Spatial survival probability for one-dimensional fluctuating interfaces in the steady state

We report numerical and analytic results for the spatial survival probability for fluctuating one-dimensional interfaces with Edwards-Wilkinson or Kardar-Parisi-Zhang dynamics in the steady state. Our numerical results are obtained from analysis of steady-state profiles generated by integrating a spatially discretized form of the Edwards-Wilkinson equation to long times. We show that the survival probability exhibits scaling behavior in its dependence on the system size and the "sampling interval" used in the measurement for both "steady-state" and "finite" initial conditions. Analytic results for the scaling functions are obtained from a path-integral treatment of a formulation of the problem in terms of one-dimensional Brownian motion. A "deterministic approximation" is used to obtain closed-form expressions for survival probabilities from the formally exact analytic treatment. The resulting approximate analytic results provide a fairly good description of the numerical data.

Low-temperature polymer precursor-based synthesis of nanocrystalline particles of lanthanum calcium manganese oxide (La0.67Ca0.33MnO3) with enhanced ferromagnetic transition temperature

We report a simple modified polymeric precursor route for the synthesis of highly crystalline and homogenous nanoparticles of lanthanum calcium manganese oxide (LCMO). The LCMO phase formation was studied by thermal analysis, x-ray powder diffraction, and infrared spectroscopy at different stages of heating. These nanocrystallites (average particle size of 30 nm) possess ferromagnetic-paramagnetic transition temperature (T-c) of 300 K, nearly 50 K higher than that of a single crystal. The Rietveld analysis of the powder x-ray diffraction data of the nanopowders reveals significant lattice contraction and reduction in unit cell anisotropy-these structural changes are correlated to the enhancement in T-c.

Joint Source-Channel Coding over a Fading Multiple Access Channel with Partial Channel State Information

In this paper we address the problem of transmission of correlated sources over a fast fading multiple access channel (MAC) with partial channel state information available at both the encoders and the decoder. We provide sufficient conditions for transmission with given distortions. Next these conditions are specialized to a Gaussian MAC (GMAC). We provide the optimal power allocation strategy and compare the strategy with various levels of channel state information.

Deformation and friction of MoS2 particles in liquid suspensions used to lubricate sliding contact

Tribology of a well known solid lubricant molybdenum disulphide is studied here in water and oil medium, over a large range of contact dimensions. Lateral force microscopy is used to identify the deformation modes, intra-crystalline slip, plastic grooving, fragmentation and fracture, of single particles The medium and agglomeration were found to dictate the deformation mode Steel on steel tribology lubricated by suspensions of these particles in liquid media was conducted over a range of contact pressure and sliding velocity. A scrutiny of the frictional data with the aid of Raman spectroscopy to identify the transfer film, suggested that the particle size, as it is at contact, is an important tribological parameter Ultrasonication of the suspension and dispersion of the particle by surfactants were used to control the apriori particle size fed into the suspension.Correspondence of friction data of the gently sonicated suspension with that of the ultrasonicated suspension with dispersants indicated the importance of liquid ingestion by these particles as it controls their mode of deformation and consequent tribology. (C) 2010 Elsevier B V All rights reserved.

Synthesis, characterization and photoluminescence properties of Gd2O3:Eu3+ nanophosphors prepared by solution combustion method

Gd2O3:Eu3+ (0.5-8.0 mol%) nanophosphors have been prepared by low temperature solution combustion method using metal nitrates as oxidizers and oxalyl dihydrazide (ODH) as a fuel. The phosphors are well characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and photoluminescence (PL) techniques. PXRD patterns of as-formed and calcined (800 degrees C, 3 h) Gd2O3 powders exhibit monoclinic phase with mean crystallite sizes ranging from 20 to 50 nm. Eu3+ doping changes the structure from monoclinic to mixed phase of monoclinic and cubic. SEM micrographs shows the products are foamy, agglomerated and fluffy in nature due to the large amount of gases liberated during combustion reaction. Upon 254 nm excitation the photoluminescence of the Gd2O3:Eu3+ particles show red emission at 611 nm corresponding to D-5(0)-> F-7(2) transition. It is observed that PL intensity increases with calcination temperature. This might be attributed to better crystallization and eliminates the defects, which serve as centers of non-radiative relaxation for nanomaterials. It is observed that the optical energy gap (E-g) is widened with increase Eu3+ content. (C) 2010 Elsevier B.V. All rights reserved.

Determination of activation energy for thermal regeneration of EL2 from its metastable state by thermally stimulated photocurrent measurements

It is shown that thermally stimulated photocurrent measurements provide a simple and effective method of determining the activation energy of thermal regeneration rate of EL2 from the metastable state to the normal state in undoped semi‐insulating GaAs. The thermal regeneration rate r is found to be 2.5×108 exp(−0.26 eV/kT) s−1.

Preparation and characterization of silane-stabilized, highly uniform, nanobimetallic Pt-Pd particles in solid and liquid matrixes

Highly uniform, stable nanobimetallic dispersions are prepared in a single si ep in the form of sols, gels, and monoliths, using organically modified silicates as the matrix and the stabilizer. The Pt-Pd bimetallic dispersions are characterized by W-vis, TEM, SEM, and XRD measurements. The evolution of silicate was followed by IR spectroscopy. XPS and CO adsorption studies reveal that the structure of the particles consists of a palladium core and a platinum shell. Electrocatalysis of ascorbic acid oxidation has been demonstrated using thin films of silicate containing the nanobimetal particles on a glassy carbon electrode.

Synthesis, Structure, and Solid-State Transformation Studies of Phosphonoacetate Based Hybrid Compounds of Uranium and Thorium

Three new phosphonoacetate hybrid frameworks based on the actinide elements uranium and thorium have been synthesized. The compounds [C4N2H14][(UO2)(2)(O3PCH2COO)(2)]center dot H2O, I,[C4N2H14][(UO2)(2)(C2O4)(O3PCH2COOH)(2)], II, and Th(H2O)(2)(O3PCH2COO)(C2O4)(0.5). H2O, III, are built up from the connectivity between the metal polyhedra and the phosphonoacetate/oxalate units. Compound II has been prepared using a solvent-free approach, by a solid state reaction at 150 degrees C. It has been shown that II can also be prepared through a room temperature mechanochemical (grinding) route. The layer arrangement in III closely resembles to that observed in I. The compounds have been characterized by powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis, and fluorescence studies.

Creep Behaviour of AE42 Magnesium Alloy and Its Composites Using Impression Creep Technique

The creep behaviour of a creep-resistant AE42 magnesium alloy has been examined in the temperature range of 150 to 240 degrees C at the stress levels ranging from 40 to 120 MPa using impression creep technique. A normal creep behaviour, i.e., strain rate decreasing with strain and then reaching a steady state, is observed at all the temperatures and stresses employed The stress exponent varies from 5.1 to 5.7 and the apparent activation energy varies from 130 to 140 kJ/mol, which suggests the high temperature climb of dislocation controlled by lattice self-diffusion being the dominant creep mechanism in the stress and temperature range employed The creep behaviour of the AE42 alloy has also been compared with its composites reinforced with Saffil short fibres and SiC particles in four combinations. All the composites exhibited a lower creep rate than the monolithic AE42 alloy tested at the same temperature and stress levels and the decrease in creep rate was greater in the longitudinal direction than in the transverse direction, as expected. All the hybrid composites, i.e., the composites reinforced with a combination of Saffil short fibres and SiC particles, exhibited creep rates comparable to the composite reinforced with 20% Saffil short fibres alone at all the temperature and stress levels employed, which is beneficial from the commercial point of view.

“Empire is a state of mind” – Imagining Eurasia in Russia –

Työssäni tarkastelen venäläistä neo-euraasianistista liikettä ja tapoja joilla liikkeen aktivistit rakentavat Euraasiasta yhtenäistä kokonaisuutta ja imperiumia. Keskeisiä tutkimuskysymyksiäni ovat: Mikä imperiumi on ja mitkä ovat sen keskeisiä motivaatioita ja teemoja? Kuinka imperiumin idea rakentuu tai käsitetään ja tämän voi tulkita? Minkälaisia seurauksia voi tulkita heidän tavallaan Euraasia nähdä olevan? Materiaalina käytän haastatteluja, jotka on kerätty Moskovassa keväällä 2008, ja liikkeen kirjallisia tuotoksia (lehdet ja Internet -sivut). Neo-euraasianistisella liikkeellä tarkoitan tässä työssä Kansainvälistä Euraasianistista liikettä (Meždunarodnoe Evrazijskoe Dviženie) ja sen alahaaraa Euraasianistista Nuorisoliittoa (Evrazijskij Sojuz Molodëži). Liike perustettiin virallisesti 2003, mutta rakentaa vahvasti historiallista yhteyttä 1930 -luvun klassiseen eurasianismiin. Tämän lisäksi sen diskurssissa on paljon neuvostoliittolaisia, fasistisia, uuskonservatiivisia ja nationalistisia piirteitä. Liikkeen johtohahmo on filosofi-geopoliitikko Alexandr Dugin. Työn tausta-ajatuksena minua kiinnostaa etenkin nk. älymystön tai intelligenttien vaikutus nationalismiin tai sosiaalisia ryhmiä määrittelevien diskurssien kehitykseen ja muutokseen.Tarkastelen materiaalia diskurssianalyyttisesta näkökulmasta. Näen diskurssianalyysin sen tutkimisena, miten sosiaalista todellisuutta tuotetaan erilaisissa sosiaalisissa käytännöissä. Samalla näiden diskurssien tutkiminen, foucautlaisen perinteen myötä, tarkastelee kriittisesti niiden tuottamia (aktualisoituneita sekä potentiaalisia) valtasuhteita. Käytän työssäni myös Benedict Andersonin kuvitellun yhteisön (imagined communities) käsitettä, joka auttaa hahmottamaan tapaa, jolla tutkimuskohteeni rakentavat imperiumia yhteisönä. Aktivistien puheessa imperiumi (imperiâ) tulee esiin pääasiallisesti positiivisesti ja ”heidän omanaan,” kun taas termi imperialismi (imperializm) pääosin negatiivisena, liittyen etenkin keskeisenä vihollisena pidettyihin Yhdysvaltoihin. Esiin nousee monta toisiinsa liittyvää teemaa, jotka jaottelen viideksi pääteemaksi. Näistä tarkastelen lähemmin imperiumia ”kaikkien kansojen hyväntekijänä (poliittinen puoli)”, ulkoisen voiman lähteenä (historiallis-geopoliittinen puoli) sekä kollektiivisen subjektin luojana (imperialistis-nationalistinen puoli). Pyrin kontekstualisoimaan diskurssin ja tarkastelemaan tapoja, joilla se ammentaa motiiveja myös historiallis-kulttuurisista tavoista hahmottaa aluetta ja sen asukkaita. Käsittelen myös kansan, kansakunnan, etnoksen ja nationalismin käsitteitä ja sitä, miten ne nousevat neo-eurasianistisessa diskursissa esiin. Imperiaalisen nationalismin (imperskij nacionalizm) käsite auttaa ymmärtämään niitä tapoja, jolla liike tekee sekä pesäeroa nationalismiin että samalla hyödyntää monia nationalistisen diskurssin perusteemoja. Eräs liikkeen diskurssin keskeisistä eroista niin sanottuun nationalismin valtavirtaan on ”kansakunnan (naciâ)” käsitteen vahva negatiivinen konnotaatio. Sen vastakohtana esiin nostetaan vahvasti kansan (narod) käsite. Samalla kuitenkin etnisen venäläisen (russkij) käsitettä käytetään tavallista laajemmin ja kattavammin kuin tavallisesti, ja ennen kaikkea Venäjä nousee imperiumin keskeisimmäksi tekijäksi. Euraasialaiseen imperiumiin liitetyistä positiivistista mielikuvista käsittelen tarkemmin monikansallisuuden ja kansojen kodin ideaa, joka nousee mielestäni huomattavaksi retoriseksi taustaksi kaikessa materiaalissa. Tähän liittyy vahvasti myös saman teeman sivujuonne, eli imperiumin ”vapauttava” rooli. Tulkitsen, että liikkeen imperiumi -diskurssilla on instrumentaalinen luonne: se legitimoi aktivistien vaatimuksia varsinkin entisen Neuvostoliiton alueen suhteen. ”Euraasialaisen kansan” ajatus toimii mahdollisena Euraasiaa yhteisenä tekijänä ”Neuvostokansan” tilalla. Sen taustalla materiaalistani päätellen siintävät kuitenkin enemmänkin Venäjä ja venäläis -spesifit vaateet kuin koko Euraasia. Pohdin myös kansakunnan (nation) hyljeksimisen syitä ja käsitteen sopivuutta Venäjälle, kuten myös venäläisyyden käsitteiden kerrostuneisuutta. Kokonaisuudessaan imperiumi tuli esiin abstraktina, utopistisena ja ”totaalisena” kokonaisuutena.

NO reduction, CO and hydrocarbon oxidation over combustion synthesized Ag/CeO2 catalyst

The combustion technique produces ionically dispersed Ag on a nano-crystalline CeO2 surface. The catalysts thus produced were characterized by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. Catalytic properties towards NO reduction, CO and hydrocarbon oxidation have been investigated using the temperature programmed reaction technique in a packed bed tubular reactor. These results are compared with alpha-Al2O3 supported finely divided Ag metal particles synthesized by the same method. Both oxidation and reduction reactions over Ag/CeO2 have been observed to occur at lower temperatures compared to Ag/Al2O3. The rate and turnover frequency of the NO+CO reaction over 1% Ag/CeO2 are 56.3 mu mol g(-1) s(-1) and 0.97 s(-1) at 225 degrees C respectively. Activation energy (E-a) values are 71 and 67 kJ mol(-1) for CO+O-2 and NO+CO reactions, respectively, over 1% Ag/CeO2 catalyst.

On The Ground State Properties Of The +/-J Ising Model

In the combinatorial method or Grassmann algebra formalism the ground state properties of the f J Ising model can be expressed in terms of the behaviour of the eigenvectors of a matrix. It is shown that a transition from localized to extended eigenvectors signals the breakdown of ferromagnetic rigidity.