Manganese-mediated ferromagnetism in La2Fe1-xMn2xCr1-xO6 perovskite oxides

We have investigated the structure and magnetic properties of the perovskite oxides of the formula La2Fe1-xMn2xCr1-xO6 (0 < x < 1.0). For 0 < x <= 0.5, the members adopt the orthorhombic (Pbnm) structure, where the transition metal atoms are disordered at the 4b sites and the MO6 (M = Fe, Mn, Cr) octahedra become increasingly distorted with increasing x. For 0.65 <= x < 1.0, the members adopt the rhombohedral (R-3c) structure that is similar to LaMnO3+delta (delta >= 0.1) where the MO6 octahedra are undistorted. While the magnetic properties of the latter series are largely similar to the parent LaMnO3+delta arising from the double-exchange (DE) between mixed valent Mn-III/Mn-IV, the magnetic properties of the orthorhombic members show a distinct (albeit weak) ferromagnetism (T-C similar to 200 K) that seems to arise from a Mn-III-mediated superexchange (SE) between Fe-III/Cr-III in the disordered perovskite structure containing Fe-III, Mn-III and Cr-III.

Search for new transparent conductors: Effect of Ge doping on the conductivity of Ga2O3, In2O3 and Ga1.4In0.6O3

Only a small amount (<= 3.5 mol%) of Ge can be doped in Ga2O3, Ga1.4In0.6O3 and In2O3 by means of solid state reactions at 1400 degrees C. All these samples are optically transparent in the visible range, but Ge-doped Ga2O3 and Ga1.4In0.6O3 are insulating. Only Ge-doped In2O3 exhibits a significant decrease in resistivity, the resistivity decreasing further on thermal quenching and H-2 reduction.The resistivity of 2.7% Ge-doped In2O3 after H-2 reduction shows a metallic behavior, and a resistivity of similar to 1 m Omega cm at room temperature, comparable to that of Sn-doped In2O3. (C) 2010 Elsevier Ltd. All rights reserved.

Kymmenen koirarodun perinnöllinen monimuotoisuus

Tämän tutkimuksen tavoitteena oli selvittää koirarotujen sisäistä ja välistä perinnöllistä muuntelua ja populaatioiden rakenteita. Tutkimuksessa käytettiin Finnzymes Oy:ltä saatua koirien mikrosatelliittimerkkeihin perustuvaa genotyypitysaineistoa. Lopullisessa aineistossa oli 395 koiraa kymmenestä keskenään varsin erilaisesta rodusta. Koirien määrä rotua kohti vaihteli 31:stä 53:een. Tutkimuksessa käytettiin 18 mikrosatelliittilokusta. Alleelirikkaus vaihteli mikrosatelliittilokuksissa välillä 2,0 – 9,9. Kaikkein muuntelevin lokus oli AHT137 ja vähiten muunteleva AHTk211. Jackrussellinterrierin alleelirikkaus oli yli kaikkien lokusten tarkasteltuna suurinta ja cavalier kingcharlesinspanielin pienintä. Eniten Hardy-Weinbergin tasapainosta poikkeavia mikrosatelliittilokuksia oli schipperke- rodulla. Coton de tulearin, saksanpaimenkoiran ja suomenlapinkoiran kaikki mikrosatelliittilokukset olivat Hardy-Weinbergin tasapainossa. Cavalier kingcharlesinspanielin havaittu heterotsygotia-aste oli matalin kaikkien lokusten yli tarkasteltuna (0,50) ja suomenlapinkoiran korkein (0,73). Ainoat tilastollisesti merkitsevät FIS-arvot olivat schipperken lokuksessa INU030 (0,39) ja kaikkien lokusten yli tarkasteltuna (0,11). Eniten populaatioiden välisiin eroihin perustuvaa muuntelua oli cavalier kingcharlesinspanielin ja pitkäkarvaisen collien välillä (FST = 0,34) ja vähiten chihuahuan ja coton de tulearin välillä (FST = 0,07). Koko aineistossa noin 17,7 % populaatioiden välisestä geneettisestä muuntelusta johtui populaatioiden välisistä eroista. Rodut ovat tulosten perusteella selvästi erillisiä populaatioita. Coton de tulearin alleeliparit olivat selvästi eniten kytkentäepätasapainossa keskenään (94) ja tiibetinspanielin vähiten (15). Pitkäkarvaisen collien tehollinen populaatiokoko oli pienin (35) ja chihuahuan suurin (86). U seiden populaatiogeneettisten tunnuslukujen perusteella nousivat esiin cavalier kingcharlesinspanieli, pitkäkarvainen collie ja schipperke perinnöllisen muuntelun vähäisyyden perusteella ja chihuahua, jackrussellinterrieri ja suomenlapinkoira keskimääräistä suuremman perinnöllisen muuntelun perusteella. Selityksiä geneettisen monimuotoisuuden vaihteluun näillä roduilla löytyy rotujen historiasta.

Noise minimization in RC-active filters using generalized impedance converters

A procedure has been given for minimizing the total output noise of a Generalized Impedance Converter (GIC), subject to constraints dictated by signal handling capability of the Operational Amplifiers and ease of microcircuit fabrication. The noise reduction is achieved only by the adjustment of RC elements of the GIC, and the total output noise after optimization in the example cited is close to the theoretical lower limit. The output noise of a higher-order filter can be reduced by RC-optimizing the individual GIC's of the active realization. Experimental results on a 20–24 kHz channel bank band-pass filter demonstrate the effectiveness of the above procedure.

Detection, epidemiology and host spectrum of cowpox and Borna disease virus infections

Several orthopoxviruses (OPV) and Borna disease virus (BDV) are enveloped, zoonotic viruses with a wide geographical distribution. OPV antibodies cross-react, and former smallpox vaccination has therefore protected human populations from another OPV infection, rodent-borne cowpox virus (CPXV). Cowpox in humans and cats usually manifests as a mild, self-limiting dermatitis and constitutional symptoms, but it can be severe and even life-threatening in the immunocompromised. Classical Borna disease is a progressive meningoencephalomyelitis in horses and sheep known in central Europe for centuries. Nowadays the virus or its close relative infects humans and also several other species in central Europe and elsewhere, but the existence of human Borna disease with its suspected neuropsychiatric symptoms is controversial. The epidemiology of BDV is largely unknown, and the present situation is even more intriguing following the recent detection of several-million-year-old, endogenized BDV genes in primate and various other vertebrate genomes. The aims of this study were to elucidate the importance of CPXV and BDV in Finland and in possible host species, and particularly to 1) establish relevant methods for the detection of CPXV and other OPVs as well as BDV in Finland, 2) determine whether CPXV and BDV exist in Finland, 3) discover how common OPV immunity is in different age groups in Finland, 4) characterize possible disease cases and clarify their epidemiological context, 5) establish the hosts and possible reservoir species of these viruses and their geographical distribution in wild rodents, and 6) elucidate the infection kinetics of BDV in the bank vole. An indirect immunofluorescence assay and avidity measurement were established for the detection, timing and verification of OPV or BDV antibodies in thousands of blood samples from humans, horses, ruminants, lynxes, gallinaceous birds, dogs, cats and rodents. The mostly vaccine-derived OPV seroprevalence was found to decrease gradually according to the year of birth of the sampled human subjects from 100% to 10% in those born after 1977. On the other hand, OPV antibodies indicating natural contact with CPXV or other OPVs were commonly found in domestic and wild animals: the horse, cow, lynx, dog, cat and, with a prevalence occasionally even as high as 92%, in wild rodents, including some previously undetected species and new regions. Antibodies to BDV were detected in humans, horses, a dog, cats, and for the first time in wild rodents, such as bank voles (Myodes glareolus). Because of the controversy within the human Borna disease field, extra verification methods were established for BDV antibody findings: recombinant nucleocapsid and phosphoproteins were produced in Escherichia coli and in a baculovirus system, and peptide arrays were additionally applied. With these verification assays, Finnish human, equine, feline and rodent BDV infections were confirmed. Taken together, wide host spectra were evident for both OPV and BDV infections based on the antibody findings, and OPV infections were found to be geographically broadly distributed. PCR amplification methods were utilised for hundreds of blood and tissue samples. The methods included conventional, nested and real-time PCRs with or without the reverse transcription step and detecting four or two genes of OPVs and BDV, respectively. OPV DNA could be amplified from two human patients and three bank voles, whereas no BDV RNA was detected in naturally infected individuals. Based on the phylogenetic analyses, the Finnish OPV sequences were closely related although not identical to a Russian CPXV isolate, and clearly different from other CPXV strains. Moreover, the Finnish sequences only equalled each other, but the short amplicons obtained from German rodents were identical to monkeypox virus, in addition to German CPXV variants. This reflects the close relationship of all OPVs. In summary, RNA of the Finnish BDV variant could not be detected with the available PCR methods, but OPV DNA infrequently could. The OPV species infecting the patients of this study was proven to be CPXV, which is most probably also responsible for the rodent infections. Multiple cell lines and some newborn rodents were utilised in the isolation of CPXV and BDV from patient and wildlife samples. CPXV could be isolated from a child with severe, generalised cowpox. BDV isolation attempts from rodents were unsuccessful in this study. However, in parallel studies, a transient BDV infection of cells inoculated with equine brain material was detected, and BDV antigens discovered in archival animal brains using established immunohistology. Thus, based on several independent methods, both CPXV and BDV (or a closely related agent) were shown to be present in Finland. Bank voles could be productively infected with BDV. This experimental infection did not result in notable pathological findings or symptoms, despite the intense spread of the virus in the central and peripheral nervous system. Infected voles commonly excreted the virus in urine and faeces, which emphasises their possible role as a BDV reservoir. Moreover, BDV RNA was regularly reverse transcribed into DNA in bank voles, which was detected by amplifying DNA by PCR without reverse transcription, and verified with nuclease treatments. This finding indicates that BDV genes could be endogenized during an acute infection. Although further transmission studies are needed, this experimental infection demonstrated that the bank vole can function as a potential BDV reservoir. In summary, multiple methods were established and applied in large panels to detect two zoonoses novel to Finland: cowpox virus and Borna disease virus. Moreover, new information was obtained on their geographical distribution, host spectrum, epidemiology and infection kinetics.

Hintakartelli toistettuna pelinä: teoriasta pääkaupunkiseudun bensiinin vähittäismyyntimarkkinoille

Tutkielman tarkoituksena oli soveltaa toistetun pelin teoria- ja empiriapohjaa suomalaiseen tutkimusaineistoon. Kartellin toimintadynamiikka on mallinnettu peliteorian osa-alueen, toistetun pelin kentäksi. Toistetussa pelissä samaa, kerran pelattua peliä pelataan useita kierroksia. Äärettömästi toistetusta pelistä muodostuu toistetun pelin yleinen teoria (The Folk Theorem), jossa jokaisella pelaajalla on yksilöllisesti rationaalinen käytössykli. Toisen pelaajan kanssa tehty yhteistyö kasvattaa pelaajan käytössykliltä kertyvää kokonaishyötyä. Kartellitutkimuksessa ei voi ohittaa oikeustieteellistä näkökulmaa, joten sekin on tiivistetysti mukana esityksessä. Äänettömässä tai implisiittisessä kartellissa ( tacit collusion ) ei avoimen kartellin tavoin ole osapuolten välistä kommunikointia, mutta sen lopputulos on sama. Tästä syystä äänetön kartelli on yhdenmukaistettuna käytöksenä kielletty. Koska myös tunnusmerkit ovat osin samat, kartellitutkimus on saanut arvokasta mittausaineistoa paljastuneiden kartellien käytöksestä. Pelkkään hintatiedostoonkin perustuvalla tutkimuksella on vankka teoreettinen ja empiirinen pohja. Oikeuskirjallisuudessa ja käytännössä hintayhteneväisyyden on yhdessä muiden tunnusmerkkien kanssa katsottu olevan indisio kartellista. Bensiinin vähittäismyyntimarkkinat ovat rakenteellisesti otollinen kenttä toistetulle pelille. Tutkielman empiirisessä osuudessa kohteena olivat pääkaupunkiseudun bensiinin vähittäismyyntimarkkinat ja tiedosto sisälsi otoksia hinta-aikasarjoista ajalta 1.8.2004 - 30.6.2005 kaikkiaan 116:ltä jakeluasemalta Espoosta, Helsingistä ja Vantaalta. Tutkimusmenetelmänä oli toistettujen mittausten varianssianalyysi post hoc-vertailuin. Tilastollisesti merkitsevä hinnoitteluyhtenevyys lähellä sijaitsevien asemien kesken löytyi 47 asemalta, ja näin ollen näillä asemilla on yksi kartellin tunnusmerkeistä. Hinnoitteluyhtenevyyden omaavat asemat muodostivat liikenneyhteyksien mukaan jaetuilla kilpailualueillaan ryhmittymiä ja kaikkiaan tällaisia yhtenevästi hinnoittelevia ryhmittymiä oli 21. Näistä ryhmittymistä 9 oli ns. sekapareja eli osapuolina olivat kylmäasema ja liikenneasema. Useimmissa tapauksissa oli kyseessä alueensa kalleimmin hinnoitteleva kylmäasema. Tutkielman tärkeimmät lähteet: Abrantes-Metz, Rosa M. – Froeb, Luke M. – Geweke, John F. – Taylor, Cristopher T. (2005): A Variance screen for collusion. Working paper no. 275, Bureau of economics, Federal Trade Commission, Washington DC 20580. Dutta, Prajit K. (1999): Strategies and Games, Theory and Practice. The MIT Press, Cambridge, Massachusetts, London, England. Harrington, Joseph E. (2004): Detecting cartels. Working paper. John Hopkins University. Ivaldi, Marc – Jullien, Bruno – Rey, Patric – Seabright, Paul – Tirole, Jean (2003): The Economics of Tacit Collusion. EU:n komission kilpailun pääosaston julkaisu. Phlips, Louis (1996): On the detection of collusion and predation. European Economic Review 40 (1996), 495–510.

The 26 July 2005 heavy rainfall event over Mumbai: numerical modeling aspects

The performance of the Advanced Regional Prediction System (ARPS) in simulating an extreme rainfall event is evaluated, and subsequently the physical mechanisms leading to its initiation and sustenance are explored. As a case study, the heavy precipitation event that led to 65 cm of rainfall accumulation in a span of around 6 h (1430 LT-2030 LT) over Santacruz (Mumbai, India), on 26 July, 2005, is selected. Three sets of numerical experiments have been conducted. The first set of experiments (EXP1) consisted of a four-member ensemble, and was carried out in an idealized mode with a model grid spacing of 1 km. In spite of the idealized framework, signatures of heavy rainfall were seen in two of the ensemble members. The second set (EXP2) consisted of a five-member ensemble, with a four-level one-way nested integration and grid spacing of 54, 18, 6 and 1 km. The model was able to simulate a realistic spatial structure with the 54, 18, and 6 km grids; however, with the 1 km grid, the simulations were dominated by the prescribed boundary conditions. The third and final set of experiments (EXP3) consisted of a five-member ensemble, with a four-level one-way nesting and grid spacing of 54, 18, 6, and 2 km. The Scaled Lagged Average Forecasting (SLAF) methodology was employed to construct the ensemble members. The model simulations in this case were closer to observations, as compared to EXP2. Specifically, among all experiments, the timing of maximum rainfall, the abrupt increase in rainfall intensities, which was a major feature of this event, and the rainfall intensities simulated in EXP3 (at 6 km resolution) were closest to observations. Analysis of the physical mechanisms causing the initiation and sustenance of the event reveals some interesting aspects. Deep convection was found to be initiated by mid-tropospheric convergence that extended to lower levels during the later stage. In addition, there was a high negative vertical gradient of equivalent potential temperature suggesting strong atmospheric instability prior to and during the occurrence of the event. Finally, the presence of a conducive vertical wind shear in the lower and mid-troposphere is thought to be one of the major factors influencing the longevity of the event.

Theory of the effects of destruction of localization by inelastic scattering in the resistivity of pure thin potassium wires

Measurements of the electrical resistivity of thin potassium wires at temperatures near 1 K have revealed a minimum in the resistivity as a function of temperature. By proposing that the electrons in these wires have undergone localization, albeit with large localization length, and that inelastic-scattering events destroy the coherence of that state, we can explain both the magnitude and shape of the temperature-dependent resistivity data. Localization of electrons in these wires is to be expected because, due to the high purity of the potassium, the elastic mean free path is comparable to the diameters of the thinnest samples, making the Thouless length lT (or inelastic diffusion length) much larger than the diameter, so that the wire is effectively one dimensional. The inelastic events effectively break the wire into a series of localized segments, whose resistances can be added to obtain the total resistance of the wire. The ensemble-averaged resistance for all possible segmented wires, weighted with a Poisson distribution of inelastic-scattering lengths along the wire, yields a length dependence for the resistance that is proportional to [L3/lin(T)], provided that lin(T)?L, where L is the sample length and lin(T) is some effective temperature-dependent one-dimensional inelastic-scattering length. A more sophisticated approach using a Poisson distribution in inelastic-scattering times, which takes into account the diffusive motion of the electrons along the wire through the Thouless length, yields a length- and temperature-dependent resistivity proportional to (L/lT)4 under appropriate conditions. Inelastic-scattering lifetimes are inferred from the temperature-dependent bulk resistivities (i.e., those of thicker, effectively three-dimensional samples), assuming that a minimum amount of energy must be exchanged for a collision to be effective in destroying the phase coherence of the localized state. If the dominant inelastic mechanism is electron-electron scattering, then our result, given the appropriate choice of the channel number parameter, is consistent with the data. If electron-phason scattering were of comparable importance, then our results would remain consistent. However, the inelastic-scattering lifetime inferred from bulk resistivity data is too short. This is because the electron-phason mechanism dominates in the inelastic-scattering rate, although the two mechanisms may be of comparable importance for the bulk resistivity. Possible reasons why the electron-phason mechanism might be less effective in thin wires than in bulk are discussed.

Kotimaisen tuorekalan tuoreuden arviointi laatuindeksimenetelmällä QIM®

Kalateollisuus ja kalakauppa tarvitsisivat menetelmän, jolla kalan säilyvyyttä voitaisiin arvioida reaaliaikaisesti ja luotettavasti. Laatuindeksimenetelmä QIM® (engl. Quality Index Method) on käytössä jo useassa Euroopan maassa useille eri kalalajeille. QIM® pyrkii lajikohtaisesti ennustamaan aistinvaraisten ominaisuuksien muutoksien perusteella jäljellä olevaa säilyvyysaikaa. Työn tavoitteena oli luoda QIM® meressä kasvatetulle siialle. Tämä on ensimmäinen suomalaiselle kalalle tehtävä QIM®, ja tavoitteena on saada meressä kasvatetun siian QIM® myös viralliseen QIM®-käsikirjaan. Tutkimus tehtiin Elintarviketurvallisuusvirasto Eviralle. Tutkittavat kalat Evira osti Kalatukku E. Eriksson Oy:ltä. QIM®-tuloksen tueksi tutkittiin yhden erän pH ja indikoitiin pilaantuminen myös mikrobiologisesti. Luotiin myös kasvatetun siian profiili (arvioijia 13). Itse tutkimusosassa kaksi profiiliraatia (n = 9) ja QIM®-raati (n = 5) arvioivat raa’an ja kypsän kalan. Tulos varmistettiin myös aistinvaraisella kalan laadunarviointimenetelmällä (Evira 8001). QIM®-raati loi QIM®-luonnoksen ja luonnoksen toimivuutta testattiin. Kiinteänä osana työn toteutusta oli myös eri vaiheiden muutosten valokuvaus. Tämän tutkimuksen mukaan luotu QIM®-luonnos on toimiva pohja validoitaessaa QIM®-menetelmää siialle. Voidaan myös todeta, että QIM® soveltuu meressä kasvatetulle siialle. Kypsän kalan aistinvaraisella laadunarviointimenetelmällä (Evira 8001) analysoitiin säilytysajankohta, jolloin kypsästä kalasta voitiin todeta kalan kauppakelvottomuus – tätä pidettiin ajanhetkenä, jolloin raa’an kalan tutkiminen voitiin lopettaa. Tutkimuksessa käytetty mikrobiologinen menetelmä ”Mikrobien lukumäärän määrittäminen” (Evira 3420/1) korreloi QIM®-tuloksen kanssa; kalanäyte oli tässä tutkimuksessa niin mikrobiologisesti arvioituna kuin laatuindeksinkin mukaan käyttökelvotonta viidentenätoista päivänä. Tutkittujen kalojen pH-arvoja ei voitu verrata laatuindeksiin, sillä tässä tutkimuksessa mitattujen pH-arvojen tuloksista ei voitu päätellä pilaantumisen etenemistä. Kun QIM® meressä kasvatetulle siialle on validoitu (Evira), valmista meressä kasvatetun siian QI-menetelmää voidaan hyödyntää jatkossa Suomen kalateollisuudessa ja -markkinoilla. Olisi hyvä, jos QIM® luotaisiin myös muille Suomen yleisimmille kauppakaloille, jotta pakkauksiin merkityt viimeiset käyttöpäivät perustuisivat yhteen yhteiseen menetelmään ja näin viimeisellä käyttöpäivällä olisi tieteellinen pohja.

High pressure study of Fe3O4 through the verwey transition

The thermopower (TEP) and electrical resistance of stoichiometric Fe3O4 crystals have been measured up to pressures of 6 GPa over the temperature range of 80-160 K. The resistance decreases markedly with increasing pressure below the Verwey transition temperature TV and TV decreases linearly with increasing pressure. The magnitude of the TEP as well as the discontinuity at TV decrease with increasing pressure. The thermopower of Fe3O4 shows an interesting upswing at low temperatures (lt;100 K) which is affected significantly by pressure.

Strength Symmetry Index: A measure of seizure adequacy in ECT

Seizure electroencephalography (EEG) was recorded from two channels-right (Rt) and left (Lt)-during bilateral electroconvulsive therapy (ECT) (n = 12) and unilateral ECT (n = 12). The EEG was also acquired into a microcomputer and was analyzed without knowledge of the clinical details. EEG recordings of both ECT procedures yielded seizures of comparable duration. The Strength Symmetry Index (SSI) was computed from the early- and midseizure phases using the fractal dimension of the EEG. The seizures of unilateral ECT were characterized by significantly smaller SSI in both phases. More unilateral than bilateral ECT seizures had a smaller than median SSI in both phases. The seizures also differed on other measures as reported in the literature. The findings indicate that SSI may be a potential measure of seizure adequacy that remains to be validated in future research.

General theories for the electrical transport properties of carbon nanotubes

We have shown that the general theories of metals and semiconductors can be employed to understand the diameter and voltage dependency of current through metallic and semiconducting carbon nanotubes, respectively. The current through a semiconducting multiwalled carbon nanotube (MWCNT) is associated with the energy gap that is different for different shells. The contribution of the outermost shell is larger as compared to the inner shells. The general theories can also explain the diameter dependency of maximum current through nanotubes. We have also compared the current carrying ability of a MWCNT and an array of the same diameter of single wall carbon nanotubes (SWCNTs) and found that MWCNTs are better suited and deserve further investigation for possible applications as interconnects.

Correlations between structure and thermodynamic properties of spinels and their applications in technology

Measurements a/the Gibbs' energy enthalpy and entrupy vffarmation oj chromites, vanadites and alumlnat.:s 0/ F", Ni. Co'. Mn, Zn Mg and Cd, using solid oxide galvanic cells over a ternperature range extending approximately lOOO°C, have shown that the '~'Ilir"!,,, J'JrIl/iJ~ tion 0/ cubic 2-3 oxide spinel phases (MX!O,), from component oxide (MO) with rock-salt and X.Os whir c(1f'l/!ldwn st!'llt'lw,·. call b,' represented by a semi-empirical correlalion, ~S~ = --LiS + L'i,SM +~S~:"d(±O.3) cal.deg-1 mol-1 where /',.SM Is the entropy 0/calian mixing oillhe tetrahedral alld octahedral sites o/the spinel and Sr:~ is tlie enfropy associaf,'d Wifh Ih,' randomization a/the lahn-Telier distortions. A review a/the methods/or evaluating the cation distriblltion lfl spille!s suggeJ{j' l/r,l! Ihe most promising scheme is based Oil octahedral site preference energies from the crystal field theory for the Iral1silioll IIIl'f"! IlIIL';. For I/""-Irallsifioll melal cal ions site preference energies are derived relative /0 thol'lt fLI, [ransilion metal ions from measured high tClllP('ftJi ure Cal iUlI disll iiJuriol1 in spine! phases thar contail! one IransilioJl metal and another non-transition metal carion. For 2-3 srinds compulatiorrs b,IS"J Oil i.!c[J;' Temkin mixing on each catioll subialtice predici JistributionJ that are In fair agreement with X-ray and 1I1'IIIrOll ditTraction, /IIdg""!ic dll.! electrical propcrries, and spectroscopic measurements. In 2-4 spineis mixing vI ions do not foliow strictly ideal slllIistli:al Jaws, Th,' OIl/up) associated with the randomizalion 0/the Jllhn-Teller dislOriioll" appear to be significant, only ill spinels witll 3d'. 3d', 3d' (ifld~UI' iOtls in tetrahedral and 3d' and 3d9 ions in octahedral positions. Application 0/this structural model for predicting the thermodynamic proputies ofspinel solid .,olutiofl5 or,' illustrated. F,lr complex systems additional contributions arising from strain fields, redox equilibria and off-center ions have to be qllalllififti. The entropy correlation for spinels provides a method for evaluating structure tran:.jormafiofl entropies in silllple o.\id.-s, ["founlllion on the relative stabilities ofoxides in different crystallCtructures is USe/III for computer ea/culaliof! a/phase dfugrullls ofIlIrer,',,1 III (N.lll1ie5 by method, similar to thost: used by Kaufman and Bernstein for refractory alloy systems. Examples oftechnoiogical appliCation tnclude the predictioll ofdeoxidation equilibria in Fe-Mn-AI-O s),slelll at 1600°C duj ,'Ulllpltfalion 0/phase relutions in Fe-Ni-Cr-S system,

Electrical characteristics of multiwalled carbon nanotube arrays and influence of pressure

We have investigated the current-voltage characteristics of carbon nanotube arrays and shown that the current through the arrays increases rapidly with applied voltage before the breakdown occurs. Simultaneous measurements of current and temperature at one end of the arrays suggest that the rapid increase of current is due to Joule heating. The current through the array and the threshold voltage are found to increase with decreasing pressure. Copyright 2012 Author(s). This article is distributed under a Creative Commons Attribution 3.0 Unported License. http://dx.doi.org/10.1063/1.3702777]

Electrical Transport Properties of Buckled Carbon Nanotube Arrays

We report on the electrical transport properties of buckled carbon nanotube arrays synthesized by pyrolysis. Analyzing the experimental data based on the general theory of semiconductors, the arrays are predicted to be semiconducting and the band gap can be evaluated. The band gap of different arrays is in 25-50 meV range.