfoliated from the SiGe stripes on the insulator. The Ge-rich SiGe stripes on insulator were formed by hololithography and modified Ge condensation processes of Si0.82Ge0.18 on SOI substrate. Ge...... nanobelts under a residual compressive strain of 2% were achieved, and the strain should be higher before partly releasing through bulge islands and breakage of the curled Ge nanobelts during the secondary oxidation process. The primary factor leading to compressive strain is thermal shrinkage of Ge...... nanobelts, which extrudes to Ge nanobelts in radial and tangent directions during the cooling process. This technique is promising for application in high-mobility Ge nano-scale transistors...

Energy scavenging based on a single-crystal PMN-PT nanobelt

Science.gov (United States)

Wu, Fan; Cai, Wei; Yeh, Yao-Wen; Xu, Shiyou; Yao, Nan

2016-03-01

Self-powered nanodevices scavenging mechanical energy require piezoelectric nanostructures with high piezoelectric coefficients. Here we report the fabrication of a single-crystal (1 - x)Pb(Mg1/3Nb2/3)O3 - xPbTiO3 (PMN-PT) nanobelt with a superior piezoelectric constant (d33 = ~550 pm/V), which is approximately ~150%, 430%, and 2100% of the largest reported values for previous PMN-PT, PZT and ZnO nanostructures, respectively. The high d33 of the single-crystalline PMN-PT nanobelt results from the precise orientation control during its fabrication. As a demonstration of its application in energy scavenging, a piezoelectric nanogenerator (PNG) is built on the single PMN-PT nanobelt, generating a maximum output voltage of ~1.2 V. This value is ~4 times higher than that of a single-CdTe PNG, ~13 times higher than that of a single-ZnSnO3 PNG, and ~26 times higher than that of a single-ZnO PNG. The profoundly increased output voltage of a lateral PNG built on a single PMN-PT nanobelt demonstrates the potential application of PMN-PT nanostructures in energy harvesting, thus enriching the material choices for PNGs.

Amorphous boron-doped sodium titanates hydrates: Efficient and reusable adsorbents for the removal of Pb{sup 2+} from water

Energy Technology Data Exchange (ETDEWEB)

Di Bitonto, Luigi; Volpe, Angela; Pagano, Michele; Bagnuolo, Giuseppe; Mascolo, Giuseppe [CNR-IRSA, Via de Blasio 5, 70132 Bari (Italy); La Parola, Valeria [CNR-ISMN, Via U. La Malfa, 153, 90146 Palermo (Italy); Di Leo, Paola [CNR-IMAA, Via S. Loja, Tito Scalo (PZ) (Italy); Pastore, Carlo, E-mail: carlo.pastore@ba.irsa.cnr.it [CNR-IRSA, Via de Blasio 5, 70132 Bari (Italy)

2017-02-15

Highlights: • Amorphous B-doped sodium titanates hydrates were mildly synthesized. • These compounds resulted efficiently used in removing Pb{sup 2+} from natural water. • Adsorption occurs with a partial ionic exchange mechanism. • Adsorbents were easily recoverable and reusable for further new cycles. - Abstract: Amorphous titanium hydroxide and boron-doped (B-doped) sodium titanates hydrates were synthetized and used as adsorbents for the removal of Pb{sup 2+} from water. The use of sodium borohydride (NaBH{sub 4}) and titanium(IV) isopropoxide (TTIP) as precursors permits a very easy synthesis of B-doped adsorbents at 298 K. The new adsorbent materials were first chemically characterized (XRD, XPS, SEM, DRIFT and elemental analysis) and then tested in Pb{sup 2+} adsorption batch experiments, in order to define kinetics and equilibrium studies. The nature of interaction between such sorbent materials and Pb{sup 2+} was also well defined: besides a pure adsorption due to hydroxyl interaction functionalities, there is also an ionic exchange between Pb{sup 2+} and sodium ions even working at pH 4.4. Langmuir model presented the best fitting with a maximum adsorption capacity up to 385 mg/g. The effect of solution pH and common ions (i.e. Na{sup +}, Ca{sup 2+} and Mg{sup 2+}) onto Pb{sup 2+} sorption were also investigated. Finally, recovery was positively conducted using EDTA. Very efficient adsorption (>99.9%) was verified even using tap water spiked with traces of Pb{sup 2+} (50 ppb).

Analysis of tensile strain enhancement in Ge nano-belts on an insulator surrounded by dielectrics

International Nuclear Information System (INIS)

Lu Wei-Fang; Li Cheng; Huang Shi-Hao; Lin Guang-Yang; Wang Chen; Yan Guang-Ming; Huang Wei; Lai Hong-Kai; Chen Song-Yan

2013-01-01

Ge nano-belts with large tensile strain are considered as one of the promising materials for high carrier mobility metal—oxide—semiconductor transistors and efficient photonic devices. In this paper, we design the Ge nano-belts on an insulator surrounded by Si 3 N 4 or SiO 2 for improving their tensile strain and simulate the strain profiles by using the finite difference time domain (FDTD) method. The width and thickness parameters of Ge nano-belts on an insulator, which have great effects on the strain profile, are optimized. A large uniaxial tensile strain of 1.16% in 50-nm width and 12-nm thickness Ge nano-belts with the sidewalls protected by Si 3 N 4 is achieved after thermal treatments, which would significantly tailor the band gap structures of Ge-nanobelts to realize the high performance devices. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Nanowires and nanobelts, v.2 nanowires and nanobelts of functional materials

CERN Document Server

Wang, Zhong Lin

2010-01-01

Nanowires, nanobelts, nanoribbons, nanorods ..., are a new class of quasi-one-dimensional materials that have been attracting a great research interest in the last few years. These non-carbon based materials have been demonstrated to exhibit superior electrical, optical, mechanical and thermal properties, and can be used as fundamental building blocks for nano-scale science and technology, ranging from chemical and biological sensors, field effect transistors to logic circuits. Nanocircuits built using semiconductor nanowires demonstrated were declared a ""breakthrough in science"" by Science

Isotherms of ion exchange on titanates of alkaline metals

International Nuclear Information System (INIS)

Fillina, L.P.; Belinskaya, F.A.

1986-01-01

Present article is devoted to isotherms of ion exchange on titanates of alkaline metals. Therefore, finely dispersed hydrated titanates of alkaline metals (lithium, sodium, potassium) with ion exchange properties are obtained by means of alkaline hydrolysis of titanium chloride at high ph rates. Sorption of cations from salts solution of Li 2 SO 4 , NaNO 3 , Ca(NO 3 ) 2 , AgNO 3 by titanates is studied.

Sb{sub 2}Te{sub 3} nanobelts and nanosheets: Hydrothermal synthesis, morphology evolution and thermoelectric properties

Energy Technology Data Exchange (ETDEWEB)

Dong, Guo-Hui [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhu, Ying-Jie, E-mail: y.j.zhu@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Cheng, Guo-Feng; Ruan, Yin-Jie [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

2013-02-15

Graphical abstract: Sb{sub 2}Te{sub 3} nanobelts and nanosheets were synthesized by a hydrothermal method, and the morphology evolution from Sb{sub 2}Te{sub 3} nanobelts to nanosheets with the prolonging hydrothermal time was observed. Highlights: Black-Right-Pointing-Pointer Hydrothermal synthesis of Sb{sub 2}Te{sub 3} nanobelts and nanosheets is demonstrated. Black-Right-Pointing-Pointer The morphology of Sb{sub 2}Te{sub 3} can be adjusted by varying hydrothermal time. Black-Right-Pointing-Pointer The morphology evolution of Sb{sub 2}Te{sub 3} from nanobelts to nanosheets is observed. Black-Right-Pointing-Pointer High Seebeck coefficients (S) of Sb{sub 2}Te{sub 3} nanobelts and nanosheets are attained. - Abstract: Sb{sub 2}Te{sub 3} nanobelts and nanosheets were synthesized by a hydrothermal method using SbCl{sub 3} and TeO{sub 2} as the antimony and tellurium source, hydrazine hydrate as a reducing reagent, polyvinyl alcohol as a surfactant and water as the solvent. The effects of experimental parameters on the product were investigated. The experiments indicated that the elemental Te formed during the reaction, acting as a reactive and self-sacrificial template for the formation of Sb{sub 2}Te{sub 3} nanobelts. The morphology evolution from Sb{sub 2}Te{sub 3} nanobelts to nanosheets with the prolonging hydrothermal time was observed. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), selected area electron diffraction (SAED), Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The thermoelectric properties of the tablet samples of Sb{sub 2}Te{sub 3} nanostructured powders with different morphologies prepared by a room-temperature pressurized method were investigated.

Vanadium dioxide nanobelts: Hydrothermal synthesis and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Zakharova, G.S., E-mail: volkov@ihim.uran.ru [Institute of Solid State Chemistry, Ural Division, Russian Academy of Sciences, Pervomaiskaya ul. 91, Yekaterinburg 620041 (Russian Federation); Hellmann, I. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW) Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Volkov, V.L. [Institute of Solid State Chemistry, Ural Division, Russian Academy of Sciences, Pervomaiskaya ul. 91, Yekaterinburg 620041 (Russian Federation); Taeschner, Ch.; Bachmatiuk, A.; Leonhardt, A.; Klingeler, R.; Buechner, B. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW) Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany)

2010-09-15

VO{sub 2} (B) nanobelts were prepared by a hydrothermal method at 180 {sup o}C using V{sub 2}O{sub 5}.nH{sub 2}O sol and H{sub 2}C{sub 2}O{sub 4}.2H{sub 2}O as starting agents. The obtained nanobelts have diameters ranging from 50 to 100 nm in width, 20-30 nm in thickness with lengths up to 1.5 {mu}m. Measurements of the static magnetic susceptibility provide evidence for two phase transitions at T{sub 1} = 225 K and T{sub 2} = 290 K, respectively. Below T{sub 1}, the data suggest the presence quasi-free as well as of strongly antiferromagnetic correlated spins associated to V{sup 4+}-ions.

Defect-mediated photoluminescence up-conversion in cadmium sulfide nanobelts (Conference Presentation)

Science.gov (United States)

Morozov, Yurii; Kuno, Masaru K.

2017-02-01

The concept of optical cooling of solids has existed for nearly 90 years ever since Pringsheim proposed a way to cool solids through the annihilation of phonons via phonon-assisted photoluminescence (PL) up-conversion. In this process, energy is removed from the solid by the emission of photons with energies larger than those of incident photons. However, actually realizing optical cooling requires exacting parameters from the condensed phase medium such as near unity external quantum efficiencies as well as existence of a low background absorption. Until recently, laser cooling has only been successfully realized in rare earth doped solids. In semiconductors, optical cooling has very recently been demonstrated in cadmium sulfide (CdS) nanobelts as well as in hybrid lead halide perovskites. For the former, large internal quantum efficiencies, sub-wavelength thicknesses, which decrease light trapping, and low background absorption, all make near unity external quantum yields possible. Net cooling by as much as 40 K has therefore been possible with CdS nanobelts. In this study, we describe a detailed investigation of the nature of efficient anti-Stokes photoluminescence (ASPL) in CdS nanobelts. Temperature-dependent PL up-conversion and optical absorption studies on individual NBs together with frequency-dependent up-converted PL intensity spectroscopies suggest that ASPL in CdS nanobelts is defect-mediated through involvement of defect levels below the band gap.

Highly sensitive formaldehyde resistive sensor based on a single Er-doped SnO_2 nanobelt

International Nuclear Information System (INIS)

Li, Shuanghui; Liu, Yingkai; Wu, Yuemei; Chen, Weiwu; Qin, Zhaojun; Gong, Nailiang; Yu, Dapeng

2016-01-01

SnO_2 nanobelts (SnO_2 NBs) and Er"3"+-doped SnO_2 nanobelts (Er–SnO_2 NBs) were synthesized by thermal evaporation. The obtained samples were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersion spectrometer (EDS), and X-ray photoelectron spectrometer (XPS). It is found that Er–SnO_2 NBs have a good morphology with smooth surface and their thickness are about 30 nm, widths between 200 nm and 600 nm, and lengths 30–80 mm. The nanobelts with good morphology were taken to develop sensors based on a single Er–SnO_2 NB/SnO_2 NB for studying sensitive properties. The results reveal that the response of a single Er–SnO_2 nanobelt device is 9 to the formaldehyde gas with a shorter response (recovery time) of 17 (25) s.

Improvement of the specific capacitance of V{sub 2}O{sub 5} nanobelts as supercapacitor electrode by tungsten doping

Energy Technology Data Exchange (ETDEWEB)

Zheng, Jiqi [School of Chemistry, Dalian University of Technology, Dalian 116024 (China); Zhang, Yifu, E-mail: yfzhang@dlut.edu.cn [School of Chemistry, Dalian University of Technology, Dalian 116024 (China); Jing, Xuyang [College of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029 (China); Wang, Qiushi; Hu, Tao [School of Chemistry, Dalian University of Technology, Dalian 116024 (China); Xing, Na [College of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029 (China); Meng, Changgong [School of Chemistry, Dalian University of Technology, Dalian 116024 (China)

2017-01-15

Tungsten doped vanadium pentoxide (W-doped V{sub 2}O{sub 5}) nanobelts were successfully synthesized by a facile hydrothermal route and combination of calcination. The results revealed that W atoms were successfully doped into the crystal lattice of V{sub 2}O{sub 5} matrix, indicating that the homogeneous solid-solutions of W-doped V{sub 2}O{sub 5} nanobelts were obtained. The electrochemical properties of W-doped V{sub 2}O{sub 5} nanobelts as supercapacitor electrode were investigated by cyclic voltammetry (CV) and galvanostatic charge discharge (GCD) methods. W-doped V{sub 2}O{sub 5} nanobelts exhibit the excellent capacity and good rate capability. Their specific capacitance are 407, 381, 350, 328, 295 and 273 F g{sup −1} at the current density of 0.5, 1, 2, 5, 10 and 20 A g{sup −1}, respectively. W-doped V{sub 2}O{sub 5} nanobelts also show excellent energy densities of 246, 217, 212, 199, 178 and 165 W h kg{sup −1} at a power densities of 0.99, 1.98, 3.96, 9.90, 19.80 and 39.60 kW kg{sup −1}. The specific capacitance of W-doped V{sub 2}O{sub 5} nanobelts is much higher than the previous values of V{sub 2}O{sub 5} materials, achieving the aim of improving the specific capacitance of V{sub 2}O{sub 5} nanobelts. - Graphical abstract: The specific capacitance of V{sub 2}O{sub 5} nanobelts can be greatly improved by W doping. - Highlights: • Homogeneous solid-solutions of W-doped V{sub 2}O{sub 5} were prepared. • W-doped V{sub 2}O{sub 5} nanobelts exhibit excellent electrochemical property. • High specific capacitance of 407 F g{sup −1} at 0.5 A g{sup −1} was achieved. • Specific capacitance of V{sub 2}O{sub 5} nanobelts was improved by doping method.

Zn doped MoO3 nanobelts and the enhanced gas sensing properties to ethanol

Science.gov (United States)

Yang, Shuang; Liu, Yueli; Chen, Tao; Jin, Wei; Yang, Tingqiang; Cao, Minchi; Liu, Shunshun; Zhou, Jing; Zakharova, Galina S.; Chen, Wen

2017-01-01

Zn doped MoO3 nanobelts with the thickness of 120-275 nm, width of 0.3-1.4 μm and length of more than 100 μm are prepared by hydrothermal reaction. The operating temperature of sensors based on Zn doped MoO3 nanobelts is 100-380 °C with a better response to low concentration of ethanol. The highest response value of sensors based on Zn doped MoO3 to 1000 ppm ethanol at 240 °C is 321, which is about 15 times higher than that of pure MoO3 nanobelts. The gas sensors based on Zn doped MoO3 nanobelts possess good selectivity to ethanol compared with methanol, ammonia, acetone and toluene, which implies that it would be a good candidate in the potential application. The improvement of gas sensing properties may be attributed to the increasing absorbed ethanol, the decreasing probability of ethoxy recombination, the promoted dehydrogenation progress at lower temperature, and the narrowed band gap by Zn doping.

Texturing of sodium bismuth titanate-barium titanate ceramics by templated grain growth

Science.gov (United States)

Yilmaz, Huseyin

2002-01-01

Sodium bismuth titanate modified with barium titanate, (Na1/2Bi 1/2)TiO3-BaTiO3 (NBT-BT), is a candidate lead-free piezoelectric material which has been shown to have comparatively high piezoelectric response. In this work, textured (Na1/2Bi1/2)TiO 3-BaTiO3 (5.5mol% BaTiO3) ceramics with pc (where pc denotes the pseudocubic perovskite cell) orientation were fabricated by Templated Grain Growth (TGG) or Reactive Templated Grain Growth (RTGG) using anisotropically shaped template particles. In the case of TGG, molten salt synthesized SrTiO3 platelets were tape cast with a (Na1/2Bi1/2)TiO3-5.5mol%BaTiO3 powder and sintered at 1200°C for up to 12 hours. For the RTGG approach, Bi4Ti3O12 (BiT) platelets were tape cast with a Na2CO3, Bi2O3, TiO 2, and BaCO3 powder mixture and reactively sintered. The TGG approach using SrTiO3 templates gave stronger texture along [001] compared to the RTGG approach using BiT templates. The textured ceramics were characterized by X-ray and electron backscatter diffraction for the quality of texture. The texture function was quantified by the Lotgering factor, rocking curve, pole figures, inverse pole figures, and orientation imaging microscopy. Electrical and electromechanical property characterization of randomly oriented and pc textured (Na1/2Bi1/2)TiO 3-5.5 mol% BaTiO3 rhombohedral ceramics showed 0.26% strain at 70 kV/cm, d33 coefficients over 500 pC/N have been obtained for highly textured samples (f ˜ 90%). The piezoelectric coefficient from Berlincourt was d33 ˜ 200 pC/N. The materials show considerable hysteresis. The presence of hysteresis in the unipolar-electric field curve is probably linked to the ferroelastic phase transition seen in the (Na 1/2Bi1/2)TiO3 system on cooling from high temperature at ˜520°C. The macroscopic physical properties (remanent polarization, dielectric constant, and piezoelectric coefficient) of random and textured ([001] pc) rhombohedral perovskites were estimated by linear averaging of single

HxMoO3 nanobelts with better performance as anode in lithium-ion batteries

International Nuclear Information System (INIS)

Ju, Xiaokang; Ning, Peigong; Tong, Xiaobing; Lin, Xiaoping; Pan, Xi; Li, Qiuhong; Duan, Xiaochuan; Wang, Taihong

2016-01-01

We first report the pure H x MoO 3 nanobelts as anode for lithium-ion batteries by a facile hydrothermal with ammonium heptamolybdate tetrahydrate ((NH 4 )6Mo 7 O 24 ∙4H 2 O) and hydrochloric acid (HCl). Owing to hydrogen-doping, Mo 5+ exists in the H x MoO 3 nanobelt, which may release extra electrons. Therefore, the electric conductance of H x MoO 3 nanobelt is enhanced greatly. Moreover, the content of hydrogen can’t be high, since the ordered structure deteriorates when amount of hydrogen increasing. The H 0.28 MoO 3 nanobelts we designed exhibit outstanding specific capacity and rate performance. The stable capacity of 920 mAh g −1 is obtained after 25 charge/discharge cycles at 100 mA g −1 . At high current densities such as 1, 2, 5 and 10 A g −1 , the H 0.28 MoO 3 electrode delivers specific capacities of about 600, 500, 420, 300 mAh g −1 , respectively. Even after 450 charge discharge cycles at 1 A g −1 , the performance of our materials can maintain the capacity of about 550 mAh g −1 . Furthermore, we provide more discussion about the lithium storage mechanism of H x MoO 3 nanobelts through ex situ XRD and FESEM. By comparing H x MoO 3 with different X, we find that low content of hydrogen can greatly improve the performance of α-MoO 3 electrodes in Li-ion batteries.

Characterization of barium titanate powder doped with sodium and potassium ions by using Rietveld refining; Caracterizacao do po de titanato de bario dopado com ions sodio e potasio com o refinamento de Rietveld

Energy Technology Data Exchange (ETDEWEB)

Andrade, M.C.; Assis, J.T.; Pereira, F.R., E-mail: mcalixto@iprj.uerj.b [Universidade do Estado do Rio de Janeiro (IPRJ/UERJ), Nova Friburgo, RJ (Brazil). Instituto Politecnico; Araujo, J.C. [Universidade do Estado do Rio de Janeiro (FFP/UERJ), Sao Goncalo, RJ (Brazil). Fac. de Formacao de Professores; Moreira, E.L.; Moraes, V.C.A.; Lopes, A.R. [Centro Brasileiro de Pesquisas Fisicas (CBPF/MCT), Rio de Janeiro, RJ (Brazil)

2009-07-01

A solid-reaction synthesis of doped barium titanate was done by employing barium carbonates, sodium, potassium and titanium oxides with classic procedures. Rietveld refining of X ray diffraction data of perovskite samples with tetragonal symmetry was applying and show good agreement. Besides, the treatment performed from 600 deg C produces nanocrystals of barium titanate with average size of 33 nm. The presence of endothermic peaks related to BaTiO{sub 3} formation at relatively low temperatures was determined by thermal analysis. A pseudo-Voigt Thompson-Cox-Hastings function was used to fit the standard samples of barium titanate. The Rietveld method has showed be efficient to detect the influences of temperature and doping on barium titanate microstructures. (author)

NbSe{sub 3} nanobelts wrapped by reduced graphene oxide for lithium ion battery with enhanced electrochemical performance

Energy Technology Data Exchange (ETDEWEB)

Li, Jing; Sun, Qi; Wang, Zhijie; Xiang, Junxiang; Zhao, Benliang [Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, Synergetic Innovation Center of Quantum Information Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Qu, Yan [The Sixth Element Materials Technology Co. Ltd, Changzhou, Jiangsu, 213145 (China); Xiang, Bin, E-mail: binxiang@ustc.edu.cn [Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, Synergetic Innovation Center of Quantum Information Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2017-08-01

Highlights: • A core-shell structure of NbSe{sub 3} nanobelts wrapped by rGO is synthesized by a PDDA assisted method. • Cushion effect of the rGO coating enhances the structure integrity. • Performance of the composites during cycling are improved remarkably compared to the pure nanobelts. - Abstract: Recently, layered transition metal chalcogenides (LTMCs) have attracted great attention as anode materials for lithium ion batteries (LIBs). However, the volume expansion and structure instability of LTMCs during the lithiation and delithiation process still remains challenging. Herein, we report NbSe{sub 3} nanobelts wrapped by reduced-graphene oxide (NbSe{sub 3}@rGO) utilized as buffer layers with enhanced electrochemical performance. The X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy were used to probe features of the NbSe{sub 3}@rGO. The NbSe{sub 3}@rGO nanobelts as anode exhibit a discharge capacity of 300 mAh/g at the current density of 100 mAh/g after 250 cycles, several times higher than pure NbSe{sub 3} nanobelts. The improved electrochemical performance of NbSe{sub 3}@rGO is attributed to a buffer effect from the rGO, cushioning the volume-change-induced strain effect on the structure of NbSe{sub 3} nanobelts during cycling.

Proceedings of the Sandia Laboratories workshop on the use of titanate ion exchangers for defense waste management

International Nuclear Information System (INIS)

Schwoebel, R.L.; Northrup, C.J.

1978-01-01

Abstracts and visual aids from the following talks are presented: removal of radionuclides from Hanford defense waste solutions; waste management programs at Savannah River Plant; application of defense waste decontamination; americium and curium recovery from nuclear waste using inorganic ion exchanger materials; removal of trace 106 Ru in nuclear waste processing; and titanate characterization and consolidation processes. Copies of three memos are included: 90 Sr radiation effects on sodium titanate loaded macroreticular resin; 238 239 Pu content in defense waste; and preparation and physical properties of sodium titanate in ion exchange resin

Facile fabrication of p-n heterojunctions for Cu2O submicroparticles deposited on anatase TiO2 nanobelts

International Nuclear Information System (INIS)

Li, Li; Lei, Jingguo; Ji, Tianhao

2011-01-01

Graphical abstract: Cu 2 O particle-deposited TiO 2 nanobelts with p-n semiconductor heterojunction structure were successfully prepared via two-step preparation process, and their visible-light photodegradation activities of Rhodamine B were investigated in detail. Highlights: → Cu 2 O particle-deposited TiO 2 nanobelts mainly with diameters in a range of 200-400 nm were successfully prepared. → The amount of Cu 2 O particles deposited on TiO 2 nanobelts can be tuned. → The composite structure with Cu 2 O particles and TiO 2 nanobelts exhibits p-n semiconductor heterojunction performance. → Photocatalytic properties of such composites. -- Abstract: In this paper, Cu 2 O particle-deposited TiO 2 nanobelts with p-n semiconductor heterojunction structure were successfully prepared via a two-step preparation process to investigate electron-transfer performance between p-type Cu 2 O and n-type TiO 2 . Various measurement results confirm that the amount of pure Cu 2 O submicroparticles, with diameters within the range of 200-400 nm and deposited on the surface of TiO 2 nanobelts, can be controlled, and that the purity of Cu 2 O is heavily affected by reaction time. Visible-light photodegradation activities of Rhodamine B show that photocatalysts have little or no photocatalytic activities mainly due to their p-n heterojunction structure, indicating that there hardly appears any electron-transfer from Cu 2 O to TiO 2 .

Photocatalytic activity of Ag3PO4 nanoparticle/TiO2 nanobelt heterostructures

Science.gov (United States)

Liu, Ruoyu; Hu, Peiguang; Chen, Shaowei

2012-10-01

Heterostructures based on Ag3PO4 nanoparticles and TiO2 nanobelts were prepared by a coprecipitation method. The crystalline structures were characterized by X-ray diffraction measurements. Electron microscopic studies showed that the Ag3PO4 nanoparticles and TiO2 nanobelts were in intimate contact which might be exploited to facilitate charge transfer between the two semiconductor materials. In fact, the heterostructures exhibited markedly enhanced photocatalytic activity as compared with unmodified TiO2 nanobelts or commercial TiO2 colloids in the photodegradation of methyl orange under UV irradiation. This was accounted for by the improved efficiency of interfacial charge separation thanks to the unique alignments of their band structures. Remarkably, whereas the photocatalytic activity of the heterostructure was comparable to that of Ag3PO4 nanoparticles alone, the heterostructures exhibited significantly better stability and reusability in repeated tests than the Ag3PO4 nanoparticles.

Hydrothermal synthesis, characterization, formation mechanism and electrochemical property of V3O7.H2O single-crystal nanobelts

International Nuclear Information System (INIS)

Zhang Yifu; Liu Xinghai; Xie Guangyong; Yu Lei; Yi Shengping; Hu Mingjie; Huang Chi

2010-01-01

Single-crystal V 3 O 7 .H 2 O nanobelts have been successfully synthesized in a large-scale by ethanol reducing of the commercial V 2 O 5 powder via a facile hydrothermal approach, without any templates and surfactants. The as-prepared V 3 O 7 .H 2 O nanobelts are up to several tens of micrometers in length, about 100 nm in width and about 20 nm in thickness in average, respectively. The 'Hydrating-Reducing-Exfoliating-Splitting' (HRES) mechanism was proposed to describe the formation of the V 3 O 7 .H 2 O nanobelts. In our research progress, it was found that the ratio of EtOH/H 2 O, the reaction time and categories of the reducing agents had significant effects on the morphology and composition of as-obtained products. Furthermore, the electrochemical properties of V 3 O 7 .H 2 O nanobelts were preformed and the results revealed that a lithium battery using those nanobelts as the positive electrode exhibited a high initial discharge capacity of 373 mAh/g.

Directed batch assembly of three-dimensional helical nanobelts through angular winding and electroplating

International Nuclear Information System (INIS)

Bell, D J; Bauert, T E; Zhang, L; Dong, L X; Sun, Y; Gruetzmacher, D; Nelson, B J

2007-01-01

This paper presents a new technique for the directed batch assembly of rolled-up three-dimensional helical nanobelts. The wet etch time is controlled in order for the loose end of the self-formed SiGe/Si/Cr nanobelts to be located over an electrode by taking advantage of the additional angular winding motion in the lateral direction. In a subsequent Au electroplating step, contacts are electroformed and the batch assembly is completed, while at the same time the conductance of the structures is increased

Topotactic conversion route to mesoporous quasi-single-crystalline Co{sub 3}O{sub 4} nanobelts with optimizable electrochemical performance

Energy Technology Data Exchange (ETDEWEB)

Tian, Li [MOE Key Laboratory of Bioinorganic and Synthetic Chemistry State Key Laboratory of Optoelectronic Materials and Technology School of Chemistry and Chemical Engineering School of Physics and Engineering Sun Yat-Sen University Guangzhou, 510275 (China); School of Chemistry and Chemical Engineering, Hunan University of Science and Technology Xiangtan, 411201 (China); Zou, Hongli; Fu, Junxiang; Yang, Xianfeng; Wang, Yi; Fu, Xionghui; Liang, Chaolun; Wu, Mingmei; Shen, Pei Kang [MOE Key Laboratory of Bioinorganic and Synthetic Chemistry State Key Laboratory of Optoelectronic Materials and Technology School of Chemistry and Chemical Engineering School of Physics and Engineering Sun Yat-Sen University Guangzhou, 510275 (China); Guo, Hongliang; Gao, Qiuming [State Key Laboratory of High Performance Ceramics and Superfine Microstructures Shanghai Institute of Ceramics, Graduate School, Chinese Academy of Sciences 1295 Dingxi Rd., Shanghai 200050 (China)

2010-02-22

The growth of mesoporous quasi-single-crystalline Co{sub 3}O{sub 4} nanobelts by topotactic chemical transformation from {alpha}-Co(OH){sub 2} nanobelts is realized. During the topotactic transformation process, the primary {alpha}-Co(OH){sub 2} nanobelt frameworks can be preserved. The phases, crystal structures, morphologies, and growth behavior of both the precursory and resultant products are characterized by powder X-ray diffraction (XRD), electron microscopy - scanning electron (SEM) and transmission electron (TEM) microscopy, and selected area electron diffraction (SAED). Detailed investigation of the formation mechanism of the porous Co{sub 3}O{sub 4} nanobelts indicates topotactic nucleation and oriented growth of textured spinel Co{sub 3}O{sub 4} nanowalls (nanoparticles) inside the nanobelts. Co{sub 3}O{sub 4} nanocrystals prefer [0001] epitaxial growth direction of hexagonal {alpha}-Co(OH){sub 2} nanobelts due to the structural matching of [0001] {alpha}-Co(OH){sub 2}//[111] Co{sub 3}O{sub 4}. The surface-areas and pore sizes of the spinel Co{sub 3}O{sub 4} products can be tuned through heat treatment of {alpha}-Co(OH){sub 2} precursors at different temperatures. The galvanostatic cycling measurement of the Co{sub 3}O{sub 4} products indicates that their charge-discharge performance can be optimized. In the voltage range of 0.0-3.0 V versus Li{sup +}/Li at 40 mA g{sup -1}, reversible capacities of a sample consisting of mesoporous quasi-single-crystalline Co{sub 3}O{sub 4} nanobelts can reach up to 1400 mA h g{sup -1}, much larger than the theoretical capacity of bulk Co{sub 3}O{sub 4} (892 mA h g{sup -1}). (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Orthorhombic MoO{sub 3} nanobelts based NO{sub 2} gas sensor

Energy Technology Data Exchange (ETDEWEB)

Mane, A.A. [Thin Film Nanomaterials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India); General Science and Humanities Department, Sant Gajanan Maharaj College of Engineering, Mahagaon, 416 503 (India); Moholkar, A.V., E-mail: avmoholkar@gmail.com [Thin Film Nanomaterials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India)

2017-05-31

Highlights: • The effect of thickness on physicochemical and NO{sub 2} gas sensing properties of sprayed MoO{sub 3} nanobelts has been reported. • The sprayed MoO{sub 3} nanobelts show the NO{sub 2} gas response of 68% for 100 ppm concentration at an operating temperature of 200 °C. • The lower detection limit of MoO{sub 3} nanobelts based NO{sub 2} sensor is found to be half of the IDLH value (20 ppm). - Abstract: Molybdenum trioxide (MoO{sub 3}) nanobelts have been deposited onto the glass substrates using chemical spray pyrolysis (CSP) deposition method. The XRD patterns reveal that films are polycrystalline having an orthorhombic crystal structure. Raman spectra confirm that the films are orthorhombic in phase. The XPS study shows the presence of two well resolved spectral lines of Mo-3d core levels appearing at the binding energy values of 232.82 eV and 235.95 eV corresponding to Mo-3d{sub 5/2} and Mo-3d{sub 3/2}, respectively. These binding energy values are assigned to Mo{sup 6+} oxidation state of fully oxidized MoO{sub 3}. The FE-SEM micrographs show the formation of nanobelts-like morphology. The AFM micrographs reveal that the RMS surface roughness increases from 16.5 nm to 17.5 nm with increase in film thickness from 470 nm to 612 nm and then decreases to 16 nm for 633 nm film thickness. The band gap energy is found to be decreased from 3.40 eV to 3.38 eV. To understand the electronic transport phenomenon in MoO{sub 3} thin films, dielectric properties are studied. For 612 nm film thickness, the highest NO{sub 2} gas response of 68% is obtained at an operating temperature of 200 °C for 100 ppm concentration with response and recovery times of 15 s and 150 s, respectively. The lower detection limit is found to be 10 ppm which is half of the immediately dangerous to life or health (IDLH) value of 20 ppm. Finally, NO{sub 2} gas sensing mechanism in an orthorhombic MoO{sub 3} crystal structure is discussed in detail.

A FAMILY OF PEROXO-TITANATE MATERIALS TAILORED FOR OPTIMAL STRONTIUM ANDACTINIDE SORPTION

International Nuclear Information System (INIS)

Hobbs, D

2006-01-01

Achieving global optimization of inorganic sorbent efficacy, as well as tailoring sorbent specificity for target sorbates would facilitate increased wide-spread use of these materials in applications such as producing potable water or nuclear waste treatment. Sodium titanates have long been known as sorbents for radionuclides; 90 Sr and transuranic elements in particular. We have developed a related class of materials, which we refer to as peroxo-titanates: these are sodium titanates or hydrous titanates synthesized in the presence of or treated post-synthesis with hydrogen peroxide. Peroxo-titanates show remarkable and universal improved sorption behavior with respect to separation of actinides and strontium from Savannah River Site (SRS) nuclear waste simulants. Enhancement in sorption kinetics can potentially result in as much as an order of magnitude increase in batch processing throughput. Peroxo-titanates have been produced by three different synthetic routes: post-synthesis peroxide-treatment of a commercially produced monosodium titanate, an aqueous-peroxide synthetic route, and an isopropanol-peroxide synthetic route. The peroxo-titanate materials are characteristically yellow to orange, indicating the presence of protonated or hydrated Ti-peroxo species; and the chemical formula can be generally written as H v Na w Ti 2 O 5 -(xH 2 O)[yH z O 2 ] where (v+w) = 2, z = 0-2, and total volatile species accounts for 25-50 wt % of the solid. Further enhancement of sorption performance is achieved by processing, storing and utilizing the peroxo-titanate as an aqueous slurry rather than a dry powder, and post-synthesis acidification. All three synthesis modifications; addition of hydrogen peroxide, use of a slurry form and acidification can be applied more broadly to the optimization of other metal oxide sorbents and other ion separations processes

One-step hydrothermal synthesis of graphene decorated V2O5 nanobelts for enhanced electrochemical energy storage.

Science.gov (United States)

Lee, Minoh; Balasingam, Suresh Kannan; Jeong, Hu Young; Hong, Won G; Lee, Han-Bo-Ram; Kim, Byung Hoon; Jun, Yongseok

2015-01-30

Graphene-decorated V2O5 nanobelts (GVNBs) were synthesized via a low-temperature hydrothermal method in a single step. V2O5 nanobelts (VNBs) were formed in the presence of graphene oxide, a mild oxidant, which also enhanced the conductivity of GVNBs. From the electron energy loss spectroscopy analysis, the reduced graphene oxide (rGO) are inserted into the layered crystal structure of V2O5 nanobelts, which further confirmed the enhanced conductivity of the nanobelts. The electrochemical energy-storage capacity of GVNBs was investigated for supercapacitor applications. The specific capacitance of GVNBs was evaluated using cyclic voltammetry (CV) and charge/discharge (CD) studies. The GVNBs having V2O5-rich composite, namely, V3G1 (VO/GO = 3:1), showed superior specific capacitance in comparison to the other composites (V1G1 and V1G3) and the pure materials. Moreover, the V3G1 composite showed excellent cyclic stability and the capacitance retention of about 82% was observed even after 5000 cycles.

A simple route to synthesize multiform structures of tin oxide nanobelts and optical properties investigation

International Nuclear Information System (INIS)

Cheng Chuanwei; Xu Guoyue; Zhang Haiqian; Li Yingying; Luo Yan; Zhang Peigen

2008-01-01

Multiform structures of SnO 2 nanobelts including of zigzag, branching and straight structures have been synthesized by a simple molten-salt assisted route. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM). The growth mechanism of zigzag nanobelts was proposed. A strong blue emission band centered in 425 nm was observed in the photoluminescence spectrum

Hydrogenated TiO{sub 2} nanobelts as highly efficient photocatalytic organic dye degradation and hydrogen evolution photocatalyst

Energy Technology Data Exchange (ETDEWEB)

Tian, Jian [School of Materials Science and Engineering, Shandong University of Science and Technology, Qingdao 266590 (China); State key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Leng, Yanhua [State key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Cui, Hongzhi, E-mail: cuihongzhi1965@163.com [School of Materials Science and Engineering, Shandong University of Science and Technology, Qingdao 266590 (China); Liu, Hong, E-mail: hongliu@sdu.edu.cn [State key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China)

2015-12-15

Highlights: • A facile synthesis of hydrogenated TiO{sub 2} nanobelts is reported. • Utilizing UV and visible light in photocatalytic degradation and H{sub 2} production. • The improved photocatalytic property is owe to Ti{sup 3+} ions and oxygen vacancies. - Abstract: TiO{sub 2} nanobelts have gained increasing interest because of its outstanding properties and promising applications in a wide range of fields. Here we report the facile synthesis of hydrogenated TiO{sub 2} (H-TiO{sub 2}) nanobelts, which exhibit excellent UV and visible photocatalytic decomposing of methyl orange (MO) and water splitting for hydrogen production. The improved photocatalytic property can be attributed to the Ti{sup 3+} ions and oxygen vacancies in TiO{sub 2} nanobelts created by hydrogenation. Ti{sup 3+} ions and oxygen vacancies can enhance visible light absorption, promote charge carrier trapping, and hinder the photogenerated electron–hole recombination. This work offers a simple strategy for the fabrication of a wide solar spectrum of active photocatalysts, which possesses significant potential for more efficient photodegradation, photocatalytic water splitting, and enhanced solar cells using sunlight as light source.

Electromechanical Characterization of Single GaN Nanobelt Probed with Conductive Atomic Force Microscope

Science.gov (United States)

Yan, X. Y.; Peng, J. F.; Yan, S. A.; Zheng, X. J.

2018-04-01

The electromechanical characterization of the field effect transistor based on a single GaN nanobelt was performed under different loading forces by using a conductive atomic force microscope (C-AFM), and the effective Schottky barrier height (SBH) and ideality factor are simulated by the thermionic emission model. From 2-D current image, the high value of the current always appears on the nanobelt edge with the increase of the loading force less than 15 nN. The localized (I-V) characteristic reveals a typical rectifying property, and the current significantly increases with the loading force at the range of 10-190 nN. The ideality factor is simulated as 9.8 within the scope of GaN nano-Schottky diode unity (6.5-18), therefore the thermionic emission current is dominant in the electrical transport of the GaN-tip Schottky junction. The SBH is changed through the piezoelectric effect induced by the loading force, and it is attributed to the enhanced current. Furthermore, a single GaN nanobelt has a high mechanical-induced current ratio that could be made use of in a nanoelectromechanical switch.

High-aspect-ratio HfC nanobelts accompanied by HfC nanowires: Synthesis, characterization and field emission properties

Energy Technology Data Exchange (ETDEWEB)

Tian, Song, E-mail: tiansong22@126.com [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); School of Materials Science and Engineering, Chongqing Jiaotong University, Chongqing 400074 (China); Zhang, Yulei; Ren, Jincui; Qiang, Xinfa; Zhang, Shouyang [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); Li, Hejun, E-mail: lihejun@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China)

2017-04-30

Highlights: • HfC naobelts accompanied by HfC nanowires were synthesized by a catalytic CVD method. • HfC nanobelts as a novel structure of HfC ceramic are reported for the first time. • HfC nanobelts have 100–200 μm in lengths and reach up to 10 μm in widths. • The synthesized product is promising field nanoemitters. - Abstract: As a key refractory carbide, hafnium carbide (HfC) is commonly used as structural materials while the field emission (FE) application of HfC in the field of vacuum microelectronics is almost the only one for functional material purposes. Based on its outstanding physical and chemical characteristics, HfC is identified as a potential candidate with satisfactory mechanical properties and long-term and/or high-temperature FE stability for future applications in high-performance field emitters. However, the development of HfC in various FE applications is hindered because it is not facile to fabricate large-scale low-dimensional HfC field nanoemitters. Herein, High-aspect-ratio HfC nanobelts accompanied by HfC nanowires were synthesized on a large scale by a traditional and simple catalytic chemical vapor deposition (CVD) method. Classical vapor–liquid–solid (VLS) theory was employed to explain the growth of the HfC nanowires and nanobelts along axial direction. The thin HfO{sub 2} shell and thin C layer surrounding the nanostructures might give rise to the diameter fluctuation of HfC nanowires and the width increase of HfC nanobelts in lateral direction. Field emission results show that the high-aspect-ratio HfC nanobelts accompanied by the nanowires are promising field nanoemitters, which exhibit excellent field emission properties with a fairly low turn-on field of ∼1.5 V μm{sup −1} and a low current fluctuation less than ∼10%. This suggests that HfC ceramics with high-aspect-ratio nanostructures are ideal cathode material for various field emission applications.

Raman selection rule of surface optical phonon in ZnS nanobelts

KAUST Repository

Ho, Chih-Hsiang

2016-02-18

We report Raman scattering results of high-quality wurtzite ZnS nanobelts (NBs) grown by chemical vapor deposition. In Raman spectrum, the ensembles of ZnS NBs exhibit first order phonon modes at 274 cm-1 and 350 cm-1, corresponding to A1/E1 transverse optical and A1/E1 longitudinal optical phonons, in addition with strong surface optical (SO) phonon mode at 329 cm-1. The existence of SO band is confirmed by its shift with different surrounding dielectric media. Polarization dependent Raman spectrum was performed on a single ZnS NB and for the first time SO phonon band has been detected on a single nanobelt. Different selection rules of SO phonon modeshown from their corresponding E1/A1 phonon modeswere attributed to the anisotropic translational symmetry breaking on the NB surface.

Raman selection rule of surface optical phonon in ZnS nanobelts

KAUST Repository

Ho, Chih-Hsiang; Varadhan, Purushothaman; Wang, Hsin-Hua; Chen, Cheng-Ying; Fang, Xiaosheng; He, Jr-Hau

2016-01-01

We report Raman scattering results of high-quality wurtzite ZnS nanobelts (NBs) grown by chemical vapor deposition. In Raman spectrum, the ensembles of ZnS NBs exhibit first order phonon modes at 274 cm-1 and 350 cm-1, corresponding to A1/E1 transverse optical and A1/E1 longitudinal optical phonons, in addition with strong surface optical (SO) phonon mode at 329 cm-1. The existence of SO band is confirmed by its shift with different surrounding dielectric media. Polarization dependent Raman spectrum was performed on a single ZnS NB and for the first time SO phonon band has been detected on a single nanobelt. Different selection rules of SO phonon modeshown from their corresponding E1/A1 phonon modeswere attributed to the anisotropic translational symmetry breaking on the NB surface.

A self-seeded, surfactant-directed hydrothermal growth of single crystalline lithium manganese oxide nanobelts from the commercial bulky particles.

Science.gov (United States)

Zhang, Lizhi; Yu, Jimmy C; Xu, An-Wu; Li, Quan; Kwong, Kwan Wai; Wu, Ling

2003-12-07

Single crystalline lithium manganese oxide nanobelts were obtained through a self-seeded, surfactant-directed growth process from the commercial bulky particles under hydrothermal treatment. A possible mechanism was proposed to explain the growth of the nanobelts. This new process could be extended to prepare other one-dimensional nanomaterials such as Se nanorods, Te nanotubes, and MnO2 nanowires.

Microwave-induced solid-state synthesis of TiO2(B) nanobelts with enhanced lithium-storage properties

International Nuclear Information System (INIS)

Qiao Yun; Hu Xianluo; Huang Yunhui

2012-01-01

A fast and economical route based on an efficient microwave-induced solid-state process has been developed to synthesize metastable TiO 2 (B) nanobelts with widths of 30–100 nm and lengths up to a few micrometers on a large scale. This new method reduces the synthesis time for the preparation of TiO 2 (B) nanobelts to less than half an hour, allowing the screening of a wide range of reaction conditions for optimizing and scaling up the production and facilitating the formation of metastable phase TiO 2 (B). The as-formed TiO 2 (B) nanobelts exhibit enhanced lithium-storage performances, compared with the TiO 2 (B) product obtained by the conventional heating. This study provides a new way for large-scale industrial production of high-quality metastable TiO 2 (B) nanostructures. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy.

Effect of Flowing Water on Sr Sorption Changes of Hydrous Sodium Titanate

Directory of Open Access Journals (Sweden)

Youko Takahatake

2017-12-01

Full Text Available Radioactive contaminated water has been generated at the Fukushima Daiichi Nuclear Power station (F1NPS. Hydrous sodium titanate (SrTreat® is able to remove radioactive Strontium (Sr from this water. Knowing the amount of radioactive nuclides in the used as-received SrTreat® is important for effective disposal and deposition of the F1NPS waste. This study investigated changes in the ability of SrTreat® to sorb Sr, and to understand the causes of changes in the sorbing. An investigation of the Sr sorption ability of SrTreat® is important for calculating the initial radioactive inventory of used SrTreat®. This study carries out Sr sorption studies with acid-base titrations and X-ray photoelectron spectroscopy (XPS to characterize the properties. After exposure to simulated treated water for 99 h, the surface structure of the SrTreat® was changed, and the percentage of sorbed Sr and the buffer capacity for protons decreased. When the amount of radioactive nuclides contained in the used SrTreat® is calculated from the sorption data of the as-received SrTreat®, the radioactive Sr content will be overestimated with a concomitant increase in the deposition and disposal costs of the used SrTreat®.

Capture of toxic radioactive and heavy metal ions from water by using titanate nanofibers

Energy Technology Data Exchange (ETDEWEB)

Xu, Jiasheng, E-mail: jiashengxu@bhu.edu.cn [Liaoning Province Key Laboratory for Synthesis and Application of Functional Compounds, College of Chemistry, Chemical Engineering and Food Safety, Center of Science and Technology Experiment, Bohai University, 19 Sci-tech Road, Jinzhou 121013 (China); Zhang, He; Zhang, Jie [Liaoning Province Key Laboratory for Synthesis and Application of Functional Compounds, College of Chemistry, Chemical Engineering and Food Safety, Center of Science and Technology Experiment, Bohai University, 19 Sci-tech Road, Jinzhou 121013 (China); Kim, Eui Jung [School of Chemical Engineering and Bioengineering, University of Ulsan, Ulsan 680-749 (Korea, Republic of)

2014-11-25

Highlights: • Three types of titanate nanofibers were prepared via a hydrothermal porcess. • These nanofibers show availability for removal of the toxic ions from water. • The equilibrium data were fitted well with the Langmuir model. - Abstract: Three types of titanate nanofibers (sodium titanate nanofibers (TNF-A), potassium/sodium titanate nanofibers (TNF-B), potassium titanate nanofibers (TNF-C)) were prepared via a hydrothermal treatment of anatase powders in different alkali solutions at 170 °C for 96 h, respectively. The as-prepared nanofibers have large specific surface area and show availability for the removal of radioactive and heavy metal ions from water system, such as Ba{sup 2+} (as substitute of {sup 226}Ra{sup 2+}) and Pb{sup 2+} ions. The TNF-A shows a better capacity in the removal of Ba{sup 2+} and Pb{sup 2+} than TNF-B and TNF-C. Structural characterization of the materials was performed with powder X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) and with inductively coupled plasma optical emission spectrometry (ICP-OES). It is found that the equilibrium data fit well with the Langmuir model. This study highlights that nanoparticles of inorganic ion exchangers with layered structure are potential materials for efficient removal of the toxic ions from contaminated water.

Titan

Science.gov (United States)

Müller-Wodarg, Ingo; Griffith, Caitlin A.; Lellouch, Emmanuel; Cravens, Thomas E.

2014-03-01

Introduction I. C. F. Müller-Wodarg, C. A. Griffith, E. Lellouch and T. E. Cravens; Prologue 1: the genesis of Cassini-Huygens W.-H. Ip, T. Owen and D. Gautier; Prologue 2: building a space flight instrument: a P.I.'s perspective M. Tomasko; 1. The origin and evolution of Titan G. Tobie, J. I. Lunine, J. Monteux, O. Mousis and F. Nimmo; 2. Titan's surface geology O. Aharonson, A. G. Hayes, P. O. Hayne, R. M. Lopes, A. Lucas and J. T. Perron; 3. Thermal structure of Titan's troposphere and middle atmosphere F. M. Flasar, R. K. Achterberg and P. J. Schinder; 4. The general circulation of Titan's lower and middle atmosphere S. Lebonnois, F. M. Flasar, T. Tokano and C. E. Newman; 5. The composition of Titan's atmosphere B. Bézard, R. V. Yelle and C. A. Nixon; 6. Storms, clouds, and weather C. A. Griffith, S. Rafkin, P. Rannou and C. P. McKay; 7. Chemistry of Titan's atmosphere V. Vuitton, O. Dutuit, M. A. Smith and N. Balucani; 8. Titan's haze R. West, P. Lavvas, C. Anderson and H. Imanaka; 9. Titan's upper atmosphere: thermal structure, dynamics, and energetics R. V. Yelle and I. C. F. Müller-Wodarg; 10. Titan's upper atmosphere/exosphere, escape processes, and rates D. F. Strobel and J. Cui; 11. Titan's ionosphere M. Galand, A. J. Coates, T. E. Cravens and J.-E. Wahlund; 12. Titan's magnetospheric and plasma environment J.-E. Wahlund, R. Modolo, C. Bertucci and A. J. Coates.

Hydrothermal synthesis and electrochemical properties of α-MoO3 nanobelts used as cathode materials for Li-ion batteries

International Nuclear Information System (INIS)

Phuruangrat, Anukorn; Chen, Jun Song; Lou, Xiong Wen; Yayapao, Oranuch; Thongtem, Somchai; Thongtem, Titipun

2012-01-01

Uniform α-MoO 3 nanobelts were successfully synthesized by the hydrothermal process at 180 C for 20 h of the acidic solutions with different pH values of 0-0.75, adjusted using HCl (conc.). XRD and SEM results revealed that the pH of the precursor solutions played an important role in the phase, impurities, and morphology of the products. At the pH=0, the perfect α-MoO 3 nanobelts with a few tens of microns long were synthesized. By the TEM characterization, orthorhombic MoO 3 has a distinctive layered structure along the [010] direction, consisting of distorted MoO 6 octahedrons connected by common corners along the [100] direction and common edges along the [001] direction. The electrochemical measurement showed that the α-MoO 3 nanobelts have high specific charge capacity. (orig.)

Growth of Fe2O3/SnO2 nanobelt arrays on iron foil for efficient photocatalytic degradation of methylene blue

Science.gov (United States)

Lei, Rui; Ni, Hongwei; Chen, Rongsheng; Zhang, Bowei; Zhan, Weiting; Li, Yang

2017-04-01

Tin(IV) oxide has been intensively employed in optoelectronic devices due to its excellent electrical and optical properties. But the high recombination rates of the photogenerated electron-hole pairs of SnO2 nanomaterials often results in low photocatalytic efficiency. Herein, we proposed a facile route to prepare a novel Fe2O3/SnO2 heterojunction structure. The nanobelt arrays grown on iron foil naturally form a Schottky-type contact and provide a direct pathway for the photogenerated excitons. Hence, the Fe2O3/SnO2 nanobelt arrays exhibit much improved photocatalytic performance with the degradation rate constant on the Fe2O3/SnO2 film of approximately 12 times to that of α-Fe2O3 nanobelt arrays.

Application of titanates, niobates, and tantalates to neutralized defense waste decontamination: materials properties, physical forms, and regeneration techniques. Final report

International Nuclear Information System (INIS)

Dosch, R.G.

1981-01-01

A study of the application of sodium titanate (ST) to the decontamination of neutralized defense waste has been completed. The work was directed at Sr removal from dissolved salt cake, simulated in this work with a 6.0 N NaNO 3 - 0.6 N NaOH solution. Three physical forms of the titanates were developed including powder, pellets, and titanate-loaded resin beads and all were found to be superior to conventional organic ion exchange in this application. When spent, the titanate materials can be calcined to an oxide from which is a stable waste form in itself or can be added directly to a glass melter to become part of a vitrified waste form. Radiation stability of titanate powder and resin forms was assessed in tests in which these materials were exposed to 60 Co radiation. The strontium exchange capacity of the powder remained constant through a dose of 3 x 10 7 rads and retained 50% capacity after a dose of 2 x 10 9 rads. The primary mechanism involved in loss of capacity was believed to be heating associated with the irradiation. The resin forms were unchanged through a dose of 5 x 10 8 rads and retained 30% capacity after a dose of 2 x 10 9 rads. The latter dose resulted in visible degradation of the resin matrix. Anion exchange resins loaded with sodium niobate and sodium tantalate were also prepared by similar methods and evaluated for this application. These materials had Sr sorption properties comparable to the titanate material; however, they would have to provide a significant improvement to justify their higher cost

Free-polymer controlling morphology of α-MoO3 nanobelts by a facile hydrothermal synthesis, their electrochemistry for hydrogen evolution reactions and optical properties

International Nuclear Information System (INIS)

Sinaim, Hathai; Ham, Dong Jin; Lee, Jae Sung; Phuruangrat, Anukorn; Thongtem, Somchai; Thongtem, Titipun

2012-01-01

Highlights: ► MoO 3 nanobelts as an n-type semiconducting material. ► It was successfully synthesized by a facile hydrothermal reaction. ► A promising material with 3.75 eV band gap for hydrogen evolution reaction (HER). - Abstract: Orthorhombic molybdenum oxide (α-MoO 3 ) nanobelts were successfully synthesized by the 100–180 °C and 2–20 h hydrothermal reactions of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O solutions containing 15 ml 2 M acid (HNO 3 , H 2 SO 4 or HCl) with no surfactant and template adding. These products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy, and electron microscopy (EM). In the present research, the product synthesized by the 180 °C and 20 h hydrothermal reaction of the solution containing HNO 3 was α-MoO 3 nanobelts with >10 μm long and 3 nanobelts were characterized by linear sweep voltammetry (LSV) and Tafel plot, including UV–vis and photoluminescence (PL) spectroscopy. These imply that α-MoO 3 nanobelts show satisfied performance for HER, with the 3.75 eV direct allowed band gap (E g ) due to the charged transition of O 2p → Mo 4d , including the emission of 437 nm wavelength at room temperature.

V2O5-C-SnO2 Hybrid Nanobelts as High Performance Anodes for Lithium-ion Batteries

Science.gov (United States)

Zhang, Linfei; Yang, Mingyang; Zhang, Shengliang; Wu, Zefei; Amini, Abbas; Zhang, Yi; Wang, Dongyong; Bao, Shuhan; Lu, Zhouguang; Wang, Ning; Cheng, Chun

2016-09-01

The superior performance of metal oxide nanocomposites has introduced them as excellent candidates for emerging energy sources, and attracted significant attention in recent years. The drawback of these materials is their inherent structural pulverization which adversely impacts their performance and makes the rational design of stable nanocomposites a great challenge. In this work, functional V2O5-C-SnO2 hybrid nanobelts (VCSNs) with a stable structure are introduced where the ultradispersed SnO2 nanocrystals are tightly linked with glucose on the V2O5 surface. The nanostructured V2O5 acts as a supporting matrix as well as an active electrode component. Compared with existing carbon-V2O5 hybrid nanobelts, these hybrid nanobelts exhibit a much higher reversible capacity and architectural stability when used as anode materials for lithium-ion batteries. The superior cyclic performance of VCSNs can be attributed to the synergistic effects of SnO2 and V2O5. However, limited data are available for V2O5-based anodes in lithium-ion battery design.

Exfoliated β-Ga2O3 nano-belt field-effect transistors for air-stable high power and high temperature electronics.

Science.gov (United States)

Kim, Janghyuk; Oh, Sooyeoun; Mastro, Michael A; Kim, Jihyun

2016-06-21

This study demonstrated the exfoliation of a two-dimensional (2D) β-Ga2O3 nano-belt and subsequent processing into a thin film transistor structure. This mechanical exfoliation and transfer method produces β-Ga2O3 nano-belts with a pristine surface as well as a continuous defect-free interface with the SiO2/Si substrate. This β-Ga2O3 nano-belt based transistor displayed an on/off ratio that increased from approximately 10(4) to 10(7) over the operating temperature range of 20 °C to 250 °C. No electrical breakdown was observed in our measurements up to VDS = +40 V and VGS = -60 V between 25 °C and 250 °C. Additionally, the electrical characteristics were not degraded after a month-long storage in ambient air. The demonstration of high-temperature/high-voltage operation of quasi-2D β-Ga2O3 nano-belts contrasts with traditional 2D materials such as transition metal dichalcogenides that intrinsically have limited temperature and power operational envelopes owing to their narrow bandgap. This work motivates the application of 2D β-Ga2O3 to high power nano-electronic devices for harsh environments such as high temperature chemical sensors and photodetectors as well as the miniaturization of power circuits and cooling systems in nano-electronics.

Enhanced degradation of persistent pharmaceuticals found in wastewater treatment effluents using TiO2 nanobelt photocatalysts

International Nuclear Information System (INIS)

Liang, Robert; Hu, Anming; Li, Wenjuan; Zhou, Y. Norman

2013-01-01

Pharmaceuticals in wastewater effluents are a current and emerging global problem and the development of cost-effective methods to facilitate their removal is needed to mitigate this issue. Advanced oxidation processes (AOPs), in particular UV/TiO 2 , have potential for wastewater treatment. In this study, TiO 2 anatase phase nanobelts (30–100 nm in width and 10 μm in length) have been synthesized using a high temperature hydrothermal method as a means to photocatalyze the oxidation of pharmaceutical contaminants. We have investigated a model dye (malachite green), three pharmaceuticals and personal care products—naproxen, carbamazepine, and theophylline—that are difficult to oxidize without AOP processes. TiO 2 nanobelts were exposed to 365 nm UV illumination and the measured photocatalytic degradation rates and adsorption parameters of pharmaceuticals were explored using kinetic models. Furthermore we have determined the degree of pharmaceutical degradation as a function of solution pH, illumination time, temperature, and concentration of contaminant. In addition, the roles of active oxygen species—hydroxyl radial (OH·), positive holes (h + ), and hydrogen peroxide (H 2 O 2 )—involved were also investigated in the degradation process. These studies offer additional applications of hierarchical TiO 2 nanobelt membranes, including those harnessing sunlight for water treatment

Enhanced degradation of persistent pharmaceuticals found in wastewater treatment effluents using TiO2 nanobelt photocatalysts

Science.gov (United States)

Liang, Robert; Hu, Anming; Li, Wenjuan; Zhou, Y. Norman

2013-10-01

Pharmaceuticals in wastewater effluents are a current and emerging global problem and the development of cost-effective methods to facilitate their removal is needed to mitigate this issue. Advanced oxidation processes (AOPs), in particular UV/TiO2, have potential for wastewater treatment. In this study, TiO2 anatase phase nanobelts (30-100 nm in width and 10 μm in length) have been synthesized using a high temperature hydrothermal method as a means to photocatalyze the oxidation of pharmaceutical contaminants. We have investigated a model dye (malachite green), three pharmaceuticals and personal care products—naproxen, carbamazepine, and theophylline—that are difficult to oxidize without AOP processes. TiO2 nanobelts were exposed to 365 nm UV illumination and the measured photocatalytic degradation rates and adsorption parameters of pharmaceuticals were explored using kinetic models. Furthermore we have determined the degree of pharmaceutical degradation as a function of solution pH, illumination time, temperature, and concentration of contaminant. In addition, the roles of active oxygen species—hydroxyl radial (OH·), positive holes (h+), and hydrogen peroxide (H2O2)—involved were also investigated in the degradation process. These studies offer additional applications of hierarchical TiO2 nanobelt membranes, including those harnessing sunlight for water treatment.

Titan!

Science.gov (United States)

Matson, Dennis L.

2010-05-01

Cassini-Huygens achieved Saturnian orbit on July 1, 2004. The first order of business was the safe delivery of the Huygens atmospheric probe to Titan that took place on January 14, 2005. Huygens descended under parachute obtaining observations all the way down to a safe landing. It revealed Titan for the first time. Stunning are the similarities between Titan and the Earth. Viewing the lakes and seas, the fluvial terrain, the sand dunes and other features through the hazy, nitrogen atmosphere, brings to mind the geological processes that created analogous features on the Earth. On Titan frozen water plays the geological role of rock; liquid methane takes the role of terrestrial water. The atmospheres of both Earth and Titan are predominately nitrogen gas. Titan's atmosphere contains 1.5% methane and no oxygen. The surface pressure on Titan is 1.5 times the Earth's. There are aerosol layers and clouds that come and go. Now, as Saturn proceeds along its solar orbit, the seasons are changing. The effects upon the transport of methane are starting to be seen. A large lake in the South Polar Region seems to be filling more as winter onsets. Will the size and number of the lakes in the South grow during winter? Will the northern lakes and seas diminish or dry up as northern summer progresses? How will the atmospheric circulation change? Much work remains not only for Cassini but also for future missions. Titan has many different environments to explore. These require more capable instruments and in situ probes. This work was conducted at the Jet Propulsion Laboratory, California Institute of Technology under contract with the National Aeronautics and Space Administration.

Polypyrrole-coated samarium oxide nanobelts: fabrication, characterization, and application in supercapacitors

Science.gov (United States)

Liu, Peng; Wang, Yunjiao; Wang, Xue; Yang, Chao; Yi, Yanfeng

2012-11-01

Polypyrrole-coated samarium oxide nanobelts were synthesized by the in situ chemical oxidative surface polymerization technique based on the self-assembly of pyrrole on the surface of the amine-functionalized Sm2O3 nanobelts. The morphologies of the polypyrrole/samarium oxide (PPy/Sm2O3) nanocomposites were characterized using transmission electron microscope. The UV-vis absorbance of these samples was also investigated, and the remarkable enhancement was clearly observed. The electrochemical behaviors of the PPy/Sm2O3 composites were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge. The results indicated that the PPy/Sm2O3 composite electrode was fully reversible and achieved a very fast Faradaic reaction. After being corrected into the weight percentage of the PPy/Sm2O3 composite at a current density of 20 mA cm-2 in a 1.0 M NaNO3 electrolyte solution, a maximum discharge capacity of 771 F g-1 was achieved in a half-cell setup configuration for the PPy/Sm2O3 composites electrode with the potential application to electrode materials for electrochemical capacitors.

Enhanced degradation of persistent pharmaceuticals found in wastewater treatment effluents using TiO{sub 2} nanobelt photocatalysts

Energy Technology Data Exchange (ETDEWEB)

Liang, Robert; Hu, Anming, E-mail: a2hu@uwaterloo.ca; Li, Wenjuan; Zhou, Y. Norman [University of Waterloo, Centre for Advanced Materials Joining, Department of Mechanical and Mechatronics Engineering (Canada)

2013-10-15

Pharmaceuticals in wastewater effluents are a current and emerging global problem and the development of cost-effective methods to facilitate their removal is needed to mitigate this issue. Advanced oxidation processes (AOPs), in particular UV/TiO{sub 2}, have potential for wastewater treatment. In this study, TiO{sub 2} anatase phase nanobelts (30-100 nm in width and 10 {mu}m in length) have been synthesized using a high temperature hydrothermal method as a means to photocatalyze the oxidation of pharmaceutical contaminants. We have investigated a model dye (malachite green), three pharmaceuticals and personal care products-naproxen, carbamazepine, and theophylline-that are difficult to oxidize without AOP processes. TiO{sub 2} nanobelts were exposed to 365 nm UV illumination and the measured photocatalytic degradation rates and adsorption parameters of pharmaceuticals were explored using kinetic models. Furthermore we have determined the degree of pharmaceutical degradation as a function of solution pH, illumination time, temperature, and concentration of contaminant. In addition, the roles of active oxygen species-hydroxyl radial (OH{center_dot}), positive holes (h{sup +}), and hydrogen peroxide (H{sub 2}O{sub 2})-involved were also investigated in the degradation process. These studies offer additional applications of hierarchical TiO{sub 2} nanobelt membranes, including those harnessing sunlight for water treatment.

Influence of High-Energy Proton Irradiation on β-Ga2O3 Nanobelt Field-Effect Transistors.

Science.gov (United States)

Yang, Gwangseok; Jang, Soohwan; Ren, Fan; Pearton, Stephen J; Kim, Jihyun

2017-11-22

The robust radiation resistance of wide-band gap materials is advantageous for space applications, where the high-energy particle irradiation deteriorates the performance of electronic devices. We report on the effects of proton irradiation of β-Ga 2 O 3 nanobelts, whose energy band gap is ∼4.85 eV at room temperature. Back-gated field-effect transistor (FET) based on exfoliated quasi-two-dimensional β-Ga 2 O 3 nanobelts were exposed to a 10 MeV proton beam. The proton-dose- and time-dependent characteristics of the radiation-damaged FETs were systematically analyzed. A 73% decrease in the field-effect mobility and a positive shift of the threshold voltage were observed after proton irradiation at a fluence of 2 × 10 15 cm -2 . Greater radiation-induced degradation occurs in the conductive channel of the β-Ga 2 O 3 nanobelt than at the contact between the metal and β-Ga 2 O 3 . The on/off ratio of the exfoliated β-Ga 2 O 3 FETs was maintained even after proton doses up to 2 × 10 15 cm -2 . The radiation-induced damage in the β-Ga 2 O 3 -based FETs was significantly recovered after rapid thermal annealing at 500 °C. The outstanding radiation durability of β-Ga 2 O 3 renders it a promising building block for space applications.

Probing the Highly Efficient Electron Transfer Dynamics between Zinc Protoporphyrin IX and Sodium Titanate Nanosheets.

Science.gov (United States)

Biswas, Sudipta; Mukherjee, Debdyuti; De, Swati; Kathiravan, Arunkumar

2016-09-15

Sodium titanate nanosheets (NaTiO2 NS) have been prepared by a new method and completely characterized by TEM, SEM, XRD, EDX, and XPS techniques. The sensitization of nanosheets is carried out with Zn protoporphyrin IX (ZnPPIX). The emission intensity of ZnPPIX is quenched by NaTiO2 NS, and the dominant process for this quenching has been attributed to the process of photoinduced electron injection from excited ZnPPIX to the nanosheets. Time resolved fluorescence measurement was used to elucidate the process of electron injection from the singlet state of ZnPPIX to the conduction band of NaTiO2 NS. Electron injection from the dye to the semiconductor is very fast (ket ≈ 10(11) s(-1)), much faster than previously reported rates. The large two-dimensional surface offered by the NaTiO2 NS for interaction with the dye and the favorable driving force for electron injection from ZnPPIX to NaTiO2 NS (ΔGinj = -0.66 V) are the two important factors responsible for such efficient electron injection. Thus, NaTiO2 NS can serve as an effective alternative to the use of TiO2 nanoparticles in dye sensitized solar cells (DSSCs).

Polypyrrole-coated samarium oxide nanobelts: fabrication, characterization, and application in supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Liu Peng, E-mail: pliu@lzu.edu.cn; Wang Yunjiao; Wang Xue; Yang Chao; Yi Yanfeng [College of Chemistry and Chemical Engineering, Lanzhou University, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province and State Key Laboratory of Applied Organic Chemistry (China)

2012-11-15

Polypyrrole-coated samarium oxide nanobelts were synthesized by the in situ chemical oxidative surface polymerization technique based on the self-assembly of pyrrole on the surface of the amine-functionalized Sm{sub 2}O{sub 3} nanobelts. The morphologies of the polypyrrole/samarium oxide (PPy/Sm{sub 2}O{sub 3}) nanocomposites were characterized using transmission electron microscope. The UV-vis absorbance of these samples was also investigated, and the remarkable enhancement was clearly observed. The electrochemical behaviors of the PPy/Sm{sub 2}O{sub 3} composites were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge. The results indicated that the PPy/Sm{sub 2}O{sub 3} composite electrode was fully reversible and achieved a very fast Faradaic reaction. After being corrected into the weight percentage of the PPy/Sm{sub 2}O{sub 3} composite at a current density of 20 mA cm{sup -2} in a 1.0 M NaNO{sub 3} electrolyte solution, a maximum discharge capacity of 771 F g{sup -1} was achieved in a half-cell setup configuration for the PPy/Sm{sub 2}O{sub 3} composites electrode with the potential application to electrode materials for electrochemical capacitors.

Static susceptibility and heat capacity studies on V{sub 3}O{sub 7}.H{sub 2}O{sub 7} nanobelts

Energy Technology Data Exchange (ETDEWEB)

Hellmann, I., E-mail: i.hellmann@ifw-dresden.d [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW) Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Zakharova, G.S.; Volkov, V.L. [Institute of Solid State Chemistry, Ural Division, Russian Academy of Sciences, Pervomaiskaya ul. 91, Yekaterinburg 620219 (Russian Federation); Taeschner, C.; Leonhardt, A.; Buechner, B.; Klingeler, R. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW) Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany)

2010-04-15

V{sub 3}O{sub 7}.H{sub 2}O nanobelts were prepared by a hydrothermal method at 190 deg. C using V{sub 2}O{sub 5}.nH{sub 2}O gel and H{sub 2}C{sub 2}O{sub 4}.2H{sub 2}O as starting agents. The obtained nanobelts have diameters ranging from 40 to 70 nm with lengths up to several micrometers. Measurements of the static magnetic susceptibility and the specific heat show a discontinuous phase transition at around T=145 K, which separates two regions of paramagnetic behavior.

In situ Sn2+-incorporation synthesis of titanate nanotubes for photocatalytic dye degradation under visible light illumination

International Nuclear Information System (INIS)

Tsai, Chien-Cheng; Chen, Liang-Che; Yeh, Te-Fu; Teng, Hsisheng

2013-01-01

Highlights: ► Sn 2+ ions sensitize titanate nanotubes for photocatalysis under visible-light illumination. ► The Sn 5s orbital replaces the O 2p orbital as the top level of the valence band of titanates. ► The presence of Sn 2+ lifts the valence band of titanate nanotubes by approximately 0.9 eV. ► The doped Sn 2+ sites are active in donating photo-induced charges to dye degradation. - Abstract: Sn 2+ -incorporated titanate nanotubes, prepared by washing a layered sodium titanate with a SnCl 2 solution for tube formation, exhibit noticeable photocatalytic activity under visible light irradiation. This in situ synthesis results in a Sn/Ti ratio of approximately 0.6. Because of the introduction of Sn 2+ ions, the Sn 5s orbital replaces the O 2p orbital as the top level of the valence band of titanate nanotubes. Optical absorption analysis shows that Sn doping reduces the bandgap of titanate nanotubes from 3.5 to 2.6 eV. Oxidation of the Sn 2+ -incorporated titanate nanotubes leads to oxidation of Sn 2+ to Sn 4+ , hence, widening the bandgap. Under visible light irradiation, Sn 2+ -incorporated titanate nanotubes effectively degrade methylene blue in an aqueous solution, whereas the bare titanate nanotubes exhibit substantially lower photocatalytic activity. Photoluminescence analysis demonstrates that the induced charges from excitation of the Sn 2+ ions tend to be relaxed through chemical interactions, rather than irradiative recombination.

Thermal effects on current-related skyrmion formation in a nanobelt

Science.gov (United States)

Zhao, Xuebing; Wang, Shasha; Wang, Chao; Che, Renchao

2018-05-01

We report an in-situ Lorentz transmission electron microscopy (LTEM) investigation to study the thermal effects on the generation of magnetic skyrmions within a nanobelt. Under an action of a moderate current pulse, magnetic skyrmions appear even in the temperature range far below the critical temperature and even at zero field. Finite element simulation reveals that the Joule heating plays an essential role in this behavior. Our results also uncover the importance of the cooling conditions in the current-related in situ LTEM research.

Dielectric behaviour of sodium and potassium doped magnesium ...

Indian Academy of Sciences (India)

Dielectric behaviour of sodium and potassium doped magnesium titanate. VISHNU SHANKER. ∗. , SANTOSH KUMAR and T SURENDAR. Department of Chemistry, National Institute of Technology, Warangal 506 004, India. MS received 10 November 2011; revised 27 February 2012. Abstract. Pure phase of magnesium ...

Phase controlled synthesis and cathodoluminescence properties of ZnS nanobelts synthesized by PVD

Science.gov (United States)

Jin, Changqing; Zhu, Kexin; Peterson, George; Zhang, Zhihong; Jian, Zengyun; Wei, Yongxing; Zheng, Deshan

2018-01-01

Zinc sulfide (ZnS) nanobelts were synthesized via physical vapor deposition to explore the electronic properties of optoelectronic nano-devices. It was determined that the mass ratio of wurtzite (WZ) phase to zincblende (ZB) phase and the preferential orientation (100) are related to the carrier-gas flow rate. The high concentration of planar defects within the phase boundary enhances phase transition. Cathodoluminescence measurements show a red shift of the 337 nm band-gap emission due to stacking and twin faults. We find a direct correlation between the magnitude of the red shift and the mass ratio of ZB phase. With an increase in the ZB phase, there is an increase in the concentration of stacking and twin faults introduced by the phase transformation, as indicated by an increasing red shift in the data. The absorption peaks at 666 and 719 nm were found by UV-vis absorption spectrum, which is attributed to surface defects. This work would help to better understand the important roles of planar defects in the phase transition and also provide us with a feasible route to control phase ratio and cathodoluminescence properties of ZnS nanobelts and other II-VI semiconductor nanostructures.

Barium titanate coated with magnesium titanate via fused salt method and its dielectric property

International Nuclear Information System (INIS)

Chen Renzheng; Cui Aili; Wang Xiaohui; Li Longtu

2003-01-01

Barium titanate fine particles were coated homogeneously with magnesium titanate via the fused salt method. The thickness of the magnesium titanate film is 20 nm, as verified by TEM and XRD. The mechanism of the coating is that: when magnesium chloride is liquated in 800 deg. C, magnesium will replace barium in barium titanate, and form magnesium titanate film on the surface of barium titanate particles. Ceramics sintered from the coated particles show improved high frequency ability. The dielectric constant is about 130 at the frequency from 1 to 800 MHz

Titan's Radioactive Haze : Production and Fate of Radiocarbon On Titan

Science.gov (United States)

Lorenz, R. D.; Jull, A. J. T.; Swindle, T. D.; Lunine, J. I.

Just as cosmic rays interact with nitrogen atoms in the atmosphere of Earth to gener- ate radiocarbon (14C), the same process should occur in Titan`s nitrogen-rich atmo- sphere. Titan`s atmosphere is thick enough that cosmic ray flux, rather than nitrogen column depth, limits the production of 14 C. Absence of a strong magnetic field and the increased distance from the sun suggest production rates of 9 atom/cm2/s, approx- imately 4 times higher than Earth. On Earth the carbon is rapidly oxidised into CO2. The fate and detectability of 14C on Titan depends on the chemical species into which it is incorporated in Titan's reducing atmosphere : as methane it would be hopelessly diluted even in only the atmosphere (ignoring the other, much more massive carbon reservoirs likely to be present on Titan, like hydrocarbon lakes.) However, in the more likely case that the 14C attaches to the haze that rains out onto the surface (as tholin, HCN or acetylene and their polymers - a much smaller carbon reservoir) , haze in the atmosphere or recently deposited on the surface would therefore be quite intrinsically radioactive. Such activity may modify the haze electrical charging and hence its coag- ulation. Measurements with compact instrumentation on future in-situ missions could place useful constraints on the mass deposition rates of photochemical material on the surface and identify locations where surface deposits of such material are `freshest`.

Pulsed laser deposition of Ag nanoparticles on titanium hydroxide/oxide nanobelt arrays for highly sensitive surface-enhanced Raman spectroscopy

International Nuclear Information System (INIS)

Jing, Yuting; Wang, Huanwen; Zhao, Jie; Yi, Huan; Wang, Xuefeng

2015-01-01

Highlights: • Silver nanoparticles (NPs) were deposited on Ti(OH) 4 nanobelt by pulsed laser deposition (PLD). • The highest enhancement factor of 10 6 and a maximum relative standard deviation (RSD) of 0.18. • Ag 2 O play important role for the high sensitivity Raman phenomenon. • Charge transfer from Ag NPs is also responsible for the enhancement ability. - Abstract: Surface-enhanced Raman scattering (SERS) substrate of Ti(OH) 4 nanobelt arrays (NBAs) was synthesized by a hydrothermal reaction, on which silver nanoparticles (NPs) were deposited by pulsed laser deposition (PLD). Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) revealed the effective high specific surface area with silver NPs decorated on three-dimensional NBAs. Using rhodamine 6G (R6G) as an analyte molecule, the highest enhancement factor of 10 6 and a maximum relative standard deviation (RSD) of 0.18 were obtained. It has been found that the specific morphology of these composite nanobelt arrays and the formation of Ag 2 O play important role for the high sensitivity Raman phenomenon. In addition, the surface plasmon resonance wavelength of Ag decorated Ti(OH) 4 NBAs and the charge transfer from Ag NPs are also responsible for the enhancement ability. For comparison SERS was investigated with silver particles decorated on TiO 2 NBAs, which is much less active

Fabrication of BiOBr nanosheets@TiO{sub 2} nanobelts p–n junction photocatalysts for enhanced visible-light activity

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yang [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Huang, Xiang [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); School of Science, Tibet University, Lhasa 850000 (China); Tan, Xin [School of Science, Tibet University, Lhasa 850000 (China); Yu, Tao, E-mail: yutao@tju.edu.cn [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Li, Xiangli [School of Environmental Science and Engineering, Tianjin University, Tianjin 300072 (China); Yang, Libin [College of Chemical Engineering and Materials Science, Tianjin University of Science & Technology, Tianjin Key Laboratory of Marine Resources and Chemistry, Tianjin 300457 (China); Wang, Shucong [School of Environmental Science and Engineering, Tianjin University, Tianjin 300072 (China)

2016-03-01

Graphical abstract: - Highlights: • BiOBr nanosheets@TiO{sub 2} nanobelts p–n junction photocatalysts have been synthesized. • The p–n junction photocatalysts improved water splitting and dye degradation activity. • BiOBr amount in the BiOBr@TiO{sub 2} photocatalysts was investigated. - Abstract: The construction of p–n junction structure is a smart strategy for improving the photocatalytic activity, since p–n junctions can inhibit the recombination of photo-induced charges. Herein, BiOBr nanosheets@TiO{sub 2} nanobelts p–n junction photocatalysts were prepared by assembling BiOBr nanosheets on the surface of TiO{sub 2} nanobelts via a hydrothermal route followed by a co-precipitation process. BiOBr@TiO{sub 2} p–n junction photocatalysts exhibited enhanced photocatalytic activity in photocatalytic H{sub 2} production over water splitting and photodegradation of Rhodamine B (RhB) under visible light irradiation. Mott–Schottky plots confirmed the formation of p–n junctions in the interface of BiOBr and TiO{sub 2}. The enhanced photocatalytic performance can be ascribed to the 1D nanostructure and the formation of p–n junctions. This work shows a potential application of low cost BiOBr as a substitute for noble metals in photocatalytic H{sub 2} production under visible light irradiation.

Layered titanates with fibrous nanotopographic features as reservoir for bioactive ions to enhance osteogenesis

Science.gov (United States)

Song, Xiaoxia; Tang, Wei; Gregurec, Danijela; Yate, Luis; Moya, Sergio Enrique; Wang, Guocheng

2018-04-01

In this study, an osteogenic environment was constructed on Ti alloy implants by in-situ formation of nanosized fibrous titanate, Na2Ti6O13, loaded with bioactive ions, i.e. Sr, Mg and Zn, to enhance surface bioactivity. The bioactive ions were loaded by ion exchange with sodium located at inter-layer positions between the TiO6 slabs, and their release was not associated with the degradation of the structural unit of the titanate. In-vitro cell culture experiments using MC3T3-E1 cells proved that both bioactive ions and nanotopographic features are critical in promoting osteogenic differentiation of the cells. It was found that the osteogenic functions of the titanate can be modulated by the type and amount of ions incorporated. This study points out that nanosized fibrous titanate formed on the Ti alloy can be a promising reservoir for bioactive ions. The major advantage of this approach over other alternatives for bioactive ion delivery using degradable bioceramic coatings is its capacity of maintaining the structural integrity of the coating and thus avoiding structural deterioration and potential mechanical failure.

Titan Casts Revealing Shadow

Science.gov (United States)

2004-05-01

A rare celestial event was captured by NASA's Chandra X-ray Observatory as Titan -- Saturn's largest moon and the only moon in the Solar System with a thick atmosphere -- crossed in front of the X-ray bright Crab Nebula. The X-ray shadow cast by Titan allowed astronomers to make the first X-ray measurement of the extent of its atmosphere. On January 5, 2003, Titan transited the Crab Nebula, the remnant of a supernova explosion that was observed to occur in the year 1054. Although Saturn and Titan pass within a few degrees of the Crab Nebula every 30 years, they rarely pass directly in front of it. "This may have been the first transit of the Crab Nebula by Titan since the birth of the Crab Nebula," said Koji Mori of Pennsylvania State University in University Park, and lead author on an Astrophysical Journal paper describing these results. "The next similar conjunction will take place in the year 2267, so this was truly a once in a lifetime event." Animation of Titan's Shadow on Crab Nebula Animation of Titan's Shadow on Crab Nebula Chandra's observation revealed that the diameter of the X-ray shadow cast by Titan was larger than the diameter of its solid surface. The difference in diameters gives a measurement of about 550 miles (880 kilometers) for the height of the X-ray absorbing region of Titan's atmosphere. The extent of the upper atmosphere is consistent with, or slightly (10-15%) larger, than that implied by Voyager I observations made at radio, infrared, and ultraviolet wavelengths in 1980. "Saturn was about 5% closer to the Sun in 2003, so increased solar heating of Titan may account for some of this atmospheric expansion," said Hiroshi Tsunemi of Osaka University in Japan, one of the coauthors on the paper. The X-ray brightness and extent of the Crab Nebula made it possible to study the tiny X-ray shadow cast by Titan during its transit. By using Chandra to precisely track Titan's position, astronomers were able to measure a shadow one arcsecond in

Novel Bioactive Titanate Layers Formed on Ti Metal and Its Alloys by Chemical Treatments

Directory of Open Access Journals (Sweden)

Tadashi Kokubo

2009-12-01

Full Text Available Sodium titanate formed on Ti metal by NaOH and heat treatments induces apatite formation on its surface in a body environment and bonds to living bone. These treatments have been applied to porous Ti metal in artificial hip joints, and have been used clinically in Japan since 2007. Calcium titanate formed on Ti-15Zr-4Nb-4Ta alloy by NaOH, CaCl2, heat, and water treatments induces apatite formation on its surface in a body environment. Titanium oxide formed on porous Ti metal by NaOH, HCl, and heat treatments exhibits osteoinductivity as well as osteoconductivity. This is now under clinical tests for application to a spinal fusion device.

MnV2O6.V2O5 cross-like nanobelt arrays: synthesis, characterization and photocatalytic properties

International Nuclear Information System (INIS)

Abbood, Hayder A.; Ahmed, Khalid Abdelazez Mohamed; Ren, Yong; Huang, Kaixun

2013-01-01

Single-crystalline MnV 2 O 6 .V 2 O 5 cross-like nanobelt arrays were successfully synthesized by hydrothermal reaction. The products were characterized by X-ray diffraction, transmission electron microscopy and high-resolution transmission electron microscopy. The effects of the reaction conditions such as pH, V 5+ /Mn 2+ ratio, carboxymethyl cellulose concentration and reaction time on the morphology of the products were studied. The band gap of the as-prepared products was calculated via diffuse reflectance spectral analysis and their activity of photocatalytic oxidation was evaluated by photodegradation of methylene blue under visible-light irradiation. The results showed that the degradation efficiency of methylene blue catalyzed by the calcinated products is remarkably enhanced due to Mn doping, suggesting that MnV 2 O 6 .V 2 O 5 cross-like nanobelt arrays are a good candidate for visible-light-driven photocatalysts. (orig.)

Structural transformation of MoO3 nanobelts into MoS2 nanotubes

International Nuclear Information System (INIS)

Deepak, Francis Leonard; Mayoral, Alvaro; Yacaman, Miguel Jose

2009-01-01

The structural transformation of MoO 3 nanobelts into MoS 2 nanotubes using a simple sulfur source has been reported. This transformation has been extensively investigated using electron microscopic and spectroscopic techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), electron diffraction (ED), and energy-dispersive X-ray analysis (SEM-EDAX and TEM-EDX). The method described in this report will serve as a generic route for the transformation of other oxide nanostructures into the chalcogenide nanostructures. (orig.)

Controllable synthesis and electrochemical hydrogen storage properties of Sb₂Se₃ ultralong nanobelts with urchin-like structures.

Science.gov (United States)

Jin, Rencheng; Chen, Gang; Pei, Jian; Sun, Jingxue; Wang, Yang

2011-09-01

The controlled synthesis of one-dimensional and three-dimensional Sb(2)Se(3) nanostructures has been achieved by a facile solvothermal process in the presence of citric acid. By simply controlling the concentration of citric acid, the nucleation, growth direction and exposed facet can be readily tuned, which brings the different morphologies and nanostructures to the final products. The as-prepared products have been characterized by means of X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM and selected area electron diffraction. Based on the electron microscope observations, a possible growth mechanism of Sb(2)Se(3) with distinctive morphologies including ultralong nanobelts, hierarchical urchin-like nanostructures is proposed and discussed in detail. The electrochemical hydrogen storage measurements reveal that the morphology plays a key role on the hydrogen storage capacity of Sb(2)Se(3) nanostructures. The Sb(2)Se(3) ultralong nanobelts with high percentage of {-111} facets exhibit higher hydrogen storage capacity (228.5 mA h g(-1)) and better cycle stability at room temperature.

Titan Aerial Daughtercraft

Data.gov (United States)

National Aeronautics and Space Administration — Saturn's giant moon Titan has become one of the most fascinating bodies in the Solar System. Titan is the richest laboratory in the solar system for studying...

Electrospinning synthesis of InVO{sub 4}/BiVO{sub 4} heterostructured nanobelts and their enhanced photocatalytic performance

Energy Technology Data Exchange (ETDEWEB)

Liu, Zhendong; Lu, Qifang, E-mail: luqf0110@126.com; Guo, Enyan; Liu, Suwen [Qilu University of Technology, Shandong Provincial Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics, School of Material Science and Engineering (China)

2016-08-15

In the present work, one-dimensional InVO{sub 4}/BiVO{sub 4} heterostructured nanobelts with the width of about 800 nm have been successfully prepared by a simple electrospinning technique followed by the subsequent calcination process. The prepared products were characterized by thermogravimetry, fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, UV–Vis absorbance spectroscopy, high-performance liquid chromatography, and photoluminescence spectroscopy. The obtained InVO{sub 4}/BiVO{sub 4} heterostructured nanobelts presented an admirable morphology and excellent photocatalytic properties for the degradation of methylene blue solution under visible-light irradiation.Graphical AbstractThe electrospun precursor samples (a and b) displayed a well-defined one-dimensional (1D) belt structure. After calcined at 550 °C for 2 h (c and d), the samples can retain well the 1D morphology. And an obvious porous structure can be found from the TEM images of the calcined samples (e and f).

Gas dependent sensing mechanism in ZnO nanobelt sensor

Energy Technology Data Exchange (ETDEWEB)

Kaur, Manmeet, E-mail: manmeet@barc.gov.in [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai (India); Kailasaganapathi, S.; Ramgir, Niranjan; Datta, Niyanta [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai (India); Kumar, Sushil [Heavy Water Plant (Manuguru), Gautaminagar, Dist. Khammam, Telangana (India); Debnath, A.K.; Aswal, D.K.; Gupta, S.K. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai (India)

2017-02-01

Highlights: • ZnO nanobelts exhibit an appreciable response towards H{sub 2}S and NO. • At room temperature, sensor recovers completely after exposure to NO (1 to 60 ppm). • At room temperature, incomplete recovery observed on exposure to higher concentrations of H{sub 2}S (> 5 ppm). • Complete recovery on exposure to concentrations higher than 5 ppm H{sub 2}S is achieved by heating the sensor films at 250 °C. • Incomplete recovery after exposure to higher concentrations of H{sub 2}S is due to formation of ZnS. - Abstract: Gas sensing properties of ZnO nanobelts synthesized using carbothermal reduction method has been investigated. At room temperature (28 °C), the sensor films exhibit an appreciable response towards H{sub 2}S and NO and response of these two gases were studied as a function of concentration. For NO the sensor films exhibit a complete reversible curve for the concentration range between 1 and 60 ppm. However, for H{sub 2}S a complete recovery was obtained for concentration <5 ppm and for higher concentration a partial recovery of the baseline resistance was observed. The reason for the incomplete recovery was investigated using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) studies of the sample before and after the H{sub 2}S exposure. After exposure, appearance of an additional peak at 26.6° corresponding to the formation of ZnS was observed in XRD. Formation of additional phase was further corroborated using the results of XPS. H{sub 2}S exposure causes decrease in the intensity of O 1s peak and appearance of sulphide peaks at binding energies of 162.8 and 161.8 eV corresponding to S-2p peaks – 2p{sub 3/2} and 2p{sub 1/2}, confirms the formation of ZnS upon exposure.

MgO nanobelt-modified graphene-tantalum wire electrode for the simultaneous determination of ascorbic acid, dopamine and uric acid

International Nuclear Information System (INIS)

Zhao, Liwei; Li, Hongji; Gao, Sumei; Li, Mingji; Xu, Sheng; Li, Cuiping; Guo, Wenlong; Qu, Changqing; Yang, Baohe

2015-01-01

Graphical abstract: Display Omitted -- Highlights: •Graphene and MgO nanobelts are deposited on tantalum wires to form biosensors. •Ascorbic acid, dopamine and uric acid are determined with the biosensors. •The biosensors show high electrocatalytic activity for oxidation of these species. •The biosensors show high selectivity and good sensitivity. -- ABSTRACT: A promising electrochemical biosensor for simultaneous detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA) was fabricated by electrochemical deposition of MgO nanobelts on a graphene-modified tantalum wire (denoted as MgO/Gr/Ta) electrode. The MgO nanobelts and graphene were verified by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Electrochemical performances of the electrodes were characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The CV results show that AA, DA and UA could be detected simultaneously using MgO/Gr/Ta electrode with peak-to-peak separation of 300 mV, 147 mV and 447 mV for AA-DA, DA-UA and AA-UA, respectively. In the threefold co-existence system, the linear calibration plots for AA, DA and UA were obtained over the concentration range of 5.0–350 μM, 0.1–7 μM and 1–70 μM with detection limits of 0.03 μM, 0.15 μM and 0.12 μM, respectively. The modified electrode shows excellent selectivity, good sensitivity and good stability, making it attractive as a sensor for simultaneous detection of AA, DA and UA in biological fluids

The TITAN reversed-field-pinch fusion reactor study

International Nuclear Information System (INIS)

1990-01-01

This report discusses the following topics: overview of titan-2 design; titan-2 fusion-power-core engineering; titan-2 divertor engineering; titan-2 tritium systems; titan-2 safety design and radioactive-waste disposal; and titan-2 maintenance procedures

The TITAN reversed-field-pinch fusion reactor study

Energy Technology Data Exchange (ETDEWEB)

1990-01-01

This report discusses the following topics: overview of titan-2 design; titan-2 fusion-power-core engineering; titan-2 divertor engineering; titan-2 tritium systems; titan-2 safety design and radioactive-waste disposal; and titan-2 maintenance procedures.

Titan's organic chemistry

Science.gov (United States)

Sagan, C.; Thompson, W. R.; Khare, B. N.

1985-01-01

Voyager discovered nine simple organic molecules in the atmosphere of Titan. Complex organic solids, called tholins, produced by irradiation of the simulated Titanian atmosphere, are consistent with measured properties of Titan from ultraviolet to microwave frequencies and are the likely main constituents of the observed red aerosols. The tholins contain many of the organic building blocks central to life on earth. At least 100-m, and possibly kms thicknesses of complex organics have been produced on Titan during the age of the solar system, and may exist today as submarine deposits beneath an extensive ocean of simple hydrocarbons.

A green synthesis of a layered titanate, potassium lithium titanate; lower temperature solid-state reaction and improved materials performance

International Nuclear Information System (INIS)

Ogawa, Makoto; Morita, Masashi; Igarashi, Shota; Sato, Soh

2013-01-01

A layered titanate, potassium lithium titanate, with the size range from 0.1 to 30 µm was prepared to show the effects of the particle size on the materials performance. The potassium lithium titanate was prepared by solid-state reaction as reported previously, where the reaction temperature was varied. The reported temperature for the titanate preparation was higher than 800 °C, though 600 °C is good enough to obtain single-phase potassium lithium titanate. The lower temperature synthesis is cost effective and the product exhibit better performance as photocatalysts due to surface reactivity. - Graphical abstract: Finite particle of a layered titanate, potassium lithium titanate, was prepared by solid-state reaction at lower temperature to show modified materials performance. Display Omitted - Highlights: • Potassium lithium titanate was prepared by solid-state reaction. • Lower temperature reaction resulted in smaller sized particles of titanate. • 600 °C was good enough to obtain single phased potassium lithium titanate. • The product exhibited better performance as photocatalyst

Effect of sludge solids to mono-sodium titanate (MST) ratio on MST-treated sludge

International Nuclear Information System (INIS)

Saito, H.H.

1999-01-01

The Salt Disposition Systems Engineering Team has selected two cesium removal technologies for further development to replace the In-Tank Precipitation process: small tank tetraphenylborate (TPB) precipitation and crystalline silicotitanate (CST) ion exchange. In the CST ion exchange process, incoming salt solution from storage tanks containing entrained sludge solids is pretreated with monosodium titanate (MST) to adsorb strontium and plutonium. The resulting slurry is filtered using a cross-flow filter, with the permeate sent forward to CST ion exchange columns for cesium removal prior to conversion into Class A grout at the Saltstone Facility. The MST and sludge solids are to be sent for vitrification at the Defense Waste Processing Facility (DWPF). The High Level Waste Division (HLWD) requested that the Waste Processing Technology Section (WPTS) study varying the insoluble sludge solids to MST ratio to determine the relative impact of sludge and MST on filter performance. The purpose of this study was not for an exhaustive comprehensive search for an optimized insoluble sludge solids to monosodium titanate (MST) ratio, but as a scoping study to identify any effects of having an excess of either material. This document reports the results obtained

The TITAN reversed-field-pinch fusion reactor study

International Nuclear Information System (INIS)

1990-01-01

This report discusses research on the titan-1 fusion power core. The major topics covered are: titan-1 fusion-power-core engineering; titan-1 divertor engineering; titan-1 tritium systems; titan-1 safety design and radioactive-waste disposal; and titan-1 maintenance procedures

The TITAN reversed-field-pinch fusion reactor study

Energy Technology Data Exchange (ETDEWEB)

1990-01-01

This report discusses research on the titan-1 fusion power core. The major topics covered are: titan-1 fusion-power-core engineering; titan-1 divertor engineering; titan-1 tritium systems; titan-1 safety design and radioactive-waste disposal; and titan-1 maintenance procedures.

Titan's Methane Cycle is Closed

Science.gov (United States)

Hofgartner, J. D.; Lunine, J. I.

2013-12-01

Doppler tracking of the Cassini spacecraft determined a polar moment of inertia for Titan of 0.34 (Iess et al., 2010, Science, 327, 1367). Assuming hydrostatic equilibrium, one interpretation is that Titan's silicate core is partially hydrated (Castillo-Rogez and Lunine, 2010, Geophys. Res. Lett., 37, L20205). These authors point out that for the core to have avoided complete thermal dehydration to the present day, at least 30% of the potassium content of Titan must have leached into an overlying water ocean by the end of the core overturn. We calculate that for probable ammonia compositions of Titan's ocean (compositions with greater than 1% ammonia by weight), that this amount of potassium leaching is achievable via the substitution of ammonium for potassium during the hydration epoch. Formation of a hydrous core early in Titan's history by serpentinization results in the loss of one hydrogen molecule for every hydrating water molecule. We calculate that complete serpentinization of Titan's core corresponds to the release of more than enough hydrogen to reconstitute all of the methane atoms photolyzed throughout Titan's history. Insertion of molecular hydrogen by double occupancy into crustal clathrates provides a storage medium and an opportunity for ethane to be converted back to methane slowly over time--potentially completing a cycle that extends the lifetime of methane in Titan's surface atmosphere system by factors of several to an order of magnitude over the photochemically-calculated lifetime.

Chemistry and evolution of Titan's atmosphere

International Nuclear Information System (INIS)

Strobel, D.F.

1982-01-01

The chemistry and evolution of Titan's atmosphere is reviewed in the light of the scientific findings from the Voyager mission. It is argued that the present N 2 atmosphere may be Titan's initial atmosphere rather than photochemically derived from an original NH 3 atmosphere. The escape rate of hydrogen from Titan is controlled by photochemical production from hydrocarbons. CH 4 is irreversibly converted to less hydrogen rich hydrocarbons, which over geologic time accumulate on the surface to a layer thickness of approximately 0.5 km. Magnetospheric electrons interacting with Titan's exosphere may dissociate enough N 2 into hot, escaping N atoms to remove approximately 0.2 of Titan's present atmosphere over geologic time. The energy dissipation of magnetospheric electrons exceeds solar e.u.v. energy deposition in Titan's atmosphere by an order of magnitude and is the principal driver of nitrogen photochemistry. The environmental conditions in Titan's upper atmosphere are favorable to building up complex molecules, particularly in the north polar cap region. (author)

Titan Polar Landscape Evolution

Science.gov (United States)

Moore, Jeffrey M.

2016-01-01

With the ongoing Cassini-era observations and studies of Titan it is clear that the intensity and distribution of surface processes (particularly fluvial erosion by methane and Aeolian transport) has changed through time. Currently however, alternate hypotheses substantially differ among specific scenarios with respect to the effects of atmospheric evolution, seasonal changes, and endogenic processes. We have studied the evolution of Titan's polar region through a combination of analysis of imaging, elevation data, and geomorphic mapping, spatially explicit simulations of landform evolution, and quantitative comparison of the simulated landscapes with corresponding Titan morphology. We have quantitatively evaluated alternate scenarios for the landform evolution of Titan's polar terrain. The investigations have been guided by recent geomorphic mapping and topographic characterization of the polar regions that are used to frame hypotheses of process interactions, which have been evaluated using simulation modeling. Topographic information about Titan's polar region is be based on SAR-Topography and altimetry archived on PDS, SAR-based stereo radar-grammetry, radar-sounding lake depth measurements, and superposition relationships between geomorphologic map units, which we will use to create a generalized topographic map.

Three-dimensional graphene sheets with NiO nanobelt outgrowths for enhanced capacity and long term high rate cycling Li-ion battery anode material

Science.gov (United States)

Shi, Waipeng; Zhang, Yingmeng; Key, Julian; Shen, Pei Kang

2018-03-01

An efficient synthesis method to grow well attached NiO nanobelts from 3D graphene sheets (3DGS) is reported herein. Ni-ion exchanged resin provides the initial Ni reactant portion, which serves both as a catalyst to form 3DGS and then as a seeding agent to grow the NiO nanobelts. The macroporous structure of 3DGS provides NiO containment to achieve a high cycling stability of up to 445 mAh g-1 after 360 cycles (and >112% capacity retention after 515 cycles) at a high current density of 2 A g-1. With a 26.8 wt.% content of NiO on 3DGS, increases in specific and volumetric capacity were 41.6 and 75.7% respectively over that of 3DGS at matching current densities. Therefore, the seeded growth of NiO nanobelts from 3DGS significantly boosts volumetric capacity, while 3DGS enables high rate long term cycling of the NiO. The high rate cycling stability of NiO on 3DGS can be attributed to (i) good attachment and contact to the large surface of 3DGS, (ii) high electron conductivity and rapid Li-ion transfer (via the interconnected, highly conductive graphitized walls of 3DGS) and (iii) buffering void space in 3DGS to contain volume expansion of NiO during charge/discharge.

Interaction of Titan's atmosphere with Saturn's magnetosphere

International Nuclear Information System (INIS)

Hartle, R.E.

1985-01-01

The Voyager 1 measurements made during the Titan flyby reveal that Saturn's rotating magnetospheric plasma interacts directly with Titan's neutral atmosphere and ionosphere. This results from the lack of an intrinsic magnetic field at Titan. The interaction induces a magnetosphere which deflects the flowing plasma around Titan and forms a plasma wake downstream. Within the tail of the induced magnetosphere, ions of ionospheric origin flow away from Titan. Just outside Titan's magnetosphere, a substantial ion-exosphere forms from an extensive hydrogen-nitrogen exosphere. The exospheric ions are picked up and carried downstream into the wake by the plasma flowing around Titan. Mass loading produced by the addition of exospheric ions slows the wake plasma down considerably in the vicinity of the magnetopause. 36 references

Titanic: A Statistical Exploration.

Science.gov (United States)

Takis, Sandra L.

1999-01-01

Uses the available data about the Titanic's passengers to interest students in exploring categorical data and the chi-square distribution. Describes activities incorporated into a statistics class and gives additional resources for collecting information about the Titanic. (ASK)

The age of Titan's surface

Science.gov (United States)

Neish, C. D.; Lorenz, R. D.

2010-04-01

High-resolution images of the surface of Titan taken by the Cassini spacecraft reveal a world with an extreme paucity of impact craters. Planetary surfaces are commonly dated by dividing the number of impact craters by the estimated impactor flux, but this approach has been confounded at Titan by several difficulties. First, high-resolution imaging of the surface of Titan is far from complete (in the near-infrared as well as radar). As of December 2007, Cassini RADAR images covered only 22% of its surface. However, we can use Monte-Carlo models to explore how many craters of a given size (with large or very large craters being of particular interest) may be present in the unobserved areas. Second, literature descriptions of the crater formation rate (e.g. Korycansky and Zahnle 2005 and Artemieva and Lunine 2005) are apparently not in agreement. We discuss possible resolutions. Third, since surface modification processes are ongoing, the actual number of craters on Titan's surface remains uncertain, as craters may be eroded beyond recognition, or obscured by lakes or sand seas. In this connection, we use the Earth as an analogue. The Earth is in many ways the most "Titan-like" world in the solar system, with extensive modification by erosion, burial, tectonism, and volcanism. We compare the observed number of terrestrial craters to the expected terrestrial impactor flux to determine the crater reduction factor for a world similar to Titan. From this information, we can back out the actual number of craters on Titan's surface and estimate its crater retention age. An accurate age estimate will be critical for constraining models of Titan's formation and evolution.

The Titan Sky Simulator ™ - Testing Prototype Balloons in Conditions Approximating those in Titan's Atmosphere

Science.gov (United States)

Nott, Julian

This paper will describe practical work flying prototype balloons in the "The Titan Sky Simulator TM " in conditions approximating those found in Titan's atmosphere. Saturn's moon, Titan, is attracting intense scientific interest. This has led to wide interest in exploring it with Aerobots, balloons or airships. Their function would be similar to the Rovers exploring Mars, but instead of moving laboriously across the rough terrain on wheels, they would float freely from location to location. To design any balloon or airship it is essential to know the temperature of the lifting gas as this influences the volume of the gas, which in turn influences the lift. To determine this temperature it is necessary to know how heat is transferred between the craft and its surroundings. Heat transfer for existing balloons is well understood. However, Titan conditions are utterly different from those in which balloons have ever been flown, so heat transfer rates cannot currently be calculated. In particular, thermal radiation accounts for most heat transfer for existing balloons but over Titan heat transfer will be dominated by convection. To be able to make these fundamental calculations, it is necessary to get fundamental experimental data. This is being obtained by flying balloons in a Simulator filled with nitrogen gas at very low temperature, about 95° K / minus 180° C, typical of Titan's temperatures. Because the gas in the Simulator is so cold, operating at atmospheric pressure the density is close to that of Titan's atmosphere. "The Titan Sky Simulator TM " has an open interior approximately 4.5 meter tall and 2.5 meters square. It has already been operated at 95° K/-180° C. By the time of the Conference it is fully expected to have data to present from actual balloons flying at this temperature. Perhaps the most important purpose of this testing is to validate numerical [computational fluid dynamics] models being developed by Tim Colonius of Caltech. These numerical

The atmospheric temperature structure of Titan

Science.gov (United States)

Mckay, Christopher P.; Pollack, J. B.; Courtin, Regis; Lunine, Jonathan I.

1992-01-01

The contribution of various factors to the thermal structure of Titan's past and present atmosphere are discussed. A one dimensional model of Titan's thermal structure is summarized. The greenhouse effect of Titan's atmosphere, caused primarily by pressure induced opacity of N2, CH4, and H2, is discussed together with the antigreenhouse effect dominated by the haze which absorbs incident sunlight. The implications for the atmosphere of the presence of an ocean on Titan are also discussed.

A novel 3D structure composed of strings of hierarchical TiO{sub 2} spheres formed on TiO{sub 2} nanobelts with high photocatalytic properties

Energy Technology Data Exchange (ETDEWEB)

Jiang, Yongjian [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, School of Renewable Energy, North China Electric Power University, Beijing 102206 (China); Li, Meicheng, E-mail: mcli@ncepu.edu.cn [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, School of Renewable Energy, North China Electric Power University, Beijing 102206 (China); Suzhou Institute, North China Electric Power University, Suzhou 215123 (China); Song, Dandan; Li, Xiaodan; Yu, Yue [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, School of Renewable Energy, North China Electric Power University, Beijing 102206 (China)

2014-03-15

A novel hierarchical titanium dioxide (TiO{sub 2}) composite nanostructure with strings of anatase TiO{sub 2} hierarchical micro-spheres and rutile nanobelts framework (TiO{sub 2} HSN) is successfully synthesized via a one-step hydrothermal method. Particularly, the strings of hierarchical spheres are assembled by very thin TiO{sub 2} nanosheets, which are composed of highly crystallized anatase nanocrystals. Meanwhile, the HSN has a large surface area of 191 m{sup 2}/g, which is about 3 times larger than Degussa P25. More importantly, the photocatalytic activity of HSN and P25 were evaluated by the photocatalytic oxidation decomposition of methyl orange (MO) under UV light illumination, and the TiO{sub 2} HSN shows enhanced photocatalytic activity compared with Degussa P25, as result of its continuous hierarchical structures, special conductive channel and large specific surface area. With these features, the hierarchical TiO{sub 2} may have more potential applications in the fields of dye-sensitized solar cells and lithium ion batteries. -- Graphical abstract: Novel TiO{sub 2} with anatase micro-spheres and rutile nanobelts is synthesized. Enhanced photocatalysis is attributed to hierarchical structures (3D spheres), conductive channel (1D nanobelts) and large specific surface area (2D nanosheet). Highlights: • The novel TiO{sub 2} nanostructure (HSN) is fabricated for the first time. • HSN is composed of strings of anatase hierarchical spheres and rutile nanobelt. • HSN presents a larger S{sub BET} of 191 m{sup 2}/g, 3 times larger than the Degussa P25 (59 m{sup 2}/g). • HSN owns three kinds of dimensional TiO{sub 2} (1D, 2D and 3D) simultaneously. • HSN exhibits better photocatalytic performance compared with Degussa P25.

Synthesis of {alpha}-Fe{sub 2}O{sub 3} nanobelts and nanoflakes by thermal oxidation and study to their magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Su Xinghua [School of Materials Science and Engineering, Chang' an University, Xi' an 710061 (China); Yu Chengshou [Department of Materials Science and Engineering, Lanzhou University, Lanzhou 730000 (China); Qiang Chengwen, E-mail: qiangchw04@gmail.com [Department of Materials Science and Engineering, Lanzhou University, Lanzhou 730000 (China); Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China)

2011-08-15

{alpha}-Fe{sub 2}O{sub 3} nanobelts and nanoflakes have been successfully synthesized by oxidation of iron-coated ITO glass in air. The X-ray diffraction, Raman spectrum and scanning electron microscopy are carried out to characterize the nanobelts and nanoflakes. The formation mechanism has been presented. Significantly, the magnetic investigations show that the magnetic properties are strongly shape-dependent. The magnetization measurements of belt-like and flake-like {alpha}-Fe{sub 2}O{sub 3} in perpendicular exhibit ferromagnetic feature with the coercivity (H{sub c}) and saturation magnetization (M{sub s}) of 334.5 Oe and 1.35 emu/g, 239.5 Oe and 0.12 emu/g, respectively. For the parallel, belt-like and flake-like {alpha}-Fe{sub 2}O{sub 3} also exhibit ferromagnetic feature with the H{sub c} and M{sub s} of 205.5 Oe and 1.44 emu/g, 159.6 Oe and 0.15 emu/g, respectively.

Titan Orbiter Aerorover Mission

Science.gov (United States)

Sittler Jr., E. C.; Acuna, M.; Burchell, M. J.; Coates, A.; Farrell, W.; Flasar, M.; Goldstein, B. E.; Gorevan, S.; Hartle, R. E.; Johnson, W. T. K.

2001-01-01

We propose a combined Titan orbiter and Titan Aerorover mission with an emphasis on both in situ and remote sensing measurements of Titan's surface, atmosphere, ionosphere, and magnetospheric interaction. The biological aspect of the Titan environment will be emphasized by the mission (i.e., search for organic materials which may include simple organics to 'amono' analogues of amino acids and possibly more complex, lightening detection and infrared, ultraviolet, and charged particle interactions with Titan's surface and atmosphere). An international mission is assumed to control costs. NASA will provide the orbiter, launch vehicle, DSN coverage and operations, while international partners will provide the Aerorover and up to 30% of the cost for the scientific instruments through collaborative efforts. To further reduce costs we propose a single PI for orbiter science instruments and a single PI for Aerorover science instruments. This approach will provide single command/data and power interface between spacecraft and orbiter instruments that will have redundant central DPU and power converter for their instruments. A similar approach could be used for the Aerorover. The mission profile will be constructed to minimize conflicts between Aerorover science, orbiter radar science, orbiter radio science, orbiter imaging science, and orbiter fields and particles (FP) science. Additional information is contained in the original extended abstract.

Filtration of Sludge and Sodium Nonatitanate Solutions

International Nuclear Information System (INIS)

Poirier, M.R.

2000-01-01

The proposed facility designs for the ion exchange and solvent extraction flowsheets under development to treat high level waste at the Savannah River Site use crossflow filtration to remove entrained sludge and monosodium titanate (MST). Bench-scale and pilot-scale testing performed with simulated feed streams showed much lower filtration rates than desired for the process. This report documents an investigation of the impact on filtration of using Honeywell sodium nonatitanate (ST), rather than MST, for strontium and actinide removal

Titan AVIATR - Aerial Vehicle for In Situ and Airborne Titan Reconnaissance

Science.gov (United States)

Kattenhorn, Simon A.; Barnes, J. W.; McKay, C. P.; Lemke, L.; Beyer, R. A.; Radebaugh, J.; Adamkovics, M.; Atkinson, D. H.; Burr, D. M.; Colaprete, T.; Foch, R.; Le Mouélic, S.; Merrison, J.; Mitchell, J.; Rodriguez, S.; Schaller, E.

2010-10-01

Titan AVIATR - Aerial Vehicle for In Situ and Airborne Titan Reconnaissance - is a small (120 kg), nuclear-powered Titan airplane in the Discovery/New Frontiers class based on the concept of Lemke (2008 IPPW). The scientific goals of the mission are designed around the unique flexibility offered by an airborne platform: to explore Titan's diversity of surface landforms, processes, and compositions, as well as to study and measure the atmospheric circulation, aerosols, and humidity. AVIATR would address and surpass many of the science goals of hot-air balloons in Titan flagship studies. The strawman instrument payload is narrowly focused on the stated scientific objectives. The optical remote sensing suite comprises three instruments - an off-nadir high-resolution 2-micron camera, a horizon-looking 5-micron imager, and a 1-6 micron pushbroom near-infrared spectrometer. The in situ instruments include atmospheric structure, a methane humidity sensor, and a raindrop detector. An airplane has operational advantages over a balloon. Its piloted nature allows a go-to capability to image locations of interest in real time, thereby allowing for directed exploration of many features of primary geologic interest: Titan's sand dunes, mountains, craters, channels, and lakes. Subsequent imaging can capture changes in these features during the primary mission. AVIATR can fly predesigned routes, building up large context mosaics of areas of interest before swooping down to low altitude to acquire high-resolution images at 30-cm spatial sampling, similar to that of HiRISE at Mars. The elevation flexibility of the airplane allows us to acquire atmospheric profiles as a function of altitude at any desired location. Although limited by the direct-to-Earth downlink bandwidth, the total scientific data return from AVIATR will be >40 times that returned from Huygens. To maximize the science per bit, novel data storage and downlink techniques will be employed, including lossy compression

Titanate nanotube thin films with enhanced thermal stability and high-transparency prepared from additive-free sols

Energy Technology Data Exchange (ETDEWEB)

Koroesi, Laszlo, E-mail: korosi@enviroinvest.hu [Supramolecular and Nanostructured Materials Research Group of the Hungarian Academy of Sciences, University of Szeged, Aradi vertanuk tere 1, H-6720 Szeged (Hungary); Department of Biotechnology, Nanophage Therapy Center, Enviroinvest Corporation, Kertvaros utca 2, H-7632 Pecs (Hungary); Papp, Szilvia [Supramolecular and Nanostructured Materials Research Group of the Hungarian Academy of Sciences, University of Szeged, Aradi vertanuk tere 1, H-6720 Szeged (Hungary); Department of Biotechnology, Nanophage Therapy Center, Enviroinvest Corporation, Kertvaros utca 2, H-7632 Pecs (Hungary); Hornok, Viktoria [Supramolecular and Nanostructured Materials Research Group of the Hungarian Academy of Sciences, University of Szeged, Aradi vertanuk tere 1, H-6720 Szeged (Hungary); Oszko, Albert [Department of Physical Chemistry and Materials Science, University of Szeged, Aradi vertanuk tere 1, H-6720 Szeged (Hungary); Petrik, Peter; Patko, Daniel; Horvath, Robert [Institute for Technical Physics and Materials Science MFA, Research Center for Natural Sciences, Konkoly-Thege ut 29-33, H-1121 Budapest (Hungary); Dekany, Imre [Supramolecular and Nanostructured Materials Research Group of the Hungarian Academy of Sciences, University of Szeged, Aradi vertanuk tere 1, H-6720 Szeged (Hungary)

2012-08-15

Titanate nanotubes were synthesized from TiO{sub 2} in alkaline medium by a conventional hydrothermal method (150 Degree-Sign C, 4.7 bar). To obtain hydrogen titanates, the as-prepared sodium titanates were treated with either HCl or H{sub 3}PO{sub 4} aqueous solutions. A simple synthesis procedure was devised for stable titanate nanotube sols without using any additives. These highly stable ethanolic sols can readily be used to prepare transparent titanate nanotube thin films of high quality. The resulting samples were studied by X-ray diffraction, N{sub 2}-sorption measurements, Raman spectroscopy, transmission and scanning electron microscopy, X-ray photoelectron spectroscopy and spectroscopic ellipsometry. The comparative results of using two kinds of acids shed light on the superior thermal stability of the H{sub 3}PO{sub 4}-treated titanate nanotubes (P-TNTs). X-ray photoelectron spectroscopy revealed that P-TNTs contains P in the near-surface region and the thermal stability was enhanced even at a low ({approx}0.5 at%) concentration of P. After calcination at 500 Degree-Sign C, the specific surface areas of the HCl- and H{sub 3}PO{sub 4}-treated samples were 153 and 244 m{sup 2} g{sup -1}, respectively. The effects of H{sub 3}PO{sub 4} treatment on the structure, morphology and porosity of titanate nanotubes are discussed. - Graphical Abstract: TEM picture (left) shows P-TNTs with diameters about 5-6 nm. Inset shows a stable titanate nanotube sol illuminated by a 532 nm laser beam. Due to the presence of the nanoparticles the way of the light is visible in the sol. Cross sectional SEM picture (right) as well as ellipsometry revealed the formation of optical quality P-TNT films with thicknesses below 50 nm. Highlights: Black-Right-Pointing-Pointer H{sub 3}PO{sub 4} treatment led to TNTs with high surface area even after calcination at 500 Degree-Sign C. Black-Right-Pointing-Pointer H{sub 3}PO{sub 4}-treated TNTs preserved their nanotube morphology up to 500

Titan's greenhouse and antigreenhouse effects

Science.gov (United States)

Mckay, Christopher P.; Pollack, James B.; Courtin, Regis

1992-01-01

Thermal mechanisms active in Titan's atmosphere are discussed in a brief review of data obtained during the Voyager I flyby in 1980. Particular attention is given to the greenhouse effect (GHE) produced by atmospheric H2, N2, and CH4; this GHE is stronger than that on earth, with CH4 and H2 playing roles similar to those of H2O and CO2 on earth. Also active on Titan is an antigreenhouse effect, in which dark-brown and orange organic aerosols block incoming solar light while allowing IR radiation from the Titan surface to escape. The combination of GHE and anti-GHE leads to a surface temperature about 12 C higher than it would be if Titan had no atmosphere.

Study of growth of gadolinium-doped ceria nanobelts by a hydrothermal microwave system; Estudo do crescimento de nanofitas de ceria dopada com gadolinio por sistema de aquecimento por micro-ondas

Energy Technology Data Exchange (ETDEWEB)

Goncalves, R.F.; Castro, D.A.; Santos, M.R.C.; Figueiredo, A.T.; Godinho Junior, M. [Universidade Federal de Goias (UFG), Catalao, GO (Brazil). Dept. de Quimica; Barrado, C.M. [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Inst. de Ciencias Exatas e Naturais; Leite, E.R. [Universidade Federal de Sao Carlos (INCTMN/UFSCar), SP (Brazil). Dept. de Qumica

2013-07-15

Cerium oxide (ceria) has attracted attention because of its important applications such as solid oxide fuel cells, catalysts for automobile exhaust gas, catalysts to obtain hydrogen, UV blockers, biomaterials, etc.. Control methods for synthesis of ceria are of great importance to explain or predict these properties. Thus, the objective of this work was to study the growth of cerium oxide nanobelts in a microwave-assisted hydrothermal system, where in 8 min 330 nm nanobelts were obtained at 130 deg C and 3 atm. The results collaborate to the research on reformers for ethanol and/or solid oxide fuel cells anode. (author)

Titan Orbiter with Aerorover Mission (TOAM)

Science.gov (United States)

Sittler, Edward C.; Cooper, J. F.; Mahaffey, P.; Esper, J.; Fairbrother, D.; Farley, R.; Pitman, J.; Kojiro, D. R.; TOAM Team

2006-12-01

We propose to develop a new mission to Titan called Titan Orbiter with Aerorover Mission (TOAM). This mission is motivated by the recent discoveries of Titan, its atmosphere and its surface by the Huygens Probe, and a combination of in situ, remote sensing and radar mapping measurements of Titan by the Cassini orbiter. Titan is a body for which Astrobiology (i.e., prebiotic chemistry) will be the primary science goal of any future missions to it. TOAM is planned to use an orbiter and balloon technology (i.e., aerorover). Aerobraking will be used to put payload into orbit around Titan. The Aerorover will probably use a hot air balloon concept using the waste heat from the MMRTG 500 watts. Orbiter support for the Aerorover is unique to our approach for Titan. Our strategy to use an orbiter is contrary to some studies using just a single probe with balloon. Autonomous operation and navigation of the Aerorover around Titan will be required, which will include descent near to the surface to collect surface samples for analysis (i.e., touch and go technique). The orbiter can provide both relay station and GPS roles for the Aerorover. The Aerorover will have all the instruments needed to sample Titan’s atmosphere, surface, possible methane lakes-rivers, use multi-spectral imagers for surface reconnaissance; to take close up surface images; take core samples and deploy seismometers during landing phase. Both active and passive broadband remote sensing techniques will be used for surface topography, winds and composition measurements.

Enhancement of the piezoelectric properties of sodium lanthanum bismuth titanate (Na0.5La0.5Bi4Ti4O15) through modification with cobalt

International Nuclear Information System (INIS)

Wang Chunming; Wang Jinfeng; Zheng Limei; Zhao Minglei; Wang Chunlei

2010-01-01

The dielectric, piezoelectric, and electromechanical properties of B-site cobalt-modified sodium lanthanum bismuth titanate (Na 0.5 La 0.5 Bi 4 Ti 4 O 15 , NLBT) piezoelectric ceramics were investigated. The piezoelectric properties of NLBT ceramics can be enhanced by cobalt modifications. The NLBT ceramics modified with 0.2 wt.% cobalt trioxide (NLBT-C4) possess good piezoelectric properties, with piezoelectric coefficient d 33 of 27 pC/N, electromechanical coupling factors (k p and k t ) of 6.5% and 28.5%, and mechanical quality factor Q m (k p mode) of 3400. The Curie temperature T c of cobalt-modified NLBT ceramics was found to slightly higher than that of pure NLBT ceramics. A large dielectric abnormity in dielectric loss tan δ was observed in NLBT ceramics, which can be significantly suppressed by cobalt modification. Thermal annealing studies presented the cobalt-modified NLBT ceramics possess stable piezoelectric properties.

Titan's Ammonia Feature

Science.gov (United States)

Smythe, W.; Nelson, R.; Boryta, M.; Choukroun, M.

2011-01-01

NH3 has long been considered an important component in the formation and evolution of the outer planet satellites. NH3 is particularly important for Titan, since it may serve as the reservoir for atmospheric nitrogen. A brightening seen on Titan starting in 2004 may arise from a transient low-lying fog or surface coating of ammonia. The spectral shape suggests the ammonia is anhydrous, a molecule that hydrates quickly in the presence of water.

Organic chemistry on Titan: Surface interactions

Science.gov (United States)

Thompson, W. Reid; Sagan, Carl

1992-01-01

The interaction of Titan's organic sediments with the surface (solubility in nonpolar fluids) is discussed. How Titan's sediments can be exposed to an aqueous medium for short, but perhaps significant, periods of time is also discussed. Interactions with hydrocarbons and with volcanic magmas are considered. The alteration of Titan's organic sediments over geologic time by the impacts of meteorites and comets is discussed.

AVIATR - Aerial Vehicle for In-situ and Airborne Titan Reconnaissance A Titan Airplane Mission Concept

Science.gov (United States)

Barnes, Jason W.; Lemke, Lawrence; Foch, Rick; McKay, Christopher P.; Beyer, Ross A.; Radebaugh, Jani; Atkinson, David H.; Lorenz, Ralph D.; LeMouelic, Stephane; Rodriguez, Sebastien;

TSSM: The in situ exploration of Titan

Science.gov (United States)

Coustenis, A.; Lunine, J. I.; Lebreton, J. P.; Matson, D.; Reh, K.; Beauchamp, P.; Erd, C.

2008-09-01

The Titan Saturn System Mission (TSSM) mission was born when NASA and ESA decided to collaborate on two missions independently selected by each agency: the Titan and Enceladus mission (TandEM), and Titan Explorer, a 2007 Flagship study. TandEM, the Titan and Enceladus mission, was proposed as an L-class (large) mission in response to ESA's Cosmic Vision 2015-2025 Call. The mission concept is to perform remote and in situ investigations of Titan primarily, but also of Enceladus and Saturn's magentosphere. The two satellites are tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini-Huygens mission. These bodies still hold mysteries requiring a complete exploration using a variety of vehicles and instruments. TSSM will study Titan as a system, including its upper atmosphere, the interactions with the magnetosphere, the neutral atmosphere, surface, interior, origin and evolution, as well as the astrobiological potential of Titan. It is an ambitious mission because its targets are two of the most exciting and challenging bodies in the Solar System. It is designed to build on but exceed the scientific and technological accomplishments of the Cassini- Huygens mission, exploring Titan and Enceladus in ways that are not currently possible (full close-up and in situ coverage over long periods of time for Titan, several close flybys of Enceladus). One overarching goal of the TSSM mission is to explore in situ the atmosphere and surface of Titan. In the current mission architecture, TSSM consists of an orbiter (under NASA's responsibility) with a large host of instruments which would perform several Enceladus and Titan flybys before stabilizing in an orbit around Titan alone, therein delivering in situ elements (a Montgolfière, or hot air balloon, and a probe/lander). The latter are being studied by ESA. The balloon will circumnavigate Titan above the equator at an altitude of about 10 km for several months. The

Diurnal variations of Titan

Science.gov (United States)

Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Mueller-Wodarg, I. C. F.; Kasprzak, W. T.; Waite, J. H.

2009-04-01

We present our analysis of the diurnal variations of Titan's ionosphere (between 1,000 and 1,400 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from 8 close encounters of the Cassini spacecraft with Titan. Though there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ~700 cm-3 below ~1,300 km. Such a plateau is associated with the combination of distinct diurnal variations of light and heavy ions. Light ions (e.g. CH5+, HCNH+, C2H5+) show strong diurnal variation, with clear bite-outs in their nightside distributions. In contrast, heavy ions (e.g. c-C3H3+, C2H3CNH+, C6H7+) present modest diurnal variation, with significant densities observed on the nightside. We propose that the distinctions between light and heavy ions are associated with their different chemical loss pathways, with the former primarily through "fast" ion-neutral chemistry and the latter through "slow" electron dissociative recombination. The INMS data suggest day-to-night transport as an important source of ions on Titan's nightside, to be distinguished from the conventional scenario of auroral ionization by magnetospheric particles as the only ionizing source on the nightside. This is supported by the strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes. We construct a time-dependent ion chemistry model to investigate the effects of day-to-night transport on the ionospheric structures of Titan. The predicted diurnal variation has similar general characteristics to those observed, with some apparent discrepancies which could be reconciled by imposing fast horizontal thermal winds in Titan's upper atmosphere.

Self-assembly of palladium nanoparticles: Synthesis of nanobelts, nanoplates and nanotrees using vitamin B1 and their application in carbon-carbon coupling reactions

Science.gov (United States)

An environmentally friendly one-step method to synthesize palladium (Pd) nanobelts, nanoplates and nanotrees using vitamin B1 without using any special capping agents at room temperature is described. This greener method, which uses water as benign solvent and vitamin B1 as a red...

Amino acidis derived from Titan tholins

Science.gov (United States)

Khare, Bishun N.; Sagan, Carl; Ogino, Hiroshi; Nagy, Bartholomew; Er, Cevat

1986-01-01

The production of amino acids by acid treatment of Titan tholin is experimentally investigated. The synthesis of Titan tholin and the derivatization of amino acids to N-trifluoroacetyl isopropyl esters are described. The gas chromatography/mass spectroscopy analysis of the Titan tholins reveals the presence of glycine, alpha and beta alainine, and aspartic acid, and the total yield of amino acids is about 0.01.

Bismuth titanate nanorods and their visible light photocatalytic properties

International Nuclear Information System (INIS)

Pei, L.Z.; Liu, H.D.; Lin, N.; Yu, H.Y.

2015-01-01

Highlights: • Bismuth titanate nanorods have been synthesized by a simple hydrothermal process. • The size of bismuth titanate nanorods can be controlled by growth conditions. • Bismuth titanate nanorods show good photocatalytic activities of methylene blue and Rhodamine B. - Abstract: Bismuth titanate nanorods have been prepared using a facile hydrothermal process without additives. The bismuth titanate products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and UV-vis diffusion reflectance spectrum. XRD pattern shows that the bismuth titanate nanorods are composed of cubic Bi 2 Ti 2 O 7 phase. Electron microscopy images show that the length and diameter of the bismuth titanate nanorods are 50-200 nm and 2 μm, respectively. Hydrothermal temperature and reaction time play important roles on the formation and size of the bismuth titanate nanorods. UV-vis diffusion reflectance spectrum indicates that bismuth titanate nanorods have a band gap of 2.58 eV. The bismuth titanate nanorods exhibit good photocatalytic activities in the photocatalytic degradation of methylene blue (MB) and Rhodamine B (RB) under visible light irradiation. The bismuth titanate nanorods with cubic Bi 2 Ti 2 O 7 phase are a promising candidate as a visible light photocatalyst

Hubble Observes Surface of Titan

Science.gov (United States)

1994-01-01

Scientists for the first time have made images of the surface of Saturn's giant, haze-shrouded moon, Titan. They mapped light and dark features over the surface of the satellite during nearly a complete 16-day rotation. One prominent bright area they discovered is a surface feature 2,500 miles across, about the size of the continent of Australia.Titan, larger than Mercury and slightly smaller than Mars, is the only body in the solar system, other than Earth, that may have oceans and rainfall on its surface, albeit oceans and rain of ethane-methane rather than water. Scientists suspect that Titan's present environment -- although colder than minus 289 degrees Fahrenheit, so cold that water ice would be as hard as granite -- might be similar to that on Earth billions of years ago, before life began pumping oxygen into the atmosphere.Peter H. Smith of the University of Arizona Lunar and Planetary Laboratory and his team took the images with the Hubble Space Telescope during 14 observing runs between Oct. 4 - 18. Smith announced the team's first results last week at the 26th annual meeting of the American Astronomical Society Division for Planetary Sciences in Bethesda, Md. Co-investigators on the team are Mark Lemmon, a doctoral candidate with the UA Lunar and Planetary Laboratory; John Caldwell of York University, Canada; Larry Sromovsky of the University of Wisconsin; and Michael Allison of the Goddard Institute for Space Studies, New York City.Titan's atmosphere, about four times as dense as Earth's atmosphere, is primarily nitrogen laced with such poisonous substances as methane and ethane. This thick, orange, hydrocarbon haze was impenetrable to cameras aboard the Pioneer and Voyager spacecraft that flew by the Saturn system in the late 1970s and early 1980s. The haze is formed as methane in the atmosphere is destroyed by sunlight. The hydrocarbons produced by this methane destruction form a smog similar to that found over large cities, but is much thicker

Nanotubes, nanobelts, nanowires, and nanorods of silicon carbide from the wheat husks

Energy Technology Data Exchange (ETDEWEB)

Qadri, S. B.; Rath, B. B.; Gorzkowski, E. P.; Feng, J.; Qadri, S. N.; Caldwell, J. D. [Materials Science and Component Technology Directorate, Naval Research Laboratory, Washington, District of Columbia 20375 (United States)

2015-09-14

Nanotubes, nanowires, nanobelts, and nanorods of SiC were synthesized from the thermal treatment of wheat husks at temperatures in excess of 1450 °C. From the analysis based on x-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy, it has been found that the processed samples of wheat husk consisted of 2H and 3C polytypes of SiC exhibiting the nanostructure shapes. These nanostructures of silicon carbide formed from wheat husks are of technological importance for designing advance composites, applications in biotechnology, and electro-optics. The thermodynamics of the formation of SiC is discussed in terms of the rapid solid state reaction between hydrocarbons and silica on the molecular scale, which is inherently present in the wheat husks.

The rotation of Titan and Ganymede

Science.gov (United States)

Van Hoolst, Tim; Coyette, Alexis; Baland, Rose-Marie; Trinh, Antony

2016-10-01

The rotation rates of Titan and Ganymede, the largest satellites of Saturn and Jupiter, are on average equal to their orbital mean motion. Here we discuss small deviations from the average rotation for both satellites and evaluate the polar motion of Titan induced by its surface fluid layers. We examine different causes at various time scales and assess possible consequences and the potential of using librations and polar motion as probes of the interior structure of the satellites.The rotation rate of Titan and Ganymede cannot be constant on the orbital time scale as a result of the gravitational torque of the central planet acting on the satellites. Titan is moreover expected to show significant polar motion and additional variations in the rotation rate due to angular momentum exchange with the atmosphere, mainly at seasonal periods. Observational evidence for deviations from the synchronous state has been reported several times for Titan but is unfortunately inconclusive. The measurements of the rotation variations are based on determinations of the shift in position of Cassini radar images taken during different flybys. The ESA JUICE (JUpiter ICy moons Explorer) mission will measure the rotation variations of Ganymede during its orbital phase around the satellite starting in 2032.We report on different theoretical aspects of the librations and polar motion. We consider the influence of the rheology of the ice shell and take into account Cassini measurements of the external gravitational field and of the topography of Titan and similar Galileo data about Ganymede. We also evaluate the librations and polar motion induced by Titan's hydrocarbon seas and use the most recent results of Titan's atmosphere dynamics. We finally evaluate the potential of rotation variations to constrain the satellite's interior structure, in particular its ice shell and ocean.

Future Exploration of Titan and Enceladus

Science.gov (United States)

Matson, D. L.; Coustenis, A.; Lunine, J.; Lebreton, J.; Reh, K.; Beauchamp, P.

2009-05-01

The future exploration of Titan and Enceladus has become very important for the planetary community. The study conducted last year of the Titan Saturn System Mission (TSSM) led to an announcement in which ESA and NASA prioritized future OPF missions, stating that TSSM is planned after EJSM (for details see http://www.lpi.usra.edu/opag/). TSSM consists of a TSSM Orbiter that would carry two in situ elements: the Titan Montgolfiere hot air balloon and the Titan Lake Lander. The mission could launch in the 2023-2025 timeframe on a trajectory to arrive ~9 years later for a 4-year mission in the Saturn system. Soon after arrival at Saturn, the montgolfiere would be delivered to Titan to begin its mission of airborne, scientific observations of Titan from an altitude of about 10 km. The montgolfiere would have a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) power system and would be designed to last at least 6-12 months in Titan's atmosphere. With the predicted winds and weather, that would be sufficient to circumnavigate the globe! On a subsequent fly-by, the TSSM orbiter would release the Lake Lander on a trajectory toward Titan for a targeted entry. It would descend through the atmosphere making scientific measurements, much like Huygens did, and then land and float on one of Titan's seas. This would be its oceanographic phase, making a physical and chemical assessment of the sea. The Lake Lander would operate 8-10 hours until its batteries become depleted. Following the delivery of the in situ elements, the TSSM orbiter would explore the Saturn system via a 2-year tour that includes in situ sampling of Enceladus' plumes as well as Titan flybys. After the Saturn system tour, the TSSM orbiter would enter orbit around Titan for a global survey phase. Synergistic and coordinated observations would be carried out between the TSSM orbiter and the in situ elements. The scientific requirements were developed by the international TSSM Joint Science Definition

Clash of the Titans

Science.gov (United States)

Subramaniam, Karthigeyan

2010-01-01

WebQuests and the 5E learning cycle are titans of the science classroom. These popular inquiry-based strategies are most often used as separate entities, but the author has discovered that using a combined WebQuest and 5E learning cycle format taps into the inherent power and potential of both strategies. In the lesson, "Clash of the Titans,"…

TITAN'S TRANSPORT-DRIVEN METHANE CYCLE

International Nuclear Information System (INIS)

Mitchell, Jonathan L.

2012-01-01

The mechanisms behind the occurrence of large cloud outbursts and precipitation on Titan have been disputed. A global- and annual-mean estimate of surface fluxes indicated only 1% of the insolation, or ∼0.04 W m –2 , is exchanged as sensible and/or latent fluxes. Since these fluxes are responsible for driving atmospheric convection, it has been argued that moist convection should be quite rare and precipitation even rarer, even if evaporation globally dominates the surface-atmosphere energy exchange. In contrast, climate simulations indicate substantial cloud formation and/or precipitation. We argue that the top-of-atmosphere (TOA) radiative imbalance is diagnostic of horizontal heat transport by Titan's atmosphere, and thus constrains the strength of the methane cycle. Simple calculations show the TOA radiative imbalance is ∼0.5-1 W m –2 in Titan's equatorial region, which implies 2-3 MW of latitudinal heat transport by the atmosphere. Our simulation of Titan's climate suggests this transport may occur primarily as latent heat, with net evaporation at the equator and net accumulation at higher latitudes. Thus, the methane cycle could be 10-20 times previous estimates. Opposing seasonal transport at solstices, compensation by sensible heat transport, and focusing of precipitation by large-scale dynamics could further enhance the local, instantaneous strength of Titan's methane cycle by a factor of several. A limited supply of surface liquids in regions of large surface radiative imbalance may throttle the methane cycle, and if so, we predict more frequent large storms over the lakes district during Titan's northern summer.

Magnetic-field and temperature dependence of the energy gap in InN nanobelt

Directory of Open Access Journals (Sweden)

K. Aravind

2012-03-01

Full Text Available We present tunneling measurements on an InN nanobelt which shows signatures of superconductivity. Superconducting transition takes place at temperature of 1.3K and the critical magnetic field is measured to be about 5.5kGs. The energy gap extrapolated to absolute temperature is about 110μeV. As the magnetic field is decreased to cross the critical magnetic field, the device shows a huge zero-bias magnetoresistance ratio of about 400%. This is attributed to the suppression of quasiparticle subgap tunneling in the presence of superconductivity. The measured magnetic-field and temperature dependence of the superconducting gap agree well with the reported dependences for conventional metallic superconductors.

Chemical investigation of Titan and Triton tholins

Science.gov (United States)

Mcdonald, Gene D.; Thompson, W. R.; Heinrich, Michael; Khare, Bishun N.; Sagan, Carl

1994-01-01

We report chromatographic and spectroscopic analyses of both Titan and Triton tholins, organic solids made from the plasma irradiation of 0.9:0.1 and 0.999:0.001 N2/CH4 gas mixtures, respectively. The lower CH4 mixing ratio leads to a nitrogen-richer tholin (N/C greater than 1), probably including nitrogen heterocyclic compounds. Unlike Titan tholin, bulk Triton tholin is poor in nitriles. From high-pressure liquid chromatography, ultraviolet and infrared spectroscopy, and molecular weight estimation by gel filtration chromatography, we conclude that (1) several H2O-soluble fractions, each with distinct UV and IR spectral signatures, are present, (2) these fractions are not identical in the two tholins, (3) the H2O-soluble fractions of Titan tholins do not contain significant amounts of nitriles, despite the major role of nitriles in bulk Titan tholin, and (4) the H2O-soluble fractions of both tholins are mainly molcules containing about 10 to 50 (C + N) atoms. We report yields of amino acids upon hydrolysis of Titan and Triton tholins. Titan tholin is largely insoluble in the putative hydrocarbon lakes or oceans on Titan, but can yield the H2O-soluble species investigated here upon contact with transient (e.g., impact-generated) liquid water.

The Exploration of Titan and the Saturnian System

Science.gov (United States)

Coustenis, Athena

The exploration of the outer solar system and in particular of the giant planets and their environments is an on-going process with the Cassini spacecraft currently around Saturn, the Juno mission to Jupiter preparing to depart and two large future space missions planned to launch in the 2020-2025 time frame for the Jupiter system and its satellites (Europa and Ganymede) on the one hand, and the Saturnian system and Titan on the other hand [1,2]. Titan, Saturn's largest satellite, is the only other object in our Solar system to possess an extensive nitrogen atmosphere, host to an active organic chemistry, based on the interaction of N2 with methane (CH4). Following the Voyager flyby in 1980, Titan has been intensely studied from the ground-based large telescopes (such as the Keck or the VLT) and by artificial satellites (such as the Infrared Space Observatory and the Hubble Space Telescope) for the past three decades. Prior to Cassini-Huygens, Titan's atmospheric composition was thus known to us from the Voyager missions and also through the explorations by the ISO. Our perception of Titan had thus greatly been enhanced accordingly, but many questions remained as to the nature of the haze surrounding the satellite and the composition of the surface. The recent revelations by the Cassini-Huygens mission have managed to surprise us with many discoveries [3-8] and have yet to reveal more of the interesting aspects of the satellite. The Cassini-Huygens mission to the Saturnian system has been an extraordinary success for the planetary community since the Saturn-Orbit-Insertion (SOI) in July 2004 and again the very successful probe descent and landing of Huygens on January 14, 2005. One of its main targets was Titan. Titan was revealed to be a complex world more like the Earth than any other: it has a dense mostly nitrogen atmosphere and active climate and meteorological cycles where the working fluid, methane, behaves under Titan conditions the way that water does on

Seasonal Changes in Titan's Meteorology

Science.gov (United States)

Turtle, E. P.; DelGenio, A. D.; Barbara, J. M.; Perry, J. E.; Schaller, E. L.; McEwen, A. S.; West, R. A.; Ray, T. L.

2011-01-01

The Cassini Imaging Science Subsystem has observed Titan for 1/4 Titan year, and we report here the first evidence of seasonal shifts in preferred locations of tropospheric methane clouds. South \\polar convective cloud activity, common in late southern summer, has become rare. North \\polar and northern mid \\latitude clouds appeared during the approach to the northern spring equinox in August 2009. Recent observations have shown extensive cloud systems at low latitudes. In contrast, southern mid \\latitude and subtropical clouds have appeared sporadically throughout the mission, exhibiting little seasonality to date. These differences in behavior suggest that Titan s clouds, and thus its general circulation, are influenced by both the rapid temperature response of a low \\thermal \\inertia surface and the much longer radiative timescale of Titan s cold thick troposphere. North \\polar clouds are often seen near lakes and seas, suggesting that local increases in methane concentration and/or lifting generated by surface roughness gradients may promote cloud formation. Citation

Maintenance procedures for the TITAN-I and TITAN-II reversed field pinch reactors

International Nuclear Information System (INIS)

Grotz, S.P.; Duggan, W.; Krakowski, R.; Najmabadi, F.; Wong, C.P.C.

1989-01-01

The TITAN reactor is a compact, high-power-density (neutron wall loading 18 MW/m 2 ) machine, based on the reversed-field-pinch (RFP) confinement concept. Two designs for the fusion power core have been examined: TITAN-I is based on a self-cooled lithium loop with a vanadium-alloy structure for the first wall, blanket and shield; and TITAN-II is based on an aqueous loop-in-pool design with a LiNO 3 solution as the coolant and breeder. The compact design of the TITAN fusion power core, (FPC) reduces the system to a few small and relatively low mass components, making toroidal segmentation of the FPC unnecessary. A single-piece maintenance procedure is possible. The potential advantages of single-piece maintenance procedures are: (1) Short period of down time; (2) improved reliability; (3) no adverse effects resulting from unequal levels of irradiation; and (4) ability to continually modify the FPC design. Increased availability can be expected from a fully pre-tested, single-piece FPC. Pre-testing of the FPC throughout the assembly process and prior to installation into the reactor vault is discussed. (orig.)

The tides of Titan.

Science.gov (United States)

Iess, Luciano; Jacobson, Robert A; Ducci, Marco; Stevenson, David J; Lunine, Jonathan I; Armstrong, John W; Asmar, Sami W; Racioppa, Paolo; Rappaport, Nicole J; Tortora, Paolo

2012-07-27

We have detected in Cassini spacecraft data the signature of the periodic tidal stresses within Titan, driven by the eccentricity (e = 0.028) of its 16-day orbit around Saturn. Precise measurements of the acceleration of Cassini during six close flybys between 2006 and 2011 have revealed that Titan responds to the variable tidal field exerted by Saturn with periodic changes of its quadrupole gravity, at about 4% of the static value. Two independent determinations of the corresponding degree-2 Love number yield k(2) = 0.589 ± 0.150 and k(2) = 0.637 ± 0.224 (2σ). Such a large response to the tidal field requires that Titan's interior be deformable over time scales of the orbital period, in a way that is consistent with a global ocean at depth.

Titan through Time: Evolution of Titan's Atmosphere and its Hydrocarbon Cycle on the Surface

Science.gov (United States)

Gilliam, Ashley E.

The Introduction and Appendix i-A outline briefly the history of Titan exploration since its discovery by Christiaan Huygens in 1675 through the recent International Mission of Cassini-Huygens.. Chapter 1: This chapter discusses two possible pathways of loss of the two main gases from Titan's post-accretional atmosphere, methane (CH 4) and ammonia (NH3), by the mechanisms of thermal escape and emission from the interior coupled with thermal escape. Chapter 2: In this chapter, a simple photolysis model is created, where the second most abundant component of the present-day Titan atmosphere, methane (CH4), can either escape the atmosphere or undergo photolytic conversion to ethane (C2H6). Chapter 3: This chapter examines different fluvial features on Titan, identified by the Cassini spacecraft, and evaluates the possibilities of channel formation by two mechanisms: dissolution of ice by a concentrated solution of ammonium sulfate, and by mechanical erosion by flow of liquid ammonia and liquid ethane. Chapter 4: This chapter presents: (1) new explicit mathematical solutions of mixed 1st and 2nd order chemical reactions, represented by ordinary differential first-degree and Riccati equations; (2) the computed present-day concentrations of the three gases in Titan's scale atmosphere, treated as at near-steady state; and (3) an analysis of the reported and computed atmospheric concentrations of CH4, CH 3, and C2H6 on Titan, based on the reaction rate parameters of the species, the rate parameters taken as constants representative of their mean values. Chapter 5: This chapter examines the possible reactions of methane formation in terms of the thermodynamic relationships of the reactions that include pure carbon as graphite, the gases H2, CO2, H2 O, and serpentinization and magnetite formation from olivine fayalite. (Abstract shortened by ProQuest.).

Effect of post treatments on the structure and thermal stability of titanate nanotubes

Energy Technology Data Exchange (ETDEWEB)

Qamar, M [Institute/Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Yoon, C R [Institute/Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Oh, H J [Institute/Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Kim, D H [Department of Advanced Materials Engineering, Hanyang University, Haendang-dong, Seondong-gu, Seoul 133-791 (Korea, Republic of); Jho, J H [Department of Advanced Materials Engineering, Hanyang University, Haendang-dong, Seondong-gu, Seoul 133-791 (Korea, Republic of); Lee, K S [Department of Advanced Materials Engineering, Hanyang University, Haendang-dong, Seondong-gu, Seoul 133-791 (Korea, Republic of); Lee, W J [Korea Electrotechnology Research Institute, 28-1 Sungju-Dong, Changwon, Gyeongnam 641-120 (Korea, Republic of); Lee, H G [Department of Advanced Materials Engineering, Korea Polytechnic University, Jeongwang 1-dong, Siheung-si, Gyeonggi-do 429-793 (Korea, Republic of); Kim, S J [Institute/Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of)

2006-12-28

TiO{sub 2} sol was prepared hydrothermally in an autoclave from aqueous TiOCl{sub 2} solutions as a starting precursor. Titanate nanotubes were obtained when the sol-gel-derived TiO{sub 2} sol was treated chemically with a 10 M NaOH solution and subsequently heated in the autoclave at 150 {sup 0}C for 48 h. The samples were characterized using XRD, TEM, SEM, EDX, Raman spectroscopy, and a BET surface area analyser. The effect of post treatments, such as washing with and without hydrochloric acid and calcination, on the phase structure, shape and morphology, pore structures, and BET surface area of the titanate nanotubes was investigated. When a sample containing 7.08 wt% Na (after washing only with water) was calcined at different temperatures from 300 to 900 {sup 0}C, it showed the formation of a mixture of sodium trititanates and sodium hexatitanates and was found to preserve the tubular morphology at higher temperatures. However, a sample containing 0.06 wt% Na obtained after prolonged washing with hydrochloric acid followed by heat treatment showed the formation of TiO{sub 2} anatase involving TiO{sub 2} (B) as an intermediate at lower temperatures and anatase was further transformed to the rutile phase when the temperature was raised. On the basis of different observations, a general formula Na{sub x}H{sub 2-x}Ti{sub 3}O{sub 7}{center_dot}nH{sub 2}O has been proposed for the trititanate nanotubes.

Titan LEAF: A Sky Rover Granting Targeted Access to Titan's Lakes and Plains

Science.gov (United States)

Ross, Floyd; Lee, Greg; Sokol, Daniel; Goldman, Benjamin; Bolisay, Linden

2016-10-01

Northrop Grumman, in collaboration with L'Garde Inc. and Global Aerospace Corporation (GAC), has been developing the Titan Lifting Entry Atmospheric Flight (T-LEAF) sky rover to roam the atmosphere and observe at close quarters the lakes and plains of Titan. T-LEAF also supports surface exploration and science by providing precision delivery of in situ instruments to the surface.T-LEAF is a maneuverable, buoyant air vehicle. Its aerodynamic shape provides its maneuverability, and its internal helium envelope reduces propulsion power requirements and also the risk of crashing. Because of these features, T-LEAF is not restricted to following prevailing wind patterns. This freedom of mobility allows it be commanded to follow the shorelines of Titan's methane lakes, for example, or to target very specific surface locations.T-LEAF utilizes a variable power propulsion system, from high power at ~200W to low power at ~50W. High power mode uses the propellers and control surfaces for additional mobility and maneuverability. It also allows the vehicle to hover over specific locations for long duration surface observations. Low power mode utilizes GAC's Titan Winged Aerobot (TWA) concept, currently being developed with NASA funding, which achieves guided flight without the use of propellers or control surfaces. Although slower than high powered flight, this mode grants increased power to science instruments while still maintaining control over direction of travel.Additionally, T-LEAF is its own entry vehicle, with its leading edges protected by flexible thermal protection system (f-TPS) materials already being tested by NASA's Hypersonic Inflatable Aerodynamic Decelerator (HIAD) group. This f-TPS technology allows T-LEAF to inflate in space, like HIAD, and then enter the atmosphere fully deployed. This approach accommodates entry velocities from as low as ~1.8 km/s if entering from Titan orbit, up to ~6 km/s if entering directly from Saturn orbit, like the Huygens probe

Characterizing the Upper Atmosphere of Titan using the Titan Global Ionosphere- Thermosphere Model: Nitrogen and Methane.

Science.gov (United States)

Bell, J. M.; Waite, J. H.; Bar-Nun, A.; Bougher, S. W.; Ridley, A. J.; Magee, B.

2008-12-01

Recently, a great deal of effort has been put forth to explain the Cassini Ion-Neutral Mass Spectrometer (Waite et al [2004]) in-situ measurements of Titan's upper atmosphere (e.g. Muller-Wodarg [2008], Strobel [2008], Yelle et al [2008]). Currently, the community seems to agree that large amounts of CH4 are escaping from Titan's upper atmosphere at a rate of roughly 2.0 x 1027 molecules of CH4/s (3.33 x 1028 amu/s), representing a significant mass source to the Kronian Magnetosphere. However, such large escape fluxes from Titan are currently not corroborated by measurements onboard the Cassini Spacecraft. Thus, we posit another potential scenario: Aerosol depletion of atmospheric methane. Using the three-dimensional Titan Global Ionosphere-Thermosphere Model (T-GITM) (Bell et al [2008]), we explore the possible removal mechanisms of atmospheric gaseous constituents by these aerosols. Titan simulations are directly compared against Cassini Ion-Neutral Mass Spectrometer in-situ densities of N2 and CH4. From this work, we can then compare and contrast this aerosol depletion scenario against the currently posited hydrodynamic escape scenario, illustrating the merits and shortcomings of both.

Diurnal variations of Titan's ionosphere

Science.gov (United States)

Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Müller-Wodarg, I. C. F.; Cravens, T. E.; Kasprzak, W. T.; Waite, J. H.

2009-06-01

We present our analysis of the diurnal variations of Titan's ionosphere (between 1000 and 1300 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from eight close encounters of the Cassini spacecraft with Titan. Although there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ˜700 cm-3 below ˜1300 km. Such a plateau is a combined result of significant depletion of light ions and modest depletion of heavy ones on Titan's nightside. We propose that the distinctions between the diurnal variations of light and heavy ions are associated with their different chemical loss pathways, with the former primarily through “fast” ion-neutral chemistry and the latter through “slow” electron dissociative recombination. The strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes suggests a scenario in which the ions created on Titan's dayside may survive well to the nightside. The observed asymmetry between the dawn and dusk ion density profiles also supports such an interpretation. We construct a time-dependent ion chemistry model to investigate the effect of ion survival associated with solid body rotation alone as well as superrotating horizontal winds. For long-lived ions, the predicted diurnal variations have similar general characteristics to those observed. However, for short-lived ions, the model densities on the nightside are significantly lower than the observed values. This implies that electron precipitation from Saturn's magnetosphere may be an additional and important contributor to the densities of the short-lived ions observed on Titan's nightside.

Quantitative analysis method for niobium in lead zirconate titanate

International Nuclear Information System (INIS)

Hara, Hideo; Hashimoto, Toshio

1986-01-01

Lead zirconate titanate (PZT) is a strong dielectric ceramic having piezoelectric and pyroelectric properties, and is used most as a piezoelectric material. Also it is a main component of lead lanthanum zirconate titanate (PLZT), which is a typical electrical-optical conversion element. Since these have been developed, the various electronic parts utilizing the piezoelectric characteristics have been put in practical use. The characteristics can be set up by changing the composition of PZT and the kinds and amount of additives. Among the additives, niobium has the action to make metallic ion vacancy in crystals, and by the formation of this vacancy, to ease the movement of domain walls in crystal grains, and to increase resistivity. Accordingly, it is necessary to accurately determine the niobium content for the research and development, quality control and process control. The quantitative analysis methods for niobium used so far have respective demerits, therefore, the authors examined the quantitative analysis of niobium in PZT by using an inductively coupled plasma emission spectro-analysis apparatus which has remarkably developed recently. As the result, the method of dissolving a specimen with hydrochloric acid and hydrofluoric acid, and masking unstable lead with ethylene diamine tetraacetic acid 2 sodium and fluoride ions with boric acid was established. The apparatus, reagents, the experiment and the results are reported. (Kako, I.)

Titan the earth-like moon

CERN Document Server

Coustenis, Athena

1999-01-01

This is the first book to deal with Titan, one of the most mysterious bodies in the solar system. The largest satellite of the giant planet Saturn, Titan is itself larger than the planet Mercury, and is unique in being the only known moon with a thick atmosphere. In addition, its atmosphere bears a startling resemblance to the Earth's, but is much colder.The American and European space agencies, NASA and ESA, have recently combined efforts to send a huge robot spacecraft to orbit Saturn and land on Titan. This book provides the background to this, the greatest deep space venture of our time, a

Titan and habitable planets around M-dwarfs.

Science.gov (United States)

Lunine, Jonathan I

2010-01-01

The Cassini-Huygens mission discovered an active "hydrologic cycle" on Saturn's giant moon Titan, in which methane takes the place of water. Shrouded by a dense nitrogen-methane atmosphere, Titan's surface is blanketed in the equatorial regions by dunes composed of solid organics, sculpted by wind and fluvial erosion, and dotted at the poles with lakes and seas of liquid methane and ethane. The underlying crust is almost certainly water ice, possibly in the form of gas hydrates (clathrate hydrates) dominated by methane as the included species. The processes that work the surface of Titan resemble in their overall balance no other moon in the solar system; instead, they are most like that of the Earth. The presence of methane in place of water, however, means that in any particular planetary system, a body like Titan will always be outside the orbit of an Earth-type planet. Around M-dwarfs, planets with a Titan-like climate will sit at 1 AU--a far more stable environment than the approximately 0.1 AU where Earth-like planets sit. However, an observable Titan-like exoplanet might have to be much larger than Titan itself to be observable, increasing the ratio of heat contributed to the surface atmosphere system from internal (geologic) processes versus photons from the parent star.

Titan's geoid and hydrology: implications for Titan's geological evolution

Science.gov (United States)

Sotin, Christophe; Seignovert, Benoit; Lawrence, Kenneth; MacKenzie, Shannon; Barnes, Jason; Brown, Robert

2014-05-01

A 1x1 degree altitude map of Titan is constructed from the degree 4 gravity potential [1] and Titan's shape [2] determined by the Radio Science measurements and RADAR observations of the Cassini mission. The amplitude of the latitudinal altitude variations is equal to 300 m compared to 600 m for the amplitude of the latitudinal shape variations. The two polar caps form marked depressions with an abrupt change in topography at exactly 60 degrees at both caps. Three models are envisaged to explain the low altitude of the polar caps: (i) thinner ice crust due to higher heat flux at the poles, (ii) fossil shape acquired if Titan had higher spin rate in the past, and (iii) subsidence of the crust following the formation of a denser layer of clathrates as ethane rain reacts with the H2O ice crust [3]. The later model is favored because of the strong correlation between the location of the cloud system during the winter season and the latitude of the abrupt change in altitude. Low altitude polar caps would be the place where liquids would run to and eventually form large seas. Indeed, the large seas of Titan are found at the deepest locations at the North Pole. However, the lakes and terrains considered to be evaporite candidates due to their spectral characteristics in the infrared [4,5] seem to be perched. Lakes may have been filled during Titan's winter and then slowly evaporated leaving material on the surface. Interestingly, the largest evaporite deposits are located at the equator in a deep depression 150 m below the altitude of the northern seas. This observation seems to rule out the presence of a global subsurface hydrocarbon reservoir unless the evaporation rate at the equator is faster than the transport of fluids from the North Pole to the equator. This work has been performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. [1] Iess L. et al. (2012) Science, doi 10.1126/science.1219631. [2] Lorenz R.D. (2013

Nonthermal atmospheric escape from Mars and Titan

International Nuclear Information System (INIS)

Lammer, H.; Bauer, S.J.

1991-01-01

Energy flux spectra and particle concentrations of the hot O and N coronae from Mars and Titan, respectively, resulting primarily from dissociative recombination of molecular ions, have been calculated by means of a Monte Carlo method. The calculated energy flux spectra lead to an escape flux null esc ∼ 6 x 10 6 cm -2 s -1 for Mars and null esc ∼ 2 x 10 6 cm -2 s -1 for Titan, corresponding to a mass loss of about 0.14 kg/s for Mars and about 0.3 kg/s for Titan. (The contribution of electron impact ionization on N 2 amounts to only about 25% of Titan's mass loss.) Mass loss via solar and magnetospheric wind is also estimated using newly calculated mass loading limits. The mass loss via ion pickup from the extended hot atom corona for Mars amounts to about 0.25 kg/s (O + ) and for Titan to about 50 g/s (N 2 + or H 2 CN + ). Thus, the total mass loss rate from Mars and Titan is about the same, i.e., 0.4 kg/s

A whiff of nebular gas in Titan's atmosphere - Potential implications for the conditions and timing of Titan's formation

Science.gov (United States)

Glein, Christopher R.

2017-09-01

In situ data from the GCMS instrument on the Huygens probe indicate that Titan's atmosphere contains small amounts of the primordial noble gases 36Ar and 22Ne (tentative detection), but it is unknown how they were obtained by the satellite. Based on the apparent similarity in the 22Ne/36Ar (atom) ratio between Titan's atmosphere and the solar composition, a previously neglected hypothesis for the origin of primordial noble gases in Titan's atmosphere is suggested - these species may have been acquired near the end of Titan's formation, when the moon could have gravitationally captured some nebular gas that would have been present in its formation environment (the Saturnian subnebula). These noble gases may be remnants of a primary atmosphere. This could be considered the simplest hypothesis to explain the 22Ne/36Ar ratio observed at Titan. However, the 22Ne/36Ar ratio may not be exactly solar if these species can be fractionated by external photoevaporation in the solar nebula, atmospheric escape from Titan, or sequestration on the surface of Titan. While the GCMS data are consistent with a 22Ne/36Ar ratio of 0.05 to 2.5 times solar (1σ range), simple estimates that attempt to account for some of the effects of these evolutionary processes suggest a sub-solar ratio, which may be depleted by approximately one order of magnitude. Models based on capture of nebular gas can explain why the GCMS did not detect any other primordial noble gas isotopes, as their predicted abundances are below the detection limits (especially for 84Kr and 132Xe). It is also predicted that atmospheric Xe on Titan should be dominated by radiogenic 129Xe if the source of primordial Xe is nebular gas. Of order 10-2-10-1 bar of primordial H2 may have been captured along with the noble gases from a gas-starved disk, but this H2 would have quickly escaped from the initial atmosphere. To have the opportunity to capture nebular gas, Titan should have formed within ∼10 Myr of the formation of the

Coupled atmosphere-ocean models of Titan's past

Science.gov (United States)

Mckay, Christopher P.; Pollack, James B.; Lunine, Jonathan I.; Courtin, Regis

1993-01-01

The behavior and possible past evolution of fully coupled atmosphere and ocean model of Titan are investigated. It is found that Titan's surface temperature was about 20 K cooler at 4 Gyr ago and will be about 5 K warmer 0.5 Gyr in the future. The change in solar luminosity and the conversion of oceanic CH4 to C2H6 drive the evolution of the ocean and atmosphere over time. Titan appears to have experienced a frozen epoch about 3 Gyr ago independent of whether an ocean is present or not. This finding may have important implications for understanding the inventory of Titan's volatile compounds.

Synthesis and characterizaton of inorganic materials for sodium-ion batteries

Science.gov (United States)

Shanmugam, Rengarajan

Development of low-cost energy storage devices is critical for wide-scale implementation of intermittent renewable energy technologies and improving the electricity grid. Commercial devices remain prohibitively expensive or lack the performance specifications for a wider market reach. Na-ion batteries would perfectly suited for these large-scale applications as the raw materials (such as soda ash, salt, etc.) are plentiful, inexpensive and geographically unconstrained. However, extensive materials research on insertion electrodes is required for better understanding of the electrochemical and structural properties and engineering high performance Na-ion batteries. This thesis research involves exploratory study on new insertion materials with various crystallographic structure-types and extensive characterization of promising new inorganic compositions. Tunnel-type materials, sodium nickel phosphate-Na4Ni7(PO4)6, and sodium cobalt titanate- Na0.8Co0.4Ti1.6O4, were investigated to capitalize on the intrinsic structural stability offered by framework materials. Sol-gel and solid-state reaction synthetic techniques were employed for inorganic powder synthesis. Galvanostatic and potentiostatic testing confirm reversible sodium insertion/de-insertion reactions albeit with inadequate electrochemical characteristics (high voltage hysteresis> 1V). Subsequent efforts involved investigating layer-structured materials supporting fast ionic transport for better electrochemical performance. P2-sodium nickel titanate, Na2/3[Ni1/3Ti2/3]O2 (P2NT), with prismatic sodium co-ordination, was synthesized by solid-state technique. The 'bifunctional' oxide contains Ni2+/4+ and Ti4+/3+ redox couples with redox potentials of 3.6 V, 0.7 V vs. Na/Na+, respectively. This bifunctional approach would simplify electrode processing and provide cost reduction opportunities in battery manufacturing. The structural changes monitored using ex-situ XRD demonstrate a favorably broad solid

Titan atmospheric composition by hypervelocity shock layer analysis

International Nuclear Information System (INIS)

Nelson, H.F.; Park, C.; Whiting, E.E.

1989-01-01

The Cassini Mission, a NASA/ESA cooperative project which includes a deployment of probe into the atmosphere of Titan, is described, with particular attention given to the shock radiometer experiment planned for the Titan probe for the analysis of Titan's atmosphere. Results from a shock layer analysis are presented, demonstrating that the mole fractions of the major species (N2, CH4, and, possibly Ar) in the Titan atmosphere can be successfully determined by the Titan-probe radiometer, by measuring the intensity of the CN(violet) radiation emitted in the shock layer during the high velocity portion of the probe entry between 200 and 400 km altitude. It is shown that the sensitivity of the CN(violet) radiation makes it possible to determine the mole fractions of N2, CH4, and Ar to about 0.015, 0.003, and 0.01, respectively, i.e., much better than the present uncertainties in the composition of Titan atmosphere. 29 refs

Ceria and strontium titanate based electrodes

DEFF Research Database (Denmark)

2010-01-01

A ceramic anode structure obtainable by a process comprising the steps of: (a) providing a slurry by dispersing a powder of an electronically conductive phase and by adding a binder to the dispersion, in which said powder is selected from the group consisting of niobium-doped strontium titanate......, vanadium-doped strontium titanate, tantalum-doped strontium titanate, and mixtures thereof, (b) sintering the slurry of step (a), (c) providing a precursor solution of ceria, said solution containing a solvent and a surfactant, (d) impregnating the resulting sintered structure of step (b...

Anion and cation diffusion in barium titanate and strontium titanate

International Nuclear Information System (INIS)

Kessel, Markus Franz

2012-01-01

Perovskite oxides show various interesting properties providing several technical applications. In many cases the defect chemistry is the key to understand and influence the material's properties. In this work the defect chemistry of barium titanate and strontium titanate is analysed by anion and cation diffusion experiments and subsequent time-of-flight secondary ion mass spectrometry (ToF-SIMS). The reoxidation equation for barium titanate used in multi-layer ceramic capacitors (MLCCs) is found out by a combination of different isotope exchange experiments and the analysis of the resulting tracer diffusion profiles. It is shown that the incorporation of oxygen from water vapour is faster by orders of magnitude than from molecular oxygen. Chemical analysis shows the samples contain various dopants leading to a complex defect chemistry. Dysprosium is the most important dopant, acting partially as a donor and partially as an acceptor in this effectively acceptor-doped material. TEM and EELS analysis show the inhomogeneous distribution of Dy in a core-shell microstructure. The oxygen partial pressure and temperature dependence of the oxygen tracer diffusion coefficients is analysed and explained by the complex defect chemistry of Dy-doped barium titanate. Additional fast diffusion profiles are attributed to fast diffusion along grain boundaries. In addition to the barium titanate ceramics from an important technical application, oxygen diffusion in cubic, nominally undoped BaTiO 3 single crystals has been studied by means of 18 O 2 / 16 O 2 isotope exchange annealing and subsequent determination of the isotope profiles in the solid by ToF-SIMS. It is shown that a correct description of the diffusion profiles requires the analysis of the diffusion through the surface space-charge into the material's bulk. Surface exchange coefficients, space-charge potentials and bulk diffusion coefficients are analysed as a function of oxygen partial pressure and temperature. The

Radiophase development in hot-pressed alkoxide-derived titanate ceramics for nuclear waste stabilization

International Nuclear Information System (INIS)

Dickson, F.J.; Mitamura, H.; White, T.J.

1989-01-01

This paper reports phase development as a function of hot-pressing temperature studied in alkoxide-derived titanate-based ceramics doped with a 10 wt% loading of a sodium-rich (NAR) and a sodium-poor (NAP) simulated high-level waste. Pyrochlore was found to be the most abundant phase in both calcine powders. A pseudobrookite phase existed metastably at hot-pressing temperatures between 890 degrees and 920 degrees C. After hot-pressing at 1100 degrees C, the final phase assemblage for the NAP material consisted of zirconolite, hollandite-type, perovskite, alloy, and reduced rutile (Magneli phases). In addition, NAR samples contained hibonite, freudenbergite, and loveringite. Phase development was driven to completion over a very narrow temperature range (≤50 degrees C), beginning at 870 degrees and 850 degrees C for NAP and NAR, respectively, although full densification was not achieved below 1100 degrees C. Both waste forms exhibited comparable microstructure and aqueous durability

Titan's methane clock

Science.gov (United States)

Nixon, C. A.; Jennings, D. E.; Romani, P. N.; Teanby, N. A.; Irwin, P. G. J.; Flasar, F. M.

2010-04-01

Measurements of the 12C/13C and D/H isotopic ratios in Titan's methane show intriguing differences from the values recorded in the giant planets. This implies that either (1) the atmosphere was differently endowed with material at the time of formation, or (2) evolutionary processes are at work in the moon's atmosphere - or some combination of the two. The Huygens Gas Chromatograph Mass Spectrometer Instrument (GCMS) found 12CH4/13CH4 = 82 +/- 1 (Niemann et al. 2005), some 7% lower than the giant planets' value of 88 +/- 7 (Sada et al. 1996), which closely matches the terrestrial inorganic standard of 89. The Cassini Composite Infrared Spectrometer (CIRS) has previously reported 12CH4/13CH4 of 77 +/-3 based on nadir sounding, which we now revise upwards to 80 +/- 4 based on more accurate limb sounding. The CIRS and GCMS results are therefore in agreement about an overall enrichment in 13CH4 of ~10%. The value of D/H in Titan's CH4 has long been controversial: historical measurements have ranged from about 8-15 x 10-5 (e.g. Coustenis et al. 1989, Coustenis et al. 2003). A recent measurement based on CIRS limb data by Bezard et al. (2007) puts the D/H in CH4 at (13 +/- 1) x 10-5, very much greater than in Jupiter and Saturn, ~2 x 10-5 (Mahaffy et al. 1998, Fletcher et al. 2009). To add complexity, the 12C/13C and D/H vary among molecules in Titan atmosphere, typically showing enhancement in D but depletion in 13C in the daughter species (H2, C2H2, C2H6), relative to the photochemical progenitor, methane. Jennings et al. (2009) have sought to interpret the variance in carbon isotopes as a Kinetic Isotope Effect (KIE), whilst an explanation for the D/H in all molecules remains elusive (Cordier et al. 2008). In this presentation we argue that evolution of isotopic ratios in Titan's methane over time forms a ticking 'clock', somewhat analogous to isotopic ratios in geochronology. Under plausible assumptions about the initial values and subsequent replenishment, various

Titan Orbiter Aerorover Mission with Enceladus Science (TOAMES)

Science.gov (United States)

Sittler, E.; Cooper, J.; Mahaffy, P.; Fairbrother, D.; de Pater, I.; Schulze-Makuch, D.; Pitman, J.

2007-08-01

same time made us aware of how little we understand about these bodies. For example, the source, and/or recycling mechanism, of methane in Titan's atmosphere is still puzzling. Indeed, river beds (mostly dry) and lakes have been spotted, and occasional clouds have been seen, but the physics to explain the observations is still mostly lacking, since our "image" of Titan is still sketchy and quite incomplete. Enceladus, only 500 km in extent, is even more puzzling, with its fiery plumes of vapor, dust and ice emanating from its south polar region, "feeding" Saturn's E ring. Long term variability of magnetospheric plasma, neutral gas, E-ring ice grain density, radio emissions, and corotation of Saturn's planetary magnetic field in response to Enceladus plume activity are of great interest for Saturn system science. Both Titan and Enceladus are bodies of considerable astrobiological interest in view of high organic abundances at Titan and potential subsurface liquid water at Enceladus. We propose to develop a new mission to Titan and Enceladus, the Titan Orbiter Aerorover Mission with Enceladus Science (TOAMES), to address these questions using novel new technologies. TOAMES is a multi-faceted mission that starts with orbit insertion around Saturn using aerobraking with Titan's extended atmosphere. We then have an orbital tour around Saturn (for 1-2 years) and close encounters with Enceladus, before it goes into orbit around Titan (via aerocapture). During the early reconnaissance phase around Titan, perhaps 6 months long, the orbiter will use altimetry, radio science and remote sensing instruments to measure Titan's global topography, subsurface structure and atmospheric winds. This information will be used to determine where and when to release the Aerorover, so that it can navigate safely around Titan and identify prime sites for surface sampling and analysis. In situ instruments will sample the upper atmosphere which may provide the seed population for the complex

Spacecraft Exploration of Titan and Enceladus

Science.gov (United States)

Matson, D.; Coustenis, A.; Lunine, J. I.; Lebreton, J.; Reh, K.; Beauchamp, P.; Erd, C.

2009-12-01

The future exploration of Titan and Enceladus is very important for planetary science. The study titled Titan Saturn System Mission (TSSM) led to an announcement in which ESA and NASA prioritized future OPF missions, stating that TSSM is planned after EJSM (for details see http://www.lpi.usra.edu/opag/). The TSSM concept consists of an Orbiter that would carry two in situ elements: the Titan Montgolfiere hot air balloon and the Titan Lake Lander. This mission could launch in the 2023-2025 timeframe on a trajectory to arrive ~9 years later and begin a 4-year mission in the Saturnian system. At an appropriate time after arrival at Saturn, the montgolfiere would be delivered to Titan to begin its mission of airborne, scientific observations of Titan from an altitude of about 10 km above the surface. The montgolfiere would have a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) power system whose waste heat would warm the gas in the balloon, providing buoyancy. It would be designed to survive at least 6-12 months in Titan’s atmosphere. With the predicted winds and weather, it should be possible to circumnavigate the globe! Later, on a subsequent fly-by, the TSSM orbiter would send the Lake Lander to Titan. It would descend through the atmosphere making scientific measurements, much like Huygens did, and then land and float on one of Titan’s seas. This would be its oceanographic phase of making a physical and chemical assessment of the sea. The Lake Lander would operate for 8-10 hours until its batteries become depleted. Following the delivery of the in situ elements, the TSSM orbiter would then explore the Saturn system for two years on a tour that includes in situ sampling of Enceladus’ plumes as well as flybys of Titan. After the Saturn tour, the TSSM orbiter would go into orbit around Titan and carry out a global survey phase. Synergistic observations would be carried out by the TSSM orbiter and the in situ elements. The scientific requirements for

Antimony doped cadmium selenium nanobelts with enhanced electrical and optoelectrical properties

Energy Technology Data Exchange (ETDEWEB)

Zhang, Lijie [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou 325027 (China); Yu, Hongfei; Cao, Wei; Dong, Youqing; Zou, Chao; Yang, Yun [Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou 325027 (China); Huang, Shaoming, E-mail: smhuang@wzu.edu.cn [Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou 325027 (China); Dai, Ning [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Zhu, Da-Ming, E-mail: ZhuD@umkc.edu [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); University of Missouri-Kansas City, Kansas City, MO 64110 (United States)

2014-07-01

Intrinsic and Sb-doped CdSe nanobelts (NBs) were synthesized via a thermal evaporation technique. The electrical transport properties of field effect transistors (FETs) fabricated using the NBs were investigated. The results indicate that the Sb-doped NBs behave as n-type semiconductors with improved electrical conductivity (10⁻¹ to 100 S/cm) compared with the intrinsic CdSe. Photodetectors made of single NB were also fabricated and investigated. The results show that Sb-doped NB photodetectors exhibit much higher responsivity (1.5 × 10⁴ A/W) and external quantum efficiency (1.2 × 10⁵) but lower on/off current ratio (~253) and longer response time (≤40 ms). Furthermore, both electrical transport and optoelectrical properties of the as-synthesized CdSe NBs can be tuned by changing the doping concentration. The results indicate that the as-synthesized NBs are excellent building blocks for constructing electronic and optoelectronic devices.

Schottky junction photovoltaic devices based on CdS single nanobelts.

Science.gov (United States)

Ye, Y; Dai, L; Wu, P C; Liu, C; Sun, T; Ma, R M; Qin, G G

2009-09-16

Schottky junction photovoltaic (PV) devices were fabricated on single CdS nanobelts (NBs). Au was used as the Schottky contact, and In/Au was used as the ohmic contact to CdS NB. Typically, the Schottky junction exhibits a well-defined rectifying behavior in the dark with a rectification ratio greater than 10(3) at +/- 0.3 V; and the PV device exhibits a clear PV behavior with an open circuit photovoltage of about 0.16 V, a short circuit current of about 23.8 pA, a maximum output power of about 1.6 pW, and a fill factor of 42%. Moreover, the output power can be multiplied by connecting two or more of the Schottky junction PV devices, made on a single CdS NB, in parallel or in series. This study demonstrates that the 1D Schottky junction PV devices, which have the merits of low cost, easy fabrication and material universality, can be an important candidate for power sources in nano-optoelectronic systems.

Titan Montgolfiere Terrestrial Test Bed, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — With the Titan Saturn System Mission, NASA is proposing to send a Montgolfiere balloon to probe the atmosphere of Titan. To better plan this mission and create a...

Titan Montgolfiere Terrestrial Test Bed, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — With the Titan Saturn System Mission, NASA is proposing to send a Montgolfiere balloon to probe the atmosphere of Titan. In order to better plan this mission and...

AVIATR—Aerial Vehicle for In-situ and Airborne Titan Reconnaissance

DEFF Research Database (Denmark)

Barnes, Jason W.; Lemke, Lawrence; Foch, Rick

2012-01-01

We describe a mission concept for a stand-alone Titan airplane mission: Aerial Vehicle for In-situ and Airborne Titan Reconnaissance (AVIATR). With independent delivery and direct-to-Earth communications, AVIATR could contribute to Titan science either alone or as part of a sustained Titan...... Exploration Program. As a focused mission, AVIATR as we have envisioned it would concentrate on the science that an airplane can do best: exploration of Titan's global diversity. We focus on surface geology/hydrology and lower-atmospheric structure and dynamics. With a carefully chosen set of seven...... of a Space Vehicle (SV) for cruise, an Entry Vehicle (EV) for entry and descent, and the Air Vehicle (AV) to fly in Titan's atmosphere. Using an Earth-Jupiter gravity assist trajectory delivers the spacecraft to Titan in 7.5 years, after which the AVIATR AV would operate for a 1-Earth-year nominal mission...

HST observations of the limb polarization of Titan

Science.gov (United States)

Bazzon, A.; Schmid, H. M.; Buenzli, E.

2014-12-01

Context. Titan is an excellent test case for detailed studies of the scattering polarization from thick hazy atmospheres. Accurate scattering and polarization parameters have been provided by the in situ measurements of the Cassini-Huygens landing probe. For Earth-bound observations Titan can only be observed at a backscattering situation, where the disk-integrated polarization is close to zero. However, with resolved imaging polarimetry a second order polarization signal along the entire limb of Titan can be measured. Aims: We present the first limb polarization measurements of Titan, which are compared as a test to our limb polarization models. Methods: Previously unpublished imaging polarimetry from the HST archive is presented, which resolves the disk of Titan. We determine flux-weighted averages of the limb polarization and radial limb polarization profiles, and investigate the degradation and cancelation effects in the polarization signal due to the limited spatial resolution of our observations. Taking this into account we derive corrected values for the limb polarization in Titan. The results are compared with limb polarization models, using atmosphere and haze scattering parameters from the literature. Results: In the wavelength bands between 250 nm and 2 μm a strong limb polarization of about 2 - 7% is detected with a position angle perpendicular to the limb. The fractional polarization is highest around 1 μm. As a first approximation, the polarization seems to be equally strong along the entire limb. The comparison of our data with model calculations and the literature shows that the detected polarization is compatible with expectations from previous polarimetric observations taken with Voyager 2, Pioneer 11, and the Huygens probe. Conclusions: Our results indicate that ground-based monitoring measurements of the limb-polarization of Titan could be useful for investigating local haze properties and the impact of short-term and seasonal variations of

Experimental basis for a Titan probe organic analysis

International Nuclear Information System (INIS)

Mckay, C.P.; Scattergood, T.W.; Borucki, W.J.; Kasting, J.F.; Miller, S.L.; California Univ., San Diego, La Jolla)

1986-01-01

The recent Voyager flyby of Titan produced evidence for at least nine organic compounds in that atmosphere that are heavier than methane. Several models of Titan's atmosphere, as well as laboratory simulations, suggest the presence of organics considerably more complex that those observed. To ensure that the in situ measurements are definitive with respect to Titan's atmosphere, experiment concepts, and the related instrumentation, must be carefully developed specifically for such a mission. To this end, the possible composition of the environment to be analyzed must be bracketed and model samples must be provided for instrumentation development studies. Laboratory studies to define the optimum flight experiment and sampling strategy for a Titan entry probe are currently being conducted. Titan mixtures are being subjected to a variety of energy sources including high voltage electron from a DC discharge, high current electric shock, and laser detonation. Gaseous and solid products are produced which are then analyzed. Samples from these experiements are also provided to candidate flight experiments as models for instrument development studies. Preliminary results show that existing theoretical models for chemistry in Titan's atmosphere cannot adequetely explain the presence and abundance of all trace gases observed in these experiments

History and challenges of barium titanate: Part I

Directory of Open Access Journals (Sweden)

Vijatović M.M.

2008-01-01

Full Text Available Barium titanate is the first ferroelectric ceramics and a good candidate for a variety of applications due to its excellent dielectric, ferroelectric and piezoelectric properties. Barium titanate is a member of a large family of compounds with the general formula ABO3 called perovskites. Barium titanate can be prepared using different methods. The synthesis method depends on the desired characteristics for the end application. The used method has a significant influence on the structure and properties of barium titanate materials. In this review paper, Part I contains a study of the BaTiO3 structure and frequently used synthesis methods.

Titan's organic chemistry: Results of simulation experiments

Science.gov (United States)

Sagan, Carl; Thompson, W. Reid; Khare, Bishun N.

1992-01-01

Recent low pressure continuous low plasma discharge simulations of the auroral electron driven organic chemistry in Titan's mesosphere are reviewed. These simulations yielded results in good accord with Voyager observations of gas phase organic species. Optical constants of the brownish solid tholins produced in similar experiments are in good accord with Voyager observations of the Titan haze. Titan tholins are rich in prebiotic organic constituents; the Huygens entry probe may shed light on some of the processes that led to the origin of life on Earth.

The commercial evolution of the Titan program

Science.gov (United States)

Isakowitz, Steven

1988-07-01

The present status evaluation of proprietary efforts to turn the once exclusively government-requirements-oriented Titan launch vehicle into a successful commercial competitor is divided into three phases. The first phase notes recent changes in U.S. space transportation policy and the Titan configurations evaluated for commercial feasibility. The second phase is a development history for the current vehicle's marketing organization and the right-to-use agreement for a launch site. Phase three projects the prospective marketing climate for a commercial Titan vehicle and its planned improvements.

Preparation and characterization of titanate nanotubes/carbon composites

International Nuclear Information System (INIS)

Wang Xiaodong; Pan Hui; Xue Xiaoxiao; Qian Junjie; Yu Laigui; Yang Jianjun; Zhang Zhijun

2011-01-01

Highlights: → Titanate nanotubes/carbon composites were synthesized from TiO 2 -carbon composites. → The carbon shell of TiO 2 particles obstructed the reaction between TiO 2 and NaOH. → TEM, XRD, and Raman spectra reveal the formation processes of the TNT/CCs. - Abstract: Titanate nanotubes/carbon composites(TNT/CCs) were synthesized by allowing carbon-coated TiO 2 (CCT) powder to react with a dense aqueous solution of NaOH at 120 deg. C for a proper period of time. As-prepared CCT and TNT/CCs were characterized by means of transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectrometry. The processes for formation of titanate nanotubes/carbon composites were discussed. It was found that the TiO 2 particles in TiO 2 -carbon composite were enwrapped by a fine layer of carbon with a thickness of about 4 nm. This carbon layer functioned to inhibit the transformation from anatase TiO 2 to orthorhombic titanate. As a result, the anatase TiO 2 in CCT was incompletely transformed into orthorhombic titanate nanotubes upon 24 h of reaction in the dense and hot NaOH solution. When the carbon layers were gradually peeled off along with the formation of more orthorhombic titanate nanotubes at extended reaction durations (e.g., 72 h), anatase TiO 2 particles in CCT were completely transformed into orthorhombic titanate nanotubes, yielding TNT/CCs whose morphology was highly dependent on the reaction time and temperature.

Selections from 2017: Discoveries in Titan's Atmosphere

Science.gov (United States)

Kohler, Susanna

2017-12-01

Editors note:In these last two weeks of 2017, well be looking at a few selections that we havent yet discussed on AAS Nova from among the most-downloaded paperspublished in AAS journals this year. The usual posting schedule will resume in January.Carbon Chain Anions and the Growth of Complex Organic Molecules in Titans IonospherePublished July2017Main takeaway:Graphic depicting some of the chemical reactions taking place in Titans atmosphere, leading to the generation of organic haze particles. [ESA]In a recently published study led by Ravi Desai (University College London), scientists used data from the Cassini mission to identify negatively charged molecules known as carbon chain anions in the atmosphere of Saturns largest moon, Titan.Why its interesting:Carbon chain anions are the building blocks ofmore complex molecules, and Titans thick nitrogen and methane atmosphere mightmimic the atmosphere of earlyEarth. This first unambiguous detection of carbon chain anions in a planet-like atmosphere might therefore teach us about the conditions and chemical reactions that eventually led to the development of life on Earth. And ifwe can use Titan to learn about how complex molecules grow from these anion chains, we may be able to identify auniversal pathway towards the ingredients for life.What weve learned so far:Cassini measured fewer and fewer lower-mass anions the deeper in Titans ionosphere that it looked and at the same time,an increase in the number of precursors to larger aerosol molecules further down. This tradeoff strongly suggests that the anions are indeed involved in building up the more complex molecules, seeding their eventual growth into the complex organic haze of Titans lower atmosphere.CitationR. T. Desai et al 2017 ApJL 844 L18. doi:10.3847/2041-8213/aa7851

Niobium-doped strontium titanates as SOFC anodes

DEFF Research Database (Denmark)

Blennow Tullmar, Peter; Kammer Hansen, Kent; Wallenberg, L. Reine

2008-01-01

been synthesized with a recently developed modified glycine-nitrate process. The synthesized powders have been calcined and sintered in air or in 9% H(2) / N(2) between 800 - 1400 degrees C. After calcination the samples were single phase Nb-doped strontium titanate with grain sizes of less than 100 nm...... in diameter on average. The phase purity, defect structure, and microstructure of the materials have been analyzed with SEM, XRD, and TGA. The electrical conductivity of the Nb-doped titanate decreased with increasing temperature and showed a phonon scattering conduction mechanism with sigma > 120 S...... ability of the Nb-doped titanates to be used as a part of a SOFC anode. However, the catalytic activity of the materials was not sufficient and it needs to be improved if titanate based materials are to be realized as constituents in SOFC anodes....

Volatile products controlling Titan's tholins production

KAUST Repository

Carrasco, Nathalie

2012-05-01

A quantitative agreement between nitrile relative abundances and Titan\\'s atmospheric composition was recently shown with a reactor simulating the global chemistry occurring in Titan\\'s atmosphere (Gautier et al. [2011]. Icarus, 213, 625-635). Here we present a complementary study on the same reactor using an in situ diagnostic of the gas phase composition. Various initial N 2/CH 4 gas mixtures (methane varying from 1% to 10%) are studied, with a monitoring of the methane consumption and of the stable gas neutrals by in situ mass spectrometry. Atomic hydrogen is also measured by optical emission spectroscopy. A positive correlation is found between atomic hydrogen abundance and the inhibition function for aerosol production. This confirms the suspected role of hydrogen as an inhibitor of heterogeneous organic growth processes, as found in Sciamma-O\\'Brien et al. (Sciamma-O\\'Brien et al. [2010]. Icarus, 209, 704-714). The study of the gas phase organic products is focussed on its evolution with the initial methane amount [CH 4] 0 and its comparison with the aerosol production efficiency. We identify a change in the stationary gas phase composition for intermediate methane amounts: below [CH 4] 0=5%, the gas phase composition is mainly dominated by nitrogen-containing species, whereas hydrocarbons are massively produced for [CH 4] 0>5%. This predominance of N-containing species at lower initial methane amount, compared with the maximum gas-to solid conversion observed in Sciamma-O\\'Brien et al. (2010) for identical methane amounts confirms the central role played by N-containing gas-phase compounds to produce tholins. Moreover, two protonated imines (methanimine CH 2NH and ethanamine CH 3CHNH) are detected in the ion composition in agreement with Titan\\'s INMS measurements, and reinforcing the suspected role of these chemical species on aerosol production. © 2012 Elsevier Inc.

Selective adsorption and ion exchange of metal cations and anions with silico-titanates and layered titanates

International Nuclear Information System (INIS)

Anthony, R.G.; Philip, C.V.

1993-01-01

Metal ions may be removed from aqueous wastes from metal processing plants and from refineries. They may also be used in concentrating radioactive elements found in dilute, aqueous, nuclear wastes. A new series of silico-titanates and alkali titanates are shown to have specific selectivity for cations of lead, mercury, and cadmium and the dichromate anion in solutions with low and high pH. Furthermore, one particular silico-titanate, TAM-5, was found to be highly selective for Cs + and Sr 2+ in solutions of 5.7 M Na + and 0.6 M Oh - . A high potential exists for these materials for removing Cs + and Sr 2+ from radioactive aqueous wastes containing high concentrations of Na + at high and low pH

Radiation effects in uranium-niobium titanates

International Nuclear Information System (INIS)

Lian, J.; Wang, S.X.; Wang, L.M.; Ewing, R.C.

2000-01-01

Pyrochlore is an important actinide host phase proposed for the immobilization of high level nuclear wastes and excess weapon plutonium.[1] Synthetic pyrochlore has a great variety of chemical compositions due to the possibility of extensive substitutions in the pyrochlore structure.[2] During the synthesis of pyrochlore, additional complex titanate phases may form in small quantities. The response of these phases to radiation damage must be evaluated because volume expansion of minor phases may cause micro-fracturing. In this work, two complex uranium-niobium titanates, U 3 NbO 9.8 (U-rich titanate) and Nb 3 UO 10 (Nb-rich titanate) were synthesized by the alkoxide/nitrate route at 1300 deg. C under an argon atmosphere. The phase composition and structure were analyzed by EDS, BSE, XRD, EMPA and TEM techniques. An 800 KeVKr 2+ irradiation was performed using the IVEM-Tandem Facility at Argonne National Laboratory in a temperature range from 30 K to 973 K. The radiation effects were observed by in situ TEM

The TITAN Reversed-Field Pinch fusion reactor study

International Nuclear Information System (INIS)

1988-03-01

The TITAN Reversed-Field Pinch (RFP) fusion reactor study is a multi-institutional research effort to determine the technical feasibility and key developmental issues of an RFP fusion reactor, especially at high power density, and to determine the potential economics, operations, safety, and environmental features of high-mass-power-density fusion systems. The TITAN conceptual designs are DT burning, 1000 MWe power reactors based on the RFP confinement concept. The designs are compact, have a high neutron wall loading of 18 MW/m 2 and a mass power density of 700 kWe/tonne. The inherent characteristics of the RFP confinement concept make fusion reactors with such a high mass power density possible. Two different detailed designs have emerged: the TITAN-I lithium-vanadium design, incorporating the integrated-blanket-coil concept; and the TITAN-II aqueous loop-in-pool design with ferritic steel structure. This report contains a collection of 16 papers on the results of the TITAN study which were presented at the International Symposium on Fusion Nuclear Technology. This collection describes the TITAN research effort, and specifically the TITAN-I and TITAN-II designs, summarizing the major results, the key technical issues, and the central conclusions and recommendations. Overall, the basic conclusions are that high-mass power-density fusion reactors appear to be technically feasible even with neutron wall loadings up to 20 MW/m 2 ; that single-piece maintenance of the FPC is possible and advantageous; that the economics of the reactor is enhanced by its compactness; and the safety and environmental features need not to be sacrificed in high-power-density designs. The fact that two design approaches have emerged, and others may also be possible, in some sense indicates the robustness of the general findings

Advances in Architectural Elements For Future Missions to Titan

Science.gov (United States)

Reh, Kim; Coustenis, Athena; Lunine, Jonathan; Matson, Dennis; Lebreton, Jean-Pierre; Vargas, Andre; Beauchamp, Pat; Spilker, Tom; Strange, Nathan; Elliott, John

2010-05-01

The future exploration of Titan is of high priority for the solar system exploration community as recommended by the 2003 National Research Council (NRC) Decadal Survey [1] and ESA's Cosmic Vision Program themes. Recent Cassini-Huygens discoveries continue to emphasize that Titan is a complex world with very many Earth-like features. Titan has a dense, nitrogen atmosphere, an active climate and meteorological cycles where conditions are such that the working fluid, methane, plays the role that water does on Earth. Titan's surface, with lakes and seas, broad river valleys, sand dunes and mountains was formed by processes like those that have shaped the Earth. Supporting this panoply of Earth-like processes is an ice crust that floats atop what might be a liquid water ocean. Furthermore, Titan is rich in very many different organic compounds—more so than any place in the solar system, except Earth. The Titan Saturn System Mission (TSSM) concept that followed the 2007 TandEM ESA CV proposal [2] and the 2007 Titan Explorer NASA Flagship study [3], was examined [4,5] and prioritized by NASA and ESA in February 2009 as a mission to follow the Europa Jupiter System Mission. The TSSM study, like others before it, again concluded that an orbiter, a montgolfiere hot-air balloon and a surface package (e.g. lake lander, Geosaucer (instrumented heat shield), …) are very high priority elements for any future mission to Titan. Such missions could be conceived as Flagship/Cosmic Vision L-Class or as individual smaller missions that could possibly fit into NASA New Frontiers or ESA Cosmic Vision M-Class budgets. As a result of a multitude of Titan mission studies, a clear blueprint has been laid out for the work needed to reduce the risks inherent in such missions and the areas where advances would be beneficial for elements critical to future Titan missions have been identified. The purpose of this paper is to provide a brief overview of the flagship mission architecture and

Cosmic-rays induced Titan tholins and their astrobiological significances

Science.gov (United States)

Kobayashi, Kensei; Taniuchi, Toshinori; Hosogai, Tomohiro; Kaneko, Takeo; Takano, Yoshinori; Khare, Bishun; McKay, Chris

Titan is the largest satellite of Saturn. It is quite unique satellite since it has a dense atmosphere composed of nitrogen and methane, and has been sometimes considered as a model of primitive Earth. In Titan atmosphere, a wide variety of organic compounds and mists made of complex organics. Such solid complex organics are often referred to as tholins. A number of laboratory experiments simulating reactions in Titan atmosphere have been conducted. In most of them, ultraviolet light and discharges (simulating actions of electrons in Saturn magnetosphere) were used, which were simulation of the reactions in upper dilute atmosphere of Titan. We examined possible formation of organic compounds in the lower dense atmosphere of Titan, where cosmic rays are major energies. A Mixture of 35 Torr of methane and 665 Torr of nitrogen was irradiated with high-energy protons (3 MeV) from a van de Graaff accelerator (TIT, Japan) or from a Tandem accelerator (TIARA, QUBS, JAEA, Japan). In some experiments, 13 C-labelled methane was used. We also performed plasma discharges in a mixture of methane (10 %) and nitrogen (90 %) to simulate the reactions in the upper atmosphere of Titan. Solid products by proton irradiation and those by plasma discharges are hereafter referred to as PI-tholins and PD-tholins, respectively. The resulting PI-tholins were observed with SEM and AFM. They were characterized by pyrolysis-GC/MS, gel permeation chromatography, FT-IR, etc. Amino acids in PI-and PD-tholins were analyzed by HPLC, GC/MS and MALDI-TOF-MS after acid hydrolysis. 18 O-Labelled water was used in some cases during hydrolysis. Filamentary and/or globular-like structures were observed by SEM and AFM. By pyrolysis-GC/MS of PI-tholins, ammonia and hydrogen cyanide were detected, which was the same as the results obtained in Titan atmosphere during the Huygens mission. A wide variety of amino acids were detected after hydrolysis of both tholins. It was proved that oxygen atoms in the amino

A high energy and power Li-ion capacitor based on a TiO2 nanobelt array anode and a graphene hydrogel cathode.

Science.gov (United States)

Wang, Huanwen; Guan, Cao; Wang, Xuefeng; Fan, Hong Jin

2015-03-25

A novel hybrid Li-ion capacitor (LIC) with high energy and power densities is constructed by combining an electrochemical double layer capacitor type cathode (graphene hydrogels) with a Li-ion battery type anode (TiO(2) nanobelt arrays). The high power source is provided by the graphene hydrogel cathode, which has a 3D porous network structure and high electrical conductivity, and the counter anode is made of free-standing TiO(2) nanobelt arrays (NBA) grown directly on Ti foil without any ancillary materials. Such a subtle designed hybrid Li-ion capacitor allows rapid electron and ion transport in the non-aqueous electrolyte. Within a voltage range of 0.0-3.8 V, a high energy of 82 Wh kg(-1) is achieved at a power density of 570 W kg(-1). Even at an 8.4 s charge/discharge rate, an energy density as high as 21 Wh kg(-1) can be retained. These results demonstrate that the TiO(2) NBA//graphene hydrogel LIC exhibits higher energy density than supercapacitors and better power density than Li-ion batteries, which makes it a promising electrochemical power source. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Infrared characterization of strontium titanate thin films

International Nuclear Information System (INIS)

Almeida, B.G.; Pietka, A.; Mendes, J.A.

2004-01-01

Strontium titanate thin films have been prepared at different oxygen pressures with various post-deposition annealing treatments. The films were deposited by pulsed laser ablation at room temperature on Si(0 0 1) substrates with a silica buffer layer. Infrared reflectance measurements were performed in order to determine relevant film parameters such as layer thicknesses and chemical composition. The infrared reflectance spectra were fitted by using adequate dielectric function forms for each layer. The fitting procedure provided the extraction of the dielectric functions of the strontium titanate film, the silica layer and the substrate. The as-deposited films are found to be amorphous, and their infrared spectra present peaks corresponding to modes with high damping constants. As the annealing time and temperature increases the strontium titanate layer becomes more ordered so that it can be described by its SrTiO 3 bulk mode parameters. Also, the silica layer grows along with the ordering of the strontium titanate film, due to oxidation during annealing

Titan after Cassini Huygens

Science.gov (United States)

Beauchamp, P. M.; Lunine, J.; Lebreton, J.; Coustenis, A.; Matson, D.; Reh, K.; Erd, C.

2008-12-01

In 2005, the Huygens Probe gave us a snapshot of a world tantalizingly like our own, yet frozen in its evolution on the threshold of life. The descent under parachute, like that of Huygens in 2005, is happening again, but this time in the Saturn-cast twilight of winter in Titan's northern reaches. With a pop, the parachute is released, and then a muffled splash signals the beginning of the first floating exploration of an extraterrestrial sea-this one not of water but of liquid hydrocarbons. Meanwhile, thousands of miles away, a hot air balloon, a "montgolfiere," cruises 6 miles above sunnier terrain, imaging vistas of dunes, river channels, mountains and valleys carved in water ice, and probing the subsurface for vast quantities of "missing" methane and ethane that might be hidden within a porous icy crust. Balloon and floater return their data to a Titan Orbiter equipped to strip away Titan's mysteries with imaging, radar profiling, and atmospheric sampling, much more powerful and more complete than Cassini was capable of. This spacecraft, preparing to enter a circular orbit around Saturn's cloud-shrouded giant moon, has just completed a series of flybys of Enceladus, a tiny but active world with plumes that blow water and organics from the interior into space. Specialized instruments on the orbiter were able to analyze these plumes directly during the flybys. Titan and Enceladus could hardly seem more different, and yet they are linked by their origin in the Saturn system, by a magnetosphere that sweeps up mass and delivers energy, and by the possibility that one or both worlds harbor life. It is the goal of the NASA/ESA Titan Saturn System Mission (TSSM) to explore and investigate these exotic and inviting worlds, to understand their natures and assess the possibilities of habitability in this system so distant from our home world. Orbiting, landing, and ballooning at Titan represent a new and exciting approach to planetary exploration. The TSSM mission

Low-Latitude Ethane Rain on Titan

Science.gov (United States)

Dalba, Paul A.; Buratti, Bonnie J.; Brown, R. H.; Barnes, J. W.; Baines, K. H.; Sotin, C.; Clark, R. N.; Lawrence, K. J.; Nicholson, P. D.

2012-01-01

Cassini ISS observed multiple widespread changes in surface brightness in Titan's equatorial regions over the past three years. These brightness variations are attributed to rainfall from cloud systems that appear to form seasonally. Determining the composition of this rainfall is an important step in understanding the "methanological" cycle on Titan. I use data from Cassini VIMS to complete a spectroscopic investigation of multiple rain-wetted areas. I compute "before-and-after" spectral ratios of any areas that show either deposition or evaporation of rain. By comparing these spectral ratios to a model of liquid ethane, I find that the rain is most likely composed of liquid ethane. The spectrum of liquid ethane contains multiple absorption features that fall within the 2-micron and 5-micron spectral windows in Titan's atmosphere. I show that these features are visible in the spectra taken of Titan's surface and that they are characteristically different than those in the spectrum of liquid methane. Furthermore, just as ISS saw the surface brightness reverting to its original state after a period of time, I show that VIMS observations of later flybys show the surface composition in different stages of returning to its initial form.

Reduced-graphene-oxide-and-strontium-titanate-based double ...

Indian Academy of Sciences (India)

GO)/strontium titanate were pre- ... R-GO and strontium titanate were synthesized and characterized before ... Microwave absorption capabilities of the composite absorbers were investigated using a .... was backed with a conducting metal sheet.

Cryovolcanism on Titan

Science.gov (United States)

Mitri, G.; Showman, A. P.; Lunine, J. I.; Lopes, R. M.

2008-12-01

Remote sensing observations yield evidence for cryovolcanism on Titan, and evolutionary models support (but do not require) the presence of an ammonia-water subsurface ocean. The impetus for invoking ammonia as a constituent in an internal ocean and cryovolcanic magma comes from two factors. First, ammonia-water liquid has a lower freezing temperature than pure liquid water, enabling cryovolcanism under the low- temperature conditions prevalent in the outer Solar System. Second, pure water is negatively buoyant with respect to pure water ice, which discourages eruption from the subsurface ocean to the surface. In contrast, the addition of ammonia to the water decreases its density, hence lessening this problem of negative buoyancy. A marginally positive buoyant ammonia-water mixture might allow effusive eruptions from a subsurface ocean. If the subsurface ocean were positively buoyant, all the ammonia would have been erupted very early in Titan's history. Contrary to this scenario, Cassini-Huygens has so far observed neither a global abundance nor a complete dearth of cryovolcanic features. Further, an ancient cryovolcanic epoch cannot explain the relative youth of Titan's surface. Crucial to invoking ammonia-water resurfacing as the source of the apparently recent geological activity is not how to make ammonia-water volcanism work (because the near neutral buoyancy of the ammonia-water mixture encourages an explanation), but rather how to prevent eruption from occurring so easily that cryovolcanic activity is over early on. Although cryovolcanism by ammonia-water has been proposed as a resurfacing process on Titan, few models have specifically dealt with the problem of how to transport ammonia-water liquid onto the surface. We proposed a model of cryovolcanism that involve cracking at the base of the ice shell and formation of ammonia-water pockets in the ice. While the ammonia-water pockets cannot easily become neutral buoyant and promote effusive eruptions

The greenhouse and antigreenhouse effects on Titan

Science.gov (United States)

Mckay, Christopher P.; Pollack, James B.; Courtin, Regis

1991-01-01

The parallels between the atmospheric thermal structure of the Saturnian satellite Titan and the hypothesized terrestrial greenhouse effect can serve as bases for the evaluation of competing greenhouse theories. Attention is presently drawn to the similarity between the roles of H2 and CH4 on Titan and CO2 and H2O on earth. Titan also has an antigreenhouse effect due to a high-altitude haze layer which absorbs at solar wavelengths, while remaining transparent in the thermal IR; if this haze layer were removed, the antigreenhouse effect would be greatly reduced, exacerbating the greenhouse effect and raising surface temperature by over 20 K.

Physical model construction for electrical anisotropy of single crystal zinc oxide micro/nanobelt using finite element method

International Nuclear Information System (INIS)

Yu, Guangbin; Tang, Chaolong; Song, Jinhui; Lu, Wenqiang

2014-01-01

Based on conductivity characterization of single crystal zinc oxide (ZnO) micro/nanobelt (MB/NB), we further investigate the physical mechanism of nonlinear intrinsic resistance-length characteristic using finite element method. By taking the same parameters used in experiment, a model of nonlinear anisotropic resistance change with single crystal MB/NB has been deduced, which matched the experiment characterization well. The nonlinear resistance-length comes from the different electron moving speed in various crystal planes. As the direct outcome, crystallography of the anisotropic semiconducting MB/NB has been identified, which could serve as a simple but effective method to identify crystal growth direction of single crystal semiconducting or conductive nanomaterial

Raising the Titanic.

Science.gov (United States)

Baker, Romona

1990-01-01

Described is an activity in which groups of students investigate engineering principles by writing a feasibility study to raise the luxury liner, Titanic. The problem statement and directions, and suggestions for problem solutions are included. (CW)

Titan Lifting Entry & Atmospheric Flight (T-LEAF) Science Mission

Science.gov (United States)

Lee, G.; Sen, B.; Ross, F.; Sokol, D.

2016-12-01

Northrop Grumman has been developing the Titan Lifting Entry & Atmospheric Flight (T-LEAF) sky rover to roam the lower atmosphere and observe at close quarters the lakes and plains of Saturn's ocean moon, Titan. T-LEAF also supports surface exploration and science by providing precision delivery of in-situ instruments to the surface of Titan. T-LEAF is a highly maneuverable sky rover and its aerodynamic shape (i.e., a flying wing) does not restrict it to following prevailing wind patterns on Titan, but allows mission operators to chart its course. This freedom of mobility allows T-LEAF to follow the shorelines of Titan's methane lakes, for example, or to target very specific surface locations. We will present a straw man concept of T-LEAF, including size, mass, power, on-board science payloads and measurement, and surface science dropsonde deployment CONOPS. We will discuss the various science instruments and their vehicle level impacts, such as meteorological and electric field sensors, acoustic sensors for measuring shallow depths, multi-spectral imagers, high definition cameras and surface science dropsondes. The stability of T-LEAF and its long residence time on Titan will provide for time to perform a large aerial survey of select prime surface targets deployment of dropsondes at selected locations surface measurements that are coordinated with on-board remote measurements communication relay capabilities to orbiter (or Earth). In this context, we will specifically focus upon key factors impacting the design and performance of T-LEAF science: science payload accommodation, constraints and opportunities characteristics of flight, payload deployment and measurement CONOPS in the Titan atmosphere. This presentation will show how these factors provide constraints as well as enable opportunities for novel long duration scientific studies of Titan's surface.

Experimental simulations of ethylene evaporites on Titan

Science.gov (United States)

Czaplinski, E.; Farnsworth, K.; Singh, S.; Chevrier, V.

2017-12-01

Titan has an abundance of lakes and seas, as identified by the Cassini spacecraft. Major components of these liquid bodies include methane (CH4) and ethane (C2H6), however minor constituents are also thought to exist (e.g. ethylene (C2H4)). As the lakes and seas evaporate, 5-μm-bright deposits, resembling evaporite deposits on Earth, are left behind in a "bathtub ring" fashion. Previous studies include models of evaporites, and observations of the 5-μm-bright regions, but the community is still lacking a complete suite of experimental evaporite studies. In this study, we experimentally investigate evaporites in order to determine their composition and how they affect infrared spectra during the evaporation process. The University of Arkansas owns a specialized chamber that simulates the surface conditions of Titan ( 90 K and 1.5 bar). Gaseous hydrocarbons are condensed within the chamber and analyzed with Fourier Transform Infrared (FTIR) Spectroscopy and band depth calculations. In this study, three types of experiments were performed: ethane/ethylene, methane/ethylene, and methane/ethane/ethylene. For these experiments, methane was the only species that readily evaporated at Titan conditions (due to its high volatility), while ethane, being the more stable solvent, did not readily evaporate. Therefore, we will present spectral results of ethylene evaporite formation within these mixtures. Our results imply that evaporite formation is strongly dependent on the composition of the solvent. The north polar lakes of Titan are predicted to be methane-rich, indicating that they may be more likely to form evaporites. Alternatively, Ontario Lacus, a south polar lake, is predominately composed of ethane, which may make it more difficult to form evaporites. As we continue to study Titan's mysterious lakes and seas, we hope to draw insights on their exact composition, conditions for evaporite formation, habitability potential, and comparing Titan to prebiotic Earth.

Titan's Topography and Shape at the End of the Cassini Mission

Science.gov (United States)

Corlies, P.; Hayes, A. G.; Birch, S. P. D.; Lorenz, R.; Stiles, B. W.; Kirk, R.; Poggiali, V.; Zebker, H.; Iess, L.

2017-12-01

With the conclusion of the Cassini mission, we present an updated topographic map of Titan, including all the available altimetry, SARtopo, and stereophotogrammetry topographic data sets available from the mission. We use radial basis functions to interpolate the sparse data set, which covers only ˜9% of Titan's global area. The most notable updates to the topography include higher coverage of the poles of Titan, improved fits to the global shape, and a finer resolution of the global interpolation. We also present a statistical analysis of the error in the derived products and perform a global minimization on a profile-by-profile basis to account for observed biases in the input data set. We find a greater flattening of Titan than measured, additional topographic rises in Titan's southern hemisphere and better constrain the possible locations of past and present liquids on Titan's surface.

Application of TITAN for Simulation of Particle Streaming in a Duct

Directory of Open Access Journals (Sweden)

Royston Katherine

2016-01-01

Full Text Available The TITAN hybrid deterministic transport code is applied to the simulation of particle streaming in a nuclear power plant duct. A simple model is used consisting of a concrete duct emerging from the pressure vessel with an isotropic surface source with a U-235 fission spectrum located at the pressure vessel end. Multiple methods of simulating the duct using the TITAN code are considered to demonstrate the flexibility of the code and the advantages of TITAN's algorithms. These methods include a discrete ordinates (SN calculation, a characteristics method calculation, and the use of a fictitious quadrature set with simplified ray-tracing. The TITAN code's results are compared with MCNP5 solutions. While all TITAN solutions are obtained in a shorter computation time than the MCNP5 solution, the TITAN solution with the fictitious quadrature set shows the largest speedup.

Tritium systems for the TITAN reversed-field pinch fusion reactor design

International Nuclear Information System (INIS)

Martin, R.C.; Sze, D.K.; Bartlit, J.R.; Gierszewski, P.J.

1987-01-01

Tritium systems for the TITAN reversed-field pinch (RFP) fusion reactor study have been designed for two blanket concepts. The TITAN-1 design uses a self-cooled liquid-lithium blanket. The TITAN-2 design uses a self-cooled aqueous-solution blanket, with lithium nitrate dissolved in the water for tritium breeding. Tritium inventory, release, and safety margins are within regulatory limits, at acceptable costs. Major issues for TITAN-1 are plasma-driven permeation, the need for a secondary coolant loop, tritium storage requirements, redundancy in the plasma exhaust system, and minimal isotopic distillation of the exhaust. TITAN-1 fuel cleanup, reprocessing, and air detritiation systems are described in detail

The seasonal cycle of Titan's detached haze

Science.gov (United States)

West, Robert A.; Seignovert, Benoît; Rannou, Pascal; Dumont, Philip; Turtle, Elizabeth P.; Perry, Jason; Roy, Mou; Ovanessian, Aida

2018-04-01

Titan's `detached' haze, seen in Voyager images in 1980 and 1981 and monitored by the Cassini Imaging Science Subsystem (ISS) during the period 2004-2017, provides a measure of seasonal activity in Titan's mesosphere with observations over almost half of Saturn's seasonal cycle. Here we report on retrieved haze extinction profiles that reveal a depleted layer (having a diminished aerosol content), visually manifested as a gap between the main haze and a thin, detached upper layer. Our measurements show the disappearance of the feature in 2012 and its reappearance in 2016, as well as details after the reappearance. These observations highlight the dynamical nature of the detached haze. The reappearance seems congruent with earlier descriptions by climate models but more complex than previously described. It occurs in two steps, first as haze reappearing at 450 ± 20 km and one year later at 510 ± 20 km. These observations provide additional tight and valuable constraints about the underlying mechanisms, especially for Titan's mesosphere, that control Titan's haze cycle.

The mechanochemical stability of hydrogen titanate nanostructures

International Nuclear Information System (INIS)

Plodinec, M.; Friscic, I.; Ivekovic, D.; Tomasic, N.; Su, D.S.; Zhang, J.; Gajovic, A.

2010-01-01

The structural stability of some nanostructured titanates was investigated in terms of their subsequent processing and possible applications. With the aim to investigate their mechanochemical stability, we applied high-energy ball milling and studied the resulting induced phase transitions. Hydrogen titanates with two different morphologies, microcrystals and nanotubes, were taken into consideration. The phase-transition sequence was studied by Raman spectroscopy and X-ray powder diffraction, while the morphology and crystal structure, on the nanoscale, were analyzed by high-resolution transmission electron microscopy. During the mechanochemical treatment of both morphologies, the phase transitions from hydrogen titanate to TiO 2 anatase and subsequently to TiO 2 rutile were observed. In the case of hydrogen trititanate crystals, the phase transition to anatase starts after a longer milling time than in the case of the titanate nanotubes, which is explained by the larger particle size of the crystalline powder. However, the phase transition from anatase to rutile occurred more quickly in the crystalline powder than in the case of the nanotubes.

The tide in the seas of Titan

International Nuclear Information System (INIS)

Sagan, C.; Dermott, S.F.

1982-01-01

It is argued that, if Titan has oceans consisting of liquid methane, then the present high eccentricity of the satellite necessitates that the depth would be greater than 400 m. Such an ocean should be detectable by radar. The effects of tidal dissipation due to the possible existence of an ocean on Titan are considered. (author)

Landscape Evolution of Titan

Science.gov (United States)

Moore, Jeffrey

2012-01-01

Titan may have acquired its massive atmosphere relatively recently in solar system history. The warming sun may have been key to generating Titan's atmosphere over time, starting from a thin atmosphere with condensed surface volatiles like Triton, with increased luminosity releasing methane, and then large amounts of nitrogen (perhaps suddenly), into the atmosphere. This thick atmosphere, initially with much more methane than at present, resulted in global fluvial erosion that has over time retreated towards the poles with the removal of methane from the atmosphere. Basement rock, as manifested by bright, rough, ridges, scarps, crenulated blocks, or aligned massifs, mostly appears within 30 degrees of the equator. This landscape was intensely eroded by fluvial processes as evidenced by numerous valley systems, fan-like depositional features and regularly-spaced ridges (crenulated terrain). Much of this bedrock landscape, however, is mantled by dunes, suggesting that fluvial erosion no longer dominates in equatorial regions. High midlatitude regions on Titan exhibit dissected sedimentary plains at a number of localities, suggesting deposition (perhaps by sediment eroded from equatorial regions) followed by erosion. The polar regions are mainly dominated by deposits of fluvial and lacustrine sediment. Fluvial processes are active in polar areas as evidenced by alkane lakes and occasional cloud cover.

Reduced-graphene-oxide-and-strontium-titanate-based double

Indian Academy of Sciences (India)

Microwave-absorbing materials based on reduced graphene oxide (r-GO)/ strontium titanate were prepared by embedding in epoxy matrix. R-GO and strontium titanate were synthesized and characterized before composite fabrication. Microstructures of the constituent elements were studied by scanning electron ...

Cation interdiffusion in polycrystalline calcium and strontium titanate

International Nuclear Information System (INIS)

Butler, E.P.; Jain, H.; Smyth, D.M.

1991-01-01

This paper discusses a method that has been developed to study bulk lattice interdiffusion between calcium and strontium titanate by fabrication of a diffusion couple using cosintering. The measured interdiffusion coefficients, D(C), indicate that strontium impurity diffusion in calcium titanate occurs at a faster rate than calcium impurity diffusion in strontium titanate. These interdiffusion coefficients are composition independent when the concentration of the calcium cation exceeds that of the strontium cation; otherwise D(C) is strongly composition dependent. Investigations into the effect of cation nonstoichiometry give results that are consistent with a defect incorporation reaction in which excess TiO 2 , within the solid solubility limit, produces A-site cation vacancies as compensating defects. The interdiffusion coefficients increase with increasing concentrations of TiO 2 , so it is concluded that interdiffusion of these alkaline-earth cations in their titanates occurs via a vacancy mechanism

Mission Techniques for Exploring Saturn's icy moons Titan and Enceladus

Science.gov (United States)

Reh, Kim; Coustenis, Athena; Lunine, Jonathan; Matson, Dennis; Lebreton, Jean-Pierre; Vargas, Andre; Beauchamp, Pat; Spilker, Tom; Strange, Nathan; Elliott, John

2010-05-01

The future exploration of Titan is of high priority for the solar system exploration community as recommended by the 2003 National Research Council (NRC) Decadal Survey [1] and ESA's Cosmic Vision Program themes. Cassini-Huygens discoveries continue to emphasize that Titan is a complex world with very many Earth-like features. Titan has a dense, nitrogen atmosphere, an active climate and meteorological cycles where conditions are such that the working fluid, methane, plays the role that water does on Earth. Titan's surface, with lakes and seas, broad river valleys, sand dunes and mountains was formed by processes like those that have shaped the Earth. Supporting this panoply of Earth-like processes is an ice crust that floats atop what might be a liquid water ocean. Furthermore, Titan is rich in very many different organic compounds—more so than any place in the solar system, except Earth. The Titan Saturn System Mission (TSSM) concept that followed the 2007 TandEM ESA CV proposal [2] and the 2007 Titan Explorer NASA Flagship study [3], was examined [4,5] and prioritized by NASA and ESA in February 2009 as a mission to follow the Europa Jupiter System Mission. The TSSM study, like others before it, again concluded that an orbiter, a montgolfiѐre hot-air balloon and a surface package (e.g. lake lander, Geosaucer (instrumented heat shield), …) are very high priority elements for any future mission to Titan. Such missions could be conceived as Flagship/Cosmic Vision L-Class or as individual smaller missions that could possibly fit within NASA's New Frontiers or ESA's Cosmic Vision M-Class budgets. As a result of a multitude of Titan mission studies, several mission concepts have been developed that potentially fit within various cost classes. Also, a clear blueprint has been laid out for early efforts critical toward reducing the risks inherent in such missions. The purpose of this paper is to provide a brief overview of potential Titan (and Enceladus) mission

Detailed exploration of Titan with a Montgolfiere aerobot

Science.gov (United States)

Spilker, T.; Tipex Team

The International Cassini/Huygens (CH) mission has verified the expectation that Saturn's moon Titan offers many opportunities for studying high-priority planetary and astrobiology science objectives. CH results to date show that this world, though entirely alien in its frigid environment, presents an Earth-like and diverse appearance due to the relative balance of competing forces such as geology/tectonics, meteorology, aeronomy, and cosmic impacts. But with the limitations of a single Huygens probe, and a finite number of Cassini flybys limited in proximity and remote sensing resolution by Titan's thick atmosphere and hazes, there is much science to be done there after the CH mission has ended. Detailed exploration of Titan's surface and lower atmosphere, especially for astrobiological objectives, is best addressed by in situ investigations. The atmosphere and its hazes severely restrict orbital remote sensing: Titan cannot be mapped from orbit in the same manner as Mars, at (essentially) arbitrarily high resolution, and limited infrared (IR) windows allow only gross compositional interpretations. After CH indeed there will be further orbital investigations to be carried out, notably completion of the global mapping by Synthetic Aperture Radar and IR mapping spectrometry begun by CH, at the best resolutions practical from orbit. But to fully understand Titan as an evolving, planetary-scale body and an abode of preserved protobiological chemistry will require a platform that has access to, and mobility at, the surface and the lowest few kilometers of the atmosphere. The TiPEx study team weighed the options for Titan in situ exploration, and finds that a mission based on a Montgolfiere (a type of hot-air balloon) aerobot is the best candidate for post-CH exploration. Ground-based platforms of the type used to date on Mars are far too limited in range to sample the diversity of Titan, and do not adequately investigate the lower atmosphere. Titan's cold, dense

Surface-Atmosphere Connections on Titan: A New Window into Terrestrial Hydroclimate

Science.gov (United States)

Faulk, Sean

This dissertation investigates the coupling between the large-scale atmospheric circulation and surface processes on Titan, with a particular focus on methane precipitation and its influence on surface geomorphology and hydrology. As the only body in the Solar System with an active hydrologic cycle other than Earth, Titan presents a valuable laboratory for studying principles of hydroclimate on terrestrial planets. Idealized general circulation models (GCMs) are used here to test hypotheses regarding Titan's surface-atmosphere connections. First, an Earth-like GCM simulated over a range of rotation rates is used to evaluate the effect of rotation rate on seasonal monsoon behavior. Slower rotation rates result in poleward migration of summer rain, indicating a large-scale atmospheric control on Titan's observed dichotomy of dry low latitudes and moist high latitudes. Second, a Titan GCM benchmarked against observations is used to analyze the magnitudes and frequencies of extreme methane rainstorms as simulated by the model. Regional patterns in these extreme events correlate well with observed geomorphic features, with the most extreme rainstorms occurring in mid-latitude regions associated with high alluvial fan concentrations. Finally, a planetary surface hydrology scheme is developed and incorporated into a Titan GCM to evaluate the roles of surface flow, subsurface flow, infiltration, and groundmethane evaporation in Titan's climate. The model reproduces Titan's observed surface liquid and cloud distributions, and reaches an equilibrium state with limited interhemispheric transport where atmospheric transport is approximately balanced by subsurface transport. The equilibrium state suggests that Titan's current hemispheric surface liquid asymmetry, favoring methane accumulation in the north, is stable in the modern climate.

Phase I Technical Report for the Engineering of Monosodium Titanate

International Nuclear Information System (INIS)

NASH, CHARLES

2004-01-01

Monosodium titanate (MST) is an inorganic adsorbent that effectively removes strontium, plutonium, uranium, and other trace elements from alkaline salt supernate. Current plans use the MST in batch contact processes to treat Savannah River Site (SRS) waste solutions that require 90Sr and actinide removal to meet low level disposal criteria. More effective use of MST may be realized if the MST could be engineered into a form suitable for a continuous treatment process such as an adsorption column. The main benefits of column operation are (1) enhanced loading due to equilibration with feed adsorbate levels versus product levels, and (2) a small footprint relative to that of a batch contact tank. The current baseline MST material features particles of nominally 0.5-35 micron in size, which are much too fine for use in an adsorption column. An extensive review of the literature and consultation with technical experts identified candidate methods to produce engineered forms of MST. From this list a review team selected five candidate methods for further study. Laboratory syntheses at Savannah River National Laboratory (SRNL) and offsite produced representative samples for characterization and performance testing. Testing identified two suitable methods. The two methods include internal gelation, which is patented technology of Oak Ridge National Laboratory, and internal hydrolysis, a method in which the MST is produced within a porous substrate. A commercial sodium titanate, SrTreat(R), produced by Fortum Engineering (Finland), demonstrated good performance as well although plutonium removal kinetics appeared much slower than observed for the other engineered MST materials

Progressive Climate Change on Titan: Implications for Habitability

Science.gov (United States)

Moore, J. M.; A. D. Howard

2014-01-01

Titan's landscape is profoundly shaped by its atmosphere and comparable in magnitude perhaps with only the Earth and Mars amongst the worlds of the Solar System. Like the Earth, climate dictates the intensity and relative roles of fluvial and aeolian activity from place to place and over geologic time. Thus Titan's landscape is the record of climate change. We have investigated three broad classes of Titan climate evolution hypotheses (Steady State, Progressive, and Cyclic), regulated by the role, sources, and availability of methane. We favor the Progressive hypotheses, which we will outline here, then discuss their implication for habitability.

Decontamination of 2-chloroethyl ethylsulfide using titanate nanoscrolls

Science.gov (United States)

Kleinhammes, Alfred; Wagner, George W.; Kulkarni, Harsha; Jia, Yuanyuan; Zhang, Qi; Qin, Lu-Chang; Wu, Yue

2005-08-01

Titanate nanoscrolls, a recently discovered variant of TiO 2 nanocrystals, are tested as reactive sorbent for chemical warfare agent (CWA) decontamination. The large surface area of the uncapped tubules provides the desired rapid absorption of the contaminant while water molecules, intrinsic constituents of titanate nanoscrolls, provide the necessary chemistry for hydrolytic reaction. In this study the decomposition of 2-chloroethyl ethylsulfide (CEES), a simulant for the CWA mustard, was monitored using 13C NMR. The NMR spectra reveal reaction products as expected from the hydrolysis of CEES. This demonstrates that titanate nanoscrolls could potentially be employed as a decontaminant for CWAs.

Crater Topography on Titan: Implications for Landscape Evolution

Science.gov (United States)

Neish, Catherine D.; Kirk, R.L.; Lorenz, R. D.; Bray, V. J.; Schenk, P.; Stiles, B. W.; Turtle, E.; Mitchell, K.; Hayes, A.

2013-01-01

We present a comprehensive review of available crater topography measurements for Saturn's moon Titan. In general, the depths of Titan's craters are within the range of depths observed for similarly sized fresh craters on Ganymede, but several hundreds of meters shallower than Ganymede's average depth vs. diameter trend. Depth-to-diameter ratios are between 0.0012 +/- 0.0003 (for the largest crater studied, Menrva, D approximately 425 km) and 0.017 +/- 0.004 (for the smallest crater studied, Ksa, D approximately 39 km). When we evaluate the Anderson-Darling goodness-of-fit parameter, we find that there is less than a 10% probability that Titan's craters have a current depth distribution that is consistent with the depth distribution of fresh craters on Ganymede. There is, however, a much higher probability that the relative depths are uniformly distributed between 0 (fresh) and 1 (completely infilled). This distribution is consistent with an infilling process that is relatively constant with time, such as aeolian deposition. Assuming that Ganymede represents a close 'airless' analogue to Titan, the difference in depths represents the first quantitative measure of the amount of modification that has shaped Titan's surface, the only body in the outer Solar System with extensive surface-atmosphere exchange.

Synthesis and structural characterization of Ce-doped bismuth titanate

International Nuclear Information System (INIS)

Pavlovic, Nikolina; Srdic, Vladimir V.

2009-01-01

Ce-modified bismuth titanate nanopowders Bi 4-x Ce x Ti 3 O 12 (x ≤ 1) have been synthesized using a coprecipitation method. DTA/TG, FTIR, XRD, SEM/EDS and BET methods were used in order to investigate the effect of Ce-substitution on the structure, morphology and sinterability of the obtained powders. The phase structure investigation revealed that after calcinations at 600 deg. C powder without Ce addition exhibited pure bismuth titanate phase; however, powders with Ce (x = 0.25, 0.5 and 0.75) had bismuth titanate pyrochlore phase as the second phase. The strongest effect of Ce addition on the structure was noted for the powder with the highest amount of Ce (x = 1) having a cubic pyrochlore structure. The presence of pure pyrochlore phase was explained by its stabilization due to the incorporation of cerium ions in titanate structure. Ce-modified bismuth titanate ceramic had a density over 95% of theoretical density and the fracture in transgranular manner most probably due to preferable distribution of Ce in boundary region

Heavy Ion Formation in Titan's Ionosphere: Magnetospheric Introduction of Free Oxygen and a Source of Titan's Aerosols?

Science.gov (United States)

Sittler, E. C., Jr.; Ali, A.; Cooper, J. F.; Hartle, R. E.; Johnson, R. E.; Coates, A. J.; Young, D. T.

2009-01-01

Discovery by Cassini's plasma instrument of heavy positive and negative ions within Titan's upper atmosphere and ionosphere has advanced our understanding of ion neutral chemistry within Titan's upper atmosphere, primarily composed of molecular nitrogen, with approx.2.5% methane. The external energy flux transforms Titan's upper atmosphere and ionosphere into a medium rich in complex hydrocarbons, nitriles and haze particles extending from the surface to 1200 km altitudes. The energy sources are solar UV, solar X-rays, Saturn's magnetospheric ions and electrons, solar wind and shocked magnetosheath ions and electrons, galactic cosmic rays (CCR) and the ablation of incident meteoritic dust from Enceladus' E-ring and interplanetary medium. Here it is proposed that the heavy atmospheric ions detected in situ by Cassini for heights >950 km, are the likely seed particles for aerosols detected by the Huygens probe for altitudes <100km. These seed particles may be in the form of polycyclic aromatic hydrocarbons (PAH) containing both carbon and hydrogen atoms CnHx. There could also be hollow shells of carbon atoms, such as C60, called fullerenes which contain no hydrogen. The fullerenes may compose a significant fraction of the seed particles with PAHs contributing the rest. As shown by Cassini, the upper atmosphere is bombarded by magnetospheric plasma composed of protons, H(2+) and water group ions. The latter provide keV oxygen, hydroxyl and water ions to Titan's upper atmosphere and can become trapped within the fullerene molecules and ions. Pickup keV N(2+), N(+) and CH(4+) can also be implanted inside of fullerenes. Attachment of oxygen ions to PAH molecules is uncertain, but following thermalization O(+) can interact with abundant CH4 contributing to the CO and CO2 observed in Titan's atmosphere. If an exogenic keV O(+) ion is implanted into the haze particles, it could become free oxygen within those aerosols that eventually fall onto Titan's surface. The process

Titan's Stratospheric Condensibles at High Northern Latitudes During Northern Winter

Science.gov (United States)

Anderson, Carrie; Samuelson, R.; Achterberg, R.

2012-01-01

The Infrared Interferometer Spectrometer (IRIS) instrument on board Voyager 1 caught the first glimpse of an unidentified particulate feature in Titan's stratosphere that spectrally peaks at 221 per centimeter. Until recently, this feature that we have termed 'the haystack,' has been seen persistently at high northern latitudes with the Composite Infrared Spectrometer (CIRS) instrument onboard Cassini, The strength of the haystack emission feature diminishes rapidly with season, becoming drastically reduced at high northern latitudes, as Titan transitions from northern winter into spring, In contrast to IRIS whose shortest wavenumber was 200 per centimeter, CIRS extends down to 10 per centimeter, thus revealing an entirely unexplored spectral region in which nitrile ices have numerous broad lattice vibration features, Unlike the haystack, which is only found at high northern latitudes during northern winter/early northern spring, this geometrically thin nitrile cloud pervades Titan's lower stratosphere, spectrally peaking at 160 per centimeter, and is almost global in extent spanning latitudes 85 N to 600 S, The inference of nitrile ices are consistent with the highly restricted altitude ranges over which these features are observed, and appear to be dominated by a mixture of HCN and HC3N, The narrow range in altitude over which the nitrile ices extend is unlike the haystack, whose vertical distribution is significantly broader, spanning roughly 70 kilometers in altitude in Titan's lower stratosphere, The nitrile clouds that CIRS observes are located in a dynamically stable region of Titan's atmosphere, whereas CH4 clouds, which ordinarily form in the troposphere, form in a more dynamically unstable region, where convective cloud systems tend to occur. In the unusual situation where Titan's tropopause cools significantly from the HASI 70.5K temperature minimum, CH4 should condense in Titan's lower stratosphere, just like the aforementioned nitrile clouds, although

Thermogravimetric study of the kinetics of lithium titanate reduction by hydrogen

International Nuclear Information System (INIS)

Sonak, Sagar; Rakesh, R.; Jain, Uttam; Mukherjee, Abhishek; Kumar, Sanjay; Krishnamurthy, Nagaiyar

2014-01-01

Highlights: • Li 2 TiO 3 powder is synthesized by the gel combustion route. • Activation energy of reduction of Li 2 TiO 3 by H 2 found out to be 27.45 kJ/mol H 2 . • Non-stoichiometric phase of Li 2 TiO 3 is formed in hydrogen atmosphere. • One-dimensional diffusion appears to be the most probable mechanism of reduction. - Abstract: The lithium titanate powder was synthesized by gel-combustion route. The mechanism and the kinetics of hydrogen interaction with lithium titanate powder were studied using non-isothermal thermogravimetric technique. Lithium titanate underwent reduction in hydrogen atmosphere which led to the formation of oxygen deficient non-stoichiometric compound in lithium titanate. One-dimensional diffusion appeared to be the most probable reaction mechanism. The activation energy for reduction of lithium titanate under hydrogen atmosphere was found to be 27.4 kJ/mol/K. Structural changes after hydrogen reduction in lithium titanate were observed in X-ray diffraction analysis

Screening of spontaneous polarization in lead titanate crystals

International Nuclear Information System (INIS)

Gavrilyachenko, V.G.; Semenchev, A.F.; Fesenko, E.G.

1996-01-01

Results of experimental investigations into electric conductivity of lead titanate crystals with different domain structure including single-domain are reported. The data obtained give grounds to believe that spontaneous titanate polarization is realized by the surface level and charge volumetric of free carriers and ionized impurity

Fabrication and properties of yttrium doped barium titanate film by RF sputtering

International Nuclear Information System (INIS)

Igarashi, H.; Yuasa, M.; Okazaki, K.

1985-01-01

Semiconductive barium titanate films were fabricated by RF sputtering on fused quartz, alumina and barium titanate ceramic substrates using barium titanate ceramic with a small amount of yttria as a target. The films on the barium titanate substrates turned blue color and showed a small PTC effect by heat-treating at 1000 0 C in the air after deposition at the substrate temperature of 600 0 C

Titanic exploration with GIS

Science.gov (United States)

Kerski, J.J.

2004-01-01

To help teachers and students investigate one of the world's most famous historical events using the geographic perspective and GIS tools and methods, the U.S. Geological Survey (USGS) created a set of educational lessons based on the RMS Titanic's April 1912 sailing. With these lessons, student researchers can learn about latitude and longitude, map projections, ocean currents, databases, maps, and images through the analysis of the route, warnings, sinking, rescue, and eventual discovery of the submerged ocean liner in 1985. They can also consider the human and physical aspects of the maiden voyage in the North Atlantic Ocean at a variety of scales, from global to regional to local. Likewise, their investigations can reveal how the sinking of the Titanic affected future shipping routes.

Exfoliation and thermal transformations of Nb-substituted layered titanates

DEFF Research Database (Denmark)

Song, H.; Sjåstad, Anja O.; Fjellvåg, Helmer

2011-01-01

Single-layer Nb-substituted titanate nanosheets of ca. 1 nm thickness were obtained by exfoliating tetrabutylammonium (TBA)-intercalated Nb-substituted titanates in water. AFM images and turbidity measurements reveal that the exfoliated nanosheets crack and corrugate when sonicated. Upon heating...... factors for increasing the transformation temperatures for conversion of the nanosheets to anatase and finally into rutile. It is further tempting to link the delay in crystallization to morphology limitations originating from the nanosheets. The present work shows that layered Nb-titanates...

A vacuum pressure sensor based on ZnO nanobelt film

International Nuclear Information System (INIS)

Zheng, X J; Cao, X C; Sun, J; Yuan, B; Zhu, Z; Zhang, Y; Li, Q H

2011-01-01

A vacuum pressure sensor was fabricated by assembling ZnO nanobelt film on the interdigital electrodes, and the current-voltage characteristics were measured with an Agilent semiconductor parameter tester. Under different pressures of 1.0 x 10 3 , 6.7 x 10 -3 , 8.2 x 10 -4 and 9.5 x 10 -5 mbar, the currents are 8.71, 28.1, 46.1 and 89.6 nA, and the pressure sensitive resistances are 1150, 356, 217 and 112 MΩ, respectively. In the range of 10 -5 -10 3 mbar the smaller the pressure is, the higher the current is. The pressure sensitive resistance of the vacuum pressure sensor increases linearly with the logarithmic pressure, and the measurement range is at least one order of magnitude wider than that of the previous sensors. Under the final pressure, the vacuum pressure sensor has maximum sensitivity (9.29) and power consumption of 0.9 μW. The sensitivity is larger than that of the previous sensor based on a ZnO single nanowire at that pressure, and the power consumption is much lower than that for the sensor based on a ZnO nanowire array. The pressure sensitive mechanism is reasonably explained by using oxygen chemisorption and energy band theory.

TandEM: Titan and Enceladus mission

Science.gov (United States)

Coustenis, A.; Atreya, S.K.; Balint, T.; Brown, R.H.; Dougherty, M.K.; Ferri, F.; Fulchignoni, M.; Gautier, D.; Gowen, R.A.; Griffith, C.A.; Gurvits, L.I.; Jaumann, R.; Langevin, Y.; Leese, M.R.; Lunine, J.I.; McKay, C.P.; Moussas, X.; Muller-Wodarg, I.; Neubauer, F.; Owen, T.C.; Raulin, F.; Sittler, E.C.; Sohl, F.; Sotin, Christophe; Tobie, G.; Tokano, T.; Turtle, E.P.; Wahlund, J.-E.; Waite, J.H.; Baines, K.H.; Blamont, J.; Coates, A.J.; Dandouras, I.; Krimigis, T.; Lellouch, E.; Lorenz, R.D.; Morse, A.; Porco, C.C.; Hirtzig, M.; Saur, J.; Spilker, T.; Zarnecki, J.C.; Choi, E.; Achilleos, N.; Amils, R.; Annan, P.; Atkinson, D.H.; Benilan, Y.; Bertucci, C.; Bezard, B.; Bjoraker, G.L.; Blanc, M.; Boireau, L.; Bouman, J.; Cabane, M.; Capria, M.T.; Chassefiere, E.; Coll, P.; Combes, M.; Cooper, J.F.; Coradini, A.; Crary, F.; Cravens, T.; Daglis, I.A.; de Angelis, E.; De Bergh, C.; de Pater, I.; Dunford, C.; Durry, G.; Dutuit, O.; Fairbrother, D.; Flasar, F.M.; Fortes, A.D.; Frampton, R.; Fujimoto, M.; Galand, M.; Grasset, O.; Grott, M.; Haltigin, T.; Herique, A.; Hersant, F.; Hussmann, H.; Ip, W.; Johnson, R.; Kallio, E.; Kempf, S.; Knapmeyer, M.; Kofman, W.; Koop, R.; Kostiuk, T.; Krupp, N.; Kuppers, M.; Lammer, H.; Lara, L.-M.; Lavvas, P.; Le, Mouelic S.; Lebonnois, S.; Ledvina, S.; Li, Ji; Livengood, T.A.; Lopes, R.M.; Lopez-Moreno, J. -J.; Luz, D.; Mahaffy, P.R.; Mall, U.; Martinez-Frias, J.; Marty, B.; McCord, T.; Salvan, C.M.; Milillo, A.; Mitchell, D.G.; Modolo, R.; Mousis, O.; Nakamura, M.; Neish, Catherine D.; Nixon, C.A.; Mvondo, D.N.; Orton, G.; Paetzold, M.; Pitman, J.; Pogrebenko, S.; Pollard, W.; Prieto-Ballesteros, O.; Rannou, P.; Reh, K.; Richter, L.; Robb, F.T.; Rodrigo, R.; Rodriguez, S.; Romani, P.; Bermejo, M.R.; Sarris, E.T.; Schenk, P.; Schmitt, B.; Schmitz, N.; Schulze-Makuch, D.; Schwingenschuh, K.; Selig, A.; Sicardy, B.; Soderblom, L.; Spilker, L.J.; Stam, D.; Steele, A.; Stephan, K.; Strobel, D.F.; Szego, K.; Szopa,

2009-01-01

TandEM was proposed as an L-class (large) mission in response to ESA’s Cosmic Vision 2015–2025 Call, and accepted for further studies, with the goal of exploring Titan and Enceladus. The mission concept is to perform in situ investigations of two worlds tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini–Huygens mission. These bodies still hold mysteries requiring a complete exploration using a variety of vehicles and instruments. TandEM is an ambitious mission because its targets are two of the most exciting and challenging bodies in the Solar System. It is designed to build on but exceed the scientific and technological accomplishments of the Cassini–Huygens mission, exploring Titan and Enceladus in ways that are not currently possible (full close-up and in situ coverage over long periods of time). In the current mission architecture, TandEM proposes to deliver two medium-sized spacecraft to the Saturnian system. One spacecraft would be an orbiter with a large host of instruments which would perform several Enceladus flybys and deliver penetrators to its surface before going into a dedicated orbit around Titan alone, while the other spacecraft would carry the Titan in situ investigation components, i.e. a hot-air balloon (Montgolfière) and possibly several landing probes to be delivered through the atmosphere.

Organic matter in the Titan lakes, and comparison with primitive Earth

Science.gov (United States)

Khare, Bishun N.; McKay, C.; Wilhite, P.; Beeler, D.; Carter, M.; Schurmeier, L.; Jagota, S.; Kawai, J.; Nna-Mvondo, D.; Cruikshank, D.; Embaye, T.

2013-06-01

Titan is the only world in the solar system besides the Earth that has liquid on its surface. The liquid in the lakes is thought to be composed primarily of ethane with methane and nitrogen in solution. The clouds are thought to be composed of liquid methane drops. Surface liquid is present in polar lakes and in surface materials at equatorial sites. Studying the chemical processing that potentially results from organic material interacting with this liquid is one of the main goals of proposed missions to Titan. We have been engaged in producing tholin under Titan-like conditions for more than three decades, first at the Laboratory for Planetary Studies at Cornell University in collaboration with Late Dr. Carl Sagan and for over a decade at Laboratory for Planetary Studies at NASA Ames Research Center and Carl Sagan Center for the Study of Life in the Universe, SETI Institute. Our focus is to understand the capabilities for analysis of tholin solubility in liquid methane and ethane for flight instruments. Our results are expected to contribute to an understanding of the organic chemistry on Titan and to the development of an explicit and targeted scientific strategy for near term analysis of the products of organic-liquid interactions on Titan. Organics are produced as a haze in Titan's high atmosphere due to photolysis of methane with the Sun's extreme ultraviolet light and subsequent reaction with N. Also tholins are formed at a much higher level on Titan by charged particles of Saturn magnetosphere. However, the presence of organics is not the sole feature, which makes Titan significant to astrobiology; organics are widely present in the outer solar system. The reason Titan is a prime target for future outer solar system missions is the combination of organic material and liquid on the surface; liquid that could over a medium for further organic synthesis. NASA recently selected for further study a Discovery proposal TiME to investigate the chemistry of the

Nanostructured titanate with different metal ions on the surface of metallic titanium: a facile approach for regulation of rBMSCs fate on titanium implants.

Science.gov (United States)

Ren, Na; Li, Jianhua; Qiu, Jichuan; Sang, Yuanhua; Jiang, Huaidong; Boughton, Robert I; Huang, Ling; Huang, Wei; Liu, Hong

2014-08-13

Titanium (Ti) is widely used for load-bearing bio-implants, however, it is bio-inert and exhibits poor osteo-inductive properties. Calcium and magnesium ions are considered to be involved in bone metabolism and play a physiological role in the angiogenesis, growth, and mineralization of bone tissue. In this study, a facile synthesis approach to the in situ construction of a nanostructure enriched with Ca(2+) and Mg(2+) on the surface of titanium foil is proposed by inserting Ca(2+) and Mg(2+) into the interlayers of sodium titanate nanostructures through an ion-substitution process. The characteriz 0.67, and 0.73 nm ation results validate that cations can be inserted into the interlayer regions of the layered nanostructure without any obvious change of morphology. The cation content is positively correlated to the concentration of the solutions employed. The biological assessments indicate that the type and the amount of cations in the titanate nanostructure can alter the bioactivity of titanium implants. Compared with a Na(+) filled titanate nanostructure, the incorporation of divalent ions (Mg(2+) , Ca(2+) ) can effectively enhance protein adsorption, and thus also enhance the adhesion and differentiation ability of rat bone-marrow stem cells (rBMSCs). The Mg(2+) /Ca(2+) -titanate nanostructure is a promising implantable material that will be widely applicable in artificial bones, joints, and dental implants. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simulating the 3-D Structure of Titan's Upper Atmosphere

Science.gov (United States)

Bell, J. M.; Waite, H.; Westlake, J.; Magee, B.

2009-05-01

We present results from the 3-D Titan Global Ionosphere-Thermosphere Model (Bell et al [2009], PSS, in review). We show comparisons between simulated N2, CH4, and H2 density fields and the in-situ data from the Cassini Ion Neutral Mass Spectrometer (INMS). We describe the temperature and wind fields consistent with these density calculations. Variations with local time, longitude, and latitude will be addressed. Potential plasma heating sources can be estimated using the 1-D model of De La Haye et al [2007, 2008] and the impacts on the thermosphere of Titan can be assessed in a global sense in Titan-GITM. Lastly, we will place these findings within the context of recent work in modeling the 2-D structure of Titan's upper atmosphere (Mueller-Wodarg et al [2008]).

METHANE GAS STABILIZES SUPERCOOLED ETHANE DROPLETS IN TITAN'S CLOUDS

International Nuclear Information System (INIS)

Wang, Chia C.; Lang, E. Kathrin; Signorell, Ruth

2010-01-01

Strong evidence for ethane clouds in various regions of Titan's atmosphere has recently been found. Ethane is usually assumed to exist as ice particles in these clouds, although the possible role of liquid and supercooled liquid ethane droplets has been recognized. Here, we report on infrared spectroscopic measurements of ethane aerosols performed in the laboratory under conditions mimicking Titan's lower atmosphere. The results clearly show that liquid ethane droplets are significantly stabilized by methane gas which is ubiquitous in Titan's nitrogen atmosphere-a phenomenon that does not have a counterpart for water droplets in Earth's atmosphere. Our data imply that supercooled ethane droplets are much more abundant in Titan's clouds than previously anticipated. Possibly, these liquid droplets are even more important for cloud processes and the formation of lakes than ethane ice particles.

Crater relaxation on Titan aided by low thermal conductivity sand infill

Science.gov (United States)

Schurmeier, Lauren R.; Dombard, Andrew J.

2018-05-01

Titan's few impact craters are currently many hundreds of meters shallower than the depths expected. Assuming these craters initially had depths equal to that of similar-size fresh craters on Ganymede and Callisto (moons of similar size, composition, and target lithology), then some process has shallowed them over time. Since nearly all of Titan's recognized craters are located within the arid equatorial sand seas of organic-rich dunes, where rain is infrequent, and atmospheric sedimentation is expected to be low, it has been suggested that aeolian infill plays a major role in shallowing the craters. Topographic relaxation at Titan's current heat flow was previously assumed to be an unimportant process on Titan due to its low surface temperature (94 K). However, our estimate of the thermal conductivity of Titan's organic-rich sand is remarkably low (0.025 W m-1 K-1), and when in thick deposits, will result in a thermal blanketing effect that can aid relaxation. Here, we simulate the relaxation of Titan's craters Afekan, Soi, and Sinlap including thermal effects of various amounts of sand inside and around Titan's craters. We find that the combination of aeolian infill and subsequent relaxation can produce the current crater depths in a geologically reasonable period of time using Titan's current heat flow. Instead of needing to fill completely the missing volume with 100% sand, only ∼62%, ∼71%, and ∼97%, of the volume need be sand at the current basal heat flux for Afekan, Soi, and Sinlap, respectively. We conclude that both processes are likely at work shallowing these craters, and this finding contributes to why Titan overall lacks impact craters in the arid equatorial regions.

Freeze cast porous barium titanate for enhanced piezoelectric energy harvesting

Science.gov (United States)

Roscow, J. I.; Zhang, Y.; Kraśny, M. J.; Lewis, R. W. C.; Taylor, J.; Bowen, C. R.

2018-06-01

Energy harvesting is an important developing technology for a new generation of self-powered sensor networks. This paper demonstrates the significant improvement in the piezoelectric energy harvesting performance of barium titanate by forming highly aligned porosity using freeze casting. Firstly, a finite element model demonstrating the effect of pore morphology and angle with respect to poling field on the poling behaviour of porous ferroelectrics was developed. A second model was then developed to understand the influence of microstructure-property relationships on the poling behaviour of porous freeze cast ferroelectric materials and their resultant piezoelectric and energy harvesting properties. To compare with model predictions, porous barium titanate was fabricated using freeze casting to form highly aligned microstructures with excellent longitudinal piezoelectric strain coefficients, d 33. The freeze cast barium titanate with 45 vol.% porosity had a d 33  =  134.5 pC N‑1 compared to d 33  =  144.5 pC N‑1 for dense barium titanate. The d 33 coefficients of the freeze cast materials were also higher than materials with uniformly distributed spherical porosity due to improved poling of the aligned microstructures, as predicted by the models. Both model and experimental data indicated that introducing porosity provides a large reduction in the permittivity () of barium titanate, which leads to a substantial increase in energy harvesting figure of merit, , with a maximum of 3.79 pm2 N‑1 for barium titanate with 45 vol.% porosity, compared to only 1.40 pm2 N‑1 for dense barium titanate. Dense and porous barium titanate materials were then used to harvest energy from a mechanical excitation by rectification and storage of the piezoelectric charge on a capacitor. The porous barium titanate charged the capacitor to a voltage of 234 mV compared to 96 mV for the dense material, indicating a 2.4-fold increase that was similar to that

Thermal conductivity reduction in oxygen-deficient strontium titanates

NARCIS (Netherlands)

Yu, Choongho; Scullin, Matthew L.; Huijben, Mark; Ramesh, Ramamoorthy; Majumdar, Arun

2008-01-01

We report significant thermal conductivity reduction in oxygen-deficient lanthanum-doped strontium titanate (Sr1−xLaxTiO3−δ) films as compared to unreduced strontium titanates. Our experimental results suggest that the oxygen vacancies could have played an important role in the reduction. This could

The Greenhouse and Anti-Greenhouse Effects on Titan

Science.gov (United States)

McKay, C. P.; Cuzzi, Jeffrey N. (Technical Monitor)

1994-01-01

Titan is the largest moon of Saturn and is the only moon in the solar system with a substantial atmosphere. Its atmosphere is mostly made of nitrogen, with a few percent CH4, 0.1% H2 and an uncertain level of Ar (less than 10%). The surface pressure is 1.5 atms and the surface temperature is 95 K, decreasing to 71 at the tropopause before rising to stratospheric temperatures of 180 K. In pressure and composition Titan's atmosphere is the closest twin to Earth's. The surface of Titan remains unknown, hidden by the thick smog layer, but it may be an ocean of liquid methane and ethane. Titan's atmosphere has a greenhouse effect which is much stronger than the Earth's - 92% of the surface warming is due to greenhouse radiation. However an organic smog layer in the upper atmosphere produces an anti-greenhouse effect that cuts the greenhouse warming in half - removing 35% of the incoming solar radiation. Models suggest that during its formation Titan's atmosphere was heated to high temperatures due to accretional energy. This was followed by a cold Triton-like period which gradually warmed to the present conditions. The coupled greenhouse and haze anti-greenhouse may be relevant to recent suggestions for haze shielding of a CH4 - NH3 early atmosphere on Earth or Mars. When the NASA/ESA mission to the Saturn System, Cassini, launches in a few years it will carry a probe that will be sent to the surface of Titan and show us this world that is strange and yet in many ways similar to our own.

Potassium ions intercalated into g-C3N4-modified TiO2 nanobelts for the enhancement of photocatalytic hydrogen evolution activity under visible-light irradiation

Science.gov (United States)

Ma, Jian; Zhou, Wei; Tan, Xin; Yu, Tao

2018-05-01

Solar-to-chemical energy conversion is a challenging photochemical reaction for renewable energy storage. In recent decades, photocatalytic H2 evolution has been studied extensively. TiO2 is a well-established semiconductor in the field of photocatalytic H2 production; however, its low efficiency for solar energy utilization, and high photocarrier recombination rate, restrict its photocatalytic efficiency. Here, a series of K-intercalated g-C3N4-modified TiO2 nanobelts (TCN–Kx) with different dosages of K atoms were fabricated using a hydrothermal method followed by a calcination process. XRD, TEM and XPS tests indicate that a tight interfacial connection is formed between K–g-C3N4 and the TiO2 nanobelts. DFT calculations indicated that K dopants prefer to be at the interlayer sites of g-C3N4, suggesting increased charge transfer efficiency. The H2 production efficiency of the TCN–Kx composite materials from water splitting under visible-light irradiation was clearly improved. Steady fluorescence spectroscopy and photocurrent measurements confirmed that the improvement in photocatalytic H2 production activity was due to the superior charge separation and electron transfer efficiency of TCN–Kx composite materials.

Synthesis and characterization of novel lanthanide- and actinide-containing titanates and zircono-titanates; relevance to nuclear waste disposal

International Nuclear Information System (INIS)

Shoup, S.L.S.

1995-08-01

Before experiments using actinide elements are performed, synthetic routes are tested using lanthanides of comparable ionic radii as surrogates. Compound and solid solution formation in several lanthanide-containing titanate and zircono-titanate systems have been established using X-ray diffraction (XRD) analysis, which helped to define interesting and novel experiments, some of which have been performed and are discussed, for selected actinide elements. The aqueous solubilities of several lanthanide- and actinide-containing compounds, representative of the systems studied, were tested in several leachants, including the WIPP open-quotes Aclose quotes brine, following modified Materials Characterization Center procedures (MCC-3). The WIPP open-quotes Aclose quotes brine is a synthetic substitute for that found in nature at the Waste Isolation Pilot Plant (WIPP) in New Mexico. The concentrations of cerium, used as a surrogate for plutonium, leached by the WIPP open-quotes Aclose quotes brine from all the cerium-containing compounds and solid solutions tested were below the Inductively Coupled Plasma (ICP) atomic emission spectrometry limit of detection (10 ppm) established for cerium in this brine. The concentrations of plutonium leached from the two plutonium-containing solid solutions were less than 1 ppm as determined by gross alpha counting and alpha pulse height analysis. Concentrations of strontium leached by the WIPP brine from stable strontium containing titanate compounds, studied as possible immobilizers of both 90 Sr and actinide elements, were also quite low. These compound and solid solution formation investigations and the aqueous solubility studies suggest that the types of titanate and zircono-titanate compounds and solid solutions studied in this work appear to be useful as host matrices for nuclear waste immobilization

Barium Titanate Nanoparticles for Biomarker Applications

International Nuclear Information System (INIS)

Matar, O; Hondow, N S; Brydson, R M D; Milne, S J; Brown, A P; Posada, O M; Wälti, C; Saunders, M; Murray, C A

2015-01-01

A tetragonal crystal structure is required for barium titanate nanoparticles to exhibit the nonlinear optical effect of second harmonic light generation (SHG) for use as a biomarker when illuminated by a near-infrared source. Here we use synchrotron XRD to elucidate the tetragonal phase of commercially purchased tetragonal, cubic and hydrothermally prepared barium titanate (BaTiO 3 ) nanoparticles by peak fitting with reference patterns. The local phase of individual nanoparticles is determined by STEM electron energy loss spectroscopy (EELS), measuring the core-loss O K-edge and the Ti L 3 -edge energy separation of the t 2g , e g peaks. The results show a change in energy separation between the t 2g and e g peak from the surface and core of the particles, suggesting an intraparticle phase mixture of the barium titanate nanoparticles. HAADF-STEM and bright field TEM-EDX show cellular uptake of the hydrothermally prepared BaTiO 3 nanoparticles, highlighting the potential for application as biomarkers. (paper)

Tritium breeding experiments with lithium titanate in thermal-type mockups

International Nuclear Information System (INIS)

Klix, Axel; Takahashi, Akito; Ochiai, Kentaro; Nishitani, Takeo

2004-01-01

Lithium titanate, an advanced tritium breeding material, is currently investigated in integral mock-up experiments at FNS. A method was developed which allows to measure low tritium concentrations directly in this material. The local tritium production rate was obtained by small lithium titanate pellet detectors inserted into the breeding layers which are dissolved after irradiation of the assemblies, and the accumulated tritium was counted by liquid scintillation techniques. The measurement method was applied in mock0-up experiments with candidate materials for the future DEMO reactor breeding blanket. Experimental assemblies consisted of sheets of low activation ferritic steel F82H, lithium titanate, and berylium. Tritium production rate profiles were obtained and compared with results from calculations with the Monte Carlo neutron transport code MCNP-4C. In case of the mock-ups with 95% enriched lithium titanate, the C/E ratios were within the error estimate while larger discrepancies were observed in case of 40% enriched lithium titanate. (author)

Development of partitioning method: adsorption behavior of Sr on titanic acid pelletized with binder

Energy Technology Data Exchange (ETDEWEB)

Mizoguchi, Kenichi; Yamaguchi, Isoo; Morita, Yasuji; Yamagishi, Isao; Fujiwara, Takeshi; Kubota, Masumitsu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1998-05-01

The adsorption behavior of Sr was examined with the titanic acid with the binder and with binderless titanic acid. Then the effect of the difference of the neutralizer was also examined. When the initial concentration of Sr was constant, distribution coefficient (Kd) increased with pH after adsorption. At pH 4, Kd decreased in order of the titanic acid neutralized with NH{sub 4}OH solution without the binder > the titanic acid neutralized with NH{sub 4}OH solution and pelletized with the binder > the titanic acid neutralized with KOH solution and pelletized with the binder. At pH 6, Kd decreased with increasing the concentration of Sr in the solution, but the decreasing tendency of Kd for each titanic acid was the same. Adsorption kinetics was examined with titanic acids neutralized with NH{sub 4}OH solution, keeping the initial concentration of Sr and the initial pH constant. It took about one hour to reach Kd of 100mL/g for the titanic acid without the binder but over 10 hours for the titanic acid pelletized with the binder. It was confirmed that by pelletizing titanic acid with the binder, Kd of Sr became small and it took very long time to reach the adsorption equilibrium. However, by sufficient conditioning with water of the titanic acid pelletized with the binder, 1) it took about half time of titanic acid without conditioning to reach Kd of 100mL/g, 2) after 24 hours mixing, Kd for the titanic acid pelletized with the binder was almost equal to that for the titanic acid without the binder, 3) apparent ion exchange capacity obtained through a column test became over about 1meq/g. (J.P.N.)

Development of partitioning method: adsorption behavior of Sr on titanic acid pelletized with binder

International Nuclear Information System (INIS)

Mizoguchi, Kenichi; Yamaguchi, Isoo; Morita, Yasuji; Yamagishi, Isao; Fujiwara, Takeshi; Kubota, Masumitsu

1998-05-01

The adsorption behavior of Sr was examined with the titanic acid with the binder and with binderless titanic acid. Then the effect of the difference of the neutralizer was also examined. When the initial concentration of Sr was constant, distribution coefficient (Kd) increased with pH after adsorption. At pH 4, Kd decreased in order of the titanic acid neutralized with NH 4 OH solution without the binder > the titanic acid neutralized with NH 4 OH solution and pelletized with the binder > the titanic acid neutralized with KOH solution and pelletized with the binder. At pH 6, Kd decreased with increasing the concentration of Sr in the solution, but the decreasing tendency of Kd for each titanic acid was the same. Adsorption kinetics was examined with titanic acids neutralized with NH 4 OH solution, keeping the initial concentration of Sr and the initial pH constant. It took about one hour to reach Kd of 100mL/g for the titanic acid without the binder but over 10 hours for the titanic acid pelletized with the binder. It was confirmed that by pelletizing titanic acid with the binder, Kd of Sr became small and it took very long time to reach the adsorption equilibrium. However, by sufficient conditioning with water of the titanic acid pelletized with the binder, 1) it took about half time of titanic acid without conditioning to reach Kd of 100mL/g, 2) after 24 hours mixing, Kd for the titanic acid pelletized with the binder was almost equal to that for the titanic acid without the binder, 3) apparent ion exchange capacity obtained through a column test became over about 1meq/g. (J.P.N.)

Plasma environment of Titan: a 3-D hybrid simulation study

Directory of Open Access Journals (Sweden)

S. Simon

2006-05-01

Full Text Available Titan possesses a dense atmosphere, consisting mainly of molecular nitrogen. Titan's orbit is located within the Saturnian magnetosphere most of the time, where the corotating plasma flow is super-Alfvénic, yet subsonic and submagnetosonic. Since Titan does not possess a significant intrinsic magnetic field, the incident plasma interacts directly with the atmosphere and ionosphere. Due to the characteristic length scales of the interaction region being comparable to the ion gyroradii in the vicinity of Titan, magnetohydrodynamic models can only offer a rough description of Titan's interaction with the corotating magnetospheric plasma flow. For this reason, Titan's plasma environment has been studied by using a 3-D hybrid simulation code, treating the electrons as a massless, charge-neutralizing fluid, whereas a completely kinetic approach is used to cover ion dynamics. The calculations are performed on a curvilinear simulation grid which is adapted to the spherical geometry of the obstacle. In the model, Titan's dayside ionosphere is mainly generated by solar UV radiation; hence, the local ion production rate depends on the solar zenith angle. Because the Titan interaction features the possibility of having the densest ionosphere located on a face not aligned with the ram flow of the magnetospheric plasma, a variety of different scenarios can be studied. The simulations show the formation of a strong magnetic draping pattern and an extended pick-up region, being highly asymmetric with respect to the direction of the convective electric field. In general, the mechanism giving rise to these structures exhibits similarities to the interaction of the ionospheres of Mars and Venus with the supersonic solar wind. The simulation results are in agreement with data from recent Cassini flybys.

Aerosol chemistry in Titan's ionosphere: simultaneous growth and etching processes

Science.gov (United States)

Carrasco, Nathalie; Cernogora, Guy; Jomard, François; Etcheberry, Arnaud; Vigneron, Jackie

2016-10-01

Since the Cassini-CAPS measurements, organic aerosols are known to be present and formed at high altitudes in the diluted and partially ionized medium that is Titan's ionosphere [1]. This unexpected chemistry can be further investigated in the laboratory with plasma experiments simulating the complex ion-neutral chemistry starting from N2-CH4 [2]. Two sorts of solid organic samples can be produced in laboratory experiments simulating Titan's atmospheric reactivity: grains in the volume and thin films on the reactor walls. We expect that grains are more representative of Titan's atmospheric aerosols, but films are used to provide optical indices for radiative models of Titan's atmosphere.The aim of the present study is to address if these two sorts of analogues are chemically equivalent or not, when produced in the same N2-CH4 plasma discharge. The chemical compositions of both these materials are measured by using elemental analysis, XPS analysis and Secondary Ion Mass Spectrometry. We find that films are homogeneous but significantly less rich in nitrogen and hydrogen than grains produced in the same experimental conditions. This surprising difference in their chemical compositions is explained by the efficient etching occurring on the films, which stay in the discharge during the whole plasma duration, whereas the grains are ejected after a few minutes [3]. The impact for our understanding of Titan's aerosols chemical composition is important. Our study shows that chemical growth and etching process are simultaneously at stake in Titan's ionosphere. The more the aerosols stay in the ionosphere, the more graphitized they get through etching process. In order to infer Titan's aerosols composition, our work highlights a need for constraints on the residence time of aerosols in Titan's ionosphere. [1] Waite et al. (2009) Science , 316, p. 870[2] Szopa et al. (2006) PSS, 54, p. 394[3] Carrasco et al. (2016) PSS, 128, p. 52

Plasma environment of Titan: a 3-D hybrid simulation study

Directory of Open Access Journals (Sweden)

S. Simon

2006-05-01

Full Text Available Titan possesses a dense atmosphere, consisting mainly of molecular nitrogen. Titan's orbit is located within the Saturnian magnetosphere most of the time, where the corotating plasma flow is super-Alfvénic, yet subsonic and submagnetosonic. Since Titan does not possess a significant intrinsic magnetic field, the incident plasma interacts directly with the atmosphere and ionosphere. Due to the characteristic length scales of the interaction region being comparable to the ion gyroradii in the vicinity of Titan, magnetohydrodynamic models can only offer a rough description of Titan's interaction with the corotating magnetospheric plasma flow. For this reason, Titan's plasma environment has been studied by using a 3-D hybrid simulation code, treating the electrons as a massless, charge-neutralizing fluid, whereas a completely kinetic approach is used to cover ion dynamics. The calculations are performed on a curvilinear simulation grid which is adapted to the spherical geometry of the obstacle. In the model, Titan's dayside ionosphere is mainly generated by solar UV radiation; hence, the local ion production rate depends on the solar zenith angle. Because the Titan interaction features the possibility of having the densest ionosphere located on a face not aligned with the ram flow of the magnetospheric plasma, a variety of different scenarios can be studied. The simulations show the formation of a strong magnetic draping pattern and an extended pick-up region, being highly asymmetric with respect to the direction of the convective electric field. In general, the mechanism giving rise to these structures exhibits similarities to the interaction of the ionospheres of Mars and Venus with the supersonic solar wind. The simulation results are in agreement with data from recent Cassini flybys.

Effects of hydrothermal post-treatment on microstructures and morphology of titanate nanoribbons

International Nuclear Information System (INIS)

Yu Huogen; Yu Jiaguo; Cheng Bei; Zhou Minghua

2006-01-01

Titanate nanoribbons were prepared via a hydrothermal treatment of rutile-type TiO 2 powders in a 10 M NaOH solution at 200 deg. C for 48 h. The as-prepared titanate nanoribbons were then hydrothermally post-treated at 150 deg. C for 12-36 h. The titanate nanoribbons before and after hydrothermal post-treatment were characterized with FESEM, XRD, TEM, UV-VIS and nitrogen adsorption-desorption isotherms. The results showed that the hydrothermal post-treatment not only promoted the phase transformation from titanate to anatase TiO 2 , but also was beneficial to the removal of Na + ions remained in the titanate nanoribbons. After hydrothermal post-treatment, the TiO 2 samples retained the one-dimensional structure feature of the titanate nanoribbons and showed an obvious increase in the specific surface area and the pore volume

Multi-wavelength search for complex molecules in Titan's Atmosphere

Science.gov (United States)

Nixon, C. A.; Cordiner, M. A.; Greathouse, T. K.; Richter, M.; Kisiel, Z.; Irwin, P. G.; Teanby, N. A.; Kuan, Y. J.; Charnley, S. B.

2017-12-01

Titan's atmosphere is one of the most complex astrochemical environments known: the photochemistry of methane and nitrogen, induced by solar UV and Saturn magnetospheric electron impacts, creates a bonanza of organic molecules like no other place in the solar system. Cassini has unveiled the first glimpses of Titan's chemical wonderland, but many gaps remain. In particular, interpreting the mass spectra of Titan's upper atmosphere requires external knowledge, to disentangle the signature of molecules from their identical-mass brethren. Cassini infrared spectroscopy with CIRS has helped to some extent, but is also limited by low spectral resolution. Potentially to the rescue, comes high-resolution spectroscopy from the Earth at infrared and sub-millimeter wavelengths, where molecules exhibit vibrational and rotational transitions respectively. In this presentation, we describe the quest to make new, unique identifications of large molecules in Titan's atmosphere, focusing specifically on cyclic molecules including N-heterocycles. This molecular family is of high astrobiological significance, forming the basic ring structure for DNA nucleobases. We present the latest spectroscopic observations of Titan from ALMA and NASA's IRTF telescope, discussing present findings and directions for future work.

Surface tiny grain-dependent enhanced rate performance of MoO3 nanobelts with pseudocapacitance contribution for lithium-ion battery anode

Science.gov (United States)

Cao, Liyun; He, Juju; Li, Jiayin; Yan, Jingwen; Huang, Jianfeng; Qi, Ying; Feng, Liangliang

2018-07-01

In order to improve the rate performance of MoO3, a novel MoO3 nanobelt with tiny grains on surface (named as d-MoO3) is fabricated via one-step facile hydrothermal method with citric acid adding, in which citric acid (CA) serves as a weak reductant as well as surface modification agent. When tested as an anode in LIBs, d-MoO3 displays an improved discharge capacity of 787 mAh·g-1 at 0.1 A g-1 over 100 cycles with capacity retention of ∼91% while MoO3 decays to 50 mAh·g-1 in the 100th cycle. Notably, d-MoO3 delivers enhanced rate capability (536 and 370 mAh·g-1 at high rates of 5 and 10 A g-1 respectively). We consider these excellent electrochemical properties of d-MoO3 electrode are associated with the tiny grains on MoO3 surface, which effectively maintains the electrode's structural integrity. Even though d-MoO3 nanobelt suffers from a degree of in-situ pulverization after several cycles, these pulverized active particles can still maintain stable electrochemical contact and are highly exposed to electrolyte, realizing ultrahigh e-/Li+ diffusion kinetics. In addition, part extrinsic pseudocapacitance contribution to the Li+ storage also explains the high-rate performance. Combining all these merits, d-MoO3 is potentially a high-energy, high-power and well-stable anode material for Li ion batteries (LIBs).

Calorimetric measurements on hafnium titanate

International Nuclear Information System (INIS)

Kandan, R.; Prabhakara Reddy, B.; Panneerselvam, G.; Nagarajan, K.

2012-01-01

Owing to its desirable nuclear and mechanical properties such as good absorption cross-section for thermal neutrons (105 barns), hafnium titanate (HfTiO 4 ) finds application as control rods for nuclear reactors. An accurate knowledge of the thermo physical properties of this material is necessary for design of control rod and for modeling its performance. Heat capacity is an important thermodynamic property that determines the temperature dependent variation of all other thermodynamic properties. Hence enthalpy increments of hafnium titanate (HfTiO 4 ) were measured in the temperature range 803-1663 K by employing the method of inverse drop calorimetry using high temperature differential calorimeter

Acetylene on Titan

Science.gov (United States)

Singh, Sandeep; McCord, Thomas B.; Combe, Jean-Philippe; Rodriguez, Sebastien; Cornet, Thomas; Le Mouélic, Stéphane; Clark, Roger Nelson; Maltagliati, Luca; Chevrier, Vincent

2016-10-01

Saturn's moon Titan possesses a thick atmosphere that is mainly composed of N2 (98%), CH4 (2 % overall, but 4.9% close to the surface) and less than 1% of minor species, mostly hydrocarbons [1]. A dissociation of N2 and CH4 forms complex hydrocarbons in the atmsophere and acetylene (C2H2) and ethane (C2H6) are produced most abundently. Since years, C2H2 has been speculated to exist on the surface of Titan based on its high production rate in the stratosphere predicted by photochemical models [2,3] and from its detection as trace gas sublimated/evaporated from the surface after the landing of the Huygens probe by the Gas Chromatograph Mass Spectrometer (GCMS) [1]. Here we show evidence of acetylene (C2H2) on the surface of Titan by detecting absorption bands at 1.55 µm and 4.93 µm using Cassini Visual and Infrared Mapping Spectrometer (VIMS) [4] at equatorial areas of eastern Shangri-La, and Fensal-Aztlan/Quivira.An anti-correlation of absorption band strength with albedo indicates greater concentrations of C2H2 in the dark terrains, such as sand dunes and near the Huygens landing site. The specific location of the C2H2 detections suggests that C2H2 is mobilized by surface processes, such as surface weathering by liquids through dissolution/evaporation processes.References:[1]Niemann et al., Nature 438, 779-784 (2005).[2]Lavvas et al., Planetary and Space Science 56, 67 - 99 (2008).[3]Lavvas et al., Planetary and Space Science 56, 27 - 66 (2008).[4] Brown et al., The Cassini-Huygens Mission 111-168 (Springer, 2004).

Activation and waste disposal of the TITAN RFP [reversed-field-pinch] reactors

International Nuclear Information System (INIS)

Cheng, E.T.; Conn, R.W.

1988-01-01

The TITAN-I lithium self-cooled and TITAN-II aqueous lithium nitrate solution-cooled fusion reactors are based on the reversed-field-pinch (RFP) toroidal confinement concept and operate at high power density with an 18.1 MW/m 2 neutron wall loading. These designs were analyzed to study the activation and waste disposal aspects of such high-power density reactors. It was found that because of the use of V-3Ti-1Si (TITAN-I) and reduced activation ferritic steel (TITAN-II) as structural alloys for the first wall, blanket, reflector, and shield components, all the TITAN components except the divertor collector plates can be classified as shallow-land burial (10CFR61 Class C or better) nuclear waste for disposal, provided that the impurity elements, niobium and molybdenum, can be controlled below about 1 and 0.3 appm levels, respectively. The average annual disposal masses were estimated to be 150 and 96 tonnes, respectively, for the 1,000 MW TITAN-I and TITAN-II reactors. This corresponds to about 11% of the total mass in the fusion power core of both reactors. The divertor collector plates are fabricated with tungsten because of its low particle sputtering properties. These divertor collector plates in the TITAN-I reactor will be qualified as Class C waste after 18.1 MW-y/m 2 operation. The waste disposal rating of the divertor collector plates in the TITAN-II reactor, however, is estimated to be a factor of 4 higher than allowed for Class C disposal, because of the soft neutron spectrum in the beryllium environment. The annual disposal mass of this non-Class C waste is 0.35 tons, about 0.04% of the average annual discharge mass for the TITAN-II reactor. An additional 74 m 3 annual discharge of Class C waste containing 14 C may be needed for the TITAN-II reactor because of the use of nitrate salt in the aqueous coolant as the tritium breeder. 13 refs., 6 tabs

金属纳米带的制备及其在电化学传感器中的应用研究进展%Development of Preparation of Metal Nanobelts and Its Application in Electrochemical Sensors

Institute of Scientific and Technical Information of China (English)

杨光明; 李丽; 徐国良; 徐凤; 杨云慧

2011-01-01

综述了金、银等金属纳米带的制备方法(真空冷凝法和模板法)及其在电化学传感器中的应用,展望了其发展前景.着重介绍了真空冷凝法的制备原理、装置、过程等;讨论了模板法中不同类型的有机分子模板(模板作用、兼顾模板和还原剂作用)、制备过程中的反应体系(水热、超声等)、模板分子与金属离子的物质的量比和反应时间等对纳米带微观形貌的影响.%The development of preparation of metal nanobelts(Evaporation-condensation method and the soft template method) and its application in electrochemical sensors are reviewed. The prospects and development trend of metal nanobelts are discussed. The principle, process and installation of evaporation-condensation method are discussed. Effects of the morphological characterizations of the metal nanobelts are reviewed such as different template (Only template action, template and reducing agent action), synthetic conditions (hydro-thermal synthesis and ultrasonic irradiation etc. ) and reaction time.

Production and global transport of Titan's sand particles

Science.gov (United States)

Barnes, Jason W.; Lorenz, Ralph D.; Radebaugh, Jani; Hayes, Alexander G.; Arnold, Karl; Chandler, Clayton

2015-06-01

Previous authors have suggested that Titan's individual sand particles form by either sintering or by lithification and erosion. We suggest two new mechanisms for the production of Titan's organic sand particles that would occur within bodies of liquid: flocculation and evaporitic precipitation. Such production mechanisms would suggest discrete sand sources in dry lakebeds. We search for such sources, but find no convincing candidates with the present Cassini Visual and Infrared Mapping Spectrometer coverage. As a result we propose that Titan's equatorial dunes may represent a single, global sand sea with west-to-east transport providing sources and sinks for sand in each interconnected basin. The sand might then be transported around Xanadu by fast-moving Barchan dune chains and/or fluvial transport in transient riverbeds. A river at the Xanadu/Shangri-La border could explain the sharp edge of the sand sea there, much like the Kuiseb River stops the Namib Sand Sea in southwest Africa on Earth. Future missions could use the composition of Titan's sands to constrain the global hydrocarbon cycle.

Exploring inner structure of Titan's dunes from Cassini Radar observations

Science.gov (United States)

Sharma, P.; Heggy, E.; Farr, T. G.

2013-12-01

Linear dunes discovered in the equatorial regions of Titan by the Cassini-Huygens mission are morphologically very similar to many terrestrial linear dune fields. These features have been compared with terrestrial longitudinal dune fields like the ones in Namib desert in western Africa. This comparison is based on the overall parallel orientation of Titan's dunes to the predominant wind direction on Titan, their superposition on other geomorphological features and the way they wrap around topographic obstacles. Studying the internal layering of dunes has strong implications in understanding the hypothesis for their origin and evolution. In Titan's case, although the morphology of the dunes has been studied from Cassini Synthetic Aperture Radar (SAR) images, it has not been possible to investigate their internal structure in detail as of yet. Since no radar sounding data is available for studying Titan's subsurface yet, we have developed another technique to examine the inner layering of the dunes. In this study, we utilize multiple complementary radar datasets, including radar imaging data for Titan's and Earth's dunes and Ground Penetrating Radar (GPR)/radar sounding data for terrestrial dunes. Based on dielectric mixing models, we suggest that the Cassini Ku-band microwaves should be able to penetrate up to ~ 3 m through Titan's dunes, indicating that the returned radar backscatter signal would include contributions from both surface and shallow subsurface echoes. This implies that the shallow subsurface properties can be retrieved from the observed radar backscatter (σ0). In our analysis, the variation of the radar backscatter as a function of dune height is used to provide an insight into the layering in Titan's dunes. We compare the variation of radar backscatter with elevation over individual dunes on Titan and analogous terrestrial dunes in three sites (Great Sand Sea, Siwa dunes and Qattaniya dunes) in the Egyptian Sahara. We observe a strong, positive

ATOMIC CARBON IN THE UPPER ATMOSPHERE OF TITAN

International Nuclear Information System (INIS)

Zhang, X.; Yung, Y. L.; Ajello, J. M.

2010-01-01

The atomic carbon emission C I line feature at 1657 A ( 3 P 0 J - 3 P J ) in the upper atmosphere of Titan is first identified from the airglow spectra obtained by the Cassini Ultra-violet Imaging Spectrograph. A one-dimensional photochemical model of Titan is used to study the photochemistry of atomic carbon on Titan. Reaction between CH and atomic hydrogen is the major source of atomic carbon, and reactions with hydrocarbons (C 2 H 2 and C 2 H 4 ) are the most important loss processes. Resonance scattering of sunlight by atomic carbon is the dominant emission mechanism. The emission intensity calculations based on model results show good agreement with the observations.

Titan's icy scar

Science.gov (United States)

Griffith, C. A.; Penteado, P. F.; Turner, J. D.; Neish, C. D.; Mitri, G.; Montiel, M. J.; Schoenfeld, A.; Lopes, R. M. C.

2017-09-01

We conduct a Principal Components Analysis (PCA) of Cassini/VIMS [1] infrared spectral windows to identify and quantify weak surface features, with no assumptions on the haze and surface characteris- tics. This study maps the organic sediments, supplied by past atmospheres, as well as ice-rich regions that constitute Titan's bedrock.

Ion Irradiation Damage in Zirconate and Titanate Ceramics for Pu Disposition

International Nuclear Information System (INIS)

Stewart, Martin W.; Begg, Bruce D.; Finnie, K.; Colella, Michael; Li, H.; McLeod, Terry; Smith, Katherine L.; Zhang, Zhaoming; Weber, William J.; Thevuthasan, Suntharampillai

2004-01-01

In this paper, we discuss the effect of ion irradiation on pyrochlore-rich titanate and defect-fluorite zirconate ceramics designed for plutonium immobilization. Samples, with Ce as an analogue for Pu, were made via oxide routes and consolidated by cold-pressing and sintering. Ion irradiation damage was carried out with 2 MeV Au2+ ions to a fluence of 5 ions nm-2 in the accelerator facilities within the Environmental Molecular Sciences Laboratory at Pacific Northwest National Laboratory. Irradiated and non-irradiated samples were examined by x-ray diffraction, scanning and transmission electron microscopy, x-ray photoelectron and infrared spectroscopy, and spectroscopic ellipsometry. Samples underwent accelerated leach testing at pH 1.75 (nitric acid) at 90 C for 28 days. The zirconate samples were more ion-irradiation damage resistant than the titanate samples, showing little change after ion-irradiation whereas the titanate samples formed an amorphous surface layer ∼ 500 nm thick. While all samples had high aqueous durability, the titanate leach rate was ∼ 5 times that of the zirconate. The ion-irradiation increased the leach rate of the titanate without impurities by ∼ 5 times. The difference in the leach rates between irradiated and unirradiated zirconate samples is small. However, the zirconates were less able to incorporate impurities than the titanate ceramics and required higher sintering temperatures, ∼ 1500 C compared to 1350 C for the titanates.

Description of tritium release from lithium titanate at constant temperature

Energy Technology Data Exchange (ETDEWEB)

Pena, L; Lagos, S; Jimenez, J; Saravia, E [Comision Chilena de Energia Nuclear, Santiago (Chile)

1998-03-01

Lithium Titanate Ceramics have been prepared by the solid-state route, pebbles and pellets were fabricated by extrusion and their microstructure was characterized in our laboratories. The ceramic material was irradiated in the La Reina Reactor, RECH-1. A study of post-irradiation annealing test, was performed measuring Tritium release from the Lithium Titanate at constant temperature. The Bertone`s method modified by R. Verrall is used to determine the parameters of Tritium release from Lithium Titanate. (author)

Titan's cold case files - Outstanding questions after Cassini-Huygens

Science.gov (United States)

Nixon, C. A.; Lorenz, R. D.; Achterberg, R. K.; Buch, A.; Coll, P.; Clark, R. N.; Courtin, R.; Hayes, A.; Iess, L.; Johnson, R. E.; Lopes, R. M. C.; Mastrogiuseppe, M.; Mandt, K.; Mitchell, D. G.; Raulin, F.; Rymer, A. M.; Todd Smith, H.; Solomonidou, A.; Sotin, C.; Strobel, D.; Turtle, E. P.; Vuitton, V.; West, R. A.; Yelle, R. V.

2018-06-01

The entry of the Cassini-Huygens spacecraft into orbit around Saturn in July 2004 marked the start of a golden era in the exploration of Titan, Saturn's giant moon. During the Prime Mission (2004-2008), ground-breaking discoveries were made by the Cassini orbiter including the equatorial dune fields (flyby T3, 2005), northern lakes and seas (T16, 2006), and the large positive and negative ions (T16 & T18, 2006), to name a few. In 2005 the Huygens probe descended through Titan's atmosphere, taking the first close-up pictures of the surface, including large networks of dendritic channels leading to a dried-up seabed, and also obtaining detailed profiles of temperature and gas composition during the atmospheric descent. The discoveries continued through the Equinox Mission (2008-2010) and Solstice Mission (2010-2017) totaling 127 targeted flybys of Titan in all. Now at the end of the mission, we are able to look back on the high-level scientific questions from the start of the mission, and assess the progress that has been made towards answering these. At the same time, new scientific questions regarding Titan have emerged from the discoveries that have been made. In this paper we review a cross-section of important scientific questions that remain partially or completely unanswered, ranging from Titan's deep interior to the exosphere. Our intention is to help formulate the science goals for the next generation of planetary missions to Titan, and to stimulate new experimental, observational and theoretical investigations in the interim.

Latitudinal and altitudinal controls of Titan's dune field morphometry

Science.gov (United States)

Le Gall, A.; Hayes, A. G.; Ewing, R.; Janssen, M. A.; Radebaugh, J.; Savage, C.; Encrenaz, P.; the Cassini Radar Team

2012-01-01

Dune fields dominate ˜13% of Titan's surface and represent an important sink of carbon in the methane cycle. Herein, we discuss correlations in dune morphometry with altitude and latitude. These correlations, which have important implications in terms of geological processes and climate on Titan, are investigated through the microwave electromagnetic signatures of dune fields using Cassini radar and radiometry observations. The backscatter and emissivity from Titan's dune terrains are primarily controlled by the amount of interdune area within the radar footprint and are also expected to vary with the degree of the interdunal sand cover. Using SAR-derived topography, we find that Titan's main dune fields (Shangri-La, Fensal, Belet and Aztlan) tend to occupy the lowest elevation areas in Equatorial regions occurring at mean elevations between ˜-400 and ˜0 m (relative to the geoid). In elevated dune terrains, we show a definite trend towards a smaller dune to interdune ratio and possibly a thinner sand cover in the interdune areas. A similar correlation is observed with latitude, suggesting that the quantity of windblown sand in the dune fields tends to decrease as one moves farther north. The altitudinal trend among Titan's sand seas is consistent with the idea that sediment source zones most probably occur in lowlands, which would reduce the sand supply toward elevated regions. The latitudinal preference could result from a gradual increase in dampness with latitude due to the asymmetric seasonal forcing associated with Titan's current orbital configuration unless it is indicative of a latitudinal preference in the sand source distribution or wind transport capacity.

ALMA observations of Titan's atmospheric chemistry and seasonal variation

Science.gov (United States)

Cordiner, Martin

2017-04-01

Titan is the largest moon of Saturn, with a thick (1.45 bar) atmosphere composed primarily of molecular nitrogen and methane. Photochemistry in Titan's upper atmosphere results in the production of a wide range of organic molecules, including hydrocarbons, nitriles and aromatics, some of which could be of pre-biotic relevance. Thus, we obtain insights into the possible molecular inventories of primitive (reducing) planetary atmospheres. Titan's atmosphere also provides a unique laboratory for testing our understanding of fundamental processes involving the chemistry and spectroscopy of complex organic molecules. In this talk, results will be presented from our studies using the Atacama Large Millimeter/submillimeter Array (ALMA) during the period 2012-2015, focussing in particular on the detection and mapping of emission from various nitrile species. By combining data from multiple ALMA observations, our spectra have reached an unprecedented sensitivity level, enabling the first spectroscopic detection and mapping of C2H3CN (vinyl cyanide) on Titan. Liquid-phase simulations of Titan's seas indicate that vinyl cyanide molecules could combine to form vesicle membranes (similar to the cells of terrestrial biology), and the astrobiological implications of this discovery will be discussed. Furthermore, ALMA observations provide instantaneous snapshot mapping of Titan's entire Earth-facing hemisphere, for gases inaccessible to previous instruments. Combined with complementary data obtained from the Cassini Saturn orbiter, as well as theoretical models and laboratory studies, our observed, seasonally variable, spatially resolved abundance patterns are capable of providing new insights into photochemical production and transport in primitive planetary atmospheres in the Solar System and beyond.

Crater topography on Titan: Implications for landscape evolution

Science.gov (United States)

Neish, C.; Kirk, R.; Lorenz, R.; Bray, V.; Schenk, P.; Stiles, B.; Turtle, E.; Cassini Radar Team

2012-04-01

Unique among the icy satellites, Titan’s surface shows evidence for extensive modification by fluvial and aeolian erosion, which act to change the topography of its surface over time. Quantifying the extent of this landscape evolution is difficult, since the original, ‘non-eroded’ surface topography is generally unknown. However, fresh craters on icy satellites have a well-known shape and morphology, which has been determined from extensive studies on the airless worlds of the outer solar system (Schenk et al., 2004). By comparing the topography of craters on Titan to similarly sized, pristine analogues on airless bodies, we can obtain one of the few direct measures of the amount of erosion that has occurred on Titan. Cassini RADAR has imaged >30% of the surface of Titan, and more than 60 potential craters have been identified in this data set (Wood et al., 2010; Neish and Lorenz, 2012). Topographic information for these craters can be obtained from a technique known as ‘SARTopo’, which estimates surface heights by comparing the calibration of overlapping synthetic aperture radar (SAR) beams (Stiles et al., 2009). We present topography data for several craters on Titan, and compare the data to similarly sized craters on Ganymede, for which topography has been extracted from stereo-derived digital elevation models (Bray et al., 2012). We find that the depths of craters on Titan are generally within the range of depths observed on Ganymede, but several hundreds of meters shallower than the average (Fig. 1). A statistical comparison between the two data sets suggests that it is extremely unlikely that Titan’s craters were selected from the depth distribution of fresh craters on Ganymede, and that is it much more probable that the relative depths of Titan are uniformly distributed between ‘fresh’ and ‘completely infilled’. This is consistent with an infilling process that varies linearly with time, such as aeolian infilling. Figure 1: Depth of

Investigation on corrosion resistance of metal superficially modified with alkoxy titanates

International Nuclear Information System (INIS)

Yao Kangde; Song Shizhe; Shen Ningxiang

1991-01-01

A study has been made in order to determine corrosion protection performance of alkoxy titanate modified iron in a 3% NaCl solution. The effectiveness of alkoxy titanates as corrosion retarders for chloride environments is confirmed by both stepped potential sweep technique and electrochemical impedance spectroscopy (EIS). Ion microanalysis (IMA) depth profiles are used to elucidate the corrosion inhibitive action of different alkoxy titanate. (orig.)

A Direct Simulation Monte Carlo Model Of Thermal Escape From Titan

Science.gov (United States)

Johnson, Robert E.; Tucker, O. J.

2008-09-01

Recent analysis of density profiles vs. altitude from the Ion Neutral Mass Spectrometer (INMS) on Cassini (Waite et al. 2005) suggest Titan could have loss a significant amount of atmosphere in 4 Gyr at present escape rates (e.g., Johnson 2008). Strobel 2008 applied a slow hydrodynamic escape model to Titan's atmosphere using solar heating below the exobase to drive upward thermal conduction and power escape. However, near the exobase continuum models become problematic as a result of the increasing rarefaction in the atmosphere. The microscopic nature of DSMC is directly suitable to model atmosphere flow in nominal exobase region (e.g., Michael et. al. 2005). Our Preliminary DSMC models have shown no evidence for slow hydrodynamic escape of N2 and CH4 from Titan's atmosphere using boundary conditions normalized to the atmospheric properties in Strobel (2008). In this paper we use a 1D radial Direct Simulation Monte Carlo (DSMC) model of heating in Titan's upper atmosphere to estimate the escape rate as a function of the Jean's parameter. In this way we can test under what conditions the suggested deviations from Jeans escape would occur. In addition, we will be able to extract the necessary energy deposition to power the heavy molecule loss rates suggested in recent models (Strobel 2008; Yelle et. al. 2008). Michael, M. Johnson, R.E. 2005 Energy Deposition of pickup ions and heating of Titan's atmosphere. Planat. Sp. Sci. 53, 1510-1514 Johnson, R.E., "Sputtering and Heating of Titan's Upper Atmosphere", Proc Royal Soc. (London) (2008) Strobel, D.F. 2008 Titan's hydrodynamically escaping atmosphere. Icarus 193, 588-594 Yelle, R.V., J. Cui and I. C.F. Muller-Wodarg 2008 Methane Escape from Titan's Atmosphere. J. Geophys. Res in press Waite, J.H., Jr., Niemann, H.B., Yelle, R.V. et al. 2005 Ion Neutral Mass Spectrometer Results from the First Flyby of Titan. Science 308, 982-986

Cassini/CIRS Observations of Water Vapor in Titan's Stratosphere

Science.gov (United States)

Bjoraker, Gordon L.; Achterberg, R. K.; Anderson, C. M.; Samuelson, R. E.; Carlson, R. C.; Jennings, D. E.

2008-01-01

The Composite Infrared Spectrometer (CIRS) on the Cassini spacecraft has obtained spectra of Titan during most of the 44 flybys of the Cassini prime mission. Water vapor on Titan was first detected using whole-disk observations from the Infrared Space Observatory (Coustenis et al 1998, Astron. Astrophys. 336, L85-L89). CIRS data permlt the retrieval of the latitudinal variation of water on Titan and some limited information on its vertical profile. Emission lines of H2O on Titan are very weak in the CIRS data. Thus, large spectral averages as well as improvements in calibration are necessary to detect water vapor. Water abundances were retrieved in nadir spectra at 55 South, the Equator, and at 19 North. Limb spectra of the Equator were also modeled to constrain the vertical distribution of water. Stratospheric temperatures in the 0.5 - 4.0 mbar range were obtained by inverting spectra of CH4 in the v4 band centered at 1304/cm. The temperature in the lower stratosphere (4 - 20 mbar) was derived from fitting pure rotation lines of CH4 between 80 and 160/cm. The origin of H2O and CO2 is believed to be from the ablation of micrometeorites containing water ice, followed by photochemistry. This external source of water originates either within the Saturn system or from the interplanetary medium. Recently, Horst et al (J. Geophys. Res. 2008, in press) developed a photochemical model of Titan in which there are two external sources of oxygen. Oxygen ions (probably from Enceladus) precipitate into Titan's atmosphere to form CO at very high altitudes (1100 km). Water ice ablation at lower altitudes (700 km) forms H2O and subsequent chemistry produces CO2. CIRS measurements of CO, CO2, and now of H2O will provide valuable constraints to these photochemical models and - improve our understanding of oxygen chemistry on Titan.

Lightning generation in Titan due to the electrical self-polarization properties of Methane

Science.gov (United States)

Quintero, A.; Falcón, N.

2009-05-01

We describe an electrical charge process in Titan's thunderclouds, due to the self-polarization properties or pyroelectricity of methane, which increases the internal electric field in thunderclouds and facilitates the charge generation and separation processes. Microphysics that generates lightning flashes is associated with the physical and chemical properties of the local atmosphere, so methane could be the principal agent of the electrical activity because of its great concentration in Titan's atmosphere. Besides, Titan's electrical activity should not be very influenced by Saturn's magnetosphere because lightning occurs at very low altitude above Titan's surface, compared with the greater distance of Saturn's magnetosphere and Titan's troposphere. Using an electrostatic treatment, we calculate the internal electric field of Titan's thunderclouds due to methane's pyroelectrical properties, 7.05×10^11 Vm^-1; and using the telluric capacitor approximation for thunderclouds, we calculate the total charge obtained for a typical Titan thundercloud, 2.67×10^9 C. However, it is not right to use an electrostatic treatment because charge times are very fast due to the large methane concentration in Titan's clouds and the life time of thunderclouds is very low (around 2 hours). We consider a time dependent mechanism, employing common Earth atmospheric approaches, because of the similitude in chemical composition of both atmospheres (mainly nitrogen), so the typical charge of a thundercloud in Titan should reach between 20 C to 40 C, like on Earth. We obtain that lightning occurs with a frequency between 2 and 6 KHz. In Titan's atmosphere, methane concentration is higher than on Earth, and atmospheric electrical activity is stronger, so this model could be consistent with the observed phenomenology.

Titan: a laboratory for prebiological organic chemistry

Science.gov (United States)

Sagan, C.; Thompson, W. R.; Khare, B. N.

1992-01-01

When we examine the atmospheres of the Jovian planets (Jupiter, Saturn, Uranus, and Neptune), the satellites in the outer solar system, comets, and even--through microwave and infrared spectroscopy--the cold dilute gas and grains between the stars, we find a rich organic chemistry, presumably abiological, not only in most of the solar system but throughout the Milky Way galaxy. In part because the composition and surface pressure of the Earth's atmosphere 4 x 10(9) years ago are unknown, laboratory experiments on prebiological organic chemistry are at best suggestive; but we can test our understanding by looking more closely at the observed extraterrestrial organic chemistry. The present Account is restricted to atmospheric organic chemistry, primarily on the large moon of Saturn. Titan is a test of our understanding of the organic chemistry of planetary atmospheres. Its atmospheric bulk composition (N2/CH4) is intermediate between the highly reducing (H2/He/CH4/NH3/H2O) atmospheres of the Jovian planets and the more oxidized (N2/CO2/H2O) atmospheres of the terrestrial planets Mars and Venus. It has long been recognized that Titan's organic chemistry may have some relevance to the events that led to the origin of life on Earth. But with Titan surface temperatures approximately equal to 94 K and pressures approximately equal to 1.6 bar, the oceans of the early Earth have no ready analogue on Titan. Nevertheless, tectonic events in the water ice-rich interior or impact melting and slow re-freezing may lead to an episodic availability of liquid water. Indeed, the latter process is the equivalent of a approximately 10(3)-year-duration shallow aqueous sea over the entire surface of Titan.

Theoretical Calculations on Sediment Transport on Titan, and the Possible Production of Streamlined Forms

Science.gov (United States)

Burr, D. M.; Emery, J. P.; Lorenz, R. D.

2005-01-01

The Cassini Imaging Science System (ISS) has been returning images of Titan, along with other Saturnian satellites. Images taken through the 938 nm methane window see down to Titan's surface. One of the purposes of the Cassini mission is to investigate possible fluid cycling on Titan. Lemniscate features shown recently and radar evidence of surface flow prompted us to consider theoretically the creation by methane fluid flow of streamlined forms on Titan. This follows work by other groups in theoretical consideration of fluid motion on Titan's surface.

The safety designs for the TITAN reversed-field pinch reactor study

International Nuclear Information System (INIS)

Wong, C.P.C.; Cheng, E.T.; Creedon, R.L.; Hoot, C.G.; Schultz, K.R.; Grotz, S.P.; Blanchard, J.; Sharafat, S.; Najmabadi, F.

1989-01-01

TITAN is a study to investigate the potential of the reversed-field pinch concept as a compact, high-power density energy system. Two reactor concepts were developed, a self-cooled lithium design with vanadium structure and an aqueous solution loop-in-pool design, both operating at 18 MW/m 2 . The key safety features of the TITAN-I lithium-vanadium blanket design are in material selection, fusion power core configuration selection, lithium piping connections, and passive lithium drain tank system. Based on these safety features and results from accident evaluation, TITAN-I can at least be rated at a level 3 of safety assurance. For the TITAN-II aqueous loop-in-pool design, the key passive feature is the complete submersion of the fusion power core and the corresponding primary coolant loop system into a pool of low temperature water. Based on this key safety design feature, the TITAN-II design can be rated at a level 2 of safety assurance. (orig.)

The safety designs for the TITAN reversed-field pinch reactor study

International Nuclear Information System (INIS)

Wong, C.P.C.; Cheng, E.T.; Creedon, R.L.; Hoot, C.G.; Schultz, K.R.; Grotz, S.P.; Blanchard, J.P.; Sharafat, S.; Najmabadi, F.

1988-01-01

TITAN is a study to investigate the potential of the reversed-field pinch concept as a compact, high-power density energy system. Two reactor concepts were developed, a self-cooled lithium design with vanadium structure and an aqueous solution loop-in-pool design, both operating at 18 MW/m 2 . The key safety features of the TITAN-I lithium-vanadium blanket design are in material selection, fusion power core configuration selection, lithium piping connections and passive lithium drain tank system. Based on these safety features and results from accident evaluation, TITAN-I can at least be rated as level 3 of safety assurance. For the TITAN-II aqueous loop-in-pool design, the key passive feature is the complete submersion of the fusion power core and the corresponding primary coolant loop system into a pool of low temperature water. Based on this key safety design feature, the TITAN-II design can be rated as level 2 of safety assurance. 7 refs., 2 figs

Tritium release from lithium titanate, a low-activation tritium breeding material

International Nuclear Information System (INIS)

Kopasz, J.P.; Miller, J.M.; Johnson, C.E.

1994-01-01

The goals for fusion power are to produce energy in as safe, economical, and environmentally benign a manner as possible. To ensure environmentally sound operation low-activation materials should be used where feasible. The ARIES Tokamak Reactor Study has based reactor designs on the concept of using low-activation materials throughout the fusion reactor. For the tritium breeding blanket, the choices for low activation tritium breeding materials are limited. Lithium titanate is an alternative low-activation ceramic material for use in the tritium breeding blanket. To date, very little work has been done on characterizing the tritium release for lithium titanate. We have thus performed laboratory studies of tritium release from irradiated lithium titanate. The results indicate that tritium is easily removed from lithium titanate at temperatures as low as 600 K. The method of titanate preparation was found to affect the tritium release, and the addition of 0.1% H 2 to the helium purge gas did not improve tritium recovery. ((orig.))

Detection and mapping of organic molecules in Titan's atmosphere using ALMA

Science.gov (United States)

Cordiner, Martin

2016-06-01

Titan's atmospheric photochemistry results in the production of a wide range of organic molecules, including hydrocarbons, nitriles, aromatics and other complex species of possible pre-biotic relevance. Studies of Titan's atmospheric chemistry thus provide a unique opportunity to explore the origin and evolution of organic matter in primitive (terrestrial) planetary atmospheres. The Atacama Large Millimeter/submillimeter Array (ALMA) is a powerful new facility, well suited to the study of molecular emission from Titan's upper and middle-atmosphere. Results will be presented from our ongoing studies of Titan using ALMA data obtained during the period 2012-2014 [1,2], including detection and mapping of emission from C2H5CN, HNC, HC3N, CH3CN and CH3CCH. In addition, combining data from multiple ALMA Band 6 observations, we obtained high-resolution spectra with unprecedented sensitivity, enabling the first detection of C2H3CN (vinyl cyanide) on Titan, and derived a mean C2H3CN C2H5CN abundance ratio above 300 km of 0.3. Vinyl cyanide has recently been investigated as a possible constituent of (pre-biotic) vesicle membranes in Titan's liquid CH4 oceans [3]. Radiative transfer models and possible chemical formation pathways for the detected molecules will be discussed. ALMA observations provide instantaneous snapshot mapping of Titan's entire Earth-facing hemisphere for gases inaccessible to previous studies, and therefore provide new insights into photochemical production and transport, particularly at higher altitudes. Our maps show spatially resolved peaks in Titan's northern and southern hemispheres, consistent with the molecular distributions found in previous studies at infrared wavelengths by Voyager and Cassini, but high-altitude longitudinal asymmetries in our nitrile data indicate that the mesosphere may be more spatially variable than previously thought.

Miller-Urey Experiments to Assess the Production of Amino Acids under Impact Conditions on Early Titan

Science.gov (United States)

Turse, Carol; Khan, A.; Leitner, J. J.; Firneis, M. G.; Schulze-Makuch, D.

2012-05-01

We performed Miller-Urey type experiments to determine the organic synthesis of amino acids under conditions that have likely occurred on Saturn's moon Titan and are also relevant to Jupiter's moon Europa. We conducted the first set of experiments under early Earth conditions, similar to the original Miller-Urey experiments (Miller, 1953). In brief, the 250ml round bottom flask was filled with approximately 200mL of filtered sterile water and the apparatus was placed under vacuum for 10 minutes to purge the water of gases. The system was then flushed with hydrogen gas and placed under vacuum three times. Gases were then added in the following order: hydrogen gas to 0.1 bar, methane gas to 0.45 bar and ammonia to 0.45 bar ( 1bar total). The water was then brought to a boil and the spark was applied using the tesla coil up to a maximum of 50,000 volts. The apparatus was run for approximately 5-7 days. Between the runs the apparatus was cleaned using a hot 10% sodium hydroxide solution followed by a dilute sulfuric acid wash and four rinses with Millipure water. In the second set of experiments we simulated conditions that could have existed on an early, warm Titan or after an asteroid strike on Titan (Schulze-Makuch and Grinspoon, 2005), particularly if the strike would have occurred in the subpolar areas that exhibit vast ethane-methane lakes. If the asteroid or comet would be of sufficient size, it would also puncture the icy crust and access a vast reservoir of the subsurface liquid ammonia-water mixture. Thompson and Sagan (1992) showed that a liquid water-ammonia body could exist for millions of years on Titan after an asteroid impact. Thus, we modified the experimental conditions as described above and report on the results. Assuming a moderate impact in the subpolar areas of Titan, we used an atmosphere of currently 1.5 bar, but increased the partial pressure of methane to 1 bar (and 0.1 bar ammonia assuming a minor amount of ammonia-water ice being evaporated

The Influence of Runoff and Surface Hydrology on Titan's Weather and Climate

Science.gov (United States)

Faulk, S.; Lora, J. M.; Mitchell, J.; Moon, S.

2017-12-01

Titan's surface liquid distribution has been shown by general circulation models (GCMs) to greatly influence the hydrological cycle, producing characteristic weather and seasonal climate patterns. Simulations from the Titan Atmospheric Model (TAM) with imposed polar methane "wetlands" reservoirs realistically produce observed cloud features and temperature profiles of Titan's atmosphere, whereas "aquaplanet" simulations with a global methane ocean are not as successful. In addition, wetlands simulations, unlike aquaplanet simulations, demonstrate strong correlations between extreme rainfall behavior and observed geomorphic features, indicating the influential role of precipitation in shaping Titan's surface. The wetlands configuration is, in part, motivated by Titan's large-scale topography featuring low-latitude highlands and high-latitude lowlands, with the implication being that methane may concentrate in the high-latitude lowlands by way of runoff and subsurface flow of a global or regional methane table. However, the extent to which topography controls the surface liquid distribution and thus impacts the global hydrological cycle by driving surface and subsurface flow is unclear. Here we present TAM simulations wherein the imposed wetlands reservoirs are replaced by a surface runoff scheme that allows surface liquid to self-consistently redistribute under the influence of topography. We discuss the impact of surface runoff on the surface liquid distribution over seasonal timescales and compare the resulting hydrological cycle to observed cloud and surface features, as well as to the hydrological cycles of the TAM wetlands and aquaplanet simulations. While still idealized, this more realistic representation of Titan's hydrology provides new insight into the complex interaction between Titan's atmosphere and surface, demonstrates the influence of surface runoff on Titan's global climate, and lays the groundwork for further surface hydrology developments in Titan

Impact of Strontium Nitrate and Sodium Permanganate Addition on Solid-Liquid Separation of SRS High Level Waste

International Nuclear Information System (INIS)

Poirier, M.R.

2002-01-01

As a pretreatment step for the caustic side solvent extraction (CSSX) flowsheet, the process contacts the incoming salt solution containing entrained sludge with monosodium titanate (MST) to adsorb strontium and actinides. An operation filters the resulting slurry to remove the sludge and MST. Previous work for the River Protection Program at Hanford suggests that addition of strontium nitrate and sodium permanganate for strontium and actinide removal, rather than MST, improves the filtration rate for comparable waste streams

IN SITU MEASUREMENTS OF THE SIZE AND DENSITY OF TITAN AEROSOL ANALOGS

Energy Technology Data Exchange (ETDEWEB)

Hoerst, S. M.; Tolbert, M. A, E-mail: sarah.horst@colorado.edu [Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO (United States)

2013-06-10

The organic haze produced from complex CH{sub 4}/N{sub 2} chemistry in the atmosphere of Titan plays an important role in processes that occur in the atmosphere and on its surface. The haze particles act as condensation nuclei and are therefore involved in Titan's methane hydrological cycle. They also may behave like sediment on Titan's surface and participate in both fluvial and aeolian processes. Models that seek to understand these processes require information about the physical properties of the particles including their size and density. Although measurements obtained by Cassini-Huygens have placed constraints on the size of the haze particles, their densities remain unknown. We have conducted a series of Titan atmosphere simulation experiments and measured the size, number density, and particle density of Titan aerosol analogs, or tholins, for CH{sub 4} concentrations from 0.01% to 10% using two different energy sources, spark discharge and UV. We find that the densities currently in use by many Titan models are higher than the measured densities of our tholins.

Infrared Spectra and Optical Constants of Nitrile Ices Relevant to Titan's Atmosphere

Science.gov (United States)

Anderson, Carrie; Ferrante, Robert F.; Moore, W. James; Hudson, Reggie; Moore, Marla H.

2011-01-01

Spectra and optical constants of nitrile ices known or suspected to be in Titan?s atmosphere have been determined from 2.0 to 333.3 microns (approx.5000 to 30/cm). These results are relevant to the ongoing modeling of Cassini CIRS observations of Titan?s winter pole. Ices studied were: HCN, hydrogen cyanide; C2N2, cyanogen; CH3CN, acetonitrile; C2H5CN, propionitrile; and HC3N, cyanoacetylene. Optical constants were calculated, using Kramers-Kronig analysis, for each nitrile ice?s spectrum measured at a variety of temperatures, in both the amorphous- and crystalline phases. Spectra were also measured for many of the nitriles after quenching at the annealing temperature and compared with those of annealed ices. For each of these molecules we also measured the real component, n, of the refractive index for amorphous and crystalline phases at 670 nm. Several examples of the information contained in these new data sets and their usefulness in modeling Titan?s observed features will be presented (e.g., the broad emission feature at 160/cm; Anderson and Samuelson, 2011).

IN SITU MEASUREMENTS OF THE SIZE AND DENSITY OF TITAN AEROSOL ANALOGS

International Nuclear Information System (INIS)

Hörst, S. M.; Tolbert, M. A

2013-01-01

The organic haze produced from complex CH 4 /N 2 chemistry in the atmosphere of Titan plays an important role in processes that occur in the atmosphere and on its surface. The haze particles act as condensation nuclei and are therefore involved in Titan's methane hydrological cycle. They also may behave like sediment on Titan's surface and participate in both fluvial and aeolian processes. Models that seek to understand these processes require information about the physical properties of the particles including their size and density. Although measurements obtained by Cassini-Huygens have placed constraints on the size of the haze particles, their densities remain unknown. We have conducted a series of Titan atmosphere simulation experiments and measured the size, number density, and particle density of Titan aerosol analogs, or tholins, for CH 4 concentrations from 0.01% to 10% using two different energy sources, spark discharge and UV. We find that the densities currently in use by many Titan models are higher than the measured densities of our tholins.

Technological properties and structure of titanate melts

International Nuclear Information System (INIS)

Morozov, A.A.

2002-01-01

Power substantiation of existence of tough stream of complex anion ([TiO 6 ] 8- ) as a prevalent unit in titanate melts is given on the base of up-to-date knowledge about structure of metallurgical slags and results of investigations of thermophysical properties of these melts. It is shown that high crystallization ability of titanate melts at technological temperatures is determined by heterogeneity of liquid state - by presence up to 30 % of dispersed particles of solid phase solutions in matrix liquid [ru

Observations of CO in Titan's Atmosphere Using ALMA

Science.gov (United States)

Serigano, Joseph; Nixon, Conor A.; Cordiner, Martin; Irwin, Patrick G. J.; Teanby, Nicholas; Charnley, Steven B.; Lindberg, Johan E.; Remijan, Anthony J.

2015-11-01

The advent of the Atacama Large Millimeter/submillimeter Array (ALMA) has provided a powerful facility for probing the atmospheres of solar system targets at long wavelengths (84-720 GHz) where the rotational lines of small, polar molecules are prominent. In the dense, nitrogen-dominated atmosphere of Titan, photodissociation of molecular nitrogen and methane leads to a wealth of complex hydrocarbons and nitriles in small abundances. Past millimeter/submillimeter observations, including ground-based observations as well as those by the Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft, have proven the significance of this wavelength region for the derivation of vertical mixing profiles, latitudinal and seasonal variations, and molecular detections. Previous ALMA studies of Titan have presented mapping and vertical column densities of hydrogen isocyanide (HNC) and cyanoacetylene (HC3N) (Cordiner et al. 2014) as well as the first spectroscopic detection of ethyl cyanide (C2H5CN) in Titan’s atmosphere (Cordiner et al. 2015).Here, we report several submillimetric observations of carbon monoxide (CO) and its isotopologues 13CO, C18O, and C17O in Titan’s atmosphere obtained with flux calibration data from the ALMA Science Archive. We employ NEMESIS, a line-by-line radiative transfer code, to determine the stratospheric abundances of these molecules. The abundance of CO in Titan's atmosphere is determined to be approximately 50±1 ppm, constant with altitude, and isotopic ratios are determined to be approximately 12C/13C = 90, 16O/18O = 470, and 16O/17O = 2800. This report presents the first spectroscopic detection of C17O in the outer solar system, detected at >11σ confidence. This talk will focus on isotopic ratios in CO in Titan's atmosphere and will compare our results to previously measured values for Titan and other bodies in the Solar System. General implications for the history of Titan from measurements of CO and its isotopologues will be

Titan's Primordial Soup: Formation of Amino Acids via Low Temperature Hydrolysis of Tholins

Science.gov (United States)

Neish, Catherine; Somogyi, Á.; Smith, M. A.

2009-09-01

Titan, Saturn's largest moon, is a world rich in the "stuff of life". Reactions occurring in its dense nitrogen-methane atmosphere produce a wide variety of organic molecules, which subsequently rain down onto its surface. Water - thought to be another important ingredient for life - is likewise abundant on Titan. Theoretical models of Titan's formation predict that its interior consists of an ice I layer several tens of kilometers thick overlying a liquid ammonia-rich water layer several hundred kilometers thick (Tobie et al., 2005). Though its surface temperature of 94K dictates that Titan is on average too cold for liquid water to persist at its surface, melting caused by impacts and/or cryovolcanism may lead to its episodic availability. Impact melt pools on Titan would likely remain liquid for 102 - 104 years before freezing (O'Brien et al., 2005). The combination of complex organic molecules and transient locales of liquid water make Titan an interesting natural laboratory for studying prebiotic chemistry. In this work, we sought to determine what biomolecules might be formed under conditions analogous to those found in transient liquid water environments on Titan. We hydrolyzed Titan organic haze analogues, or "tholins", in 13 wt. % ammonia-water at 253K and 293K for a year. Using a combination of high resolution mass spectroscopy and tandem mass spectroscopy fragmentation techniques, four amino acids were identified in the hydrolyzed tholin sample. These four species have been assigned as the amino acids asparagine, aspartic acid, glutamine, and glutamic acid. This represents the first detection of biologically relevant molecules created under conditions similar to those found in impact melt pools and cryolavas on Titan. Future missions to Titan should therefore carry instrumentation capable of detecting amino acids and other prebiotically relevant molecules on its surface This work was supported by the NASA Exobiology Program.

Rheology Of MonoSodium Titanate (MST) And Modified Mst (mMST) Mixtures Relevant To The Salt Waste Processing Facility

Energy Technology Data Exchange (ETDEWEB)

Koopman, D. C.; Martino, C. J.; Shehee, T. C.; Poirier, M. R.

2013-07-31

The Savannah River National Laboratory performed measurements of the rheology of suspensions and settled layers of treated material applicable to the Savannah River Site Salt Waste Processing Facility. Suspended solids mixtures included monosodium titanate (MST) or modified MST (mMST) at various solid concentrations and soluble ion concentrations with and without the inclusion of kaolin clay or simulated sludge. Layers of settled solids were MST/sludge or mMST/sludge mixtures, either with or without sorbed strontium, over a range of initial solids concentrations, soluble ion concentrations, and settling times.

Rheology Of MonoSodium Titanate (MST) And Modified Mst (mMST) Mixtures Relevant To The Salt Waste Processing Facility

International Nuclear Information System (INIS)

Koopman, D. C.; Martino, C. J.; Shehee, T. C.; Poirier, M. R.

2013-01-01

The Savannah River National Laboratory performed measurements of the rheology of suspensions and settled layers of treated material applicable to the Savannah River Site Salt Waste Processing Facility. Suspended solids mixtures included monosodium titanate (MST) or modified MST (mMST) at various solid concentrations and soluble ion concentrations with and without the inclusion of kaolin clay or simulated sludge. Layers of settled solids were MST/sludge or mMST/sludge mixtures, either with or without sorbed strontium, over a range of initial solids concentrations, soluble ion concentrations, and settling times

MICROSTRUCTURE CHARACTERISTIC OF ALUMINUM TITANATE SYNTHESIED BY BOTH SOLID- STATE AND SOL-GEL PROCESSES

Directory of Open Access Journals (Sweden)

M. Khosravi Saghezchi

2015-12-01

Full Text Available A comparing study on formation and microstructure features of aluminum titanate is investigated through both solid-state and sol-gel processes. Aluminum titanate formed by firing at 1350ºC and 1450ºC for 4h in solid-state process. In the sol-gel process formation of submicron sized particles is followed by addition of sucrose into the transparent sol. XRD analysis was confirmed the formation of aluminum titanate at 1400ºC  in lower duration of calcination (3h without any additives in the sol-gel process. In this work 2wt% MgO is added to the samples as the additive for forming acceleration of aluminum titanate. The influence of MgO addition and heat treatment are studied on phase formation and microstructure development of aluminum titanate in both procedures. Additive optimizes aluminum titanate formation at lower temperatures (1300-1350ºC. Phase and microstructure studies of Mg containing samples optimally show significance in aluminum titanate formation.

Titanate nanotube coatings on biodegradable photopolymer scaffolds

Energy Technology Data Exchange (ETDEWEB)

Beke, S., E-mail: szabolcs.beke@iit.it [Department of Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Kőrösi, L. [Department of Biotechnology, Nanophage Therapy Center, Enviroinvest Corporation, Kertváros u. 2, H-7632, Pécs (Hungary); Scarpellini, A. [Department of Nanochemistry, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Anjum, F.; Brandi, F. [Department of Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy)

2013-05-01

Rigid, biodegradable photopolymer scaffolds were coated with titanate nanotubes (TNTs) by using a spin-coating method. TNTs were synthesized by a hydrothermal process at 150 °C under 4.7 bar ambient pressure. The biodegradable photopolymer scaffolds were produced by mask-assisted excimer laser photocuring at 308 nm. For scaffold coating, a stable ethanolic TNT sol was prepared by a simple colloid chemical route without the use of any binding compounds or additives. Scanning electron microscopy along with elemental analysis revealed that the scaffolds were homogenously coated by TNTs. The developed TNT coating can further improve the surface geometry of fabricated scaffolds, and therefore it can further increase the cell adhesion. Highlights: ► Biodegradable scaffolds were produced by mask-assisted UV laser photocuring. ► Titanate nanotube deposition was carried out without binding compounds or additives. ► The titanate nanotube coating can further improve the surface geometry of scaffolds. ► These reproducible platforms will be of high importance for biological applications.

Large catchment area recharges Titan's Ontario Lacus

Science.gov (United States)

Dhingra, Rajani D.; Barnes, Jason W.; Yanites, Brian J.; Kirk, Randolph L.

2018-01-01

We seek to address the question of what processes are at work to fill Ontario Lacus while other, deeper south polar basins remain empty. Our hydrological analysis indicates that Ontario Lacus has a catchment area spanning 5.5% of Titan's surface and a large catchment area to lake surface area ratio. This large catchment area translates into large volumes of liquid making their way to Ontario Lacus after rainfall. The areal extent of the catchment extends to at least southern mid-latitudes (40°S). Mass conservation calculations indicate that runoff alone might completely fill Ontario Lacus within less than half a Titan year (1 Titan year = 29.5 Earth years) assuming no infiltration. Cassini Visual and Infrared Mapping Spectrometer (VIMS) observations of clouds over the southern mid and high-latitudes are consistent with precipitation feeding Ontario's large catchment area. This far-flung rain may be keeping Ontario Lacus filled, making it a liquid hydrocarbon oasis in the relatively dry south polar region.

Development of Preparation of Metal Nanobelts and Its Application in Electrochemical Sensors%金属纳米带的制备及其在电化学传感器中的应用研究进展

Institute of Scientific and Technical Information of China (English)

杨光明; 李丽; 徐国良; 徐凤; 杨云慧

2012-01-01

综述了金、银等金属纳米带的制备方法(真空冷凝法和模板法)及其在电化学传感器中的应用,展望了其发展前景.着重介绍了真空冷凝法的制备原理、装置、过程等；讨论了模板法中不同类型的有机分子模板(模板作用、兼顾模板和还原剂作用)、制备过程中的反应体系(水热、超声等)、模板分子与金属离子的物质的量比和反应时间等对纳米带微观形貌的影响.%The development of preparation of metal nanobelts (Evaporation-condensation method and the soft template method) and its application in electrochemical sensors are reviewed. The prospects and development trend of metal nanobelts are discussed. The principle, process and installation of evaporation-condensation method are discussed. Effects of the morphological characterizations of the metal nanobelts are reviewed such as different template (Only template action, template and reducing agent action), synthetic conditions (hydro-thermal synthesis and ultrasonic irradiation etc. ) and reaction time.

Light scattering measurements with Titan's aerosols analogues produced by dusty plasma

Science.gov (United States)

Hadamcik, E.; Renard, J.-B.; Szopa, C.; Cernogora, G.; Levasseur-Regourd, A. C.

The Titan s atmosphere contains solid aerosols produced by the photochemistry of nitrogen and methane These aerosols are at the origin of the characteristic brown yellow colour of Titan During the descent of the Huygens probe the 14 th January 2005 optical measurements of the Titan s haze and Titan s surface have been done In order to explain the obtained results laboratory simulations are necessary We produce analogues of the Titan s aerosols in a RF capacitively coupled low-pressure plasma in a N 2 --CH 4 mixture representative of the Titan s atmosphere Szopa et al 2006 Szopa et al this conference The morphology of the produced solid aerosols is observed by SEM analyses They are quasi spherical and their mean size is function of the plasma conditions Moreover their colour changes from yellow to brown as a function of CH 4 ratio in the plasma In order to have information on the optical properties of the produced aerosols measurements have been performed with the PROGRA2 experiment Renard et al 2002 The PROGRA2 experiment measures the phase dependence of the linear polarization of the light scattered by dust particles for two wavelengths 543 5 nm and 632 8 nm The particles are lifted either in microgravity in the CNES ESA dedicated airplane or by an air-draught in ground-based conditions The aim of this work is to build a database for further modelling of the optical properties of Titan s in connection with the Huygens data These particles have also an astrophysical interest as organic compounds Hadamcik et

Study of the growth of CeO2 nanoparticles onto titanate nanotubes

Science.gov (United States)

Marques, Thalles M. F.; Ferreira, Odair P.; da Costa, Jose A. P.; Fujisawa, Kazunori; Terrones, Mauricio; Viana, Bartolomeu C.

2015-12-01

We report the study of the growth of CeO2 nanoparticles on the external walls and Ce4+ intercalation within the titanate nanotubes. The materials were fully characterized by multiple techniques, such as: Raman spectroscopy, infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The ion exchange processes in the titanate nanotubes were carried out using different concentrations of Ce4+ in aqueous solution. Our results indicate that the growth of CeO2 nanoparticles grown mediated by the hydrolysis in the colloidal species of Ce and the attachment onto the titanate nanotubes happened and get it strongly anchored to the titanate nanotube surface by a simple electrostatic interaction between the nanoparticles and titanate nanotubes, which can explain the small size and even distribution of nanoparticles on titanate supports. It was demonstrated that it is possible to control the amount and size of CeO2 nanoparticles onto the nanotube surface, the species of the Ce ions intercalated between the layers of titanate nanotubes, and the materials could be tuned for using in specific catalysis in according with the amount of CeO2 nanoparticles, their oxygen vacancies/defects and the types of Ce species (Ce4+ or Ce3+) present into the nanotubes.

Thermal stability of titanate nanorods and titania nanowires formed from titanate nanotubes by heating

Czech Academy of Sciences Publication Activity Database

Brunátová, T.; Matěj, Z.; Oleynikov, P.; Vesely, J.; Danis, S.; Popelková, Daniela; Kuzel, R.

2014-01-01

Roč. 98, December (2014), s. 26-36 ISSN 1044-5803 Institutional support: RVO:61389013 Keywords : titania nanowires * titanate nanorods * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.845, year: 2014

Coexistence of Dunes and Humid Conditions at Titan's Tropics

Science.gov (United States)

Radebaugh, Jani; Lorenz, R. D.; Lunine, J. I.; Kirk, R. L.; Ori, G. G.; Farr, T. G.; Malaska, M.; Le Gall, A.; Liu, Z. Y. C.; Encrenaz, P. J.; Paillou, P.; Hayes, A.; Lopes, R. M. C.; Turtle, E. P.; Wall, S. D.; Stofan, E. R.; Wood, C. A.; Cassini RADAR Team

2012-10-01

At Titan's equatorial latitudes there are tens of thousands of dunes, a landform typical of desert environments where sand does not become anchored by vegetation or fluids. Model climate simulations predict generally dry conditions at the equator and humid conditions near the poles of Titan, where lakes of methane/ethane are found. However, moderate relative methane humidity was observed at the Huygens landing site, recent rainfall was seen by Cassini ISS near the Belet Sand Sea, and a putative transient lake in Shangri-La was observed by Cassini VIMS, all of which indicate abundant fluids may be present, at least periodically, at Titan's equatorial latitudes. Terrestrial observations and studies demonstrate dunes can exist and migrate in conditions of high humidity. Active dunes are found in humid climates, indicating the movement of sand is not always prohibited by the presence of fluids. Sand mobility is related to precipitation, evaporation and wind speed and direction. If dune surfaces become wetted by rainfall or rising subsurface fluids, they can become immobilized. However, winds can act to dry the uppermost layers, freeing sands for saltation and enabling dune migration in wet conditions. Active dunes are found in tropical NE Brazil and NE Australia, where there are alternating dry and wet periods, a condition possible for Titan's tropics. Rising and falling water levels lead to the alteration of dune forms, mainly from being anchored by vegetation, but also from cementation by carbonates or clays. Studies of Titan's dunes, which could undergo anchoring of organic sediments by hydrocarbon fluids, could inform the relative strength of vegetation vs. cementation at humid dune regions on Earth. Furthermore, a comprehensive survey of dune morphologies near regions deemed low by SARTopo and stereo, where liquids may collect in wet conditions, could reveal if bodies of liquid have recently existed at Titan's tropics.

Crystal structure of red lead titanate thin films

International Nuclear Information System (INIS)

Bursill, L.A.; Peng, J.L.; Jiang, B.; Li, X.

1998-01-01

Orange-red lead titanate thin films are examined by high-resolution transmission electron microscopy and diffraction. It is remarkable that the structure is based on that of tetragonal-tungsten-bronze (TTB) rather than perovskite-type. The chemical basis for this result is examined. It is deduced that the TTB structure is stabilized by inclusion of hydroxyl ions during synthesis by a sol-gel route involving hydrolysis of n-Butyl titanate

Predicting Passenger Survival Rates on the Titanic

OpenAIRE

Prateek Chanda

2017-01-01

The sinking of the RMS Titanic is one of the most infamous shipwrecks in history. On April 15, 1912, during her maiden voyage, the Titanic sank after colliding with an iceberg, killing 1502 out of 2224 passengers and crew. This sensational tragedy shocked the international community and led to better safety regulations for ships. One of the reasons that the shipwreck led to such loss of life was that there were not enough lifeboats for the passengers and crew. Although there was some el...

Behavior under Extreme Conditions: The Titanic Disaster

OpenAIRE

Bruno S. Frey; David A. Savage; Benno Torgler

2011-01-01

During the night of April 14, 1912, the RMS Titanic collided with an iceberg on her maiden voyage. Two hours and 40 minutes later she sank, resulting in the loss of 1,501 lives—more than two-thirds of her 2,207 passengers and crew. This remains one of the deadliest peacetime maritime disasters in history and by far the most famous. For social scientists, evidence about how people behaved as the Titanic sunk offers a quasi-natural field experiment to explore behavior under extreme conditions o...

Spectroscopy of carbonated chains: experimental investigation and observation of Titan's atmosphere

International Nuclear Information System (INIS)

Jolly, Antoine

2012-01-01

In this report for an Accreditation to Supervise Research (HDR), the author proposes an overview of his research works. These works first addressed quantitative spectroscopy and more particularly the measurement of absolute absorption coefficients which are necessary parameters for the quantification of molecules which are remotely sensed through their spectroscopic signature. Secondly, the author addresses the adjustment of line lists in the infrared for a better investigation of recent observations of Titan's atmosphere made by the Cassini mission. Thirdly, he reports the use of this line list for the processing of observations of Titan. The last part addresses an experimental atmospheric simulation which aims at reproducing Titan's atmosphere by submitting its main components (nitrogen and methane) to an energetic flow representative of what is present on Titan

Titan's Surface Composition from Cassini VIMS Solar Occultation Observations

Science.gov (United States)

McCord, Thomas; Hayne, Paul; Sotin, Christophe

2013-04-01

Titan's surface is obscured by a thick absorbing and scattering atmosphere, allowing direct observation of the surface within only a few spectral win-dows in the near-infrared, complicating efforts to identify and map geologi-cally important materials using remote sensing IR spectroscopy. We there-fore investigate the atmosphere's infrared transmission with direct measure-ments using Titan's occultation of the Sun as well as Titan's reflectance measured at differing illumination and observation angles observed by Cas-sini's Visual and Infrared Mapping Spectrometer (VIMS). We use two im-portant spectral windows: the 2.7-2.8-mm "double window" and the broad 5-mm window. By estimating atmospheric attenuation within these windows, we seek an empirical correction factor that can be applied to VIMS meas-urements to estimate the true surface reflectance and map inferred composi-tional variations. Applying the empirical corrections, we correct the VIMS data for the viewing geometry-dependent atmospheric effects to derive the 5-µm reflectance and 2.8/2.7-µm reflectance ratio. We then compare the cor-rected reflectances to compounds proposed to exist on Titan's surface. We propose a simple correction to VIMS Titan data to account for atmospheric attenuation and diffuse scattering in the 5-mm and 2.7-2.8 mm windows, generally applicable for airmass water ice for the majority of the low-to-mid latitude area covered by VIMS measurements. Four compositional units are defined and mapped on Titan's surface based on the positions of data clusters in 5-mm vs. 2.8/2.7-mm scatter plots; a simple ternary mixture of H2O, hydrocarbons and CO2 might explain the reflectance properties of these surface units. The vast equatorial "dune seas" are compositionally very homogeneous, perhaps suggesting transport and mixing of particles over very large distances and/or and very consistent formation process and source material. The composi-tional branch characterizing Tui Regio and Hotei Regio is

Ethane ocean on Titan

Science.gov (United States)

Lunine, J. I.; Stevenson, D. J.; Yung, Y.L.

1983-01-01

Voyager I radio occultation data is employed to develop a qualitative model of an ethane ocean on Titan. It is suggested that the ocean contains 25 percent CH4 and that the ocean is in dynamic equilibrium with an N2 atmosphere. Previous models of a CH4 ocean are discounted due to photolysis rates of CH4 gas. Tidal damping of Titan's orbital eccentricity is taken as evidence for an ocean layer approximately 1 km deep, with the ocean floor being covered with a solid C2H2 layer 100 to 200 m thick. The photolytic process disrupting the CH4, if the estimates of the oceanic content of CH4 are correct, could continue for at least one billion years. Verification of the model is dependent on detecting CH4 clouds in the lower atmosphere, finding C2H6 saturation in the lower troposphere, or obtaining evidence of a global ocean.

Organic chemistry on Titan

Science.gov (United States)

Chang, S.; Scattergood, T.; Aronowitz, S.; Flores, J.

1979-01-01

Features taken from various models of Titan's atmosphere are combined in a working composite model that provides environmental constraints within which different pathways for organic chemical synthesis are determined. Experimental results and theoretical modeling suggest that the organic chemistry of the satellite is dominated by two processes: photochemistry and energetic particle bombardment. Photochemical reactions of CH4 in the upper atmosphere can account for the presence of C2 hydrocarbons. Reactions initiated at various levels of the atmosphere by cosmic rays, Saturn 'wind', and solar wind particle bombardment of a CH4-N2 atmospheric mixture can account for the UV-visible absorbing stratospheric haze, the reddish appearance of the satellite, and some of the C2 hydrocarbons. In the lower atmosphere photochemical processes will be important if surface temperatures are sufficiently high for gaseous NH3 to exist. It is concluded that the surface of Titan may contain ancient or recent organic matter (or both) produced in the atmosphere.

Equinoctial Activity Over Titan Dune Fields Revealed by Cassini/vims

Science.gov (United States)

Rodriguez, S.; Le Mouelic, S.; Barnes, J. W.; Hirtzig, M.; Rannou, P.; Sotin, C.; Brown, R. H.; Bow, J.; Vixie, G.; Cornet, T.; Bourgeois, O.; Narteau, C.; Courrech Du Pont, S.; Le Gall, A.; Reffet, E.; Griffith, C. A.; Jaumann, R.; Stephan, K.; Buratti, B. J.; Clark, R. N.; Baines, K. H.; Nicholson, P. D.; Coustenis, A.

2012-12-01

Titan, the largest satellite of Saturn, is the only satellite in the solar system with a dense atmosphere. The close and continuous observations of Titan by the Cassini spacecraft, in orbit around Saturn since July 2004, bring us evidences that Titan troposphere and low stratosphere experience an exotic, but complete meteorological cycle similar to the Earth hydrological cycle, with hydrocarbons evaporation, condensation in clouds, and rainfall. Cassini monitoring campaigns also demonstrate that Titan's cloud coverage and climate vary with latitude. Titan's tropics, with globally weak meteorological activity and widespread dune fields, seem to be slightly more arid than the poles, where extensive and numerous liquid reservoirs and sustained cloud activity have been discovered. Only a few tropo-spheric clouds have been observed at Titan's tropics during the southern summer. As equinox was approaching (in August 2009), they occurred more frequently and appeared to grow in strength and size. We present here the observation of intense brightening at Titan's tropics, very close to the equinox. These detections were conducted with the Visual and Infrared Mapping Spectrometer (VIMS) onboard Cassini. We will discuss the VIMS images of the three individual events detected so far, observed during the Titan's flybys T56 (22 May 2009), T65 (13 January 2010) and T70 (21 June 2010). T56, T65 and T70 observations show an intense and transient brighten-ing of large regions very close to the equator, right over the extensive dune fields of Senkyo, Belet and Shangri-La. They all appear spectrally and morphologically different from all transient surface features or atmospheric phenomena previously reported. Indeed, these events share in particular a strong brightening at wavelengths greater than 2 μm (especially at 5 μm), making them spectrally distinct from the small tropical clouds observed before the equinox and the large storms observed near the equator in September and October

Descent imager/spectral radiometer (DISR) instrument aboard the Huygens probe of Titan

Science.gov (United States)

Tomasko, Martin G.; Doose, Lyn R.; Smith, Peter H.; Fellows, C.; Rizk, B.; See, C.; Bushroe, M.; McFarlane, E.; Wegryn, E.; Frans, E.; Clark, R.; Prout, M.; Clapp, S.

1996-10-01

The Huygen's probe of the atmosphere of Saturn's moon Titan includes one optical instrument sensitive to the wavelengths of solar radiation. The goals of this investigation fall into four broad areas: 1) the measurement of the profile of solar heating to support an improved understanding of the thermal balance of Titan and the role of the greenhouse effect in maintaining Titan's temperature structure; 2) the measurement of the size, vertical distribution, and optical properties of the aerosol and cloud particles in Titan's atmosphere to support studies of the origin, chemistry, life cycles, and role in the radiation balance of Titan played by these particles; 3) the composition of the atmosphere, particularly the vertical profile of the mixing ratio of methane, a condensable constituent in Titan's atmosphere; and 4) the physical state, composition, topography, and physical processes at work in determining the nature of the surface of Titan and its interaction with Titan's atmosphere. In order to accomplish these objectives, the Descent Imager/Spectral Radiometer (DISR) instrument makes extensive use of fiber optics to bring the light from several different sets of foreoptics to a silicon CCD detector, to a pair of InGaAs linear array detectors, and to three silicon photometers. Together these detectors permit DISR to make panoramic images of the clouds and surface of Titan, to measure the spectrum of upward and downward streaming sunlight from 350 to 1700 nm at a resolving power of about 200, to measure the reflection spectrum of >= 3000 locations on the surface, to measure the brightness and polarization of the solar aureole between 4 and 30 degrees from the sun at 500 and 935 nm, to separate the direct and diffuse downward solar flux at each wavelength measured, and to measure the continuous reflection spectrum of the ground between 850 and 1600 nm using an onboard lamp in the last 100 m of the descent.

Polycyclic aromatic hydrocarbons in the atmospheres of Titan and Jupiter

Science.gov (United States)

Sagan, Carl; Khare, B. N.; Thompson, W. R.; Mcdonald, G. D.; Wing, Michael R.; Bada, Jeffrey L.; Vo-Dinh, Tuan; Arakawa, E. T.

1993-01-01

PAHs are important components of the interstellar medium and carbonaceous chondrites, but have never been identified in the reducing atmospheres of the outer solar system. Incompletely characterized complex organic solids (tholins) produced by irradiating simulated Titan atmospheres reproduce well the observed UV/visible/IR optical constants of the Titan stratospheric haze. Titan tholin and a tholin generated in a crude simulation of the atmosphere of Jupiter are examined by two-step laser desorption/multiphoton ionization mass spectrometry. A range of two- to four-ring PAHs, some with one to four alkylation sites, are identified, with a net abundance of about 0.0001 g/g (grams per gram) of tholins produced. Synchronous fluorescence techniques confirm this detection. Titan tholins have proportionately more one- and two-ring PAHs than do Jupiter tholins, which in turn have more four-ring and larger PAHs. The four-ringed PAH chrysene, prominent in some discussions of interstellar grains, is found in Jupiter tholins.

The Titan haze revisted: Magnetospheric energy sorces quantitative tholin yields

Science.gov (United States)

Thompson, W. Reid; Mcdonald, Gene D.; Sagan, Carl

1994-01-01

We present laboratory measurements of the radiation yields of complex organic solids produced from N2/CH4 gas mixtures containing 10 or 0.1% CH4. These tholins are thought to resemble organic aerosols produced in the atmospheres of Titan, Pluto, and Triton. The tholin yields are large compared to the total yield of gaseous products: nominally, 13 (C + N)/100 eV for Titan tholin and 2.1 (C + N)/100 eV for Triton tholin. High-energy magnetospheric electrons responsible for tholin production represents a class distinct from the plasma electrons considered in models of Titan's aiglow. Electrons with E greater than 20 keV provide an energy flux approximately 1 x 10(exp -2) erg/cm/sec, implying from our measured tholin yields a mass flux of 0.5 to 4.0 x 10(exp -14) g/sq cm/sec of tholin. (The corresponding thickness of the tholin sedimentary column accumulated over 4 Gyr on Titan's surface is 4 to 30 m). This figure is in agreement with required mass fluxes computed from recent radiative transfer and sedimentation models. If, however, theses results, derived from experiments at approximately 2 mb, are applied to lower pressure levels toward peak auroral electron energy deposition and scaled with pressure as the gas-phase organic yields, the derived tholin mass flux is at least an order of magnitude less. We attrribute this difference to the fact that tholin synthesis occurs well below the level of maximum electron energy depositon and to possible contributions to tholis from UV-derived C2-hydrocarbons. We conclude that Tita tholin, produced by magnetospheric electrons, is alone sufficient to supply at least a significant fraction of Titan's haze-a result consistent with the fact that the optical properties of Titan tholin, among all proposed material, are best at reproducing Titan's geometric albedo spectrum from near UV to mid-IR in light-scattering models.

Are Titan's radial Labyrinth terrains surface expressions of large laccoliths?

Science.gov (United States)

Schurmeier, L.; Dombard, A. J.; Malaska, M.; Radebaugh, J.

2017-12-01

The Labyrinth terrain unit may be the one of the best examples of the surface expression of Titan's complicated history. They are characterized as highly eroded, dissected, and elevated plateaus and remnant ridges, with an assumed composition that is likely organic-rich based on radar emissivity. How these features accumulated organic-rich sediments and formed topographic highs by either locally uplifting or surviving pervasive regional deflation or erosion is an important question for understanding the history of Titan. There are several subsets of Labyrinth terrains, presumably with differing evolutionary histories and formation processes. We aim to explain the formation of a subset of Labyrinth terrain units informally referred to as "radial Labyrinth terrains." They are elevated and appear dome-like, circular in planform, have a strong radial dissection pattern, are bordered by Undifferentiated Plains units, and are found in the mid-latitudes. Based on their shape, clustering, and dimensions, we suggest that they may be the surface expression of large subsurface laccoliths. A recent study by Manga and Michaut (Icarus, 2017) explained Europa's lenticulae (pits, domes, spots) with the formation of saucer-shaped sills that form laccoliths around the brittle-ductile transition depth within the ice shell (1-5 km). Here, we apply the same scaling relationships and find that the larger size of radial labyrinth terrains with Titan's higher gravity implies deeper intrusion depths of around 20-40 km. This intrusion depth matches the expected brittle-ductile transition on Titan based on our finite element simulations and yield strength envelope analyses. We hypothesize that Titan's radial labyrinth terrains formed as cryovolcanic (water) intrusions that rose to the brittle-ductile transition within the ice shell where they spread horizontally, and uplifted the overlying ice. The organic-rich sedimentary cover also uplifted, becoming more susceptible to pluvial and fluvial

The key to Mars, Titan and beyond?

International Nuclear Information System (INIS)

Zubrin, R.M.

1990-01-01

This paper discusses the use of nuclear rockets using indigenous Mars propellants for future missions to Mars and Titan, which would drastically reduce the mass and cost of the mission while increasing its capability. Special attention is given to the CO2-powered nuclear rocket using indigenous Martian fuel (NIMF) vehicle for hopping around on Mars. If water is available on Mars, it could make a NIMF propellant yielding an exhaust velocity of 3.4 km/sec, good enough to allow a piloted NIMF spacecraft to ascent from the surface of Mars and propel itself directly to LEO; if water is available on Phobos, a NIMF spacecraft could travel to earth orbit and then back to Phobos or Mars without any additional propellant from earth. One of the many exciting missions beyond Mars that will be made possible by NIMF technology is the exploration of Saturn's moon Titan. A small automated NIMF Titan explorer, with foldout wings and a NERVA (Nuclear Engine for Rocket Vehicle Applications) engine, is proposed

Modified titanate perovskites in photocatalytic water splitting

Energy Technology Data Exchange (ETDEWEB)

Wlodarczak, M.; Ludwiczak, M.; Laniecki, M. [A. Mickiewicz Univ. (Poland)

2010-07-01

Received materials have structure of perovskite, what was shown by XRD diffraction patterns. Perovskite structure is present in all samples with strontium, barium and one sample with calcium. Moreover, received barium and strontium titanate are very similar to pattern materials. XRD results show, that temperature 500 C is too low to create perovskite structure in CaTiO{sub 3}. However, it is high enough in case of SrTiO{sub 3} and BaTiO{sub 3}. One regularity is obvious, surface area increases for samples calcined in lower temperature. There is a connection between surface area and dispersion of platinum. Both of them reach the greatest value to the calcium titanate. Catalytic activity was shown by all of received samples. Measurable values were received to samples calcined in 700 C. Calcium titanate had the best catalytic activity, both an amount of hydrogen and a ratio of hydrogen to platinum. There is one regularity to all samples, the ration of hydrogen to platinum increase when amount of platinum decrease. (orig.)

Fabrication of novel Ag−TiO_2 nanobelts as a photoanode for enhanced photovoltage performance in dye sensitized solar cells

International Nuclear Information System (INIS)

Wang, Yang; Li, Zhen; Cao, Ya; Li, Fei; Zhao, Wen; Liu, Xueqin; Yang, Jianbo

2016-01-01

TiO_2 nanobelts (TiO_2NBs) were successfully prepared using a solvothermal route via Ti foil as substrate in large scales. The morphology evolution process and formation mechanism of the as-obtained products were investigated in detail. On the basis of this novel structure, chemical sensitive Ag modified TiO_2NBs nanocomposites (Ag−TiO_2NBs) were fabricated. It was found that Ag−TiO_2NBs exhibit strong light absorption and efficient electron transport. According to Mott-Schottky analysis, Ag−TiO_2NBs show less surface trapping sites compared with TiO_2NBs. The Ag−TiO_2NBs photoanode fabricated in 0.01 M AgNO_3 demonstrates the best performance with a short-circuit current of 11.9 mA cm"−"2 corresponding to a photoelectric conversion efficiency of 4.89%, which is higher than that of pure TiO_2NBs based solar cell by 60%. - Graphical abstract: J-V curves of DSSCs based on TiO_2NPs, TiO_2NBs and Ag−TiO_2NBs—X under AM 1.5 conditions (100 mW cm"−"2). Ag−TiO_2NBs nanocomposites were prepared via a simple and effective method. Owing to strong light absorption and efficient electron transport, Ag−TiO_2NBs—0.01 M shows a PCE of 4.89% when prepared as a photoanode in DSSCs. - Highlights: • A facile route was adopted to construct well-dispersed Ag nanoparticles on TiO_2 nanobelts (Ag—TiO_2NBs). • Structure and photoelectrochemical properties of Ag—TiO_2NBs were studied. • Ag nanoparticles were found to modify the defects of TiO_2NBs. • Enhanced photovoltaic property of Ag—TiO_2NBs, compared to TiO_2NBs.

Silver decorated titanate/titania nanostructures for efficient solar driven photocatalysis

International Nuclear Information System (INIS)

Gong, Dangguo; Ho, Weng Chye Jeffrey; Tang Yuxin; Tay Qiuling; Lai Yuekun; Highfield, James George; Chen Zhong

2012-01-01

Photocatalysis has attracted significant interest to solve both the energy crisis and effectively combat environmental contamination. However, as the most widely used photocatalyst, titania (TiO 2 ) suffers from inefficient utilization of solar energy due to its wide band gap. In the present paper, we describe a method to extend the absorption edge of photocatalyst to visible region by the surface plasmon effect of silver. Silver ions are photo-reduced onto the surface of titanate nanotubes, which are synthesized by a conventional hydrothermal method. The as-synthesized Ag/titanate composite is transformed into Ag/titania nanoparticles by annealing at different temperatures. It is found that the interaction of Ag nanoparticles with the supports (titanate/titania) plays a key role for the visible light activity. The samples annealed at low temperature (<350 °C) do not show significant activity under our conditions, while the one annealed at 450 °C shows fast-degradation of methyl orange (MO) under visible light irradiation. The detailed mechanisms are also discussed. - Graphical abstract: Silver nanoparticles decorated titanate/titania as visible light active photocatalysts: silver nanoparticles could be excited by visible light due to its surface plasmon effect and excited electrons could be transferred to the conduction band of the semiconductor, where the reduction process occurs. Highlights: ► Uniform Ag nanoparticles are photo-reduced onto titanate and titania nanostructures. ► Titania crystal is formed by annealing hydrogen titanate at different temperatures. ► Best visible-light activity is achieved by Ag-loaded titania annealed at 450 °C. ► The visible light activity is attributed to the surface plasmonic resonance effect.

Crystal structure of red lead titanate thin films

Energy Technology Data Exchange (ETDEWEB)

Bursill, L.A.; Peng, J.L.; Jiang, B. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Li, X. [Jilin Univ., Changchun, JL (China). Dept of Chemistry

1998-09-01

Orange-red lead titanate thin films are examined by high-resolution transmission electron microscopy and diffraction. It is remarkable that the structure is based on that of tetragonal-tungsten-bronze (TTB) rather than perovskite-type. The chemical basis for this result is examined. It is deduced that the TTB structure is stabilized by inclusion of hydroxyl ions during synthesis by a sol-gel route involving hydrolysis of n-Butyl titanate 7 refs., 1 tab., 4 figs.

Titan's interior from its rotation axis orientation and its Love number

Science.gov (United States)

Baland, Rose-Marie; Gabriel, Tobie; Axel, Lefèvre

2013-04-01

The tidal Love number k2 of Titan has been recently estimated from Cassini flybys radio-tracking and is consistent with the presence of a global ocean in Titan's interior, located between two ice layers (Iess et al. 2012), in accordance with prediction from interior and evolutionary models for Titan. Previously, the orientation of the rotation axis of Titan has been measured on the basis of radar images from Cassini (Stiles et al. 2008). Titan's obliquity, is about 0.3. The measured orientation is more consistent with the presence of a global internal liquid ocean than with an entirely solid Titan (Baland et al. 2011). The global topography data of Titan seem to indicate some departure from the hydrostatic shape expected for a synchronous satellite under the influence of its rotation and the static tides raised by the central planet (Zebker et al. 2009). This may be explained by a differential tidal heating in the ice shell which flattens the poles (Nimmo and Bills 2010). A surface more flattened than expected implies compensation in depth to explain the measured gravity coefficients C20 and C22 of Iess et al. (2012). Here, all layers are assumed to have a tri-axial ellipsoid shape, but with polar and equatorial flattenings that differ from the hydrostatic expected ones. We assess the influence of this non-hydrostatic shape on the conclusions of Baland et al. (2011), which developped a Cassini state model for the orientation of the rotation axis of a synchronous satellite having an internal liquid layer. We assess the possibility to constrain Titan's interior (and particularly the structure of the water/ice layer) from both the rotation axis orientation and the Love number. We consider a range of internal structure models consistent with the mean density and the mean radius of Titan, and made of a shell, an ocean, a mantle, and a core, from the surface to the center, with various possible compositions (e.g. ammonia mixed with water for the ocean). The internal

Improvement of conditions for ceramics sintering on the base of lead zirconate-titanate

International Nuclear Information System (INIS)

Glinchuk, M.D.; Kim, P.V.; Bykov, I.P.; Lyashchenko, A.B.

1989-01-01

Lead zirconate-titanate powders of different graininess are studied for their phase composition. The finest grains of the powder consist of lead zirconate-titanate with the rhombohedral structure. Grains of 3-5 μm size are a mixture of lead zirconate-titanate and lead titanate, the latter exceeding 50% (by weight) causes the effect of anomalous expansion in the process of sintering. Control of the technological parameters of the synthesis permits producing powder with favourable correlation of the above phases and grain sizes. Sintering of such a powder induces no effect of the anomalous expansion with an increased density of the product attained

Anion and cation diffusion in barium titanate and strontium titanate; Anionen- und Kationendiffusion in Barium- und Strontiumtitanat

Energy Technology Data Exchange (ETDEWEB)

Kessel, Markus Franz

2012-12-19

Perovskite oxides show various interesting properties providing several technical applications. In many cases the defect chemistry is the key to understand and influence the material's properties. In this work the defect chemistry of barium titanate and strontium titanate is analysed by anion and cation diffusion experiments and subsequent time-of-flight secondary ion mass spectrometry (ToF-SIMS). The reoxidation equation for barium titanate used in multi-layer ceramic capacitors (MLCCs) is found out by a combination of different isotope exchange experiments and the analysis of the resulting tracer diffusion profiles. It is shown that the incorporation of oxygen from water vapour is faster by orders of magnitude than from molecular oxygen. Chemical analysis shows the samples contain various dopants leading to a complex defect chemistry. Dysprosium is the most important dopant, acting partially as a donor and partially as an acceptor in this effectively acceptor-doped material. TEM and EELS analysis show the inhomogeneous distribution of Dy in a core-shell microstructure. The oxygen partial pressure and temperature dependence of the oxygen tracer diffusion coefficients is analysed and explained by the complex defect chemistry of Dy-doped barium titanate. Additional fast diffusion profiles are attributed to fast diffusion along grain boundaries. In addition to the barium titanate ceramics from an important technical application, oxygen diffusion in cubic, nominally undoped BaTiO{sub 3} single crystals has been studied by means of {sup 18}O{sub 2}/{sup 16}O{sub 2} isotope exchange annealing and subsequent determination of the isotope profiles in the solid by ToF-SIMS. It is shown that a correct description of the diffusion profiles requires the analysis of the diffusion through the surface space-charge into the material's bulk. Surface exchange coefficients, space-charge potentials and bulk diffusion coefficients are analysed as a function of oxygen partial

Physicochemical characterisation and investigation of the bonding mechanisms of API-titanate nanotube composites as new drug carrier systems.

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Sipos, Barbara; Pintye-Hódi, Klára; Kónya, Zoltán; Kelemen, András; Regdon, Géza; Sovány, Tamás

2017-02-25

Titanate nanotube (TNT) has recently been explored as a new carrier material for active pharmaceutical ingredients (API). The aim of the present work was to reveal the physicochemical properties of API-TNT composites, focusing on the interactions between the TNTs and the incorporated APIs. Drugs belonging to different Biopharmaceutical Classification System (BCS) classes were loaded into TNTs: diltiazem hydrochloride (BCS I.), diclofenac sodium (BCS II.), atenolol (BCS III.) and hydrochlorothiazide (BCS IV.). Experimental results demonstrated that it is feasible for spiral cross-sectioned titanate nanotubes to carry drugs and maintain their bioactivity. The structural properties of the composites were characterized by a range of analytical techniques, including FT-IR, DSC, TG-MS, etc. The interactions between APIs and TNTs were identified as electrostatic attractions, mainly dominated by hydrogen bonds. Based on the results, it can be stated that the strength of the association depends on the hydrogen donor strength of the API. The drug release of incorporated APIs was evaluated from compressed tablets and compared to that of pure APIs. Differences noticed in the dissolution profiles due to incorporation showed a correlation with the strength of interactions between the APIs and the TNTs observed in the above analytical studies. Copyright © 2016 Elsevier B.V. All rights reserved.

Landform Evolution Modeling of Specific Fluvially Eroded Physiographic Units on Titan

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Moore, J. M.; Howard, A. D.; Schenk, P. M.

2015-01-01

Several recent studies have proposed certain terrain types (i.e., physiographic units) on Titan thought to be formed by fluvial processes acting on local uplands of bedrock or in some cases sediment. We have earlier used our landform evolution models to make general comparisons between Titan and other ice world landscapes (principally those of the Galilean satellites) that we have modeled the action of fluvial processes. Here we give examples of specific landscapes that, subsequent to modeled fluvial work acting on the surfaces, produce landscapes which resemble mapped terrain types on Titan.

Titan Density Reconstruction Using Radiometric and Cassini Attitude Control Flight Data

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Andrade, Luis G., Jr.; Burk, Thomas A.

2015-01-01

This paper compares three different methods of Titan atmospheric density reconstruction for the Titan 87 Cassini flyby. T87 was a unique flyby that provided independent Doppler radiometric measurements on the ground throughout the flyby including at Titan closest approach. At the same time, the onboard accelerometer provided an independent estimate of atmospheric drag force and density during the flyby. These results are compared with the normal method of reconstructing atmospheric density using thruster on-time and angular momentum accumulation. Differences between the estimates are analyzed and a possible explanation for the differences is evaluated.

Hydrothermal synthesis and processing of hydrogen titanate nanotubes for nicotine electrochemical sensing

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Mersal, Gaber A. M.; Mostafa, Nasser Y.; Omar, Abd-Elkader H.

2017-08-01

Hydrogen titanate nanotubes (HTNT) were prepared via acid washing of hydrothermally synthesized sodium titantate nanotube. HTNTs with diameters in the range 7-9 nm and length of several hundred nanometers were annealed at different temperatures and used to modify carbon paste electrode (CPE). Cyclic and square wave voltammetric techniques were used to investigate the behavior of nicotine at HTNT modified carbon paste electrode (HTNTCPE). The nicotine-oxidation reaction over HTNTCPE was irreversible and adsorption process is the rate determining step. HTNTs annealed at 500 °C showed the best response to nicotine. The nicotine concentration was determined at the ideal conditions by square wave voltammetry (SWV). The calibration was linear from 0.1 to 500.0 µmol l-1 with a correlation coefficient of 0.995. The detection limits were found to be 0.005 µmol l-1. The present HTNTCPE was used to the determination of nicotine in two cigarette brands and it showed outstanding performance with respect to detection limit and sensitivity.

Effects of additives on microstructures of titanate based nanotubes prepared by the hydrothermal process

International Nuclear Information System (INIS)

Kubo, Takashi; Sugimoto, Keijiro; Onoki, Takamasa; Nakahira, Atsushi; Yamasaki, Yuki

2009-01-01

Silica-containing TiO 2 -derived titanate nanotubes were prepared by the addition of a small amount of tetraethyl orthosilicate (TEOS) to TiO 2 -derived titanate nanotubes prepared by the hydrothermal process and a subsequent heat-treatment at 473 K in air. The microstructure and thermal behavior of synthesized silica containing TiO 2 -derived titanate nanotubes were investigated by various methods such as X-ray diffraction (XRD), X-ray absorption fine structure (XAF), and X-ray photoelectron spectroscopy (XPS). As a result, the addition of a small amount of TEOS leaded to the improvement of the thermal stability for TiO 2 -derived titanate nanotubes. XPS results revealed that Si was combined onto the surface of TiO 2 -derived titanate nanotubes, forming partial Si-O-Ti chemical bonds. Therefore, it was inferred that the thermal stability could be modified by forming partial Si-O-Ti chemical bonds at interface of silica and TiO 2 -derived titanate nanotubes. (author)

Fabrication of crystal-oriented barium-bismuth titanate ceramics in high magnetic field and subsequent reaction sintering

International Nuclear Information System (INIS)

Tanaka, Satoshi; Tomita, Yusuke; Furushima, Ryoichi; Uematsu, Keizo; Shimizu, Hiroyuki; Doshida, Yutaka

2009-01-01

High magnetic field was applied to fabricate novel lead-free piezoelectric ceramics with a textured structure. A compact of crystallographically oriented grains was prepared by dry forming in a high magnetic field from a mixed slurry of bismuth titanate and barium titanate powders. Bismuth titanate particles with a size of about 1 μ m were used as the host material. In the forming process, the slurry was poured into a mold and set in a magnetic field of 10 T until completely dried. Bismuth titanate particles were highly oriented in the slurry under the magnetic field. The dried powder compact consisted of highly oriented bismuth titanate particles and randomly oriented barium titanate particles. Barium bismuth titanate ceramics with a- and b-axis orientations were successfully produced from the dried compact by sintering at temperatures above 1100 deg. C.

Printed Barium Strontium Titanate capacitors on silicon

Energy Technology Data Exchange (ETDEWEB)

Sette, Daniele [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Luxembourg Institute of Science and Technology LIST, Materials Research and Technology Department, L-4422 Belvaux (Luxembourg); Kovacova, Veronika [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Defay, Emmanuel, E-mail: emmanuel.defay@list.lu [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Luxembourg Institute of Science and Technology LIST, Materials Research and Technology Department, L-4422 Belvaux (Luxembourg)

2015-08-31

In this paper, we show that Barium Strontium Titanate (BST) films can be prepared by inkjet printing of sol–gel precursors on platinized silicon substrate. Moreover, a functional variable capacitor working in the GHz range has been made without any lithography or etching steps. Finally, this technology requires 40 times less precursors than the standard sol–gel spin-coating technique. - Highlights: • Inkjet printing of Barium Strontium Titanate films • Deposition on silicon substrate • Inkjet printed silver top electrode • First ever BST films thinner than 1 μm RF functional variable capacitor that has required no lithography.

Self-Reconstructed Formation of a One-Dimensional Hierarchical Porous Nanostructure Assembled by Ultrathin TiO2 Nanobelts for Fast and Stable Lithium Storage.

Science.gov (United States)

Liu, Yuan; Yan, Xiaodong; Xu, Bingqing; Lan, Jinle; Yu, Yunhua; Yang, Xiaoping; Lin, Yuanhua; Nan, Cewen

2018-06-06

Owing to their unique structural advantages, TiO 2 hierarchical nanostructures assembled by low-dimensional (LD) building blocks have been extensively used in the energy-storage/-conversion field. However, it is still a big challenge to produce such advanced structures by current synthetic techniques because of the harsh conditions needed to generate primary LD subunits. Herein, a novel one-dimensional (1D) TiO 2 hierarchical porous fibrous nanostructure constructed by TiO 2 nanobelts is synthesized by combining a room-temperature aqueous solution growth mechanism with the electrospinning technology. The nanobelt-constructed 1D hierarchical nanoarchitecture is evolves directly from the amorphous TiO 2 /SiO 2 composite fibers in alkaline solutions at ambient conditions without any catalyst and other reactant. Benefiting from the unique structural features such as 1D nanoscale building blocks, large surface area, and numerous interconnected pores, as well as mixed phase anatase-TiO 2 (B), the optimum 1D TiO 2 hierarchical porous nanostructure shows a remarkable high-rate performance when tested as an anode material for lithium-ion batteries (107 mA h g -1 at ∼10 A g -1 ) and can be used in a hybrid lithium-ion supercapacitor with very stable lithium-storage performance (a capacity retention of ∼80% after 3000 cycles at 2 A g -1 ). The current work presents a scalable and cost-effective method for the synthesis of advanced TiO 2 hierarchical materials for high-power and stable energy-storage/-conversion devices.

Titan: a distant but enticing destination for human visitors.

Science.gov (United States)

Nott, Julian

2009-10-01

Until recently, very little was known about Saturn's largest satellite, Titan. But that has changed dramatically since the Cassini spacecraft started orbiting in the Saturn system in 2004. Larger than Mercury and with a dense atmosphere, Titan has many of the characteristics of a planet. Indeed, many scientists now see it as the most interesting place in the Solar System for robotic exploration, with many unique features and even the possibility of exotic forms of life. This paper points out that Titan is also a potential destination for humans. With its predominantly nitrogen atmosphere, moderate gravity, and available water and oxygen, it also appears that, once it becomes possible to travel there, it will prove to be much more hospitable for human visitors than any other destination in the Solar System.

Barium titanate thick films prepared by screen printing technique

Directory of Open Access Journals (Sweden)

Mirjana M. Vijatović

2010-06-01

Full Text Available The barium titanate (BaTiO3 thick films were prepared by screen printing technique using powders obtained by soft chemical route, modified Pechini process. Three different barium titanate powders were prepared: i pure, ii doped with lanthanum and iii doped with antimony. Pastes for screen printing were prepared using previously obtained powders. The thick films were deposited onto Al2O3 substrates and fired at 850°C together with electrode material (silver/palladium in the moving belt furnace in the air atmosphere. Measurements of thickness and roughness of barium titanate thick films were performed. The electrical properties of thick films such as dielectric constant, dielectric losses, Curie temperature, hysteresis loop were reported. The influence of different factors on electrical properties values was analyzed.

Implications of Wind-Assisted Aerial Navigation for Titan Mission Planning and Science Exploration

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Elfes, A.; Reh, K.; Beauchamp, P.; Fathpour, N.; Blackmore, L.; Newman, C.; Kuwata, Y.; Wolf, M.; Assad, C.

2010-01-01

The recent Titan Saturn System Mission (TSSM) proposal incorporates a montgolfiere (hot air balloon) as part of its architecture. Standard montgolfiere balloons generate lift through heating of the atmospheric gases inside the envelope, and use a vent valve for altitude control. A Titan aerobot (robotic aerial vehicle) would have to use radioisotope thermoelectric generators (RTGs) for electric power, and the excess heat generated can be used to provide thermal lift for a montgolfiere. A hybrid montgolfiere design could have propellers mounted on the gondola to generate horizontal thrust; in spite of the unfavorable aerodynamic drag caused by the shape of the balloon, a limited amount of lateral controllability could be achieved. In planning an aerial mission at Titan, it is extremely important to assess how the moon-wide wind field can be used to extend the navigation capabilities of an aerobot and thereby enhance the scientific return of the mission. In this paper we explore what guidance, navigation and control capabilities can be achieved by a vehicle that uses the Titan wind field. The control planning approach is based on passive wind field riding. The aerobot would use vertical control to select wind layers that would lead it towards a predefined science target, adding horizontal propulsion if available. The work presented in this paper is based on aerodynamic models that characterize balloon performance at Titan, and on TitanWRF (Weather Research and Forecasting), a model that incorporates heat convection, circulation, radiation, Titan haze properties, Saturn's tidal forcing, and other planetary phenomena. Our results show that a simple unpropelled montgolfiere without horizontal actuation will be able to reach a broad array of science targets within the constraints of the wind field. The study also indicates that even a small amount of horizontal thrust allows the balloon to reach any area of interest on Titan, and to do so in a fraction of the time needed

NIAC Phase 1 Final Study Report on Titan Aerial Daughtercraft

Science.gov (United States)

Matthies, Larry

2017-01-01

Saturns giant moon Titan has become one of the most fascinating bodies in the Solar System. Even though it is a billion miles from Earth, data from the Cassini mission reveals that Titan has a very diverse, Earth-like surface, with mountains, fluvial channels, lakes, evaporite basins, plains, dunes, and seas [Lopes 2010] (Figure 1). But unlike Earth, Titans surface likely is composed of organic chemistry products derived from complex atmospheric photochemistry [Lorenz 2008]. In addition, Titan has an active meteorological system with observed storms and precipitation-induced surface darkening suggesting a hydrocarbon cycle analogous to Earths water cycle [Turtle 2011].Titan is the richest laboratory in the solar system for studying prebiotic chemistry, which makes studying its chemistry from the surface and in the atmosphere one of the most important objectives in planetary science [Decadal 2011]. The diversity of surface features on Titan related to organic solids and liquids makes long-range mobility with surface access important [Decadal 2011]. This has not been possible to date, because mission concepts have had either no mobility (landers), no surface access (balloons and airplanes), or low maturity, high risk, and/or high development costs for this environment (e,g. large, self-sufficient, long-duration helicopters). Enabling in situ mobility could revolutionize Titan exploration, similarly to the way rovers revolutionized Mars exploration. Recent progress on several fronts has suggested that small-scale rotorcraft deployed as daughtercraft from a lander or balloon mothercraft may be an effective, affordable approach to expanding Titan surface access. This includes rapid progress on autonomous navigation capabilities of such aircraft for terrestrial applications and on miniaturization, driven by the consumer mobile electronics market, of high performance of sensors, processors, and other avionics components needed for such aircraft. Chemical analysis, for

Experimental studies on 3D printing of barium titanate ceramics for medical applications

Directory of Open Access Journals (Sweden)

Schult Mark

2016-09-01

Full Text Available The present work deals with the 3D printing of porous barium titanate ceramics. Barium titanate is a biocompatible material with piezoelectric properties. Due to insufficient flowability of the starting material for 3D printing, the barium titanate raw material has been modified in three different ways. Firstly, barium titanate powder has been calcined. Secondly, flow additives have been added to the powder. And thirdly, flow additives have been added to the calcined powder. Finally, a polymer has been added to the three materials and specimens have been printed from these three material mixtures. The 3D printed parts were then sintered at 1320°C. The sintering leads to shrinkage which differs between 29.51–71.53% for the tested material mixtures. The porosity of the parts is beneficial for cell growth which is relevant for future medical applications. The results reported in this study demonstrate the possibility to fabricate porous piezoelectric barium titanate parts with a 3D printer that can be used for medical applications. 3D printed porous barium titanate ceramics can especially be used as scaffold for bone tissue engineering, where the bone formation can be promoted by electrical stimulation.

The Michigan Titan Thermospheric General Circulation Model (TTGCM)

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Bell, J. M.; Bougher, S. W.; de Lahaye, V.; Waite, J. H.

2005-12-01

The Cassini flybys of Titan since late October, 2004 have provided data critical to better understanding its chemical and thermal structures. With this in mind, a 3-D TGCM of Titan's atmosphere from 600km to the exobase (~1450km) has been developed. This paper presents the first results from the partially operational code. Currently, the TTGCM includes static background chemistry (Lebonnois et al 2001, Vervack et al 2004) coupled with thermal conduction routines. The thermosphere remains dominated by solar EUV forcing and HCN rotational cooling, which is calculated by a full line-by-line radiative transfer routine along the lines of Yelle (1991) and Mueller-Wodarg (2000, 2002). In addition, an approximate treatment of magnetospheric heating is explored. This paper illustrates the model's capabilities as well as some initial results from the Titan Thermospheric General Circulation model that will be compared with both the Cassini INMS data and the model of Mueller-Wodarg (2000,2002).

Ferroelectric mesocrystals of bismuth sodium titanate: formation mechanism, nanostructure, and application to piezoelectric materials.

Science.gov (United States)

Hu, Dengwei; Kong, Xingang; Mori, Kotaro; Tanaka, Yasuhiro; Shinagawa, Kazunari; Feng, Qi

2013-09-16

Ferroelectric mesocrystals of Bi0.5Na0.5TiO3 (BNT) with [100]-crystal-axis orientation were successfully prepared using a topotactic structural transformation process from a layered titanate H1.07Ti1.73O4·nH2O (HTO). The formation reactions of BNT mesocrystals in HTO-Bi2O3-Na2CO3 and HTO-TiO2-Bi2O3-Na2CO3 reaction systems and their nanostructures were studied by XRD, FE-SEM, TEM, SAED, and EDS, and the reaction mechanisms were given. The BNT mesocrystals are formed by a topotactic structural transformation mechanism in the HTO-Bi2O3-Na2CO3 reaction system and by a combination mechanism of the topotactic structural transformation and epitaxial crystal growth in the HTO-TiO2-Bi2O3-Na2CO3 reaction system, respectively. The BNT mesocrystals prepared by these methods are constructed from [100]-oriented BNT nanocrystals. Furthermore, these reaction systems were successfully applied to the fabrication of [100]-oriented BNT ferroelectric ceramic materials. A BNT ceramic material with a high degree of orientation, high relative density, and small grain size was achieved.

A post-Cassini view of Titan's methane-based hydrologic cycle

Science.gov (United States)

Hayes, Alexander G.; Lorenz, Ralph D.; Lunine, Jonathan I.

2018-05-01

The methane-based hydrologic cycle on Saturn's largest moon, Titan, is an extreme analogue to Earth's water cycle. Titan is the only planetary body in the Solar System, other than Earth, that is known to have an active hydrologic cycle. With a surface pressure of 1.5 bar and temperatures of 90 to 95 K, methane and ethane condense out of a nitrogen-based atmosphere and flow as liquids on the moon's surface. Exchange processes between atmospheric, surface and subsurface reservoirs produce methane and ethane cloud systems, as well as erosional and depositional landscapes that have strikingly similar forms to their terrestrial counterparts. Over its 13-year exploration of the Saturn system, the Cassini-Huygens mission revealed that Titan's hydrocarbon-based hydrology is driven by nested methane cycles that operate over a range of timescales, including geologic, orbital (for example, Croll-Milankovitch cycles), seasonal and that of a single convective storm. In this Review Article, we describe the dominant exchange processes that operate over these timescales and present a post-Cassini view of Titan's methane-based hydrologic system.

Co-crystal formation between two organic solids on the surface of Titan

Science.gov (United States)

Cable, M. L.; Vu, T. H.; Maynard-Casely, H. E.; Hodyss, R. P.

2017-12-01

Laboratory experiments of Titan molecular materials, informed by modeling, can help us to understand the complex and dynamic surface processes occurring on this moon at cryogenic temperatures. We previously demonstrated that two common organic materials on Titan, ethane and benzene, form a unique and stable co-crystalline structure at Titan surface temperatures. We have now characterized a second co-crystal that is stable on Titan, this time between two solids: acetylene and ammonia. The co-crystal forms within minutes at Titan surface temperature, as evidenced by new Raman spectral features in the lattice vibration and C-H bending regions. In addition, a red shift of the C-H stretching mode suggests that the acetylene-ammonia co-crystal is stabilized by a network of C-H···N interactions. Thermal stability studies indicate that this co-crystal remains intact to >110 K, and experiments with liquid methane and ethane reveal the co-crystal to be resistant to fluvial or pluvial exposure. Non-covalently bound structures such as these co-crystals point to far more complex surface interactions than previously believed on Titan. New physical and mechanical properties (deformation, plasticity, density, etc.), differences in storage of key species (i.e., ethane versus methane), variations in surface transport and new chemical gradients can all result in diverse surface features and chemistries of astrobiological interest.

Titan's fluvial valleys: Morphology, distribution, and spectral properties

Science.gov (United States)

Langhans, M.H.; Jaumann, R.; Stephan, K.; Brown, R.H.; Buratti, B.J.; Clark, R.N.; Baines, K.H.; Nicholson, P.D.; Lorenz, R.D.; Soderblom, L.A.; Soderblom, J.M.; Sotin, Christophe; Barnes, J.W.; Nelson, R.

2012-01-01

Titan's fluvial channels have been investigated based on data obtained by the Synthetic Aperture Radar (SAR) instrument and the Visible and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft. In this paper, a database of fluvial features is created based on radar-SAR data aiming to unveil the distribution and the morphologic and spectral characteristics of valleys on Titan on a global scale. It will also study the spatial relations between fluvial valleys and Titan's geologic units and spectral surface units which have become accessible thanks to Cassini-VIMS data. Several distinct morphologic types of fluvial valleys can be discerned by SAR-images. Dendritic valley networks appear to have much in common with terrestrial dendritic systems owing to a hierarchical and tree-shaped arrangement of the tributaries which is indicative of an origin from precipitation. Dry valleys constitute another class of valleys resembling terrestrial wadis, an indication of episodic and strong flow events. Other valley types, such as putative canyons, cannot be correlated with rainfall based on their morphology alone, since it cannot be ruled out that they may have originated from volcanic/tectonic action or groundwater sapping. Highly developed and complex fluvial networks with channel lengths of up to 1200 km and widths of up to 10 km are concentrated only at a few locations whereas single valleys are scattered over all latitudes. Fluvial valleys are frequently found in mountainous areas. Some terrains, such as equatorial dune fields and undifferentiated plains at mid-latitudes, are almost entirely free of valleys. Spectrally, fluvial terrains are often characterized by a high reflectance in each of Titan's atmospheric windows, as most of them are located on Titan's bright 'continents'. Nevertheless, valleys are spatially associated with a surface unit appearing blue due to its higher reflection at 1.3??m in a VIMS false color RGB composite with R: 1.59/1.27??m, G: 2

The thermal structure of Titan's atmosphere

Science.gov (United States)

Mckay, Christopher P.; Pollack, James B.; Courtin, Regis

1989-01-01

The present radiative-convective model of the Titan atmosphere thermal structure obtains the solar and IR radiation in a series of spectral intervals with vertical resolution. Haze properties have been determined with a microphysics model encompassing a minimum of free parameters. It is determined that gas and haze opacity alone, using temperatures established by Voyager observations, yields a model that is within a few percent of the radiative convective balance throughout the Titan atmosphere. Model calculations of the surface temperature are generally colder than the observed value by 5-10 K; better agreement is obtained through adjustment of the model parameters. Sunlight absorption by stratospheric haze and pressure-induced gas opacity in the IR are the most important thermal structure-controlling factors.

The dynamics in the upper atmospheres of Mars and Titan

Science.gov (United States)

Bell, Jared M.

2008-06-01

This thesis explores the dynamics of two terrestrial bodies: Mars and Titan. At Mars, the coupled Mars General Circulation Model - Mars Thermospheric General Circulation Model (MGCM-MTGCM) is employed to investigate the phenomenon known as Mars winter polar warming. At Titan, a new theoretical model, the Titan Global Ionosphere - Thermosphere Model (T-GITM), is developed, based upon previous work by Ridley et al. [2006]. Using this new model, three separate numerical studies quantify the impacts of solar cycle, seasons, and lower boundary zonal winds on the Titan thermosphere structure and dynamics. At Mars, this thesis investigates thermospheric winter polar warming through three major studies: (1) a systematic analysis of vertical dust mixing in the lower atmosphere and its impact upon the dynamics of the lower thermosphere (100-130 km), (2) an interannual investigation utilizing three years of lower atmosphere infrared (IR) dust optical depth data acquired by the Thermal Emission Spectrometer (TES) instrument on board Mars Global Surveyor (MGS), and finally (3) a brief study of the MTGCM's response to variations in upward propagating waves and tides from the lower atmosphere. Ultimately, this investigation suggests that an interhemispheric summer-to-winter Hadley circulation, originating in the lower atmosphere and extending into the upper atmosphere, is responsible for thermospheric winter polar warming [ Bell etal. , 2007]. A major branch of this thesis builds upon the previous work of Müller-Wodarg et al. [2000], Müller-Wodarg et al. [2003], M7uuml;ller-Wodarg et al. [2006], and Yelle et al. [2006] as it attempts to explain the structures in Titan's upper atmosphere, between 500-1500 km. Building also upon the recent development of GITM by Ridley et al. [2006], this thesis presents a new theoretical framework, T-GITM. This model is then employed to conduct a series of numerical experiments to quantify the impacts of the solar cycle, the season, and the

Crystallinity and electrical properties of neodymium-substituted bismuth titanate thin films

International Nuclear Information System (INIS)

Chen, Y.-C.; Hsiung, C.-P.; Chen, C.-Y.; Gan, J.-Y.; Sun, Y.-M.; Lin, C.-P.

2006-01-01

We report on the properties of Nd-substituted bismuth titanate Bi 4-x Nd x Ti 3 O 12 (BNdT) thin films for ferroelectric non-volatile memory applications. The Nd-substituted bismuth titanate thin films fabricated by modified chemical solution deposition technique showed much improved properties compared to pure bismuth titanate. A pyrochlore free crystalline phase was obtained at a low annealing temperature of 640 deg. C and grain size was found to be considerably increased as the annealing temperature increased. The film properties were found to be strongly dependent on the Nd content and annealing temperatures. The measured dielectric constant of BNdT thin films was in the range 172-130 for Bi 4-x Nd x Ti 3 O 12 with x 0.0-0.75. Ferroelectric properties of Nd-substituted bismuth titanate thin films were significantly improved compared to pure bismuth titanate. For example, the observed 2P r and E c for Bi 3.25 Nd 0.75 Ti 3 O 12 , annealed at 680 deg. C, were 38 μC/cm 2 and 98 kV/cm, respectively. The improved microstructural and ferroelectric properties of BNdT thin films suggest their suitability for high density ferroelectric random access memory applications

Spectroscopic detection and mapping of vinyl cyanide on Titan

Science.gov (United States)

Cordiner, Martin; Yukiko Palmer, Maureen; Lai, James; Nixon, Conor A.; Teanby, Nicholas; Charnley, Steven B.; Vuitton, Veronique; Kisiel, Zbigniew; Irwin, Patrick; Molter, Ned; Mumma, Michael J.

2017-10-01

The first spectroscopic detection of vinyl cyanide (otherwise known as acrylonitrile; C2H3CN) on Titan was obtained by Palmer et al. (2017), based on three rotational emission lines observed with ALMA at millimeter wavelengths (in receiver band 6). The astrobiological significance of this detection was highlighted due to the theorized ability of C2H3CN molecules to combine into cell membrane-like structures under the cold conditions found in Titan's hydrocarbon lakes. Here we report the detection of three additional C2H3CN transitions at higher frequencies (from ALMA band 7 flux calibration data). We present the first emission maps for this gas on Titan, and compare the molecular distribution with that of other nitriles observed with ALMA including HC3N, CH3CN, C2H5CN and HNC. The molecular abundance patterns are interpreted based on our understanding of Titan's high-altitude photochemistry and time-variable global circulation. Similar to the short-lived HC3N molecule, vinyl cyanide is found to be most abundant in the vicinity of the southern (winter) pole, whereas the longer-lived CH3CN is more concentrated in the north. The vertical abundance profile of C2H3CN (from radiative transfer modeling), as well as its latitudinal distribution, are consistent with a short photochemical lifetime for this species. Complementary results from our more recent (2017) nitrile mapping studies at higher spatial resolution will also be discussed.REFERENCES:Palmer, M. Y., Cordiner, M. A., Nixon, C. A. et al. "ALMA detection and astrobiological potential of vinyl cyanide on Titan", Sci. Adv. 2017, 3, e1700022

Big Impacts and Transient Oceans on Titan

Science.gov (United States)

Zahnle, K. J.; Korycansky, D. G.; Nixon, C. A.

2014-01-01

We have studied the thermal consequences of very big impacts on Titan [1]. Titan's thick atmosphere and volatile-rich surface cause it to respond to big impacts in a somewhat Earth-like manner. Here we construct a simple globally-averaged model that tracks the flow of energy through the environment in the weeks, years, and millenia after a big comet strikes Titan. The model Titan is endowed with 1.4 bars of N2 and 0.07 bars of CH4, methane lakes, a water ice crust, and enough methane underground to saturate the regolith to the surface. We assume that half of the impact energy is immediately available to the atmosphere and surface while the other half is buried at the site of the crater and is unavailable on time scales of interest. The atmosphere and surface are treated as isothermal. We make the simplifying assumptions that the crust is everywhere as methane saturated as it was at the Huygens landing site, that the concentration of methane in the regolith is the same as it is at the surface, and that the crust is made of water ice. Heat flow into and out of the crust is approximated by step-functions. If the impact is great enough, ice melts. The meltwater oceans cool to the atmosphere conductively through an ice lid while at the base melting their way into the interior, driven down in part through Rayleigh-Taylor instabilities between the dense water and the warm ice. Topography, CO2, and hydrocarbons other than methane are ignored. Methane and ethane clathrate hydrates are discussed quantitatively but not fully incorporated into the model.

Titanic või turist? / Karin Paulus

Index Scriptorium Estoniae

Paulus, Karin, 1975-

2006-01-01

Tallinnas Tartu maanteel asuva endise Turisti poe (arhitektid Peep Jänes, Henno Sepmann) asemele tahavad hoone omanikud ehitada kõrghoone nimega Titanic. Hoone ajutine võtmine muinsuskaitse alla on põhjustanud kohtuvaidluse

DETECTION OF PROPENE IN TITAN'S STRATOSPHERE

Energy Technology Data Exchange (ETDEWEB)

Nixon, C. A.; Flasar, F. M. [Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Jennings, D. E. [Detector Systems Branch, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bézard, B.; Vinatier, S.; Coustenis, A. [LESIA, Observatoire de Paris, CNRS, 5 Place Jules Janssen, F-92195 Meudon Cedex (France); Teanby, N. A. [School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen' s Road, Bristol BS8 1RJ (United Kingdom); Sung, K. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, CA 91109 (United States); Ansty, T. M. [Department of Space Science, Cornell University, Ithaca, NY 14853 (United States); Irwin, P. G. J. [Atmospheric, Oceanic and Planetary Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU (United Kingdom); Gorius, N. [IACS, Catholic University of America, Washington, DC 20064 (United States); Cottini, V. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)

2013-10-10

The Voyager 1 flyby of Titan in 1980 gave a first glimpse of the chemical complexity of Titan's atmosphere, detecting many new molecules with the infrared interferometer spectrometer (IRIS). These included propane (C{sub 3}H{sub 8}) and propyne (CH{sub 3}C{sub 2}H), while the intermediate-sized C{sub 3}H {sub x} hydrocarbon (C{sub 3}H{sub 6}) was curiously absent. Using spectra from the Composite Infrared Spectrometer on Cassini, we show the first positive detection of propene (C{sub 3}H{sub 6}) in Titan's stratosphere (5σ significance), finally filling the three-decade gap in the chemical sequence. We retrieve a vertical abundance profile from 100-250 km, that varies slowly with altitude from 2.0 ± 0.8 ppbv at 125 km, to 4.6 ± 1.5 ppbv at 200 km. The abundance of C{sub 3}H{sub 6} is less than both C{sub 3}H{sub 8} and CH{sub 3}C{sub 2}H, and we remark on an emerging paradigm in Titan's hydrocarbon abundances whereby alkanes > alkynes > alkenes within the C{sub 2}H {sub x} and C{sub 3}H {sub x} chemical families in the lower stratosphere. More generally, there appears to be much greater ubiquity and relative abundance of triple-bonded species than double-bonded, likely due to the greater resistance of triple bonds to photolysis and chemical attack.

Titan Ice and Dust Experiment (TIDE): Detection and Analysis of Compounds of Interest to Astrobiology in the Lower Atmosphere and Surface of Titan

Science.gov (United States)

Kojiro, Daniel R.; Holland Paul M.; Stimac, Robert M.; Kaye, William J.; Takeruchi, Noreshige

2004-01-01

The Titan Orbiter Aerorover Mission (TOAM) is a proposed concept for the Solar System Exploration Visions Mission, Titan Explorer, a follow-on to the Cassini-Huygens mission. TOAM would use a Titan polar orbiter and a lighter-than-air aerorover to investigate the surface and atmosphere of Titan. Astrobiology issues will be addressed though TOAM investigations including, for example: Distribution and composition of organics (atmospheric, aerosol, surface); Organic chemical processes, their chemical context and energy sources; and Seasonal variations and interactions of the atmosphere and surface. The TIDE instrument will perform in-situ analyses to obtain comprehensive and sensitive molecular and elemental assays of volatile organics in the atmosphere, oceans and surface. TIDE chemical analyses are conducted by a Gas Chromatograph-Ion Mobility Spectrometer (GC-IMS). This TIDE GC-IMS was a component of the mini-Cometary Ice and Dust Experiment (mini-CIDEX) developed for the chemical analysis of a cometary environment. Both the GC and helium IMS of mini-CIDEX have been further developed to better meet the analytical and operational requirements of the TOAM. application. A Micro-ElectroMechanical System (MEMS) GC and Mini-Cell helium IMS are under development to replace their respective mini-CIDEX components, providing similar or advanced analytical capabilities.

Aluminum titanate crucible for molten uranium

International Nuclear Information System (INIS)

Asbury, J.J.

1975-01-01

An improved crucible for molten uranium is described. The crucible or crucible liner is formed of aluminum titanate which essentially eliminates contamination of uranium and uranium alloys during molten states thereof. (U.S.)

Syntheses, Structures, and Magnetic Properties of Nickel-Doped Lepidocrocite Titanates

DEFF Research Database (Denmark)

Gao, Tao; Norby, Poul; Okamoto, Hiroshi

2009-01-01

Ni-doped titanate CsxTi2−x/2Nix/2O4 and its protonic derivative HxTi2−x/2Nix/2O4·xH2O (x = 0.7) were synthesized and characterized by means of synchrotron X-ray diffraction, Raman scattering, X-ray photoelectron spectroscopy (XPS), and magnetic measurements. CsxTi2−x/2Nix/2O4 crystallizes......H2O. Ni- and Mg-codoped titanates CsxTi2−x/2(NiyMg1−y)x/2O4 (x = 0.7, 0 ≤ y ≤ 1) were also reported. The crystal structure, interlayer chemistry, and magnetic properties of the titanates depend on the Ni substitution levels, indicating opportunities for tuning of the properties by controlling...

Synergism of Saturn, Enceladus and Titan and Formation of HCNO Prebiotic Molecules

Science.gov (United States)

Sittler, Edward C.; Cooper, John F.

2011-01-01

Saturn as a system has two very exotic moons Titan and Enceladus. Titan, taking in energy from Saturn's magnetosphere, solar UV irradiation, and cosmic rays, can make HCN based molecules as discussed in earlier paper by Raulin and Owen. Space radiation effects at both moons, and as coupled by the Saturn magnetosphere, could cause an unexpected series of events potentially leading to prebiotic chemical evolution at Titan with HCNO from magnetospheric oxygen as the new ingredient. The "Old Faithful" model suggests that Enceladus, highly irradiated by Saturn magnetospheric electrons and thus having a source of chemical energy from radiolytic gas production, has episodic ejections of water vapor, carbon dioxide, and various hydrocarbons into Saturn's magnetosphere. The hydrocarbons do not survive transport through the plasma environment, but oxygen ions from Enceladus water molecules become the dominant ion species in the outer magnetosphere. At Titan, Cassini discovered that 1) keV oxygen ions, evidently from Enceladus, are bombarding Titan's upper atmosphere and 2) heavy positive and negative ions exist in significant abundances within Titan's upper atmosphere. Initial models of heavy ion formation in Titan's upper atmosphere invoked polymerization of aromatics such as benzenes and their radicals to make polycyclic aromatic hydrocarbons (PAH) , while a more recent model by Sittler et al., has raised the possibility of carbon chains forming from the polymerization of acetylene and its radicals to make fullerenes. Laboratory measurements indicate that fullerenes, which are hollow carbon shells, can trap keV oxygen ions. Clustering of the fullerenes with aerosol mixtures from PAHs and the dominant nitrogen molecules could form larger aerosols enriched in trapped oxygen. Aerosol precipitation could then convey these chemically complex structures deeper into the atmosphere and to the moon surface. Ionizing solar UV, magnetospheric electron, and galactic cosmic ray

Integration of PanDA workload management system with Titan supercomputer at OLCF

Science.gov (United States)

De, K.; Klimentov, A.; Oleynik, D.; Panitkin, S.; Petrosyan, A.; Schovancova, J.; Vaniachine, A.; Wenaus, T.

2015-12-01

The PanDA (Production and Distributed Analysis) workload management system (WMS) was developed to meet the scale and complexity of LHC distributed computing for the ATLAS experiment. While PanDA currently distributes jobs to more than 100,000 cores at well over 100 Grid sites, the future LHC data taking runs will require more resources than Grid computing can possibly provide. To alleviate these challenges, ATLAS is engaged in an ambitious program to expand the current computing model to include additional resources such as the opportunistic use of supercomputers. We will describe a project aimed at integration of PanDA WMS with Titan supercomputer at Oak Ridge Leadership Computing Facility (OLCF). The current approach utilizes a modified PanDA pilot framework for job submission to Titan's batch queues and local data management, with light-weight MPI wrappers to run single threaded workloads in parallel on Titan's multicore worker nodes. It also gives PanDA new capability to collect, in real time, information about unused worker nodes on Titan, which allows precise definition of the size and duration of jobs submitted to Titan according to available free resources. This capability significantly reduces PanDA job wait time while improving Titan's utilization efficiency. This implementation was tested with a variety of Monte-Carlo workloads on Titan and is being tested on several other supercomputing platforms. Notice: This manuscript has been authored, by employees of Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The publisher by accepting the manuscript for publication acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.

A Model of Titan-like Chemistry to Connect Experiments and Cassini Observations

Science.gov (United States)

Raymond, Alexander W.; Sciamma-O’Brien, Ella; Salama, Farid; Mazur, Eric

2018-02-01

A numerical model is presented for interpreting the chemical pathways that lead to the experimental mass spectra acquired in the Titan Haze Simulation (THS) laboratory experiments and for comparing the electron density and temperature of the THS plasma to observations made at Titan by the Cassini spacecraft. The THS plasma is a pulsed glow-discharge experiment designed to simulate the reaction of N2/CH4-dominated gas in Titan's upper atmosphere. The transient, one-dimensional model of THS chemistry tracks the evolution of more than 120 species in the direction of the plasma flow. As the minor species C2H2 and C2H4 are added to the N2/CH4-based mixture, the model correctly predicts the emergence of reaction products with up to five carbon atoms in relative abundances that agree well with measured mass spectra. Chemical growth in Titan's upper atmosphere transpires through ion–neutral and neutral–neutral chemistry, and the main reactions involving a series of known atmospheric species are retrieved from the calculation. The model indicates that the electron density and chemistry are steady during more than 99% of the 300 μs long discharge pulse. The model also suggests that the THS ionization fraction and electron temperature are comparable to those measured in Titan's upper atmosphere. These findings reaffirm that the THS plasma is a controlled analog environment for studying the first and intermediate steps of chemistry in Titan's upper atmosphere.

The MR-TOF-MS isobar separator for the TITAN facility at TRIUMF

Science.gov (United States)

Jesch, Christian; Dickel, Timo; Plaß, Wolfgang R.; Short, Devin; Ayet San Andres, Samuel; Dilling, Jens; Geissel, Hans; Greiner, Florian; Lang, Johannes; Leach, Kyle G.; Lippert, Wayne; Scheidenberger, Christoph; Yavor, Mikhail I.

2015-11-01

At TRIUMF's Ion Trap for Atomic and Nuclear Science (TITAN) a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) will extend TITAN's capabilities and facilitate mass measurements and in-trap decay spectroscopy of exotic nuclei that so far have not been possible due to strong isobaric contamination. This MR-TOF-MS will also enable mass measurements of very short-lived nuclides (half-life > 1 ms) that are produced in very low quantities (a few detected ions overall). In order to allow the installation of an MR-TOF-MS in the restricted space on the platform, on which the TITAN facility is located, novel mass spectrometric methods have been developed. Transport, cooling and distribution of the ions inside the device is done using a buffer gas-filled RFQ-based ion beam switchyard. Mass selection is achieved using a dynamic retrapping technique after time-of-flight analysis in an electrostatic isochronous reflector system. Only due to the combination of these novel methods the realization of an MR-TOF-MS based isobar separator at TITAN has become possible. The device has been built, commissioned off-line and is currently under installation at TITAN.

Iron-catalyzed oxidative biaryl cross-couplings via mixed diaryl titanates: significant influence of the order of combining aryl Grignard reagents with titanate.

Science.gov (United States)

Liu, Kun Ming; Wei, Juan; Duan, Xin Fang

2015-03-18

The mixed diaryl titanates were used for the first time to modify the reactivity of two aryl Grignard reagents. Two titanate intermediates, Ar[Ar'Ti(OR)3]MgX and Ar'[ArTi(OR)3]MgX, formed via alternating the sequence of combining Grignard reagents with ClTi(OR)3 showed a significant reactivity difference. Taking advantage of such different reactivity, two highly structurally similar aryl groups could be facilely assembled through iron-catalyzed oxidative cross-couplings using oxygen as the oxidant.

Ultrafast carrier dynamics of titanic acid nanotubes investigated by transient absorption spectroscopy.

Science.gov (United States)

Wang, Li; Zhao, Hui; Pan, Lin Yun; Weng, Yu Xiang; Nakato, Yoshihiro; Tamai, Naoto

2010-12-01

Carrier dynamics of titanic acid nanotubes (phase of H2Ti2O5.H2O) deposited on a quartz plate was examined by visible/near-IR transient absorption spectroscopy with an ultraviolet excitation. The carrier dynamics of titanic acid nanotubes follows the fast trapping process which attributed to the intrinsic tubular structure, the relaxation of shallow trapped carriers and the recombination as a second-order kinetic process. Transient absorption of titanic acid nanotubes was dominated by the absorption of surface-trapped holes in visible region around 500 nm, which was proved by the faster decay dynamics in the presence of polyvinyl alcohol as a hole-scavenger. However, the slow relaxation of free carriers was much more pronounced in the TiO2 single crystals, as compared with the transient absorption spectra of titanic acid nanotubes under the similar excitation.

Heat capacity measurements on dysprosium titanate

International Nuclear Information System (INIS)

Kandan, R.; Prabhakara Reddy, B.; Panneerselvam, G.; Nagarajan, K.

2014-01-01

Dysprosium titanate is considered as a candidate material for use in the control rods of future nuclear reactors. The Dy 2 TiO 5 compound was prepared by solid-state synthesis and characterized by XRD technique. The high temperature enthalpy increments of dysprosium titanates have been measured for the first time by employing the method of inverse drop calorimetry in the temperature range 748-1645 K by using high temperature drop calorimeter. The calorimeter, the method of measurement and the procedure adopted for enthalpy increment measurements and analysis of the measured data to compute thermodynamic functions have been described elsewhere. The measured enthalpy increments were fitted to polynomial in temperature by using the least squares method. The fit equation in the temperature range from 298 to 1800 K is given

Strontium titanate thin film deposition - structural and electronical characterization

Energy Technology Data Exchange (ETDEWEB)

Hanzig, Florian; Hanzig, Juliane; Stoecker, Hartmut; Mehner, Erik; Abendroth, Barbara; Meyer, Dirk C. [TU Bergakademie Freiberg, Institut fuer Experimentelle Physik (Germany); Franke, Michael [TU Bergakademie Freiberg, Institut fuer Elektronik- und Sensormaterialien (Germany)

2012-07-01

Strontium titanate is on the one hand a widely-used model oxide for solids which crystallize in perovskite type of structure. On the other hand, with its large band-gap energy and its mixed ionic and electronic conductivity, SrTiO{sub 3} is a promising isolating material in metal-insulator-metal (MIM) structures for resistive switching memory cells. Here, we used physical vapour deposition methods (e. g. electron-beam and sputtering) to produce strontium titanate layers. Sample thicknesses were probed with X-ray reflectometry (XRR) and spectroscopic ellipsometry (SE). Additionally, layer densities and dielectric functions were quantified with XRR and SE, respectively. Using infrared spectroscopy free electron concentrations were obtained. Phase and element composition analysis was carried out with grazing incidence X-ray diffraction and X-ray photoelectron spectroscopy. Subsequent temperature treatment of samples lead to crystallization of the initially amorphous strontium titanate.

Numerical study on lithium titanate battery thermal response under adiabatic condition

International Nuclear Information System (INIS)

Sun, Qiujuan; Wang, Qingsong; Zhao, Xuejuan; Sun, Jinhua; Lin, Zijing

2015-01-01

Highlights: • The thermal behavior of lithium titanate battery during cycling was investigated. • The temperature rate in charging was less than that of discharging in the cycling. • The temperature difference was less than 0.02 °C at 0.5 C in adiabatic condition. • The temperature distribution and thermal runaway of the battery were predicted. - Abstract: To analyze the thermal behavior of 945 mA h lithium titanate battery during charging and discharging processes, the experimental and numerical studies are performed in this work. The cathode and anode of the 945 mA h lithium titanate soft package battery are the lithium nickel–cobalt–manganese-oxide and lithium titanate, respectively. In the experiment, an Accelerating Rate Calorimeter combined with battery cycler is employed to investigate the electrochemical–thermal behavior during charge–discharge cycling under the adiabatic condition. In numerical simulation, one electrochemical-thermal model is adopted to predict the thermal response and validated with the experimental results. From both experimental and simulated results, the profile of potential and current, the heat generation, the temperature, the temperature changing rate and the temperature distribution in the cell are obtained and thermal runaway is predicted. The analysis of the electrochemical and thermal behavior is beneficial for the commercial application of lithium titanate battery in the fields of electric vehicles and hybrid electric vehicles

Behaviour of solid phase ethyl cyanide in simulated conditions of Titan

Science.gov (United States)

Couturier-Tamburelli, I.; Toumi, A.; Piétri, N.; Chiavassa, T.

2018-01-01

In order to simulate different altitudes in the atmosphere of Titan, we investigated using infrared spectrometry and mass spectrometry the photochemistry of ethyl cyanide (CH3CH2CN) ices at different temperatures. Heating experiments of the solid phase until complete desorption showed up three phase transitions with a first one appearing to be approximately at the temperature of Titan's surface (94 K), measured by the Huygens probe. Ethyl cyanide, whose presence has been suggested in solid phase in Titan, can be considered as another nitrile for photochemical models of the Titan atmosphere after our first study (Toumi et al., 2016) concerning vinyl cyanide (CH2CHCN). The desorption energy of ethyl cyanide has been calculated to be 36.75 ( ± 0.55) kJ mol-1 using IRTF and mass spectroscopical techniques. High energetic photolysis (λ > 120 nm) have been performed and we identified ethyl isocyanide, vinyl cyanide, cyanoacetylene, ethylene, acetylene, cyanhydric acid and a methylketenimine form as photoproducts from ethyl cyanide. The branching ratios of the primary products were determined at characteristic temperatures of Titan thanks to the value of the νCN stretching band strength of ethyl cyanide that has been calculated to be 4.12 × 10-18 cm molecule-1. We also report here for the first time the values of the photodissociation cross sections of C2H5CN for different temperatures.

Partially collisional model of the Titan hydrogen torus

International Nuclear Information System (INIS)

Hilton, D.A.

1987-01-01

A numerical model was developed for atomic hydrogen densities in the Titan hydrogen torus. The effects of occasional collisions were included in order to accurately simulate physical conditions inferred from the Voyager 1 and 2 Ultraviolet Spectrometer (UVS) results of Broadfoot et al. (1981) and Sandel et al. (1982). The model employed Lagrangian perturbation of orbital elements of hydrogen atoms launched from Titan and Monte Carlo simulation of collisions and loss mechanisms. The torus is found to be azimuthally symmetric with the density sharply peaked at Titan's orbit, and decreasing rapidly in the outward and perpendicular directions and more gradually inward from 17 to 5 R/sub s/. The energetic hydrogen atoms from Saturn's upper atmosphere, first predicted by Shemansky and Smith (1982), were also investigated. Collisions of these Saturnian atoms with the torus population do not contribute to the torus density, and will lead to a net loss of torus atoms if their launch speeds from Saturn extend above 40 km/sec. The Saturnian atoms produce a corona which was modeled using the theory of Chamberlain (1963)

Titan Exploration Using a Radioisotopically-Heated Montgolfiere Balloon

Science.gov (United States)

Elliott, John O.; Reh, Kim; Spilker, Tom

2007-01-01

This paper describes results of a recent Titan exploration mission study; one which includes an aerial vehicle in the form of a hot air balloon, or montgolfiere. Unlike terrestrial montgolfieres which require burning fuel, the dual use of MMRTGs to provide a continuous source of heat as well as electrical power would give the balloon an inherent ability to float for a very long time in the atmosphere of Titan. It would ride with the easterly winds at a cruising altitude of about 10,000 km, occasionally changing altitude to take advantage of possible reverse wind directions and even descending to the surface to physically sample sites of interest. Seasonal and tidal north-south winds would allow the mission to explore different latitudes, which Cassini data have shown to be amazingly diverse in geologic nature. Communication from the aerial vehicle would be relayed through an accompanying orbiter spacecraft, as well as transmitted directly to Earth, providing the potential for data return from Titan's surface equivalent to that provided by many comparable orbiter missions at much closer destinations.

Cassini-Huygens makes first close approach to Titan

Science.gov (United States)

2004-10-01

Purple zaze hi-res Size hi-res: 88 kb Credits: NASA/JPL/Space Science Institute Purple haze around Titan This NASA/ESA/ASI Cassini-Huygens image of Titan was taken with the narrow-angle camera on 3 July 2004, from a distance of about 789 000 kilometres from Titan. The image scale is 4.7 kilometres per pixel. This image shows two thin haze layers. The outer haze layer is detached and appears to float high in the atmosphere. Because of its thinness, the high haze layer is best seen at the moon's limb. The image was taken using a spectral filter sensitive to wavelengths of ultraviolet light centred at 338 nanometres. The image has been falsely coloured, the globe of Titan retains the pale orange hue our eyes would usually see, but both the main atmospheric haze and the thin detached layer have been brightened and given a purple colour to enhance their visibility. At the time of the closest approach, which is scheduled for 18:44 CEST, the spacecraft will be travelling only 1200 kilometres above the surface of the moon, almost grazing the outer atmosphere, at a speed of six kilometres per second (21 800 kilometres per hour)! Confirmation that the fly-by was successful and that all the data were received will not take place until 03:30 CEST on 27 October. This fly-by not only allows important surface science to be performed, such as radar analysis at close quarters, but also it significantly changes the orbit of the spacecraft around Saturn. Currently Cassini-Huygens has an orbital period of four months, which will change to 48 days, thus setting the course for the next close Titan fly-by on 13 December 2004 and the Huygens probe release on 25 December. Several of the observations performed during this fly-by will provide important information for ESA’s Huygens team, who will be using the data gathered to double-check atmospheric models for entry and descent on 14 January 2005. The Huygens probe will need to perform reliably in some of the most challenging and remote

Topography on Titan : New Results on Large and Small Scales

Science.gov (United States)

Lorenz, R. D.; Cassini Radar Team

2011-12-01

Although topographic coverage of Titan is and will remain sparse, some significant results have been obtained from global, regional and local measurements, via stereo, radarclinometry (shape-from-shading), autostereo (deviation from an assumed symmetric shape due to the inclined incidence), altimetry and SARtopo (monopulse) techniques. The global ellipsoidal shape (Zebker et al., 2009) provides important geophysical constraints on the interior. Hypsometry (Lorenz et al., 2011) provides insight into the balance of constructional and erosive processes and the strength of the lithosphere. Some local observations to be summarized in the talk include the measurement of mountains, the quantification of slopes that divert dunes and that drive fluid flow in river networks, as well as depth measurement of several impact craters and the assessment of candidate cryovolcanic structures. A recent new observation is a long altimetry pass T77 along the equator at the western edge of Xanadu, acquired both to constrain Titan's global shape and to understand the surface slopes and properties that may maintain the striking contrast between the dune fields of Shangri-La and the rugged and radiometrically anomalous Xanadu region. T77 also featured a SAR observation of the Ksa impact structure (discovered in SAR on T17), allowing a stereo DEM to be constructed. A feature shared by Earth and Titan is the ephemeral topography of liquids on the surface. Titan's lakes and seas likely vary in depth on geological (Myr-Gyr) and astronomical (~10 kyr) timescales : the depth of Ontario Lacus has been observed to vary on a seasonal timescale (~1 m/yr). Periodic changes of the order of 0.2-5m may occur diurnally, forced by Saturn gravitational tides. Finally, waves may be generated, at least during the windy season (which for Titan's north may be just about to begin) which can be constrained by radar and optical scattering measurements. Looking to the future, a Phase A study of the Titan Mare

Dragonfly: In Situ Exploration of Titan's Organic Chemistry and Habitability

Science.gov (United States)

Turtle, E. P.; Barnes, J. W.; Trainer, M. G.; Lorenz, R. D.

2017-12-01

Titan's abundant complex carbon-rich chemistry, interior ocean, and past presence of liquid water on the surface make it an ideal destination to study prebiotic chemical processes and document the habitability of an extraterrestrial environment. Titan exploration is a high science priority due to the level of organic synthesis that it supports. Moreover, opportunities for organics to have interacted with liquid water at the surface (e.g., in impact melt sheets) increase the potential for chemical processes to progress further, providing an unparalleled opportunity to investigate prebiotic chemistry, as well as to search for signatures of potential water-based or even hydrocarbon-based life. The diversity of Titan's surface materials and environments drives the scientific need to be able to sample a variety of locations, thus mobility is key for in situ measurements. Titan's atmosphere is 4 times denser than Earth's reducing the wing/rotor area required to generate a given amount of lift, and the low gravity reduces the required magnitude of lift, making heavier-than-air mobility highly efficient. Dragonfly is a rotorcraft lander mission proposed to NASA's New Frontiers Program to take advantage of Titan's unique natural laboratory to understand how far chemistry can progress in environments that provide key ingredients for life. Measuring the compositions of materials in different environments will reveal how far organic chemistry has progressed. Surface material can be sampled into a mass spectrometer to identify the chemical components available and processes at work to produce biologically relevant compounds. Bulk elemental surface composition can be determined by a neutron-activated gamma-ray spectrometer. Meteorology measurements can characterize Titan's atmosphere and diurnal and spatial variations therein. Geologic features can be characterized via remote-sensing observations, which also provide context for samples. Seismic sensing can probe subsurface

3D hybrid simulation of the Titan's plasma environment

Science.gov (United States)

Lipatov, Alexander; Sittler, Edward, Jr.; Hartle, Richard

2007-11-01

Titan plays an important role as a simulation laboratory for multiscale kinetic plasma processes which are key processes in space and laboratory plasmas. A development of multiscale combined numerical methods allows us to use more realistic plasma models at Titan. In this report, we describe a Particle-Ion--Fluid-Ion--Fluid--Electron method of kinetic ion-neutral simulation code. This method takes into account charge-exchange and photoionization processes. The model of atmosphere of Titan was based on a paper by Sittler, Hartle, Vinas et al., [2005]. The background ions H^+, O^+ and pickup ions H2^+, CH4^+ and N2^+ are described in a kinetic approximation, where the electrons are approximated as a fluid. In this report we study the coupling between background ions and pickup ions on the multiple space scales determined by the ion gyroradiis. The first results of such a simulation of the dynamics of ions near Titan are discussed in this report and compared with recent measurements made by the Cassini Plasma Spectrometer (CAPS, [Hartle, Sittler et al., 2006]). E C Sittler Jr., R E Hartle, A F Vinas, R E Johnson, H T Smith and I Mueller-Wodarg, J. Geophys. Res., 110, A09302, 2005.R E Hartle, E C Sittler, F M Neubauer, R E Johnson, et al., Planet. Space Sci., 54, 1211, 2006.

Electrical and thermal properties of lead titanate glass ceramics

International Nuclear Information System (INIS)

Shankar, J.; Deshpande, V.K.

2011-01-01

Glass samples with composition of (50-X)PbO-(25+X)TiO 2 -25B 2 O 3 (where X=0, 5, 10 and 12.5 mol%) were prepared using conventional quenching technique. The glass transition temperature, T g and crystallization temperature T c were determined from the DTA. These glass samples were converted to glass ceramics by following two stage heat treatment schedule. The glass ceramic samples were characterized by XRD, SEM and dielectric constant measurements. The XRD results revealed the formation of ferroelectric lead titanate (PT) as a major crystalline phase in the glass ceramics. The density increases and the CTE decreases for all glass ceramics with increase in X (mol%). This may be attributed to increase in PT phase. The SEM results which show rounded crystallites of lead titanate, also supports other results. Hysteresis loops observed at room temperature confirms the ferroelectric nature of glass ceramics. The optimized glass ceramic sample exhibits high dielectric constant which is of technical importance. -- Research Highlights: →Lead titanate glass ceramics prepared by conventional quenching technique. →Lead titanate is a major crystalline phase in the glass ceramics. →The ferroelectric nature of glass ceramics is confirmed by the hysteresis study. →The high value of ε observed at room temperature is quite promising in the study.

Safe prescribing: a titanic challenge.

Science.gov (United States)

Routledge, Philip A

2012-10-01

The challenge to achieve safe prescribing merits the adjective 'titanic'. The organisational and human errors leading to poor prescribing (e.g. underprescribing, overprescribing, misprescribing or medication errors) have parallels in the organisational and human errors that led to the loss of the Titanic 100 years ago this year. Prescribing can be adversely affected by communication failures, critical conditions, complacency, corner cutting, callowness and a lack of courage of conviction, all of which were also factors leading to the Titanic tragedy. These issues need to be addressed by a commitment to excellence, the final component of the 'Seven C's'. Optimal prescribing is dependent upon close communication and collaborative working between highly trained health professionals, whose role is to ensure maximum clinical effectiveness, whilst also protecting their patients from avoidable harm. Since humans are prone to error, and the environments in which they work are imperfect, it is not surprising that medication errors are common, occurring more often during the prescribing stage than during dispensing or administration. A commitment to excellence in prescribing includes a continued focus on lifelong learning (including interprofessional learning) in pharmacology and therapeutics. This should be accompanied by improvements in the clinical working environment of prescribers, and the encouragement of a strong safety culture (including reporting of adverse incidents as well as suspected adverse drug reactions whenever appropriate). Finally, members of the clinical team must be prepared to challenge each other, when necessary, to ensure that prescribing combines the highest likelihood of benefit with the lowest potential for harm. © 2012 The Author. British Journal of Clinical Pharmacology © 2012 The British Pharmacological Society.

[Medpor plus titanic mesh implant in the repair of orbital blowout fractures].

Science.gov (United States)

Han, Xiao-hui; Zhang, Jia-yu; Cai, Jian-qiu; Shi, Ming-guang

2011-05-10

To study the efficacy of porous polyethylene (Medpor) plus titanic mesh sheets in the repair of orbital blowout fractures. A total of 20 patients underwent open surgical reduction with the combined usage of Medpor and titanic mesh. And they were followed up for average period of 14.5 months (range: 9 - 18). There is no infection or extrusion of medpor and titanic mesh in follow-up periods. There was no instance of decreased visual acuity at post-operation. And all cases of enophthalmos were corrected. The post-operative protrusion degree of both eyes was almost identical at less than 2 mm. The movement of eye balls was satisfactory in all directions. Diplopia disappeared in 18 cases with a cure rate of 90%, 1 case improved and 1 case persisted. Medpor plus titanic mesh implant is a safe and effective treatment in the repair of orbital blow out fractures.

Synthesis, optical, structural, and electrical properties of single-crystalline CdS nanobelts

Energy Technology Data Exchange (ETDEWEB)

Alqahtani, Mohammed S. [King Saud University, Department of Physics and Astronomy, Riyadh (Saudi Arabia); Hadia, N.M.A.; Mohamed, S.H. [Sohag University, Physics Department, Faculty of Science, Sohag (Egypt)

2017-04-15

CdS nanobelts (NBs) were synthesized by vapor transport of CdS powders. The growth was carried out without any catalyst on quartz and Si (100) substrates. The synthesized CdS NBs were examined by transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM) and selected area electron diffraction (SAED), high-resolution transmission electron microscopy (HR-TEM), X-ray powder diffraction (XRD), energy dispersion analysis of X-ray (EDAX), spectrophotometer, and photoluminescence spectroscopy. CdS NBs were indexed as hexagonal wurtzite structure. The growth was via vapor-solid growth mechanism and along the [100] direction. The refractive index was evaluated in the transparent region, as suggested by Swanepoel, using the envelope method. The refractive index values and the extinction coefficient were decreased by increasing the wavelength. The calculated optical band gap was 2.50 eV. The photoluminescence (PL) spectrum of the synthesized CdS NBs exhibited a green emission peak at 510 nm and a broad red emission peak at 696 nm. The conductivity measurements were achieved, in the temperature range from 300 to 600 K, using the conventional two-probe technique. Two different slopes with different activation energies of 0.618 and 0.215 eV were obtained. The CdS NBs are likely being novel functional materials. Thus, they can be used in the manufacture of innovative optoelectronic nanodevices. (orig.)

Extrusion and properties of lead zirconate titanate piezoelectric ceramics

DEFF Research Database (Denmark)

Cai, S.; Millar, C.E.; Pedersen, L.

1997-01-01

The purpose of this work was to develop a procedure for fabricating electroceramic actuators with good piezoelectric properties. The preparation of lead zirconate titanate (PZT) piezoelectric ceramic rods and tubes by extrusion processing is described. The microstructure of extrudates was investi......The purpose of this work was to develop a procedure for fabricating electroceramic actuators with good piezoelectric properties. The preparation of lead zirconate titanate (PZT) piezoelectric ceramic rods and tubes by extrusion processing is described. The microstructure of extrudates...

Steps in growth of Nb-doped layered titanates with very high surface area suitable for water purification

International Nuclear Information System (INIS)

Milanović, Marija; Nikolić, Ljubica M.; Stijepović, Ivan; Kontos, Athanassios G.; Giannakopoulos, Konstantinos P.

2014-01-01

Nb-doped layered titanates, as highly efficient adsorbents, have been synthesized by hydrothermal reaction for variable duration and at 150 °C in a highly alkaline solution with NbCl 5 as the Nb source. The results have shown the formation of nanosheets already after 1 h of hydrothermal processing, but morphology and phase composition change as the reaction proceeds. The prepared layered titanates have been structurally investigated via scanning and transmission electron microscopy, X-ray diffraction, as well as Raman and Fourier transform infrared spectroscopies. The steps of layered titanate growth have been followed and an intermediate layered anatase phase is identified. Thus optimized growth of mesoporous titanate materials with 10% Nb atomic content present very high specific surface area of 345.3 m 2  g −1 , and perform as very efficient adsorbents for wastewater treatment applications. - Highlights: • Nb-doped layered titanates have been prepared by a hydrothermal procedure. • Introduction of Nb to precursor lowers the rate of layered titanate formation. • Steps in growth of Nb-doped layered titanates are considered. • Nb-doped layered titanates show high/fast MB adsorption from concentrated solution

Computational Science with the Titan Supercomputer: Early Outcomes and Lessons Learned

Science.gov (United States)

Wells, Jack

2014-03-01

Modeling and simulation with petascale computing has supercharged the process of innovation and understanding, dramatically accelerating time-to-insight and time-to-discovery. This presentation will focus on early outcomes from the Titan supercomputer at the Oak Ridge National Laboratory. Titan has over 18,000 hybrid compute nodes consisting of both CPUs and GPUs. In this presentation, I will discuss the lessons we have learned in deploying Titan and preparing applications to move from conventional CPU architectures to a hybrid machine. I will present early results of materials applications running on Titan and the implications for the research community as we prepare for exascale supercomputer in the next decade. Lastly, I will provide an overview of user programs at the Oak Ridge Leadership Computing Facility with specific information how researchers may apply for allocations of computing resources. This research used resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725.

Diffusion barrier performance of novel Ti/TaN double layers for Cu metallization

International Nuclear Information System (INIS)

Zhou, Y.M.; He, M.Z.; Xie, Z.

2014-01-01

Highlights: • Novel Ti/TaN double layers offering good stability as a barrier against Cu metallization have been made achievable by annealing in vacuum. • The Ti/TaN double layers improved the adhesion with Cu thin films and showed good diffusion barrier between Cu and SiO 2 /Si up to the annealing condition. • The failure mechanism of Ti/TaN bi-layer is similar with the Cu/TaN/Si metallization system in which Cu atoms diffuse through the grain boundary of barrier and react with silicon to form Cu 3 Si. - Abstract: Novel Ti/TaN double layers offering good stability as a barrier against Cu metallization have been made achievable by annealing in vacuum better than 1 × 10 −3 Pa. Ti/TaN double layers were formed on SiO 2 /Si substrates by DC magnetron sputtering and then the properties of Cu/Ti/TaN/SiO 2 /Si film stacks were studied. It was found that the Ti/TaN double layers provide good diffusion barrier between Cu and SiO 2 /Si up to 750 °C for 30 min. The XRD, Auger and EDS results show that the Cu–Si compounds like Cu 3 Si were formed by Cu diffusion through Ti/TaN barrier for the 800 °C annealed samples. It seems that the improved diffusion barrier property of Cu/Ti/TaN/SiO 2 /Si stack is due to the diffusion of nitrogen along the grain boundaries in Ti layer, which would decrease the defects in Ti film and block the diffusion path for Cu diffusion with increasing annealing temperature. The failure mechanism of Ti/TaN bi-layer is similar to the Cu/TaN/Si metallization system in which Cu atoms diffuse through the grain boundary of barrier and react with silicon to form Cu 3 Si

Studies on the effects of titanate and silane coupling agents on the performance of poly (methyl methacrylate)/barium titanate denture base nanocomposites.

Science.gov (United States)

Elshereksi, Nidal W; Ghazali, Mariyam J; Muchtar, Andanastuti; Azhari, Che H

2017-01-01

This study aimed to fabricate and characterise silanated and titanated nanobarium titanate (NBT) filled poly(methyl methacrylate) (PMMA) denture base composites and to evaluate the behaviour of a titanate coupling agent (TCA) as an alternative coupling agent to silane. The effect of filler surface modification on fracture toughness was also studied. Silanated, titanated and pure NBT at 5% were incorporated in PMMA matrix. Neat PMMA matrix served as a control. NBT was sonicated in MMA prior to mixing with the PMMA. Curing was carried out using a water bath at 75°C for 1.5h and then at 100°C for 30min. NBT was characterised via Fourier transform-infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and Brunauer-Emmett-Teller (BET) analysis before and after surface modification. The porosity and fracture toughness of the PMMA nanocomposites (n=6, for each formulation and test) were also evaluated. NBT was successfully functionalised by the coupling agents. The TCA exhibited the lowest percentage of porosity (0.09%), whereas silane revealed 0.53% porosity. Statistically significant differences in fracture toughness were observed among the fracture toughness values of the tested samples (pPMMA composites. Thus, TCA seemed to be more effective than silane. Minimising the porosity level could have the potential to reduce fungus growth on denture base resin to be hygienically accepTable Such enhancements obtained with Ti-NBT could lead to promotion of the composites' longevity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hydrothermal synthesis of highly water-dispersible anatase nanocrystals from transparent aqueous sols of titanate colloids

International Nuclear Information System (INIS)

Ban, Takayuki; Tanaka, Yusuke; Ohya, Yutaka

2011-01-01

Transparent colloidal aqueous solutions of anatase nanocrystals were hydrothermally synthesized from aqueous transparent sols with tetramethylammonium titanate colloids, the surfaces of which were modified with citric acid, by structural conversion of the titanate to anatase. This modification hindered coalescence of the titanate colloids during the hydrothermal synthesis. Although the amount of citric acid adsorbed on the colloids was reduced during hydrothermal treatment, a small amount of citric acid was adsorbed on the resulting anatase nanocrystals. Moreover, the use of the titanate colloids as a precursor was compared with the use of a citrato Ti complex, tetramethylammonium citratotitanate. The hydrothermal treatment of the transparent aqueous solutions of the Ti complex yielded opaque solutions with large anatase colloids, suggesting that the titanate colloids were useful for preparing transparent anatase colloidal solutions. Because the shape and size of resulting colloids may be dependent on the size and shape of starting colloids, the use of titanate colloids as a precursor may make it easy to control size and shape of anatase colloids.

Conventional hydrothermal synthesis of titanate nanotubes: Systematic discussions on structural, optical, thermal and morphological properties

Directory of Open Access Journals (Sweden)

S. Muniyappan

2017-12-01

Full Text Available Titanate nanotubes were successfully synthesized by hydrothermal technique under acidic-base medium. The anatase and titanate phase of the starting TiO2 and tubular titanate was confirmed by powder XRD technique. The UV–vis-NIR spectroscopy was used to study the absorption nature of titanate nanotubes and the band gap was calculated as 3.3 eV. Infrared technique was employed to detect the presence of all the functional groups in the synthesized titanate nanotube material. Thermal properties of the title material were studied by TG-DTA analyses. The shrinkage of interlayer distance of TiO2 network confirms the nanotube formation. Morphology and size information about the synthesized material were carried out using FESEM and TEM analysis. Titanate nanotubes are having the maximum length of 2.24 µm and the average diameter of 169.73 nm. EDX analysis gives out the elemental composition of the as synthesized product. This report may fetch an efficient way to synthesize TiO2 nanotubes using TiO2 nanoparticles.

77 FR 59690 - Titan Resources International, Corp.; Order of Suspension of Trading

Science.gov (United States)

2012-09-28

... a lack of current and accurate information concerning the securities of Titan Resources... concerning Titan's business operations and financial condition. The Commission is of the opinion that the public interest and the protection of investors require a suspension of trading in the securities of...

Laboratory investigation of nitrile ices of Titan's stratospheric clouds

Science.gov (United States)

Nna Mvondo, D.; Anderson, C. M.; McLain, J. L.; Samuelson, R. E.

2017-09-01

Titan's mid to lower stratosphere contains complex cloud systems of numerous organic ice particles comprised of both hydrocarbon and nitrile compounds. Most of these stratospheric ice clouds form as a result of vapor condensation formation processes. However, there are additional ice emission features such as dicyanoacetylene (C4N2) and the 220 cm-1 ice emission feature (the "Haystack") that are difficult to explain since there are no observed vapor emission features associated with these ices. In our laboratory, using a high-vacuum chamber coupled to a FTIR spectrometer, we are engaged in a dedicated investigation of Titan's stratospheric ices to interpret and constrain Cassini Composite InfraRed Spectrometer (CIRS) far-IR data. We will present laboratory transmittance spectra obtained for propionitrile (CH3CH2CN), cyanogen (C2N2) and hydrogen cyanide (HCN) ices, as well as various combinations of their mixtures, to better understand the cloud chemistry occurring in Titan's stratosphere.

Study of barium bismuth titanate prepared by mechanochemical synthesis

Directory of Open Access Journals (Sweden)

Lazarević Z.Ž.

2009-01-01

Full Text Available Barium-bismuth titanate, BaBi4Ti4O15 (BBT, a member of Aurivillius bismuth-based layer-structure perovskites, was prepared from stoichiometric amounts of barium titanate and bismuth titanate obtained via mechanochemical synthesis. Mechanochemical synthesis was performed in air atmosphere in a planetary ball mill. The reaction mechanism of BaBi4Ti4O15 and the preparation and characteristics of BBT ceramic powders were studied using XRD, Raman spectroscopy, particle analysis and SEM. The Bi-layered perovskite structure of BaBi4Ti4O15 ceramic forms at 1100 °C for 4 h without a pre-calcination step. The microstructure of BaBi4Ti4O15 exhibits plate-like grains typical for the Bi-layered structured material and spherical and polygonal grains. The Ba2+ addition leads to changes in the microstructure development, particularly in the change of the average grain size.

Photometric changes on Saturn's Titan: Evidence for active cryovolcanism

Science.gov (United States)

Nelson, R.M.; Kamp, L.W.; Lopes, R.M.C.; Matson, D.L.; Kirk, R.L.; Hapke, B.W.; Wall, S.D.; Boryta, M.D.; Leader, F.E.; Smythe, W.D.; Mitchell, K.L.; Baines, K.H.; Jaumann, R.; Sotin, Christophe; Clark, R.N.; Cruikshank, D.P.; Drossart, P.; Lunine, J.I.; Combes, M.; Bellucci, G.; Bibring, J.-P.; Capaccioni, F.; Cerroni, P.; Coradini, A.; Formisano, V.; Filacchione, G.; Langevin, Y.; McCord, T.B.; Mennella, V.; Nicholson, P.D.; Sicardy, B.; Irwin, P.G.J.; Pearl, J.C.

2009-01-01

We report infrared spectrophotometric variability on the surface of Saturn's moon Titan detected in images returned by the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini Saturn Orbiter. The changes were observed at 7??S, 138??W and occurred between October 27, 2005 and January 15, 2006. After that date the surface was unchanged until the most recent observation, March 18, 2006. We previously reported spectrophotometric variability at another location (26??S, 78??W). Cassini Synthetic Aperture RADAR (SAR) images find that the surface morphology at both locations is consistent with surface flows possibly resulting from cryovolcanic activity (Wall et al., companion paper, this issue). The VIMS-reported time variability and SAR morphology results suggest that Titan currently exhibits intermittent surface changes consistent with present ongoing surface processes. We suggest that these processes involve material from Titan's interior being extruded or effiised and deposited on the surface, as might be expected from cryovolcanism. ?? 2009.

Titan Montgolfiere Buoyancy Modulation System, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Titan is ideally suited for balloon exploration due to its low gravity and dense atmosphere. Current NASA mission architectures baseline Montgolfiere balloon...

Current—voltage characteristics of lead zirconate titanate/nickel bilayered hollow cylindrical magnetoelectric composites

International Nuclear Information System (INIS)

De-An, Pan; Shen-Gen, Zhang; Jian-Jun, Tian; Li-Jie, Qiao; Jun-Sai, Sun; Volinsky, Alex A.

2010-01-01

Current–voltage measurements obtained from lead zirconate titanate/nickel bilayered hollow cylindrical magnetoelectric composite showed that a sinusoidal current applied to the copper coil wrapped around the hollow cylinder circumference induces voltage across the lead zirconate titanate layer thickness. The current–voltage coefficient and the maximum induced voltage in lead zirconate titanate at 1 kHz and resonance (60.1 kHz) frequencies increased linearly with the number of the coil turns and the applied current. The resonance frequency corresponds to the electromechanical resonance frequency. The current–voltage coefficient can be significantly improved by optimizing the magnetoelectric structure geometry and/or increasing the number of coil turns. Hollow cylindrical lead zirconate titanate/nickel structures can be potentially used as current sensors. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Overview of the TITAN-II reversed-field pinch aqueous fusion power core design

Energy Technology Data Exchange (ETDEWEB)

Wong, C.P.C.; Creedon, R.L.; Grotz, S.; Cheng, E.T.; Sharafat, S.; Cooke, P.I.H.

1988-03-01

TITAN-II is a compact, high power density Reversed-Field Pinch fusion power reactor design based on the aqueous lithium solution fusion power core concept. The selected breeding and structural materials are LiNO/sub 3/ and 9-C low activation ferritic steel, respectively. TITAN-II is a viable alternative to the TITAN-I lithium self-cooled design for the Reversed-Field Pinch reactor to operate at a neutron wall loading of 18 MWm/sup 2/. Submerging the complete fusion power core and the primary loop in a large pool of cool water will minimize the probability of radioactivity release. Since the protection of the large pool integrity is the only requirement for the protection of the public, TITAN-II is a passive safety assurance design. 13 refs., 3 figs., 1 tab.

Overview of the TITAN-II reversed-field pinch aqueous fusion power core design

Energy Technology Data Exchange (ETDEWEB)

Wong, C.P.C.; Creedon, R.L.; Cheng, E.T. (General Atomic Co., San Diego, CA (USA)); Grotz, S.P.; Sharafat, S.; Cooke, P.I.H. (California Univ., Los Angeles (USA). Dept. of Mechanical, Aerospace and Nuclear Engineering; California Univ., Los Angeles, CA (USA). Inst. for Plasma and Fusion Research); TITAN Research Group

1989-04-01

TITAN-II is a compact, high-power-density Reversed-Field Pinch fusion power reactor design based on the aqueous lithium solution fusion power core concept. The selected breeding and structural materials are LiNO/sub 3/ and 9-C low activation ferritic steel, respectively. TITAN-II is a viable alternative to the TITAN-I lithium self-cooled design for the Reversed-Field Pinch reactor to operate at a neutron wall loading of 18 MW/m/sup 2/. Submerging the complete fusion power core and the primary loop in a large pool of cool water will minimize the probability of radioactivity release. Since the protection of the large pool integrity is the only requirement for the protection of the public, TITAN-II is a level 2 of passive safety assurance design. (orig.).

Structural and optical investigations of sol–gel derived lithium titanate thin films

International Nuclear Information System (INIS)

Łapiński, M.; Kościelska, B.; Sadowski, W.

2012-01-01

Highlights: ► Lithium titanate thin films were deposited on glass substrates by sol–gel method. ► After annealing at 550 °C samples had lithium titanate spinel structure. ► Above 80 h of annealing mixture of lithium titanate and titanium oxides was appeared. ► Optical transmittance decreased with increasing of annealing time. - Abstract: In this paper structural and optical studies of lithium titanate (LTO) thin films are presented. Nanocrystalline thin films with 800 nm thickness were prepared by sol–gel method. To examine the influence of the annealing time on as-prepared films crystallization, the coatings were heated at 550 °C for 10, 20 and 80 h. Structure of manufactured thin films was investigated using X-ray diffraction (XRD). The most visible lithium titanate phase was obtained after 20 h annealing. Increasing of annealing time over 20 h revealed appearance of titanium oxides phase. On the basis of transmission characteristic optical properties were calculated. It was found that transmission through the thin films was reduced and position of the fundamental absorption edge was shifted toward a longer wavelength with increasing of annealing time. The optical band gap was calculated for direct allowed and indirect allowed transitions from optical absorption spectra.

Remember the Titans: A Theoretical Analysis

Directory of Open Access Journals (Sweden)

Rameca Leary

2013-06-01

Full Text Available This paper addresses a pivotal time in American history, when a 1971 Supreme Court mandate required southern school districts to end segregation (Daugherity, 2011. In Alexandria, Virginia, the merger of three rival high schools yielded a racially diverse football team and coaching staff. Beforehand, blacks and whites had their own schools. Many wondered how the new T.C. Williams Titans football team would fare. This paper takes an in-depth look at the film, Remember the Titans, which is based on this story. It analyzes the film using Gordon Allport’s (1954 Intergroup Contact Theory to assess how people from different backgrounds interact within group settings. It explores how communication barriers and the absence of knowledge can lead to ignorance. A 21st century legacy is also discussed, including ideas for further research. 

Remember the Titans: A Theoretical Analysis

Directory of Open Access Journals (Sweden)

Rameca Leary

2013-06-01

Full Text Available This paper addresses a pivotal time in American history, when a 1971 Supreme Court mandate required southern school districts to end segregation (Daugherity, 2011. In Alexandria, Virginia, the merger of three rival high schools yielded a racially diverse football team and coaching staff. Beforehand, blacks and whites had their own schools. Many wondered how the new T.C. Williams Titans football team would fare. This paper takes an in-depth look at the film, Remember the Titans, which is based on this story. It analyzes the film using Gordon Allport’s (1954 Intergroup Contact Theory to assess how people from different backgrounds interact within group settings. It explores how communication barriers and the absence of knowledge can lead to ignorance. A 21st century legacy is also discussed, including ideas for further research.

Comparison of TITAN hybrid deterministic transport code and MCNP5 for simulation of SPECT

International Nuclear Information System (INIS)

Royston, K.; Haghighat, A.; Yi, C.

2010-01-01

Traditionally, Single Photon Emission Computed Tomography (SPECT) simulations use Monte Carlo methods. The hybrid deterministic transport code TITAN has recently been applied to the simulation of a SPECT myocardial perfusion study. The TITAN SPECT simulation uses the discrete ordinates formulation in the phantom region and a simplified ray-tracing formulation outside of the phantom. A SPECT model has been created in the Monte Carlo Neutral particle (MCNP)5 Monte Carlo code for comparison. In MCNP5 the collimator is directly modeled, but TITAN instead simulates the effect of collimator blur using a circular ordinate splitting technique. Projection images created using the TITAN code are compared to results using MCNP5 for three collimator acceptance angles. Normalized projection images for 2.97 deg, 1.42 deg and 0.98 deg collimator acceptance angles had maximum relative differences of 21.3%, 11.9% and 8.3%, respectively. Visually the images are in good agreement. Profiles through the projection images were plotted to find that the TITAN results followed the shape of the MCNP5 results with some differences in magnitude. A timing comparison on 16 processors found that the TITAN code completed the calculation 382 to 2787 times faster than MCNP5. Both codes exhibit good parallel performance. (author)

Modeling of synchrotron-based laboratory simulations of Titan's ionospheric photochemistry

Science.gov (United States)

Carrasco, Nathalie; Peng, Zhe; Pernot, Pascal

2014-11-01

The APSIS reactor has been designed to simulate in the laboratory with a VUV synchrotron irradiation the photochemistry occurring in planetary upper atmospheres. A N2-CH4 Titan-like gas mixture has been studied, whose photochemistry in Titan's ionospheric irradiation conditions leads to a coupled chemical network involving both radicals and ions. In the present work, an ion-neutral coupled model is developed to interpret the experimental data, taking into account the uncertainties on the kinetic parameters by Monte Carlo sampling. The model predicts species concentrations in agreement with mass spectrometry measurements of the methane consumption and product blocks intensities. Ion chemistry and in particular dissociative recombination are found to be very important through sensitivity analysis. The model is also applied to complementary environmental conditions, corresponding to Titan's ionospheric average conditions and to another existing synchrotron setup. An innovative study of the correlations between species concentrations identifies two main competitive families, leading respectively to saturated and unsaturated species. We find that the unsaturated growth family, driven by C2H2 , is dominant in Titan's upper atmosphere, as observed by the Cassini INMS. But the saturated species are substantially more intense in the measurements of the two synchrotron experimental setups, and likely originate from catalysis by metallic walls of the reactors.

Chemistry of the galactic cosmic ray induced ionosphere of Titan

Science.gov (United States)

Molina-Cuberos, G. J.; López-Moreno, J. J.; Rodrigo, R.; Lara, L. M.

1999-09-01

Titan's lower ionosphere (from 1 to 400 km) has been studied with a one-dimensional ion-neutral model. In this region of the atmosphere, galactic cosmic rays (GCRs) are the main ionization source. They penetrate to the deeper atmosphere and ionize the neutral constituents of Titan's atmosphere (mainly N2, CH4, Ar, H2, and CO) to produce N2+, N+, Ar+, CH4+, CH3+, CH2+, H2+, H+, and CO+. Fast reactions with the neutrals convert these ions into ions such as CH5+, C2H5+, and N2H+. Different pathways are proposed to obtain the ion and electron densities. The most abundant ions are cluster ions, like CH5+.CH4, HCO+.H2, and HCNH+.C2H4, and long chain hydrocarbon ions. In atmospheres very rich in N2, such as Titan's, ions like H4C7N+ and CH3CNH+ also represent an important contribution to the total positive ion density. Three-body reactions may play an important role in the dense atmosphere of Titan, and special attention is devoted to them. The calculated electron density in the lower atmosphere reaches a peak of ~2150 cm-3 at an altitude of 90 km.

Probing Small Lakes on Titan Using the Cassini RADAR Altimeter

Science.gov (United States)

Mastrogiuseppe, M.; Poggiali, V.; Hayes, A.; Lunine, J. I.; Seu, R.; Lorenz, R. D.; Mitri, G.; Mitchell, K. L.; Janssen, M. A.; Casarano, D.; Notarnicola, C.; Le Gall, A. A.

2017-12-01

The T126 Cassini's final flyby of Titan has offered a unique opportunity to observe an area in the Northern Polar terrain, where several small - medium size (10 - 50 km) hydrocarbon lakes are present and have been previously imaged by Cassini. The successful observation allowed the radar to operate at the closest approach over several small lakes, using its altimetry mode for the investigation of depth and liquid composition. Herein we present the result of a dedicate processing previously applied to altimetric data acquired over Ligeia Mare where the radar revealed the bathymetry and composition of the sea [1,2]. We show that, the optimal geometry condition met during the T126 fly-by allowed the radar to probe Titan's lakes revealing that such small liquid bodies can exceed one-hundred meters of depth. [1] M. Mastrogiuseppe et al. (2014, Mar.). The bathymetry of a Titan Sea. Geophysical Research Letters. [Online]. 41 (5), pp. 1432-1437. Available: http://dx.doi.org/10.1002/2013GL058618 [2] M.Mastrogiuseppe et al. (2016, Oct). Radar Sounding Using the Cassini Altimeter: Waveform Modeling and Monte Carlo Approach for Data Inversion of Observations of Titan's Seas, IEEE Transactions On Geoscience And Remote Sensing, Vol. 54, No. 10, doi: 10.1109/TGRS.2016.2563426.

Poster 9: Isotopic Ratios of Carbon and Oxygen in Titan's CO using ALMA

Science.gov (United States)

Serigano, Joseph; Nixion, Conor A.; Cordiner, Martin A.; Irwin, Patrick G. J.; Teanby, Nick A.; Charnley, Steven B.; Lindberg, Johan E.

2016-06-01

The advent of the Atacama Large Millimeter/Submillimeter Array (ALMA) has provided a new and powerful facility for probing the atmospheres of solar system targets at long wavelengths (84-720 GHz) where the rotational lines of small, polar molecules are prominent. In the complex atmosphere of Titan, photochemical processes dissociate and ionize molecular nitrogen and methane in the upper atmosphere, creating a complex inventory of trace hydrocarbons and nitriles. Additionally, the existence of oxygen on Titan facilitates the synthesis of molecules of potential astrobiological importance. Utilization of ground-based submillimeter observations of Titan has proven to be a powerful tool to complement results from spacecraft observations. ALMA provides the ability to probe this region in greater detail with unprecedented spectral and spatial resolution at high sensitivity, allowing for the derivation of vertical mixing profiles, molecular detections, and observations of latitudinal and seasonal variations. Recent ALMA studies of Titan have presented spectrally and spatially-resolved maps of HNC and HC3N emission (Cordiner et al. 2014), as well as the first spectroscopic detection of ethyl cyanide (C2H5CN) in Titan's atmosphere (Cordiner et al. 2015). This poster will focus on ALMA observations of carbon monoxide (CO) and its isotopologues 13CO, C18O, and C 17O in Titan's atmosphere. Molecular abundances and the vertical atmospheric temperature profile were derived by modeling the observed emission line profiles using NEMESIS, a line-by-line radiative transfer code (Irwin et al. 2008). This study reports the first spectroscopic detection of 17O in the outer solar system with C17O detected at >8σ confidence. The abundances of these molecules and isotopic ratios of 12C/13C, 16O/18O, and 16O/17O will be presented. General implications for the history of Titan from these measurements will be discussed.

Properties and DEFC tests of nafion added functionalized titanate nanotubes prepared by extrusion

Energy Technology Data Exchange (ETDEWEB)

Matos, B.R.; Goulart, C.A.; Isidoro, R.A.; Silva, J.S. da; Santiago, E.I.; Fonseca, F.C.; Tavares, A.C. [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

2016-07-01

Full text: Composite electrolyte membranes based on the incorporation of a second inorganic phase into ionomer matrices such as Nafion revealed to possess enhanced properties such as increased mechanical resistance and reduced permeability of solvents. It has been reported that surface functionalized titanate nanotubes (H2Ti3O7.nH2O) display a proton conductivity of ∼ 10-2 Scm-1, which is attractive for the use of such composites in direct ethanol fuel cells (DEFC). Herein, composite membranes based on the addition of sulfonic acid groups functionalized titanate nanotubes into Nafion matrix were prepared by grafting followed by extrusion. These membranes were characterized by infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), acid-base titration, proton conductivity measurements and DEFC tests. FTIR measurements confirmed both the grafting of the titanate nanotubes. BET measurements showed that the functionalized titanate nanotubes possess a high surface specific area. Acid-base titration evidenced that additional sulfonic acid groups are present in the composite membranes compared to the pristine ionomer. The conductivity measurements show that the increase in the titanate nanotube volume fraction into the ionomers has not resulted in a decrease of the proton conductivity. The results show that the addition of functionalized titanate nanotubes into Nafion polymer matrix resulted in an improvement of the electric transport properties, reduction of the fuel crossover and, consequently, a higher DEFC performance for the composites were observed with respect to the pristine Nafion. (author)

Properties and DEFC tests of nafion added functionalized titanate nanotubes prepared by extrusion

International Nuclear Information System (INIS)

Matos, B.R.; Goulart, C.A.; Isidoro, R.A.; Silva, J.S. da; Santiago, E.I.; Fonseca, F.C.; Tavares, A.C.

2016-01-01

Full text: Composite electrolyte membranes based on the incorporation of a second inorganic phase into ionomer matrices such as Nafion revealed to possess enhanced properties such as increased mechanical resistance and reduced permeability of solvents. It has been reported that surface functionalized titanate nanotubes (H2Ti3O7.nH2O) display a proton conductivity of ∼ 10-2 Scm-1, which is attractive for the use of such composites in direct ethanol fuel cells (DEFC). Herein, composite membranes based on the addition of sulfonic acid groups functionalized titanate nanotubes into Nafion matrix were prepared by grafting followed by extrusion. These membranes were characterized by infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), acid-base titration, proton conductivity measurements and DEFC tests. FTIR measurements confirmed both the grafting of the titanate nanotubes. BET measurements showed that the functionalized titanate nanotubes possess a high surface specific area. Acid-base titration evidenced that additional sulfonic acid groups are present in the composite membranes compared to the pristine ionomer. The conductivity measurements show that the increase in the titanate nanotube volume fraction into the ionomers has not resulted in a decrease of the proton conductivity. The results show that the addition of functionalized titanate nanotubes into Nafion polymer matrix resulted in an improvement of the electric transport properties, reduction of the fuel crossover and, consequently, a higher DEFC performance for the composites were observed with respect to the pristine Nafion. (author)

Solar Electric and Chemical Propulsion Technology Applications to a Titan Orbiter/Lander Mission

Science.gov (United States)

Cupples, Michael

2007-01-01

Several advanced propulsion technology options were assessed for a conceptual Titan Orbiter/Lander mission. For convenience of presentation, the mission was broken into two phases: interplanetary and Titan capture. The interplanetary phase of the mission was evaluated for an advanced Solar Electric Propulsion System (SEPS), while the Titan capture phase was evaluated for state-of-art chemical propulsion (NTO/Hydrazine), three advanced chemical propulsion options (LOX/Hydrazine, Fluorine/Hydrazine, high Isp mono-propellant), and advanced tank technologies. Hence, this study was referred to as a SEPS/Chemical based option. The SEPS/Chemical study results were briefly compared to a 2002 NASA study that included two general propulsion options for the same conceptual mission: an all propulsive based mission and a SEPS/Aerocapture based mission. The SEP/Chemical study assumed identical science payload as the 2002 NASA study science payload. The SEPS/Chemical study results indicated that the Titan mission was feasible for a medium launch vehicle, an interplanetary transfer time of approximately 8 years, an advanced SEPS (30 kW), and current chemical engine technology (yet with advanced tanks) for the Titan capture. The 2002 NASA study showed the feasibility of the mission based on a somewhat smaller medium launch vehicle, an interplanetary transfer time of approximately 5.9 years, an advanced SEPS (24 kW), and advanced Aerocapture based propulsion technology for the Titan capture. Further comparisons and study results were presented for the advanced chemical and advanced tank technologies.

ALMA Spectroscopy of Titan's Atmosphere: First Detections of Vinyl Cyanide and Acetonitrile Isotopologues

Science.gov (United States)

Cordiner, Martin; Y Palmer, Maureen; Nixon, Conor A.; Charnley, Steven B.; Mumma, Michael J.; Irwin, Pat G. J.; Teanby, Nick A.; Kisiel, Zbigniew; Serigano, Joseph

2015-11-01

Studies of Titan's atmospheric chemistry provide a unique opportunity to explore the origin and evolution of complex organic matter in primitive planetary atmospheres. The Atacama Large Millimeter/submillimeter Array (ALMA) is a powerful new telescope, well suited to the study of molecular emission from Titan's stratosphere and mesosphere. Here we present early results from our ongoing study to exploit the large volume of Titan data taken using ALMA in Early Science Mode (during the period 2012-2014). Combining data from multiple ALMA Band 6 observations, we obtained high-resolution mm-wave spectra with unprecedented sensitivity, enabling the first detection of vinyl cyanide (C2H3CN) in Titan's atmosphere. Initial estimates indicate a mesospheric abundance ratio with respect to ethyl cyanide (C2H5CN) of [C2H3CN]/[C2H5CN] = 0.31. In addition, we report the first detections on Titan of the 13C and 15N-substituted isotopologues of acetonitrile (13CH3CN and CH3C15N). Radiative transfer models and possible chemical formation pathways for these molecules will be discussed.

Au/TiO2 nanobelt heterostructures for the detection of cancer cells and anticancer drug activity by potential sensing

International Nuclear Information System (INIS)

Cui, Jingjie; Xu, Ping; Li, Hong; Chen, Jing; Chen, Shaowei; Gao, Li

2016-01-01

Cancer is a cell dysfunction disease. The detection of cancer cells is extremely important for early diagnosis and clinical treatments. At present, the pretreatment for the detection of cancer cells is costly, complicated and time-consuming. As different species of the analytes may give rise to specific voltammetric signals at distinctly different potentials, simple potential sensing has the specificity to detect different cellular species. By taking advantage of the different electrochemical characteristics of normal cells, cancer cells and biointeractions between anticancer drugs and cancer cells, we develop a specific, sensitive, direct, cost-effective and rapid method for the detection of cancer cells by electrochemical potential sensing based on Au/TiO 2 nanobelt heterostructure electrodes that will be of significance in early cancer diagnosis, in vitro screening of anticancer drugs  and molecular biology research. (paper)

Impurities in barium titanate posistor ceramics

Czech Academy of Sciences Publication Activity Database

Korniyenko, S. M.; Bykov, I. P.; Glinchuk, M. J.; Laguta, V. V.; Belous, A. G.; Jastrabík, Lubomír

2000-01-01

Roč. 239, - (2000), s. 1209-1218 ISSN 0015-0193 Institutional research plan: CEZ:AV0Z1010914 Keywords : barium titanate phase transition * ESR * positive temperature coefficient of resistivity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.547, year: 2000

Study of irradiation of flash lightning type in a Titan simulated atmosphere; Estudio de irradiaciones tipo relampago en una atmosfera simulada de Titan

Energy Technology Data Exchange (ETDEWEB)

Rosa C, J.G. De la

2001-07-01

Titan is the greatest satellite of the Saturn planet and the unique moon of the Solar System which presents a dense atmosphere constituted by nitrogen, methane and traces of hydrocarbons and nitriles. Constantly it is bombarded by different energy sources which interacting with the atmosphere cause countless of chemical reactions which have giving origin to the synthesis of organic molecules from its formation since 4.5 thousand millions of years ago. The electric activity was not detected in the satellite when the space probe Voyager I had its nearest match with Titan in November 1980, however, due to the presence of methane clouds rain and of convective activity in the troposphere of the satellite, it is thought in the possible existence of electrical activity in this. In this work it is studied the production of gaseous compounds generated by irradiations type flash lightning in the Titan simulated atmosphere constituted by nitrogen and methane. The lightning are imitated by laser induced plasma (LIP) with similar physical properties to the naturals produced in the Earth. The separation and identification of the organic compounds generated by simulated lightning s were carried out by attached methods of analysis such as the Gas chromatography, Infrared spectroscopy with Fourier transform (FTIR-S) and Mass spectroscopy (MS). The compounds which were identified are: hydrocarbons and nitriles, some of them already have been identified in Titan as well as the hydrogen cyanide (HCN), acetylene, etilene and cyanoacetylene. Moreover we studied the influence that different parameters of irradiation have in the production of organic molecules generated submitting to discharges type lightning the simulated atmosphere of Titan. It was realized an estimation of the available energy in the satellite which could be vanished as discharges type lightning. By means of a model based on conditions of thermodynamic equilibria it was calculated the temperature to which are freeze

Formation of titanate nanostructures under different NaOH concentration and their application in wastewater treatment

International Nuclear Information System (INIS)

Huang Jiquan; Cao Yongge; Deng Zhonghua; Tong Hao

2011-01-01

The effects of the concentration of NaOH on the formation and transformation of various titanate nanostructures were studied. With increasing NaOH concentration, three different formation mechanisms were proposed. Nanotubes can only be obtained under moderate NaOH conditions, and should transform into nanowires with prolonged hydrothermal treatment, and their formation rate is accelerated by increasing NaOH concentration. Low concentration of NaOH results in the direct formation of nanowires, while extra high concentration of NaOH leads to the formation of amorphous nanoparticles. Adsorption and photocatalysis studies show that titanate nanowires and nanotubes might be potential adsorbents for the removal of both heavy metal ions and dyes and photocatalysts for the removal of dyes from wastewater. -- Graphical abstract: The morphologies of the titanates depend deeply on the concentration of NaOH. With increasing NaOH concentration, three different formation mechanisms were proposed. The application of these titanate nanostructures in the wastewater treatment was studied. Display Omitted Research highlights: → Effect of NaOH concentration on the structures of various titanates was reported. → Three different formation mechanisms were presented with increasing NaOH concentration. → Various titanates were used as adsorbents/photocatalysts in wastewater treatment.

Titan Coupled Surface/Atmosphere Retrievals

Science.gov (United States)

West, R. A.; Pitman, K. M.

2009-05-01

Titan's thick haze obscures its surface at visible wavelengths and hinders surface photometric studies in the near-infrared. The large vertical extent of the haze produces two effects which require radiative transfer analysis beyond the capability of plane-parallel multi-scatter models. Haze aerosols extend to altitudes above 500 km and require a spherical-shell RT algorithm close to the limb or terminator. Even near nadir viewing, horizontal scattering at spatial scales less than a few hundred km requires a code capable of simulating the adjacency effect. The adjacency effect will reduce contrast more for small spatial scales than for large spatial scales, and the amount of contrast reduction depends on many factors (haze optical thickness, vertical distribution, single scattering albedo, scattering geometry, spatial scale). Titan's haze is strongly forward scattering even near 1-µm wavelength and many RT codes do a poor job. Fortunately the problem is more tractable at longer wavelengths. We show how data from the Cassini VIMS and ISS instruments can be used to understand surface contrast and atmospheric haze properties.

Materials and ceramics on the base of aluminium titanate

International Nuclear Information System (INIS)

Gulamova, D.

1997-01-01

The influence of the doping and technological parameters on the thermodynamical stability of the aluminium titanate is investigated. The condition necessary to make aluminium titanate stable and established. it is shown, how the condition of the synthesis and the content of the admixture phases affect the stability of the solid solutions. The technology of obtaining the ceramics stable with respect to decay (with thermal expansion coefficient CTE = 26x10/sup -6/ grad/sup -1/ and thermoresistancy > 80 heating cycles, sigma curve equal or greater than 80 Mpa) is worked out. (author)

Titan's Gravitational Field

Science.gov (United States)

Schubert, G.; Anderson, J. D.

2013-12-01

Titan's gravitational field is inferred from an analysis of archived radio Doppler data for six Cassini flybys. The analysis considers each flyby separately in contrast to the approach of lumping all the data together in a massive inversion. In this way it is possible to gain an improved understanding of the character of each flyby and its usefulness in constraining the gravitational coefficient C22 . Though our analysis is not yet complete and our final determination of C22 could differ from the result we report here by 1 or 2 sigma, we find a best-fit value of C22 equal to (13.21 × 0.17) × 10-6, significantly larger than the value of 10.0 × 10-6 obtained from an inversion of the lumped Cassini data. We also find no determination of the tidal Love number k2. The larger value of C22 implies a moment of inertia factor equal to 0.3819 × 0.0020 and a less differentiated Titan than is suggested by the smaller value. The larger value of C22 is consistent with an undifferentiated model of the satellite. While it is not possible to rule out either value of C22 , we prefer the larger value because its derivation results from a more hands on analysis of the data that extracts the weak hydrostatic signal while revealing the effects of gravity anomalies and unmodeled spacecraft accelerations on each of the six flybys.

Electronic structure of barium strontium titanate by soft-x-ray absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Uehara, Y. [Mitsubishi Electric Co., Hyogo (Japan); Underwood, J.H.; Gullikson, E.M.; Perera, R.C.C. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

1997-04-01

Perovskite-type titanates, such as Strontium Titanate (STO), Barium Titanate (BTO), and Lead Titanate (PTO) have been widely studied because they show good electric and optical properties. In recent years, thin films of Barium Strontium Titanate (BST) have been paid much attention as dielectrics of dynamic random access memory (DRAM) capacitors. BST is a better insulator with a higher dielectric constant than STO and can be controlled in a paraelectric phase with an appropriate ratio of Ba/Sr composition, however, few studies have been done on the electronic structure of the material. Studies of the electronic structure of such materials can be beneficial, both for fundamental physics research and for improving technological applications. BTO is a famous ferroelectric material with a tetragonal structure, in which Ti and Ba atoms are slightly displaced from the lattice points. On the other hand, BST keeps a paraelectric phase, which means that the atoms are still at the cubic lattice points. It should be of great interest to see how this difference of the local structure around Ti atoms between BTO and BST effects the electronic structure of these two materials. In this report, the authors present the Ti L{sub 2,3} absorption spectra of STO, BTO, and BST measured with very high accuracy in energy of the absorption features.

Electronic structure of barium strontium titanate by soft-x-ray absorption spectroscopy

International Nuclear Information System (INIS)

Uehara, Y.; Underwood, J.H.; Gullikson, E.M.; Perera, R.C.C.

1997-01-01

Perovskite-type titanates, such as Strontium Titanate (STO), Barium Titanate (BTO), and Lead Titanate (PTO) have been widely studied because they show good electric and optical properties. In recent years, thin films of Barium Strontium Titanate (BST) have been paid much attention as dielectrics of dynamic random access memory (DRAM) capacitors. BST is a better insulator with a higher dielectric constant than STO and can be controlled in a paraelectric phase with an appropriate ratio of Ba/Sr composition, however, few studies have been done on the electronic structure of the material. Studies of the electronic structure of such materials can be beneficial, both for fundamental physics research and for improving technological applications. BTO is a famous ferroelectric material with a tetragonal structure, in which Ti and Ba atoms are slightly displaced from the lattice points. On the other hand, BST keeps a paraelectric phase, which means that the atoms are still at the cubic lattice points. It should be of great interest to see how this difference of the local structure around Ti atoms between BTO and BST effects the electronic structure of these two materials. In this report, the authors present the Ti L 2,3 absorption spectra of STO, BTO, and BST measured with very high accuracy in energy of the absorption features

High-performance single CdS nanowire (nanobelt) Schottky junction solar cells with Au/graphene Schottky electrodes.

Science.gov (United States)

Ye, Yu; Dai, Yu; Dai, Lun; Shi, Zujin; Liu, Nan; Wang, Fei; Fu, Lei; Peng, Ruomin; Wen, Xiaonan; Chen, Zhijian; Liu, Zhongfan; Qin, Guogang

2010-12-01

High-performance single CdS nanowire (NW) as well as nanobelt (NB) Schottky junction solar cells were fabricated. Au (5 nm)/graphene combined layers were used as the Schottky contact electrodes to the NWs (NBs). Typical as-fabricated NW solar cell shows excellent photovoltaic behavior with an open circuit voltage of ∼0.15 V, a short circuit current of ∼275.0 pA, and an energy conversion efficiency of up to ∼1.65%. The physical mechanism of the combined Schottky electrode was discussed. We attribute the prominent capability of the devices to the high-performance Schottky combined electrode, which has the merits of low series resistance, high transparency, and good Schottky contact to the CdS NW (NB). Besides, a promising site-controllable patterned graphene transfer method, which has the advantages of economizing graphene material and free from additional etching process, was demonstrated in this work. Our results suggest that semiconductor NWs (NBs) are promising materials for novel solar cells, which have potential application in integrated nano-optoelectronic systems.

Geodetic data support trapping of ethane in Titan's polar crust

Science.gov (United States)

Sotin, Christophe; Rambaux, Nicolas

2016-04-01

Titan's surface is characterized by polar depressions that strongly influence interpretations of the gravity data. This study investigates several geodynamical models that can explain these depressions. For each model, the values of the three moments of inertia are computed numerically by discretizing the interior in spherical coordinates. The study shows that a Pratt model where the polar subsurface is made of ethane clathrates can explain the polar depression, the abrupt jump in altitude at about 60 degrees latitude, and the values of the degree 2 gravity coefficients. This model, proposed by Choukroun and Sotin [1], is based on the stability of ethane clathrate hydrates relative to methane clathrate hydrates. In addition to fitting the geodetic data, it explains the absence of ethane in Titan's atmosphere although ethane is the main product of the photolysis of methane. Other geophysical models based on latitudinal variations in the tidal heating production or in the heat flux at the base of the icy crust do not provide such a good match to the gravity and topographic observations. The ethane-clathrate model predicts that all the ethane produced by photolysis of methane at the present rate during the last billion years could be stored in the polar subsurface. It is consistent with the age of Titan's surface and that of Titan's atmospheric methane inferred from geological and geochemical observations by the Cassini/Huygens mission. The present study also emphasizes the role of mass anomalies on the interpretation of the degree 2 gravity coefficients. It shows that for Titan, a slow rotator, the values of the two equatorial moments of inertia (MoI) are largely affected by the polar depressions whereas the value of polar MoI is not. Therefore, as pointed out by previous calculations [2], calculating the moment of inertia (MoI) factor from the value of J2 could lead to major errors. This is not the case for our preferred Titan's model for which the negative polar

Investigations of the Structure of Titanate Nanoscrolls

International Nuclear Information System (INIS)

Sheppard, D.A.; Buckley, C.E.

2005-01-01

Full text: Nanosized materials have attracted much research lately due to their unique properties and their potential application in nanoelectronic and optoelectronic devices. Nanostructured materials have also sparked interest as possible hydrogen storage candidates. Research at Curtin University has shown titanate nanoscrolls to absorb modest amounts of hydrogen at low temperatures. Whether or not this capacity can be improved will be dependent on a thorough understanding of the structure and the way it interacts with hydrogen. Titanate nanoscrolls are made via a soft chemical process that involves ageing TiO 2 powder in a concentrated NaOH solution. The resultant nanoscrolls, once filtered and washed, are typically 8-10 nm in diameter and hundreds of nanometers long. The walls consist of 3-5 layers and the diameter of the hollow centre is typically 5 nm. A number of different structures have been assigned to nanoscrolls produced via the soft chemical process. These include anatase, H 2 Ti 3 O 7 , lepidocrocite-type structure and H 2 Ti 4 O 9 .H 2 O. Many of these structures are similar, consisting of titanate type layers, and qualitatively reproduce the X-ray diffraction data. However, preliminary data suggests that these structures are inconsistent with neutron diffraction data. Here we attempt a more quantitative analysis of the structure than those published previously using neutron and X-ray diffraction. (authors)

Titan's Emergence from Winter

Science.gov (United States)

Flasar, F. Michael; Achterberg, Richard; Jennings, Donald; Schinder, Paul

2011-01-01

We summarize the changes in Titans thermal structure derived from Cassini CIRS and radio-occultation data during the transition from winter to early spring. Titan's surface, and middle atmosphere show noticeable seasonal change, whereas that in most of the troposphere is mated. This can be understood in terms of the relatively small radiative relaxation time in the middle atmosphere and much larger time scale in the troposphere. The surface exhibits seasonal change because the heat capacity in an annual skin depth is much smaller than that in the lowest scale height of the troposphere. Surface temperatures rise 1 K at raid and high latitudes in the winter northern hemisphere and cool in the southern hemisphere. Changes in in the middle atmosphere are more complicated. Temperatures in the middle stratosphere (approximately 1 mbar) increase by a few kelvin at mid northern latitudes, but those at high latitudes first increase as that region moves out of winter shadow, and then decrease. This probably results from the combined effect of increased solar heating as the suit moves higher in the sky and the decreased adiabatic warming as the sinking motions associated with the cross-equatorial meridional cell weaken. Consistent with this interpretation, the warm temperatures observed higher up at the winter polar stratopause cool significantly.

Organic chemistry in Titan's atmosphere

Science.gov (United States)

Scattergood, T.

1982-01-01

Laboratory photochemical simulations and other types of chemical simulations are discussed. The chemistry of methane, which is the major known constituent of Titan's atmosphere was examined with stress on what can be learned from photochemistry and particle irradiation. The composition of dust that comprises the haze layer was determined. Isotope fractionation in planetary atmospheres is also discussed.

Untangling the Chemical Evolution of Titan's Atmosphere and Surface -- From Homogeneous to Heterogeneous Chemistry

Energy Technology Data Exchange (ETDEWEB)

Kaiser, Ralf I.; Maksyutenko, Pavlo; Ennis, Courtney; Zhang, Fangtong; Gu, Xibin; Krishtal, Sergey P.; Mebel, Alexander M.; Kostko, Oleg; Ahmed, Musahid

2010-03-16

The arrival of the Cassini-Huygens probe at Saturn's moon Titan - the only Solar System body besides Earth and Venus with a solid surface and a thick atmosphere with a pressure of 1.4 atm at surface level - in 2004 opened up a new chapter in the history of Solar System exploration. The mission revealed Titan as a world with striking Earth-like landscapes involving hydrocarbon lakes and seas as well as sand dunes and lava-like features interspersed with craters and icy mountains of hitherto unknown chemical composition. The discovery of a dynamic atmosphere and active weather system illustrates further the similarities between Titan and Earth. The aerosol-based haze layers, which give Titan its orange-brownish color, are not only Titan's most prominent optically visible features, but also play a crucial role in determining Titan's thermal structure and chemistry. These smog-like haze layers are thought to be very similar to those that were present in Earth's atmosphere before life developed more than 3.8 billion years ago, absorbing the destructive ultraviolet radiation from the Sun, thus acting as 'prebiotic ozone' to preserve astrobiologically important molecules on Titan. Compared to Earth, Titan's low surface temperature of 94 K and the absence of liquid water preclude the evolution of biological chemistry as we know it. Exactly because of these low temperatures, Titan provides us with a unique prebiotic 'atmospheric laboratory' yielding vital clues - at the frozen stage - on the likely chemical composition of the atmosphere of the primitive Earth. However, the underlying chemical processes, which initiate the haze formation from simple molecules, have been not understood well to date.

Fabrication of barium titanate nanoparticles/poly (methylmethacrylate composite films by a combination of deposition process and spin-coating technique

Directory of Open Access Journals (Sweden)

Yoshio Kobayashi

2014-10-01

Full Text Available The present work proposes a method for fabricating poly(methylmethacrylate (PMMA film containing barium titanate (BT nanoparticles (BT/PMMA film. BT particles with an average size of 77.6 ± 30.5 nm and a crystal size of 28.1 nm were synthesized by adding sodium hydroxide aqueous solution to titanium tetraisopropoxide/acetylacetone/i-propanol solution suspending barium hydroxide. A sodium glass plate, of which surface was modified with polyvinylpyrrolidone, was immersed into water suspending the BT particles, which resulted in deposition of the BT particles on the plate. A BT/PMMA film was fabricated by twice performance of a process composed of spin-coating of N-methyl-2-pyrrolidone (NMP dissolving PMMA on the plate, and then drying the coated plate in the atmosphere at room temperature. Spin-coating of a PMMA/NMP solution with a PMMA concentration of 150 g/L at a rotating speed of 5000 rpm provided fabrication of a BT/PMMA film with a BT volume fraction of 35.5%, a thickness of ca. 300 nm, and a transmittance of ca. 90% in the visible light region.

Cassini/VIMS hyperspectral observations of the HUYGENS landing site on Titan

Science.gov (United States)

Rodriguez, S.; Le, Mouelic S.; Sotin, Christophe; Clenet, H.; Clark, R.N.; Buratti, B.; Brown, R.H.; McCord, T.B.; Nicholson, P.D.; Baines, K.H.

2006-01-01

Titan is one of the primary scientific objectives of the NASA-ESA-ASI Cassini-Huygens mission. Scattering by haze particles in Titan's atmosphere and numerous methane absorptions dramatically veil Titan's surface in the visible range, though it can be studied more easily in some narrow infrared windows. The Visual and Infrared Mapping Spectrometer (VIMS) instrument onboard the Cassini spacecraft successfully imaged its surface in the atmospheric windows, taking hyperspectral images in the range 0.4-5.2 ??m. On 26 October (TA flyby) and 13 December 2004 (TB flyby), the Cassini-Huygens mission flew over Titan at an altitude lower than 1200 km at closest approach. We report here on the analysis of VIMS images of the Huygens landing site acquired at TA and TB, with a spatial resolution ranging from 16 to14.4 km/pixel. The pure atmospheric backscattering component is corrected by using both an empirical method and a first-order theoretical model. Both approaches provide consistent results. After the removal of scattering, ratio images reveal subtle surface heterogeneities. A particularly contrasted structure appears in ratio images involving the 1.59 and 2.03 ??m images north of the Huygens landing site. Although pure water ice cannot be the only component exposed at Titan's surface, this area is consistent with a local enrichment in exposed water ice and seems to be consistent with DISR/Huygens images and spectra interpretations. The images show also a morphological structure that can be interpreted as a 150 km diameter impact crater with a central peak. ?? 2006 Elsevier Ltd. All rights reserved.

Temperature variations in Titan's upper atmosphere: Impact on Cassini/Huygens

Directory of Open Access Journals (Sweden)

B. Kazeminejad

2005-06-01

Full Text Available Temperature variations of Titan's upper atmosphere due to the plasma interaction of the satellite with Saturn's magnetosphere and Titan's high altitude monomer haze particles can imply an offset of up to ±30K from currently estimated model profiles. We incorporated these temperature uncertainties as an offset into the recently published Vervack et al. (2004 (Icarus, Vol. 170, 91-112 engineering model and derive extreme case (i.e. minimum and maximum profiles temperature, pressure, and density profiles. We simulated the Huygens probe hypersonic entry trajectory and obtain, as expected, deviations of the probe trajectory for the extreme atmosphere models compared to the simulation based on the nominal one. These deviations are very similar to the ones obtained with the standard Yelle et al. (1997 (ESA SP-1177 profiles. We could confirm that the difference in aerodynamic drag is of an order of magnitude that can be measured by the probe science accelerometer. They represent an important means for the reconstruction of Titan's upper atmospheric properties. Furthermore, we simulated a Cassini low Titan flyby trajectory. No major trajectory deviations were found. The atmospheric torques due to aerodynamic drag, however, are twice as high for our high temperature profile as the ones obtained with the Yelle maximum profile and more than 5 times higher than the worst case estimations from the Cassini project. We propose to use the Cassini atmospheric torque measurements during its low flybys to derive the atmospheric drag and to reconstruct Titan's upper atmosphere density, pressure, and temperature. The results could then be compared to the reconstructed profiles obtained from Huygens probe measurements. This would help to validate the probe measurements and decrease the error bars.

Titan's Primordial Soup: Formation of Amino Acids via Low-Temperature Hydrolysis of Tholins

Science.gov (United States)

Neish, Catherine D.; Somogyi, Árpád; Smith, Mark A.

2010-04-01

Titan organic haze analogues, or "tholins," produce biomolecules when hydrolyzed at low temperature over long timescales. By using a combination of high-resolution mass spectroscopy and tandem mass spectrometry fragmentation techniques, four amino acids were identified in a tholin sample that had been hydrolyzed in a 13 wt % ammonia-water solution at 253 ± 1 K and 293 ± 1 K for 1 year. These four species have been assigned as the amino acids asparagine, aspartic acid, glutamine, and glutamic acid. This represents the first detection of biologically relevant molecules created under conditions thought to be similar to those found in impact melt pools and cryolavas on Titan, which are at a stage of chemical evolution not unlike the "primordial soup" of the early Earth. Future missions to Titan should therefore carry instrumentation capable of, but certainly not limited to, detecting amino acids and other prebiotic molecules on Titan's surface.

Chemistry in Titan

Science.gov (United States)

Plessis, S.; Carrasco, N.; Pernot, P.

2009-04-01

Modelling the chemical composition of Titan's ionosphere is a very challenging issue. Latest works perform either inversion of CASSINI's INMS mass spectra (neutral[1] or ion[2]), or design coupled ion-neutral chemistry models[3]. Coupling ionic and neutral chemistry has been reported to be an essential feature of accurate modelling[3]. Electron Dissociative Recombination (EDR), where free electrons recombine with positive ions to produce neutral species, is a key component of ion-neutral coupling. There is a major difficulty in EDR modelling: for heavy ions, the distribution of neutral products is incompletely characterized by experiments. For instance, for some hydrocarbon ions only the carbon repartition is measured, leaving the hydrogen repartition and thus the exact neutral species identity unknown[4]. This precludes reliable deterministic modelling of this process and of ion-neutral coupling. We propose a novel stochastic description of the EDR chemical reactions which enables efficient representation and simulation of the partial experimental knowledge. The description of products distribution in multi-pathways reactions is based on branching ratios, which should sum to unity. The keystone of our approach is the design of a probability density function accounting for all available informations and physical constrains. This is done by Dirichlet modelling which enables one to sample random variables whose sum is constant[5]. The specifics of EDR partial uncertainty call for a hierarchiral Dirichlet representation, which generalizes our previous work[5]. We present results on the importance of ion-neutral coupling based on our stochastic model. C repartition H repartition (measured) (unknown ) → C4H2 + 3H2 + H .. -→ C4 . → C4H2 + 7H → C3H8. + CH C4H+9 + e- -→ C3 + C .. → C3H3 + CH2 + 2H2 → C2H6 + C2H2 + H .. -→ C2 + C2 . → 2C2H2 + 2H2 + H (1) References [1] J. Cui, R.V. Yelle, V. Vuitton, J.H. Waite Jr., W.T. Kasprzak

Titan from Cassini-Huygens

CERN Document Server

Brown, Robert H; Waite, J. Hunter

2010-01-01

This book reviews our current knowledge of Saturn's largest moon Titan featuring the latest results obtained by the Cassini-Huygens mission. A global author team addresses Titan’s origin and evolution, internal structure, surface geology, the atmosphere and ionosphere as well as magnetospheric interactions. The book closes with an outlook beyond the Cassini-Huygens mission. Colorfully illustrated, this book will serve as a reference to researchers as well as an introduction for students.

Large Abundances of Polycyclic Aromatic Hydrocarbons in Titan's Upper Atmosphere

Science.gov (United States)

Lopez-Puertas, M.; Dinelli, B. M.; Adriani, A.; Funke, B.; Garcia-Comas, M.; Moriconi, M. L.; D'Aversa, E.; Boersma, C.; Allamandola, L. J.

2013-01-01

In this paper, we analyze the strong unidentified emission near 3.28 micron in Titan's upper daytime atmosphere recently discovered by Dinelli et al.We have studied it by using the NASA Ames PAH IR Spectroscopic Database. The polycyclic aromatic hydrocarbons (PAHs), after absorbing UV solar radiation, are able to emit strongly near 3.3 micron. By using current models for the redistribution of the absorbed UV energy, we have explained the observed spectral feature and have derived the vertical distribution of PAH abundances in Titan's upper atmosphere. PAHs have been found to be present in large concentrations, about (2-3) × 10(exp 4) particles / cubic cm. The identified PAHs have 9-96 carbons, with a concentration-weighted average of 34 carbons. The mean mass is approx 430 u; the mean area is about 0.53 sq. nm; they are formed by 10-11 rings on average, and about one-third of them contain nitrogen atoms. Recently, benzene together with light aromatic species as well as small concentrations of heavy positive and negative ions have been detected in Titan's upper atmosphere. We suggest that the large concentrations of PAHs found here are the neutral counterpart of those positive and negative ions, which hence supports the theory that the origin of Titan main haze layer is located in the upper atmosphere.

Pressure-induced absorption coefficients for radiative transfer calculations in Titan's atmosphere

Science.gov (United States)

Courtin, Regis

1988-01-01

The semiempirical theory of Birnbaum and Cohen (1976) is used to calculate the FIR pressure-induced absorption (PIA) spectra of N2, CH4, N2 + Ar, N2 + CH4, and N2 + H2 under conditions like those in the Titan troposphere. The results are presented graphically and compared with published data from laboratory measurements of PIA in the same gases and mixtures (Dagg et al., 1986; Dore et al., 1986). Good agreement is obtained, with only a slight underestimation of PIA at 300-400/cm in the case of CH4. The absorption coefficients are presented in tables, and it is suggested that the present findings are of value for evaluating the effects of tropospheric clouds on the Titan FIR spectrum and studying the greenhouse effect near the Titan surface.

Formation of barium strontium titanate powder by solid state reaction using different calcination temperatures

International Nuclear Information System (INIS)

Teoh Wah Tzu; Ahmad Fauzi Mohd Noor; Zainal Arifin Ahmad

2002-01-01

The unique electrical properties of large permittivity in Barium Strontium Titanate have been widely used to make capacitors; it can be produced by solid state reaction. In this study, the mixture of Barium Carbonate, Strontium Carbonate and Titanium Dioxide was calcined at 500 degree C, 1000 degree C, 1100 degree C , 1150 degree C, 1200 degree C, 1250 degree C and 1300 degree C. The results of the phases change in each stage were investigated via X ay Diffraction. The results show that the formation of Barium Strontium Titanate started at 1100 degree C with the presence of other phases. The mixture is fully reacted to form Barium Strontium Titanate at 1150 degree C. Only Barium Strontium Titanate was formed as the calcination temperature was set higher. (Author)

Characteristics of (Ti,Ta)N thin films prepared by using pulsed high energy density plasma

Energy Technology Data Exchange (ETDEWEB)

Feng Wenran [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Chen Guangliang [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Li Li [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Lv Guohua [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Zhang Xianhui [College of Science, Changchun University of Science and Technology, Changchun 130022, Jilin Province (China); Niu Erwu [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Liu Chizi [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Yang Size [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)

2007-07-21

(Ti,Ta)N films were prepared by pulsed high energy density plasma (PHEDP) from a coaxial gun in N{sub 2} gas. The coaxial gun is composed of a tantalum inner electrode and a titanium outer one. Material characteristics of the (Ti,Ta)N film were investigated by x-ray photoelectron spectroscopy and x-ray diffraction. The microstructure of the film was observed by a scanning electron microscope. The elemental composition and the interface of the film/substrate were analysed using Auger electron spectrometry. Our results suggest that the binary metal nitride film (Ti,Ta)N, can be prepared by PHEDP. It also shows that dense nanocrystalline (Ti,Ta)N film can be achieved.

Chemical compatibility study of lithium titanate with Indian reduced activation ferritic martensitic steel

International Nuclear Information System (INIS)

Sonak, Sagar; Jain, Uttam; Haldar, Rumu; Kumar, Sanjay

2015-01-01

Highlights: • Chemical compatibility between Li_2TiO_3 and Indian RAFM steel has been studied at ITER operating temperature. • The lithium titanate chemically reacted with ferritic martensitic steel to form a brittle and non-adherent oxide layer. • The layer grew in a parabolic manner as a function of heating time. • Diffusion of oxygen (from Li_2TiO_3) appears to be controlling the oxide layer. - Abstract: Chemical compatibility between lithium titanate and Indian reduced activation ferritic-martensitic steel (In-RAFMS) was studied for the first time under ITER operating temperature. Lithium titanate required for the study was synthesized in-house. Coupons of In-RAFMS were packed inside lithium titanate powder and heated at 550 °C up to 900 h under inert argon atmosphere. The lithium titanate chemically reacted with ferritic martensitic steel to form a brittle and non-adherent oxide layer. The layer grew in a parabolic manner as a function of heating time. Microstructural and phase evolution of this oxide layer was studied using XRD, SEM and EPMA. Iron and chromium enriched zones were found within the oxide layer. Diffusion of oxygen (from Li_2TiO_3) appears to be controlling the oxide layer.

Titan's Surface Temperatures Maps from Cassini - CIRS Observations

Science.gov (United States)

Cottini, Valeria; Nixon, C. A.; Jennings, D. E.; Anderson, C. M.; Samuelson, R. E.; Irwin, P. G. J.; Flasar, F. M.

2009-09-01

The Cassini Composite Infrared Spectrometer (CIRS) observations of Saturn's largest moon, Titan, are providing us with the ability to detect the surface temperature of the planet by studying its outgoing radiance through a spectral window in the thermal infrared at 19 μm (530 cm-1) characterized by low opacity. Since the first acquisitions of CIRS Titan data the instrument has gathered a large amount of spectra covering a wide range of latitudes, longitudes and local times. We retrieve the surface temperature and the atmospheric temperature profile by modeling proper zonally averaged spectra of nadir observations with radiative transfer computations. Our forward model uses the correlated-k approximation for spectral opacity to calculate the emitted radiance, including contributions from collision induced pairs of CH4, N2 and H2, haze, and gaseous emission lines (Irwin et al. 2008). The retrieval method uses a non-linear least-squares optimal estimation technique to iteratively adjust the model parameters to achieve a spectral fit (Rodgers 2000). We show an accurate selection of the wide amount of data available in terms of footprint diameter on the planet and observational conditions, together with the retrieved results. Our results represent formal retrievals of surface brightness temperatures from the Cassini CIRS dataset using a full radiative transfer treatment, and we compare to the earlier findings of Jennings et al. (2009). In future, application of our methodology over wide areas should greatly increase the planet coverage and accuracy of our knowledge of Titan's surface brightness temperature. References: Irwin, P.G.J., et al.: "The NEMESIS planetary atmosphere radiative transfer and retrieval tool" (2008). JQSRT, Vol. 109, pp. 1136-1150, 2008. Rodgers, C. D.: "Inverse Methods For Atmospheric Sounding: Theory and Practice". World Scientific, Singapore, 2000. Jennings, D.E., et al.: "Titan's Surface Brightness Temperatures." Ap. J. L., Vol. 691, pp. L103-L

Photoreactivity of condensed species in Titan lower atmosphere

Science.gov (United States)

Fleury, Benjamin; Gudipati, Murthy; Couturier-Tamburelli, Isabelle; Carrasco, Nathalie

2017-10-01

Photochemical processes initiated in the thermosphere of Titan at about 1000 km by the dissociation and the ionization of N2 and CH4 by the VUV solar photons [1] lead to the formation of a number of hydrocarbons and nitriles species. Some of these species can condense in the troposphere and the lower stratosphere of Titan ( 300 nm) can reach these lower atmospheric layers [4], ongoing possible further solid-state chemistry as demonstrated experimentally [5]. We will present here an experimental study simulating the reactivity of ices in the atmosphere of Titan and will discuss the photoreactivity occurring in the lower atmospheric layers of Titan despite the absorption of the most energetic photons.AcknowledgmentsThis work is supported by NASA Solar System Workings grant " Photochemistry in Titan’s Lower Atmosphere". The research work has been carried out at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration. NC acknowledges the European Research Council for their financial support (ERC Starting Grant PRIMCHEM, grant agreement n°636829).References[1] Waite, J. H., et al., The process of Tholin formation in Titan’s upper atmosphere, (2007), Science 316, 870-875.[2] Barth, E. L., Modeling survey of ices in Titan’s stratosphere, (2017), Planetary and Space Science 137, 20-31.[3] Fulchignoni, M., et al., In situ measurements of the physical characteristics of Titan’s environment, (2005), Nature 438, 785-791.[4] Tomasko, M. G., et al., Rain, winds and haze during the Huygens probe’s descent to Titan’s surface, (2005), Nature 438, 765-778.[5] Gudipati, M. S., et al., Photochemical activity of Titan’s low-altitude condensed haze, (2013), Nature Communications, 4: p1648.

ALMA OBSERVATIONS OF HCN AND ITS ISOTOPOLOGUES ON TITAN

Energy Technology Data Exchange (ETDEWEB)

Molter, Edward M.; Nixon, C. A.; Cordiner, M. A.; Charnley, S. B.; Lindberg, J. E. [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Serigano, J. [Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218 (United States); Irwin, P. G. J. [Atmospheric, Oceanic, and Planetary Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU (United Kingdom); Teanby, N. A., E-mail: edward.m.molter@nasa.gov [School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol, BS8 1RJ (United Kingdom)

2016-08-01

We present sub-millimeter spectra of HCN isotopologues on Titan, derived from publicly available ALMA flux calibration observations of Titan taken in early 2014. We report the detection of a new HCN isotopologue on Titan, H{sup 13}C{sup 15}N, and confirm an earlier report of detection of DCN. We model high signal-to-noise observations of HCN, H{sup 13}CN, HC{sup 15}N, DCN, and H{sup 13}C{sup 15}N to derive abundances and infer the following isotopic ratios: {sup 12}C/{sup 13}C = 89.8 ± 2.8, {sup 14}N/{sup 15}N = 72.3 ± 2.2, D/H = (2.5 ± 0.2) × 10{sup −4}, and HCN/H{sup 13}C{sup 15}N = 5800 ± 270 (1 σ errors). The carbon and nitrogen ratios are consistent with and improve on the precision of previous results, confirming a factor of ∼2.3 elevation in {sup 14}N/{sup 15}N in HCN compared to N{sub 2} and a lack of fractionation in {sup 12}C/{sup 13}C from the protosolar value. This is the first published measurement of D/H in a nitrile species on Titan, and we find evidence for a factor of ∼2 deuterium enrichment in hydrogen cyanide compared to methane. The isotopic ratios we derive may be used as constraints for future models to better understand the fractionation processes occurring in Titan’s atmosphere.

Fabrication of novel Ag−TiO{sub 2} nanobelts as a photoanode for enhanced photovoltage performance in dye sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Wang, Yang [Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan 430074 (China); Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Li, Zhen, E-mail: zhenli@cug.edu.cn [Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan 430074 (China); Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Cao, Ya; Li, Fei; Zhao, Wen; Liu, Xueqin; Yang, Jianbo [Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan 430074 (China); Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China)

2016-08-25

TiO{sub 2} nanobelts (TiO{sub 2}NBs) were successfully prepared using a solvothermal route via Ti foil as substrate in large scales. The morphology evolution process and formation mechanism of the as-obtained products were investigated in detail. On the basis of this novel structure, chemical sensitive Ag modified TiO{sub 2}NBs nanocomposites (Ag−TiO{sub 2}NBs) were fabricated. It was found that Ag−TiO{sub 2}NBs exhibit strong light absorption and efficient electron transport. According to Mott-Schottky analysis, Ag−TiO{sub 2}NBs show less surface trapping sites compared with TiO{sub 2}NBs. The Ag−TiO{sub 2}NBs photoanode fabricated in 0.01 M AgNO{sub 3} demonstrates the best performance with a short-circuit current of 11.9 mA cm{sup −2} corresponding to a photoelectric conversion efficiency of 4.89%, which is higher than that of pure TiO{sub 2}NBs based solar cell by 60%. - Graphical abstract: J-V curves of DSSCs based on TiO{sub 2}NPs, TiO{sub 2}NBs and Ag−TiO{sub 2}NBs—X under AM 1.5 conditions (100 mW cm{sup −2}). Ag−TiO{sub 2}NBs nanocomposites were prepared via a simple and effective method. Owing to strong light absorption and efficient electron transport, Ag−TiO{sub 2}NBs—0.01 M shows a PCE of 4.89% when prepared as a photoanode in DSSCs. - Highlights: • A facile route was adopted to construct well-dispersed Ag nanoparticles on TiO{sub 2} nanobelts (Ag—TiO{sub 2}NBs). • Structure and photoelectrochemical properties of Ag—TiO{sub 2}NBs were studied. • Ag nanoparticles were found to modify the defects of TiO{sub 2}NBs. • Enhanced photovoltaic property of Ag—TiO{sub 2}NBs, compared to TiO{sub 2}NBs.

The evolution of Titan's high-altitude aerosols under ultraviolet irradiation

Science.gov (United States)

Carrasco, Nathalie; Tigrine, Sarah; Gavilan, Lisseth; Nahon, Laurent; Gudipati, Murthy S.

2018-04-01

The Cassini-Huygens space mission revealed that Titan's thick brownish haze is initiated high in the atmosphere at an altitude of about 1,000 km, before a slow transportation down to the surface. Close to the surface, at altitudes below 130 km, the Huygens probe provided information on the chemical composition of the haze. So far, we have not had insights into the possible photochemical evolution of the aerosols making up the haze during their descent. Here, we address this atmospheric aerosol aging process, simulating in the laboratory how solar vacuum ultraviolet irradiation affects the aerosol optical properties as probed by infrared spectroscopy. An important evolution was found that could explain the apparent contradiction between the nitrogen-poor infrared spectroscopic signature observed by Cassini below 600 km of altitude in Titan's atmosphere and a high nitrogen content as measured by the aerosol collector and pyrolyser of the Huygens probe at the surface of Titan.

Radioisotope Stirling Engine Powered Airship for Atmospheric and Surface Exploration of Titan

Science.gov (United States)

Colozza, Anthony J.; Cataldo, Robert L.

2014-01-01

The feasibility of an advanced Stirling radioisotope generator (ASRG) powered airship for the near surface exploration of Titan was evaluated. The analysis did not consider the complete mission only the operation of the airship within the atmosphere of Titan. The baseline airship utilized two ASRG systems with a total of four general-purpose heat source (GPHS) blocks. Hydrogen gas was used to provide lift. The ASRG systems, airship electronics and controls and the science payload were contained in a payload enclosure. This enclosure was separated into two sections, one for the ASRG systems and the other for the electronics and payload. Each section operated at atmospheric pressure but at different temperatures. The propulsion system consisted of an electric motor driving a propeller. An analysis was set up to size the airship that could operate near the surface of Titan based on the available power from the ASRGs. The atmospheric conditions on Titan were modeled and used in the analysis. The analysis was an iterative process between sizing the airship to carry a specified payload and the power required to operate the electronics, payload and cooling system as well as provide power to the propulsion system to overcome the drag on the airship. A baseline configuration was determined that could meet the power requirements and operate near the Titan surface. From this baseline design additional trades were made to see how other factors affected the design such as the flight altitude and payload mass and volume.

Microwave-hydrothermal synthesis of barium strontium titanate nanoparticles

International Nuclear Information System (INIS)

Simoes, A.Z.; Moura, F.; Onofre, T.B.; Ramirez, M.A.; Varela, J.A.; Longo, E.

2010-01-01

Research highlights: → Barium strontium titanate nanoparticles were obtained by the Hydrothemal microwave technique (HTMW) → This is a genuine technique to obtain nanoparticles at low temperature and short times → Barium strontium titanate free of carbonates with tetragonal structure was grown at 130 o C. - Abstract: Hydrothermal-microwave method (HTMW) was used to synthesize crystalline barium strontium titanate (Ba 0.8 Sr 0.2 TiO 3 ) nanoparticles (BST) in the temperature range of 100-130 o C. The crystallization of BST with tetragonal structure was reached at all the synthesis temperatures along with the formation of BaCO 3 as a minor impurity at lower syntheses temperatures. Typical FT-IR spectra for tetragonal (BST) nanoparticles presented well defined bands, indicating a substantial short-range order in the system. TG-DTA analyses confirmed the presence of lattice OH- groups, commonly found in materials obtained by HTMW process. FE/SEM revealed that lower syntheses temperatures led to a morphology that consisted of uniform grains while higher syntheses temperature consisted of big grains isolated and embedded in a matrix of small grains. TEM has shown BST nanoparticles with diameters between 40 and 80 nm. These results show that the HTMW synthesis route is rapid, cost effective, and could serve as an alternative to obtain BST nanoparticles.

Effects of PEG4000 template on sol-gel synthesis of porous cerium titanate photocatalyst

Science.gov (United States)

Zhang, Wenjie; Tao, Yingjie; Li, Chuanguo

2018-04-01

Porous cerium titanate was synthesized by sol-gel method, using polyethylene glycol (PEG4000) as template agent. Brannerite structured CeTi2O6 in monoclinic system is the major substance formed in the materials. Formation of CeO2 and rutile TiO2 depends on the amount of PEG4000. The addition of PEG4000 leads to production of fine particles in the samples, but it does not apparently affect the band gap energy. Pore volume of the cerium titanate sample continuously increases with rising PEG4000 amount. The sample obtained using 3.5 g PEG4000 has BET surface area of 16.2 m2/g and pore volume of 0.0232 cm3/g. The addition of PEG4000 can obviously promote photocatalytic activity of cerium titanate, which can be proven by both enhanced production of hydroxyl radical and ofloxacin degradation efficiency. As much as 95.2% of the initial ofloxacin molecules are removed from the solution after 50 min of photocatalytic degradation on the cerium titanate obtained using 3.5 g PEG4000, while only 48.4% ofloxacin is removed on cerium titanate obtained without PEG4000.

Investigating the Chemical Pathways to PAH- and PANH-Based Aerosols in Titan's Atmospheric chemistry

Science.gov (United States)

Sciamma-O'Brien, Ella Marion; Contreras, Cesar; Ricketts, Claire Louise; Salama, Farid

2011-01-01

A complex organic chemistry between Titan's two main constituents, N2 and CH4, leads to the production of more complex molecules and subsequently to solid organic aerosols. These aerosols are at the origin of the haze layers giving Titan its characteristic orange color. In situ measurements by the Ion Neutral Mass Spectrometer (INMS) and Cassini Plasma Spectrometer (CAPS) instruments onboard Cassini have revealed the presence of large amounts of neutral, positively and negatively charged heavy molecules in the ionosphere of Titan. In particular, benzene (C6H6) and toluene (C6H5CH3), which are critical precursors of polycyclic aromatic hydrocarbon (PAH) compounds, have been detected, suggesting that PAHs might play a role in the production of Titan s aerosols. Moreover, results from numerical models as well as laboratory simulations of Titan s atmospheric chemistry are also suggesting chemical pathways that link the simple precursor molecules resulting from the first steps of the N2-CH4 chemistry (C2H2, C2H4, HCN ...) to benzene, and to PAHs and nitrogen-containing PAHs (or PANHs) as precursors to the production of solid aerosols.

The Titan Environmental Transmission Electron Microscope

DEFF Research Database (Denmark)

Hansen, Thomas Willum; Wagner, Jakob Birkedal; Jinschek, Jörg R.

2009-01-01

University of Denmark (DTU) provides a unique combination of techniques for studying materials of interest to the catalytic as well as the electronics and other communities [5]. DTU’s ETEM is based on the FEI Titan platform providing ultrahigh microscope stability pushing the imaging resolution into the sub...

Electronic properties of lithium titanate ceramic

International Nuclear Information System (INIS)

Padilla-Campos, Luis; Buljan, Antonio

2001-01-01

Research on tritium breeder material is fundamental to the development of deuterium-tritium type fusion reactors for producing clean, non contaminating, electrical energy, since only energy and helium, a harmless gas, are produced from the fusion reaction. Lithium titanate ceramic is one of the possible candidates for the tritium breeder material. This last material is thought to form part of the first wall of the nucleus of the reactor which will provide the necessary tritium for the fusion and will also serve as a shield. Lithium titanate has advantageous characteristics compared to other materials. Some of these are low activation under the irradiation of neutrons, good thermal stability, high density of lithium atoms and relatively fast tritium release at low temperatures. However, there are still several physical and chemical properties with respect to the tritium release mechanism and mechanical properties that have not been studied at all. This work presents a theoretical study of the electronic properties of lithium titanate ceramic and the corresponding tritiated material. Band calculations using the Extended H kel Tight-Binding approach were carried out. Results show that after substituting lithium for tritium atoms, the electronic states for the latter appear in the middle of prohibited band gap which it is an indication that the tritiated material should behave as a semiconductor, contrary to Li 2 TiO 3 which is a dielectric isolator. A study was also carried out to determine the energetically most favorable sites for the substitution of lithium for tritium atoms. Additionally, we analyzed possible pathways for the diffusion of a tritium atom within the crystalline structure of the Li 2 TiO 3

Lanthanoid titanate film structure deposited at different temperatures in vacuum

International Nuclear Information System (INIS)

Kushkov, V.D.; Zaslavskij, A.M.; Mel'nikov, A.V.; Zverlin, A.V.; Slivinskaya, A.Eh.

1991-01-01

Influence of deposition temperature on the structure of lanthanoid titanate films, prepared by the method of high-rate vacuum condensation. It is shown that formation of crystal structure, close to equilibrium samples, proceeds at 1100-1300 deg C deposition temperatures. Increase of temperature in this range promotes formation of films with higher degree of structural perfection. Amorphous films of lanthanoid titanates form at 200-1000 deg C. Deposition temperature shouldn't exceed 1400 deg C to prevent the formation of perovskite like phases in films

Internal gravity waves in Titan's atmosphere observed by Voyager radio occultation

Science.gov (United States)

Hinson, D. P.; Tyler, G. L.

1983-01-01

The radio scintillations caused by scattering from small-scale irregularities in Titan's neutral atmosphere during a radio occultation of Voyager 1 by Titan are investigated. Intensity and frequency fluctuations occurred on time scales from about 0.1 to 1.0 sec at 3.6 and 13 cm wavelengths whenever the radio path passed within 90 km of the surface, indicating the presence of variations in refractivity on length scales from a few hundred meters to a few kilometers. Above 25 km, the altitude profile of intensity scintillations closely agrees with the predictions of a simple theory based on the characteristics of internal gravity waves propagating with little or no attenuation through the vertical stratification in Titan's atmosphere. These observations support a hypothesis of stratospheric gravity waves, possibly driven by a cloud-free convective region in the lowest few kilometers of the stratosphere.

TITAN: an advanced three-dimensional neutronics/thermal-hydraulics code for light water reactor safety analysis

International Nuclear Information System (INIS)

Griggs, D.P.; Kazimi, M.S.; Henry, A.F.

1982-01-01

The initial development of TITAN, a three-dimensional coupled neutronics/thermal-hydraulics code for LWR safety analysis, has been completed. The transient neutronics code QUANDRY has been joined to the two-fluid thermal-hydraulics code THERMIT with the appropriate feedback mechanisms modeled. A detailed steady-state and transient coupling scheme based on the tandem technique was implemented in accordance with the important structural and operational characteristics of QUANDRY and THERMIT. A two channel sample problem formed the basis for steady-state and transient analyses performed with TITAN. TITAN steady-state results were compared with those obtained with MEKIN and showed good agreement. Null transients, simulated turbine trip transients, and a rod withdrawal transient were analyzed with TITAN and reasonable results were obtained

Titan Submarine: Exploring the Depths of Kraken

Data.gov (United States)

National Aeronautics and Space Administration — Titan is unique in the outer solar system in that it is the only one of the bodies outside the Earth with liquid lakes and seas on its surface. The Titanian seas,...

Noble gases, nitrogen, and methane from the deep interior to the atmosphere of Titan

Science.gov (United States)

Glein, Christopher R.

2015-04-01

Titan's thick N2-CH4 atmosphere is unlike any in the Solar System, and its origin has been shrouded in mystery for over half a century. Here, I perform a detailed analysis of chemical and isotopic data from the Cassini-Huygens mission to develop the hypothesis that Titan's (non-photochemical) atmospheric gases came from deep within. It is suggested that Titan's CH4, N2, and noble gases originated in a rocky core buried inside the giant satellite, and hydrothermal and cryovolcanic processes were critical to the creation of Titan's atmosphere. Mass balance and chemical equilibrium calculations demonstrate that all aspects of this hypothesis can be considered geochemically plausible with respect to contemporary observational, experimental, and theoretical knowledge. Specifically, I show that a rocky core with a bulk noble gas content similar to that in CI carbonaceous meteorites would contain sufficient 36Ar and 22Ne to explain their reported abundances. I also show that Henry's law constants for noble gases in relevant condensed phases can be correlated with the size of their atoms, which leads to expected mixing ratios for 84Kr (∼0.2 ppbv) and 132Xe (∼0.01 ppbv) that can explain why these species have yet to be detected (Huygens upper limit serpentinization). I show that sufficient CH4 can be produced to replenish Titan's atmosphere many times over in the face of irreversible photolysis and escape of CH4, which is consistent with the favored model of episodic cryovolcanic outgassing. There should also have been enough NH3 inside Titan so that its thermal decomposition in a hot rocky core can generate the observed atmospheric N2, and if correct this model would imply that Titan's interior has experienced vigorous hydrothermal processing. The similarity in 14N/15N between cometary NH3 and Titan's N2 is consistent with this picture. As for the isotopes in CH4, I show that their observed relative abundances can be explained by low-temperature (∼20 °C) equilibria

Low temperature alkaline pH hydrolysis of oxygen-free Titan tholins

Science.gov (United States)

Brassé, Coralie; Buch, Arnaud; Raulin, François; Coll, Patrice; Poch, Olivier; Ramirez, Sandra

2014-05-01

The largest moon of Saturn, Titan, is known for its dense, nitrogen-rich atmosphere. The organic aerosols which are produced in Titan's atmosphere are of great astrobiological interest, particularly because of their potential evolution when they reach the surface and may interact with putative ammonia-water cryomagma[1]. In this context we have followed the evolution of alkaline pH hydrolysis (25wt% ammonia-water) of Titan tholins (produced by an experimental setup using a plasma DC discharge named PLASMA) at low temperature. Urea has been identified as one of the main product of tholins hydrolysis along with several amino acids (alanine, glycine and aspartic acid). However, those molecules have also been detected in non-hydrolyzed tholins. One explanation is a possible oxygen leak in the PLASMA reactor during the tholins synthesis[2]. Following this preliminary study the synthesis protocol has been improved by isolating the whole device in a specially designed glove box which protect the PLASMA experiment from the laboratory atmosphere. Once we confirmed the non-presence of oxygen in tholins, we performed alkaline pH hydrolysis of oxygen-free tholins. Then we verify that the organic compounds cited above are still produced in-situ. Moreover, a recent study shows that the subsurface ocean may contain a lower fraction of ammonia (about 5wt% or less[3]), than the one used until now in this kind of experimental study[2, 4]. Thus, we have carried out new hydrolysis experiments which take this lower value into account. Additional studies have provided new highlights on the bulk composition of Titan for various gas species. Indeed, the observed Saturn's atmosphere enrichment constrains the composition of the planetesimals present in the feeding zone of Saturn. The enrichment in volatiles in Saturn's atmosphere has been reproduced by assuming the presence of specific gas species[5, 6], in particular CO2 and H2S. In the present study we assume that those gas species have

Verification of a hybrid adjoint methodology in Titan for single photon emission computed tomography - 316

International Nuclear Information System (INIS)

Royston, K.; Haghighat, A.; Yi, C.

2010-01-01

The hybrid deterministic transport code TITAN is being applied to a Single Photon Emission Computed Tomography (SPECT) simulation of a myocardial perfusion study. The TITAN code's hybrid methodology allows the use of a discrete ordinates solver in the phantom region and a characteristics method solver in the collimator region. Currently we seek to validate the adjoint methodology in TITAN for this application using a SPECT model that has been created in the MCNP5 Monte Carlo code. The TITAN methodology was examined based on the response of a single voxel detector placed in front of the heart with and without collimation. For the case without collimation, the TITAN response for single voxel-sized detector had a -9.96% difference relative to the MCNP5 response. To simulate collimation, the adjoint source was specified in directions located within the collimator acceptance angle. For a single collimator hole with a diameter matching the voxel dimension, a difference of -0.22% was observed. Comparisons to groupings of smaller collimator holes of two different sizes resulted in relative differences of 0.60% and 0.12%. The number of adjoint source directions within an acceptance angle was increased and showed no significant change in accuracy. Our results indicate that the hybrid adjoint methodology of TITAN yields accurate solutions greater than a factor of two faster than MCNP5. (authors)

Thermal stability of titanate nanotubes

Czech Academy of Sciences Publication Activity Database

Králová, Daniela; Kužel, R.; Kovářová, Jana; Dybal, Jiří; Šlouf, Miroslav

2009-01-01

Roč. 16, 2a (2009), s. 41-43 ISSN 1211-5894. [Struktura - Colloquium of Czech and Slovak Crystallographic Association. Hluboká nad Vltavou, 22.06.2009-25.06.2009] R&D Projects: GA ČR GA203/07/0717; GA AV ČR KAN200520704 Institutional research plan: CEZ:AV0Z40500505 Keywords : titanate nanotubes * thermal stability Subject RIV: CD - Macromolecular Chemistry

The MR-TOF-MS isobar separator for the TITAN facility at TRIUMF

Energy Technology Data Exchange (ETDEWEB)

Jesch, Christian; Dickel, Timo, E-mail: t.dickel@gsi.de; Plaß, Wolfgang R. [Justus-Liebig-University (Germany); Short, Devin [Simon Fraser University (Canada); Ayet San Andres, Samuel [Justus-Liebig-University (Germany); Dilling, Jens [TRIUMF (Canada); Geissel, Hans; Greiner, Florian; Lang, Johannes [Justus-Liebig-University (Germany); Leach, Kyle G. [Simon Fraser University (Canada); Lippert, Wayne; Scheidenberger, Christoph [Justus-Liebig-University (Germany); Yavor, Mikhail I. [Institute for Analytical Instrumentation, Russian Academy of Science (Russian Federation)

2015-11-15

At TRIUMF’s Ion Trap for Atomic and Nuclear Science (TITAN) a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) will extend TITAN’s capabilities and facilitate mass measurements and in-trap decay spectroscopy of exotic nuclei that so far have not been possible due to strong isobaric contamination. This MR-TOF-MS will also enable mass measurements of very short-lived nuclides (half-life > 1 ms) that are produced in very low quantities (a few detected ions overall). In order to allow the installation of an MR-TOF-MS in the restricted space on the platform, on which the TITAN facility is located, novel mass spectrometric methods have been developed. Transport, cooling and distribution of the ions inside the device is done using a buffer gas-filled RFQ-based ion beam switchyard. Mass selection is achieved using a dynamic retrapping technique after time-of-flight analysis in an electrostatic isochronous reflector system. Only due to the combination of these novel methods the realization of an MR-TOF-MS based isobar separator at TITAN has become possible. The device has been built, commissioned off-line and is currently under installation at TITAN.

A Three-Dimensional View of Titan's Surface Features from Cassini RADAR Stereogrammetry

Science.gov (United States)

Kirk, R. L.; Howington-Kraus, E.; Redding, B. L.; Becker, T. L.; Lee, E. M.; Stiles, B. W.; Hensley, S.; Hayes, A.; Lopes, R. M.; Lorenz, R. D.; Mitchell, K. L.; Radebaugh, J.; Paganelli, F.; Soderblom, L. A.; Stofan, E. R.; Wood, C. A.; Wall, S. D.; Cassini RADAR Team

2008-12-01

As of the end of its four-year Prime Mission, Cassini has obtained 300-1500 m resolution synthetic aperture radar images of the surface of Titan during 19 flybys. The elongated image swaths overlap extensively, and ~2% of the surface has now been imaged two or more times. The majority of image pairs have different viewing directions, and thus contain stereo parallax that encodes information about Titan's surface relief over distances of ~1 km and greater. As we have previously reported, the first step toward extracting quantitative topographic information was the development of rigorous "sensor models" that allowed the stereo systems previously used at the USGS and JPL to map Venus with Magellan images to be used for Titan mapping. The second major step toward extensive topomapping of Titan has been the reprocessing of the RADAR images based on an improved model of the satellite's rotation. Whereas the original images (except for a few pairs obtained at similar orbital phase, some of which we have mapped previously) were offset by as much as 30 km, the new versions align much better. The remaining misalignments, typically carbono)logic" cycle of precipitation, evaporation, and surface and subsurface fluid flow?

Electrochemical preparation of MnO2 nanobelts through pulse base-electrogeneration and evaluation of their electrochemical performance

Science.gov (United States)

Aghazadeh, Mustafa; Maragheh, Mohammad Ghannadi; Ganjali, Mohammad Reza; Norouzi, Parviz; Faridbod, Farnoush

2016-02-01

Cathodic electrodeposition of MnO2 from a nitrate solution, via pulsed base (OH-) electrogeneration was performed for the first time. The deposition experiments were performed in a pulse current mode in typical on-times and off-times (i.e. ton = 1 s and toff = 1 s) with a peak current density of 2 mA cm-2 (Ia = 2 mA cm-2). The structural characterizations conducted by XRD and FTIR techniques revealed that the prepared MnO2 is composed of both α and γ phases. Morphological observation by SEM and TEM showed that the prepared MnO2 is made up of nanobelts with uniform shapes (an average diameter and length of 50 nm and 1 μm, respectively). Further electrochemical measurements by cyclic voltammetry and charge-discharge techniques revealed that the prepared MnO2 nanostructures have excellent capacitive behaviors, like a specific capacitance of 235.5 F g-1 and capacity retention of 91.3% after 1000 cycling at the scan rate of 25 mV s-1.

Facile fabrication of robust TiO2@SnO2@C hollow nanobelts for outstanding lithium storage

Science.gov (United States)

Tian, Qinghua; Li, Lingxiangyu; Chen, Jizhang; Yang, Li; Hirano, Shin-ichi

2018-02-01

Elaborate fabrication of state-of-the-art nanostructure SnO2@C-based composites greatly contributes to alleviate the huge volume expansion issue of the SnO2 anodes. But the preparation processes of most of them are complicated and tedious, which is generally adverse to the development of SnO2@C-based composite anodes. Herein, a unique nanostructure of TiO2@SnO2@C hollow nanobelts (TiO2@SnO2@C HNBs), including the characteristics of one-dimensional architecture, sandwich protection, hollow structure, carbon coating, and a mechanically robust TiO2 support, has been fabricated by a facile approach for the first time. As anodes for lithium-ion batteries, the as-fabricated TiO2@SnO2@C HNBs exhibit an outstanding lithium storage performance, delivering capacity of 804.6 and 384. 5 mAh g-1 at 200 and even 1000 mA g-1 after 500 cycles, respectively. It is demonstrated that thus outstanding performance is mainly attributed to the unique nanostructure of TiO2@SnO2@C HNBs.

Environmental risks and environmental justice, or how titanic risks are not so titanic after all.

Science.gov (United States)

Alario, Margarita V; Freudenburg, William R

2010-01-01

Some of the best-known social scientific theories of risks are those that have been elaborated by Anthony Giddens and Ulrich Beck. Although their arguments differ greatly, they agree in seeing the technologically induced risks of today's "Risk Society" as global - so pervasive that they transcend all socioeconomic as well as geopolitical and national boundaries. Most empirical work, however, provides greater support for a theoretical tradition exemplified by Short and Erikson. In this paper, we argue that many of the technological mega-risks described by Giddens and Beck as "transcending" social boundaries are better described as "Titanic risks," referring not so much to their colossal impact as to the fact that - as was the case for the majority of the victims on the Titanic - actual risks are related to victims' socioeconomic as well as sociogeographic locations. Previous research has shown this to be the case with high-risk technologies, such as nuclear energy and weaponry, and also with localized ones, such as toxic waste disposal. This article illustrates that the same is true even for the most genuinely "global" risks of all, namely those associated with global climate disruption.

All Aboard the "Titanic": Character Journals Are Just the Tip of the Iceberg.

Science.gov (United States)

Mercurio, Mia Lynn

1999-01-01

Describes how a 7th-grade reading class used character journals to explore the sailing and the sinking of the "Titanic." Describes how the students took ownership of their research and enjoyed reading and writing about actual events as they became a passenger or crew member aboard the "Titanic," explored the ship, experienced…

Heteronanostructure of Ag particle on titanate nanowire membrane with enhanced photocatalytic properties and bactericidal activities

International Nuclear Information System (INIS)

Shang Lu; Li Bingjie; Dong Wenjun; Chen Benyong; Li Chaorong; Tang Weihua; Wang Ge; Wu Jian; Ying Yibin

2010-01-01

A novel seed induced method has been developed for syntheses of Ag particles on titanate nanowires, and then the heteronanostructured Ag/titanate nanowires were assembled into porous, flexible membranes. These titanate nanowires were about several hundreds micrometers in length and about 80 nm in diameter. The size of the Ag particle can be tuned within 300-700 nm. The pore size and thickness of the heteronanostructured membrane were easily controlled. An Ag/titanate nanowire membrane reactor has been developed to study the photocatalytic degradation of methamidophos in aqueous solution, and 87.0% of the methamidophos can be degraded in a concurrent filtration and photocatalytic oxidation process. The antibacterial activity was also investigated on the heteronanostructured membrane with UVA light (365 nm) irradiation, and a 99.99% satisfactory antibacterial effect on Escherichia coli was achieved.

NEITSYTMATKA BIBLIOGRAFIOIDEN MAAILMAAN JÄÄVUORIA VÄISTELLEN : Bibliografia Titanic-tietoteoksista

OpenAIRE

Posio, Paula

2016-01-01

Titanic on saavuttanut myyttiset mittasuhteet reilussa sadassa vuodessa. Onnettomuus oli merenkulun historiassa poikkeuksellinen ja yhden aikakauden loppu. Titanicista ja onnettomuudesta on selvittämättä paljon asioita, ja osa jääneekin mysteeriksi. Lisäksi tutkijat taistelevat aikaa vastaan monessa asiassa. Nämä seikat saavat tutkijat edelleen tutkimaan aihetta eri puolilta. Tämä opinnäytetyö on toiminnallinen opinnäytetyö, jossa on laadittu Titanic-tutkija Juha Peltoselle bibliografia e...

Electronic and Optical Properties of Sodium Niobate: A Density Functional Theory Study

Directory of Open Access Journals (Sweden)

Daniel Fritsch

2018-01-01

Full Text Available In recent years, much effort has been devoted to replace the most commonly used piezoelectric ceramic lead zirconate titanate Pb[ZrxTi1−x]O3 (PZT with a suitable lead-free alternative for memory or piezoelectric applications. One possible alternative to PZT is sodium niobate as it exhibits electrical and mechanical properties that make it an interesting material for technological applications. The high-temperature simple cubic perovskite structure undergoes a series of structural phase transitions with decreasing temperature. However, particularly the phases at room temperature and below are not yet fully characterised and understood. Here, we perform density functional theory calculations for the possible phases at room temperature and below and report on the structural, electronic, and optical properties of the different phases in comparison to experimental findings.

Improved cell activity on biodegradable photopolymer scaffolds using titanate nanotube coatings

Energy Technology Data Exchange (ETDEWEB)

Beke, S., E-mail: szabolcs.beke@iit.it [Nanophysics, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Barenghi, R. [IEIIT, National Research Council (CNR), Via De Marini 6, 16149 Genova (Italy); Farkas, B.; Romano, I. [Nanophysics, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Kőrösi, L. [Department of Biotechnology, Nanophage Therapy Center, Enviroinvest Corporation, Kertváros u. 2, H-7632 Pécs (Hungary); Scaglione, S. [IEIIT, National Research Council (CNR), Via De Marini 6, 16149 Genova (Italy); Brandi, F. [Nanophysics, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Istituto Nazionale di Ottica, CNR, Via G. Moruzzi 1, 56124-Pisa (Italy)

2014-11-01

The development of bioactive materials is in the premise of tissue engineering. For several years, surface functionalization of scaffolds has been one of the most promising approaches to stimulate cellular activity and finally improve implant success. Herein, we describe the development of a bioactive composite scaffold composed of a biodegradable photopolymer scaffold and titanate nanotubes (TNTs). The biodegradable photopolymer scaffolds were fabricated by applying mask-projection excimer laser photocuring at 308 nm. TNTs were synthesized and then spin-coated on the porous scaffolds. Upon culturing fibroblast cells on scaffolds, we found that nanotubes coating affects cell viability and proliferation demonstrating that TNT coatings enhance cell growth on the scaffolds by further improving their surface topography. - Highlights: • Biodegradable scaffolds were produced by mask-assisted UV laser photocuring. • Titanate nanotube deposition was carried out without binding compounds or additives. • Titanate nanotube coatings enhanced cell viability and proliferation.

Direct tritium measurement in lithium titanate for breeding blanket mock-up experiments with D-T neutrons

International Nuclear Information System (INIS)

Klix, A.; Ochiai, K.; Nishitani, T.; Takahashi, A.

2004-01-01

At Fusion Neutronics Source (FNS) of JAERI, tritium breeding experiments with blanket mock-ups consisting of advanced fusion reactor materials are in progress. The breeding zones are thin layers of lithium titanate which is one of the candidate tritium breeder materials for the DEMO fusion power reactor. It is anticipated that the application of small pellet-shaped lithium titanate detectors manufactured from the same material as the breeding layer will reduce experimental uncertainties arising from necessary corrections due to different isotopic lithium volume concentrations in breeding material and detector. Therefore, a method was developed to measure the local tritium production by means of lithium titanate pellet detectors and a liquid scintillation counting technique. The lithium titanate pellets were dissolved in concentrated hydrochloric acid solution and the resulting acidic solution was neutralized. Two ways of further processing were followed: direct incorporation into a liquid scintillation cocktail and distillation of the solution followed by mixing with liquid scintillator. Two types of lithium titanate pellets were investigated with different 6 Li enrichment and manufacturing procedure. It was found that lithium titanate is suitable for tritium production measurements. However some discrepancies in the measurement accuracy remained with one of the investigated pellet detectors when compared with a well-established lithium carbonate measurement technique and this issue needs further investigation

Satisfaction and complications with the Titan® one-touch release penile implant

DEFF Research Database (Denmark)

Lindeborg, Lisa; Fode, Mikkel; Fahrenkrug, Lasse

2014-01-01

OBJECTIVE: The aim of this study was to assess complication rates and patient satisfaction with Coloplast Titan® one-touch release (OTR) inflatable penile implants inserted at one university hospital centre between November 2008 and April 2011. MATERIAL AND METHODS: Overall, 33 patients with orga......OBJECTIVE: The aim of this study was to assess complication rates and patient satisfaction with Coloplast Titan® one-touch release (OTR) inflatable penile implants inserted at one university hospital centre between November 2008 and April 2011. MATERIAL AND METHODS: Overall, 33 patients...... with organic erectile dysfunction underwent penile implant surgery during the study period. The Titan OTR inflatable penile implants were inserted using a penoscrotal approach. Patient and partner satisfaction was assessed with the Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) questionnaire...

Indentation plasticity of barium titanate single crystals: Dislocation influence on ferroelectric domain walls

International Nuclear Information System (INIS)

Liu, D.; Chelf, M.; White, K.W.

2006-01-01

The plastic behaviors of barium titanate (001) and (110) single crystals are studied with atomic force microscopy and piezoresponse force microscopy (PFM) following nanoindendation damage. Plastic deformation mechanisms of ferroelectric barium titanate single crystals are discussed with a focus on the interaction between PFM response and dislocation activities. Nanoindentation tests indicate that the theoretical strength is approached prior to the first pop-in event, consistent with the creation of dislocation nucleation sites required for the onset of plasticity. Surface topographic and piezoelectric analyses indicate that pile-ups around indents result from dislocation activities on the primary slip system, {110} pc pc . The more complex indentation-induced domain patterns observed on (110) barium titanate are also discussed

FEI Titan G2 60-300 HOLO

Directory of Open Access Journals (Sweden)

Chris Boothroyd

2016-02-01

Full Text Available The FEI Titan G2 60-300 HOLO is a unique fourth generation transmission electron microscope, which has been specifically designed for the investigation of electromagnetic fields of materials using off-axis electron holography. It has a Lorentz lens to allow magnetic field free imaging plus two electron biprisms, which in combination enable more uniform holographic fringes to be used. The instrument also has an ultra-wide objective lens pole piece gap which is ideal for in situ experiments. For these purposes, the FEI Titan G2 60-300 HOLO is equipped with a Schottky type high-brightness electron gun (FEI X-FEG, an image Cs corrector (CEOS, a post-column energy filter system (Gatan Tridiem 865 ER as well as a 4 megapixel CCD system (Gatan UltraScan 1000 XP. Typical examples of use and technical specifications for the instrument are given below.

Single-piece maintenance procedures for the TITAN reversed-field pinch reactor

International Nuclear Information System (INIS)

Grotz, S.P.; Creedon, R.L.; Cooke, P.I.H.; Duggan, W.P.; Krakowski, R.A.; Najmabadi, F.; Wong, C.P.C.

1987-01-01

The TITAN reactor is a compact (major radius of 3.9 m and minor plasma radius of 0.6 m), high neutron wall loading (--18MW/m 2 ) fusion energy system based on the reversed-field pinch (RFP) concept. The TITAN-I fusion power core (FPC) is a lithium, self-cooled design with vanadium alloy (V-3Ti-1Si) structural material. The compact design of the TITAN fusion power core (FPC) reduces the system to a few small and relatively low mass components, making toroidal segmentation of the FPC unnecessary. A single-piece maintenance procedure in which the replaceable first wall and blanket is removed as a single unit is, therefore, possible. The TITAN FPC design provides for top access to the reactor with vertical lifts used to remove the components. The number of remote handling procedures is few and the movements are uncomplicated. The annual torus replacement requires that the reusable ohmic-heating coil set and hot-shield assembly be removed and temporarily stored in a hot cell. The used first wall and blanket assembly is drained and disconnected from the coolant supply system, then lifted to a processing room where it is cooled and prepared for Class-C waste burial. The new, pre-tested first wall and blanket assembly is then lowered into position and the removal procedure is reversed to complete the replacement process

Composition And Geometry Of Titan'S Dunes

Science.gov (United States)

Le Gall, Alice; Janssen, M. A.; Wye, L. C.; Lorenz, R. D.; Radebaugh, J.; Cassini RADAR Team

2009-09-01

Fields of linear dunes cover a large portion of Titan's equatorial regions. As the Cassini mission continues, more of them are unveiled and examined by the microwave Titan RADAR Mapper both in the active and passive modes of operation of the instrument and with an increasing variety of observational geometries. In this presentation, we will show that the joint analysis of the SAR (Synthetic Aperture Radar) and radiometry observations of the dunes at closest approach supports the idea of different composition between the dunes and the interdunes. It suggests that the icy bedrock of Titan may be exposed, or partially exposed, in the interdunes. We also see regional differences among dune fields. Dunes are highly directional features; their visibility is controlled by the look direction and the incidence angle. We have developed a backscatter and emissivity model that takes into account the topography of the dunes relative to the geometry of observation as well as the composition of the dunes and interdunes. Compared to observations and, in particular, to multiple observations of areas at the overlap of several swaths, we argue the need for a diffuse scattering mechanism. The presence of ripples in the dunes and/or interdunes might account for the recorded backscatter. In this presentation we will also report the results of the T61 experiment. The T61 HiSAR sequence (on August 25, 2009) was designed to examine a small region of the Shangri-La dune field with a substantial sampling of incidence angles around the direction perpendicular to the dunes long axis. The spot in question was already observed during the T55 SAR swath and the T61 experiment should allow us to determine the slope of the dunes.

Storms in the tropics of Titan.

Science.gov (United States)

Schaller, E L; Roe, H G; Schneider, T; Brown, M E

2009-08-13

Methane clouds, lakes and most fluvial features on Saturn's moon Titan have been observed in the moist high latitudes, while the tropics have been nearly devoid of convective clouds and have shown an abundance of wind-carved surface features like dunes. The presence of small-scale channels and dry riverbeds near the equator observed by the Huygens probe at latitudes thought incapable of supporting convection (and thus strong rain) has been suggested to be due to geological seepage or other mechanisms not related to precipitation. Here we report the presence of bright, transient, tropospheric clouds in tropical latitudes. We find that the initial pulse of cloud activity generated planetary waves that instigated cloud activity at other latitudes across Titan that had been cloud-free for at least several years. These observations show that convective pulses at one latitude can trigger short-term convection at other latitudes, even those not generally considered capable of supporting convection, and may also explain the presence of methane-carved rivers and channels near the Huygens landing site.

Solubilities of sodium nitrate, sodium nitrite, and sodium aluminate in simulated nuclear waste

International Nuclear Information System (INIS)

Reynolds, D.A.; Herting, D.L.

1984-09-01

Solubilities were determined for sodium nitrate, sodium nitrite, and sodium aluminate in synthetic nuclear waste liquor. Solubilities were determined as a function of temperature and solution composition (concentrations of sodium hydroxide, sodium nitrate, sodium nitrite, and sodium aluminate). Temperature had the greatest effect on the solubilities of sodium nitrate and sodium nitrite and a somewhat lesser effect on sodium aluminate solubility. Hydroxide had a great effect on the solubilities of all three salts. Other solution components had minor effects. 2 references, 8 figures, 11 tables

Spectroscopy, morphometry, and photoclinometry of Titan's dunefields from Cassini/VIMS

Science.gov (United States)

Barnes, J.W.; Brown, R.H.; Soderblom, L.; Sotin, Christophe; Le, Mouelic S.; Rodriguez, S.; Jaumann, R.; Beyer, R.A.; Buratti, B.J.; Pitman, K.; Baines, K.H.; Clark, R.; Nicholson, P.

2008-01-01

Fine-resolution (500 m/pixel) Cassini Visual and Infrared Mapping Spectrometer (VIMS) T20 observations of Titan resolve that moon's sand dunes. The spectral variability in some dune regions shows that there are sand-free interdune areas, wherein VIMS spectra reveal the exposed dune substrate. The interdunes from T20 are, variously, materials that correspond to the equatorial bright, 5-??m-bright, and dark blue spectral units. Our observations show that an enigmatic "dark red" spectral unit seen in T5 in fact represents a macroscopic mixture with 5-??m-bright material and dunes as its spectral endmembers. Looking more broadly, similar mixtures of varying amounts of dune and interdune units of varying composition can explain the spectral and albedo variability within the dark brown dune global spectral unit that is associated with dunes. The presence of interdunes indicates that Titan's dunefields are both mature and recently active. The spectrum of the dune endmember reveals the sand to be composed of less water ice than the rest of Titan; various organics are consistent with the dunes' measured reflectivity. We measure a mean dune spacing of 2.1 km, and find that the dunes are oriented on the average in an east-west direction, but angling up to 10?? from parallel to the equator in specific cases. Where no interdunes are present, we determine the height of one set of dunes photoclinometrically to be between 30 and 70 m. These results pave the way for future exploration and interpretation of Titan's sand dunes. ?? 2007 Elsevier Inc. All rights reserved.

Investigation of the additive induced doping effects in gelcast soft lead zirconate titanate ceramics

International Nuclear Information System (INIS)

Guo Dong; Cai Kai; Li Longtu; Gui Zhilun

2009-01-01

Due to the high sensitivity of the electrical properties of electronic ceramics to various factors, knowledge about the possible influence of the processing procedure on their electrical performance is critical for applying a new technique to the fabrication of the materials. In this study, various electrical parameters, complex impedance spectra, ferroelectric hysteresis loops, and microstructures of soft lead zirconate titanate (PZT) ceramics formed by the gelcasting technique from suspensions with various dispersants were investigated in comparison with those of the conventional dry pressed ones. We found that the sodium ion, which is the main cation in many commercial surfactants, exhibited obvious hard doping effects; thus causing deteriorated performance of the gelcast PZT ceramics. While a certain impurity ion introduced by a dispersant was also found to induce soft doping characteristics and improve the electrical performance of the materials. The results suggest that the doping effects of the metal ions or impurities introduced by the dispersants, or other additives, should be generally considered for applying a wet processing technique to forming multicomponent electronic ceramics.

Applications of inorganic ion exchangers; I-sorption and fixation of some radionuclides in synthetic iron (III)titanate ion exchanger

International Nuclear Information System (INIS)

Abou-Mesalam, M.M.; El-Naggar, I.M.

2002-01-01

Iron(III) titanate as inorganic ion exchange material has been synthesized by addition of ferric nitrate solution to titanium tetrachloride (dissolved in 4M HCI) with molar ratio equal to unity. The data obtained proposed that the chemical formula of iron(III) titanate may written either as Fe 1 .3 (TiO). 2h 2 O or Fe(TiO 4 ) 0 .76.1.5H 2 O. The surface area values of unloaded and loaded iron(III) titanate with Cs + , Co 2 + and Eu 3 + ions were measured using BET-technique. The selectiy sequence for sorption of Cs + , Co 2 + and Fu 3 + ions on iron (III) titanate was found to be; Co 2 + > Eu 3 + > Cs + . The leach rate values of Cs + , Co 2 + and Fu 3 + ions from iron (II) titanate heated to 1000 degree C different leachants were determined and shows lower values compared to those obtained from unheated iron (III) titanate (dried at 50 degree C) which elucidate the suitability of iron (III) titanate in fixation of Cs + , Co 2 + and Eu 3 + ions by thermal treatment up to1000 degree.

Upper limit set for level of lightning activity on Titan

Science.gov (United States)

Desch, M. D.; Kaiser, M. L.

1990-01-01

Because optically thick cloud and haze layers prevent lightning detection at optical wavelength on Titan, a search was conducted for lightning-radiated signals (spherics) at radio wavelengths using the planetary radioastronomy instrument aboard Voyager 1. Given the maximum ionosphere density of about 3000/cu cm, lightning spherics should be detectable above an observing frequency of 500 kHz. Since no evidence for spherics is found, an upper limit to the total energy per flash in Titan lightning of about 10 to the 6th J, or about 1000 times weaker than that of typical terrestrial lightning, is inferred.

Organic chemistry in the atmosphere. [laboratory modeling of Titan atmosphere

Science.gov (United States)

Sagan, C.

1974-01-01

The existence of an at least moderately complex organic chemistry on Titan is stipulated based on clear evidence of methane, and at least presumptive evidence of hydrogen in its atmosphere. The ratio of methane to hydrogen is the highest of any atmosphere in the solar system. Irradiation of hydrogen/methane mixtures produces aromatic and aliphatic hydrocarbons. A very reasonable hypothesis assumes that the red cloud cover of Titan is made of organic chemicals. Two-carbon hydrocarbons experimentally produced from irradiated mixtures of methane, ammonia, water, and hydrogen bear out the possible organic chemistry of the Titanian environment.

Experimental measurement of effective thermal conductivity of packed lithium-titanate pebble bed

International Nuclear Information System (INIS)

Mandal, D.; Sathiyamoorthy, D.; Vinjamur, M.

2012-01-01

Lithium titanate is a promising solid breeder material for the fusion reactor blanket. Packed lithium titanate pebble bed is considered for the blanket. The thermal energy; that will be produced in the bed during breeding and the radiated heat from the reactor core absorbed must be removed. So, the experimental thermal property data are important for the blanket design. In past, a significant amount of works were conducted to determine the effective thermal conductivity of packed solid breeder pebble bed, in helium atmosphere, but no flow of gas was considered. With increase in gas flow rate, effective thermal conductivity of pebble bed increases. Particle size and void fraction also affect the thermal properties of the bed significantly. An experimental facility with external heat source was designed and installed. Experiments were carried out with lithium-titanate pebbles of different sizes at variable gas flow rates and at different bed wall temperature. It was observed that effective thermal conductivity of pebble bed is a function of particle Reynolds number and temperature. From the experimental data two correlations have been developed to estimate the effective thermal conductivity of packed lithium-titanate pebble bed for different particle Reynolds number and at different temperatures. The experimental details and results are discussed in this paper.

Evidence for the existence of supercooled ethane droplets under conditions prevalent in Titan's atmosphere.

Science.gov (United States)

Sigurbjörnsson, Omar F; Signorell, Ruth

2008-11-07

Recent evidence for ethane clouds and condensation in Titan's atmosphere raise the question whether liquid ethane condensation nuclei and supercooled liquid ethane droplets exist under the prevalent conditions. We present laboratory studies on the phase behaviour of pure ethane aerosols and ethane aerosols formed in the presence of other ice nuclei under conditions relevant to Titan's atmosphere. Combining bath gas cooling with infrared spectroscopy, we find evidence for the existence of supercooled liquid ethane aerosol droplets. The observed homogeneous freezing rates imply that supercooled ethane could be a long-lived species in ethane-rich regions of Titan's atmosphere similar to supercooled water in the Earth's atmosphere.

Indentation plasticity of barium titanate single crystals: Dislocation influence on ferroelectric domain walls

Energy Technology Data Exchange (ETDEWEB)

Liu, D. [Department of Mechanical Engineering, University of Houston, 4800 Calhoun Road, Houston, TX 77204 (United States)]. E-mail: duo.liu@mail.uh.edu; Chelf, M. [Department of Mechanical Engineering, University of Houston, 4800 Calhoun Road, Houston, TX 77204 (United States); White, K.W. [Department of Mechanical Engineering, University of Houston, 4800 Calhoun Road, Houston, TX 77204 (United States)

2006-10-15

The plastic behaviors of barium titanate (001) and (110) single crystals are studied with atomic force microscopy and piezoresponse force microscopy (PFM) following nanoindendation damage. Plastic deformation mechanisms of ferroelectric barium titanate single crystals are discussed with a focus on the interaction between PFM response and dislocation activities. Nanoindentation tests indicate that the theoretical strength is approached prior to the first pop-in event, consistent with the creation of dislocation nucleation sites required for the onset of plasticity. Surface topographic and piezoelectric analyses indicate that pile-ups around indents result from dislocation activities on the primary slip system, {l_brace}110{r_brace}{sub pc}<11-bar 0>{sub pc}. The more complex indentation-induced domain patterns observed on (110) barium titanate are also discussed.

Phase 1 Final Report: Titan Submarine

Science.gov (United States)

Oleson, Steven R.; Lorenz, Ralph D.; Paul, Michael V.

2015-01-01

The conceptual design of a submarine for Saturn's moon Titan was a funded NASA Innovative Advanced Concepts (NIAC) Phase 1 for 2014. The proposal stated the desire to investigate what science a submarine for Titan's liquid hydrocarbon seas might accomplish and what that submarine might look like. Focusing on a flagship class science system (100 kg), it was found that a submersible platform can accomplish extensive science both above and below the surface of the Kraken Mare. Submerged science includes mapping using side-looking sonar, imaging and spectroscopy of the lake, as well as sampling of the lake's bottom and shallow shoreline. While surfaced, the submarine will not only sense weather conditions (including the interaction between the liquid and atmosphere) but also image the shoreline, as much as 2 km inland. This imaging requirement pushed the landing date to Titan's next summer period (2047) to allow for lighted conditions, as well as direct-to-Earth communication, avoiding the need for a separate relay orbiter spacecraft. Submerged and surfaced investigation are key to understanding both the hydrological cycle of Titan as well as gather hints to how life may have begun on Earth using liquid, sediment, and chemical interactions. An estimated 25 Mb of data per day would be generated by the various science packages. Most of the science packages (electronics at least) can be safely kept inside the submarine pressure vessel and warmed by the isotope power system.The baseline 90-day mission would be to sail submerged and surfaced around and through Kraken Mare investigating the shoreline and inlets to evaluate the sedimentary interaction both on the surface and then below. Depths of Kraken have yet to be sensed (Ligeia to the north is thought to be 200 m (656 ft) deep), but a maximum depth of 1,000 m (3,281 ft) for Kraken Mare was assumed for the design). The sub would spend 20 d at the interface between Kraken Mare and Ligeia Mare for clues to the drainage of

Electrophoretic growth of lead zirconate titanate nanorods

Energy Technology Data Exchange (ETDEWEB)

Limmer, S.J.; Seraji, S.; Forbess, M.J.; Wu Yun; Chou, T.P.; Nguyen, C.; Cao Guozhong [Washington Univ., Seattle, WA (United States). Dept. of Materials Science and Engineering

2001-08-16

Nanorods of lead zirconate titanate (PZT)-a ferro- and piezoelectric material-up to 10 {mu}m in length and 70 to 150 nm in diameter are produced by sol-gel electrophoresis of PZT in a track-etched polycarbonate membrane, which is used as a template. (orig.)

Insights on landscape evolution and climatic forcing on Titan

Science.gov (United States)

Lucas, A.; Daudon, C.; Rodriguez, S.; Cornet, T.; Perron, J. T.

2017-12-01

The landscapes of Titan were observed for nearly 13 years by the Cassini spacecraft and Huygens probe. With dunes, mountains, seas, lakes, rivers..., the great morphological variety observed testifies to the geological richness that Titan shares with the Earth. In this study, we combine analysis of radar and hyperspectral data provided by the Cassini-Huygens mission, with models of valley and river network evolution to better understand the processes at work that sculpt these familiar landscapes. We develop quantitative criteria for comparing 3D morphologies obtained by numerical simulation with those derived for Titan by photogrammetry. These criteria are validated on Earth's landscapes. We simulate morphologies similar to those observed and show that landscapes at the equator and poles are mainly controlled by river incision and mass wasting such as landslides for which we quantify their respective contribution. Subsequently, we relate modeling to precipitation rates of methane and show values that are to be compared with general circulation model predictions (GCM). Our results also show a very young age of formation of the observed morphologies, less than a few million years. Finally, we provide new constraints on current amplitude of the tidal effects and organic precipitation rates from atmosphere chemistry.

Nanosized lithium titanates produced by plasma technique

International Nuclear Information System (INIS)

Grabis, J; Orlovs, A; Rasmane, Dz

2007-01-01

The synthesis of nanosized lithium titanates is studied by evaporation of coarse grained commercially available titanium and lithium carbonate particles in radio-frequency plasma flow with subsequent controlling formation and growth conditions of product particles. In accordance with the XRD analysis the phase composition of the obtained powders is determined by feeding rate of precursors and strongly by ratio of lithium and titanium. The Li 2 TiO 3 and Li 4 Ti 5 O 12 particles containing small amounts of extra phases were obtained at ratio of Li/Ti = 2 and Li/Ti = 0.8 respectively, feeding rate of precursors being in the range of 0.6-0.9 kg/h. Specific surface area of powders is in the range of 20-40 m2/g depending on concentration of vapours in gas flow and cooling rate of the products. Additional calcination of nanosize particles at 800-900 deg. C improves phase composition of lithium titanates

Retention Behaviour of Copper, Zinc, Cadmium and Lead Ions on Synthesized Zirconium Titanate Ion Exchanger

International Nuclear Information System (INIS)

El-Naggar, I.M.; Abdel-Galil, E.A.; Moustafa, M.E.; Mahmoud, M.Y.

2013-01-01

Zr(IV) titanate as inorganic ion exchange material has been synthesized and utilized as the adsorbent for the removal of Cu 2+ , Zn 2+ , Cd 2+ and Pb 2+ ions from aqueous waste solutions. The experimental data were analyzed by Langmuir and Freundlich models of adsorption. The results suggest that the adsorption of the studied metals Cu 2+ , Zn 2+ , Cd 2+ and Pb 2+ ions on Zr(IV) titanate was favourable for the Freundlich isotherm more than Langmuir isotherm. The numerical values of 1/n for the studied metal ions were found to be smaller than the one (1/n L ) was found to be R L > 1 which confirmed that the prepared Zr(IV) titanate unfavourable the Langmuir isotherm. Based on the obtained results, practical separation experiments for the above mentioned cations on Zr(IV) titanate (ZrTi) column from aqueous waste solutions were carried out.

Lab-on-a-Chip Instrument Development for Titan Exploration

Science.gov (United States)

Willis, P. A.; Greer, F.; Fisher, A.; Hodyss, R. P.; Grunthaner, F.; Jiao, H.; Mair, D.; Harrison, J.

2009-12-01

This contribution will describe the initial stages of a new ASTID-funded research program initiated in Fall 2009 aimed at lab-on-a-chip system development for astrobiological investigations on Titan. This technology development builds off related work at JPL and Berkeley [1-3] on the ultrasensitive compositional and chiral analysis of amino acids on Mars in order to search for signatures of past or present life. The Mars-focused instrument system utilizes a microcapillary electrophoresis (μCE) system integrated with on-chip perfluoropolyether (PFPE) membrane valves and pumps for automated liquid sample handling, on-chip derivitization of samples with fluorescent tags, dilution, and mixing with standards for data calibration. It utilizes a four-layer wafer stack design with CE channels patterned in glass, along with a PFPE membrane, a pneumatic manifold layer, and a fluidic bus layer. Three pneumatically driven on-chip diaphragm valves placed in series are used to peristaltically pump reagents, buffers, and samples to and from capillary electrophoresis electrode well positions. Electrophoretic separation occurs in the all-glass channels near the base of the structure. The Titan specific lab-on-a-chip system under development here focuses its attention on the unique organic chemistry of Titan. In order to chromatographically separate mixtures of neutral organics such as polycyclic aromatic hydrocarbons (PAHs), the Titan-specific microfluidic platform utilizes the related technique of microcapillary electrochromatography (μCEC). This technique differs from conventional μCE in that microchannels are filled with a porous stationary phase that presents surfaces upon which analyte species can adsorb/desorb. It is this additional surface interaction that enables separations of species critical to the understanding of the astrobiological potential of Titan that are not readily separated by the μCE technique. We have developed two different approaches for the integration

The TITAN reversed-field-pinch fusion reactor study

International Nuclear Information System (INIS)

1990-01-01

This paper on titan plasma engineering contains papers on the following topics: reversed-field pinch as a fusion reactor; parametric systems studies; magnetics; burning-plasma simulations; plasma transient operations; current drive; and physics issues for compact RFP reactors

Diurnal Variations of Titan's Surface Temperatures From Cassini -CIRS Observations

Science.gov (United States)

Cottini, Valeria; Nixon, Conor; Jennings, Don; Anderson, Carrie; Samuelson, Robert; Irwin, Patrick; Flasar, F. Michael

The Cassini Composite Infrared Spectrometer (CIRS) observations of Saturn's largest moon, Titan, are providing us with the ability to detect the surface temperature of the planet by studying its outgoing radiance through a spectral window in the thermal infrared at 19 m (530 cm-1) characterized by low opacity. Since the first acquisitions of CIRS Titan data the in-strument has gathered a large amount of spectra covering a wide range of latitudes, longitudes and local times. We retrieve the surface temperature and the atmospheric temperature pro-file by modeling proper zonally averaged spectra of nadir observations with radiative transfer computations. Our forward model uses the correlated-k approximation for spectral opacity to calculate the emitted radiance, including contributions from collision induced pairs of CH4, N2 and H2, haze, and gaseous emission lines (Irwin et al. 2008). The retrieval method uses a non-linear least-squares optimal estimation technique to iteratively adjust the model parameters to achieve a spectral fit (Rodgers 2000). We show an accurate selection of the wide amount of data available in terms of footprint diameter on the planet and observational conditions, together with the retrieved results. Our results represent formal retrievals of surface brightness temperatures from the Cassini CIRS dataset using a full radiative transfer treatment, and we compare to the earlier findings of Jennings et al. (2009). The application of our methodology over wide areas has increased the planet coverage and accuracy of our knowledge of Titan's surface brightness temperature. In particular we had the chance to look for diurnal variations in surface temperature around the equator: a trend with slowly increasing temperature toward the late afternoon reveals that diurnal temperature changes are present on Titan surface. References: Irwin, P.G.J., et al.: "The NEMESIS planetary atmosphere radiative transfer and retrieval tool" (2008). JQSRT, Vol. 109, pp