1,496 research outputs found
Distressed relationships: lessons from the Norwegian banking crisis
This paper measures the economy-wide impact of bank distress on the loss of relationship benefits. We use the near-collapse of the Norwegian banking system during the period 1988 to 1991 to measure the impact of bank distress announcements on the stock prices of firms maintaining a relationship with a distressed bank. We find that although banks experience large and permanent downward revisions in their equity value during the event period, firms maintaining relationships with these banks face only small and temporary changes, on average, in stock price. In other words, the aggregate impact of bank distress on the real economy appears small. We analyze the cross-sectional variation in firm abnormal returns and find that firms that maintain international bank relationships suffer more upon announcement of bank distress
Comparing hierarchies of total functionals
In this paper we consider two hierarchies of hereditarily total and
continuous functionals over the reals based on one extensional and one
intensional representation of real numbers, and we discuss under which
asumptions these hierarchies coincide. This coincidense problem is equivalent
to a statement about the topology of the Kleene-Kreisel continuous functionals.
As a tool of independent interest, we show that the Kleene-Kreisel functionals
may be embedded into both these hierarchies.Comment: 28 page
A New, Highly Conductive, Lithium Salt/Nonionic Surfactant, Lyotropic Liquid-Crystalline Mesophase and Its Application
Cataloged from PDF version of article.Salty water! Lithium salts (LiCl, LiNO3, and LiClO4) at very high concentrations in water form lyotropic liquid crystalline (LLC) mesophases with a nonionic surfactant (10-lauryl ether) and display high ionic conductivities (10−2–10−4 S cm−1) over a broad temperature range (−10 to 80 °C) with excellent behavior as gel electrolytes in electrochemical applications
Origin of Lyotropic Liquid Crystalline Mesophase Formation and Liquid Crystalline to Mesostructured Solid Transformation in the Metal Nitrate Salt-Surfactant Systems
Cataloged from PDF version of article.The zinc nitrate salt acts as a solvent in the ZnX-C(12)EO(10) (ZnX is [Zn(H(2)O)(6)](NO(3))(2) and C(12)EO(10) is C(12)H(25)(OCH(2)CH(2))(10)OH) lyotropic liquid crystalline (LLC) mesophase with a drastic dropping on the melting point of ZnX. The salt surfactant LLC mesophase is stable down to -52 degrees C and undergoes a phase change into a solid mesostructured salt upon cooling below -52 degrees C; no phase separation is observed down to -190 degrees C. The ZnX-C(12)EO(10) mesophase displays a usual phase behavior with an increasing concentration of the solvent (ZnX) in the media with an order of bicontinuous cubic(V(1))-2D hexagonal(H(1)) - a mixture of 2D hexagonal and micelle cubic(H(1) + I)-micelle cubic(I)-micelle(L(1)) phases. The phase behaviors, specifically at low temperatures, and the first phase diagram of the ZnX-C(12)EO(10) system was investigated using polarized optical microscopy (POM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), and Raman techniques and conductivity measurements
Effect of Hygroscopicity of the Metal Salts on the Formation and Air Stability of Lyotropic Liquid Crystalline Mesophases in Hydrated Salt-Surfactant Systems
Cataloged from PDF version of article.It is known that alkali, transition metal and lanthanide salts can form lyotropic liquid crystalline (LLC) mesophases with non-ionic surfactants (such as CiH2i+1(OCH2CH2)(j)OH, denoted as CiEj). Here we combine several salt systems and show that the percent deliquescence relative humidity (%DRH) value of a salt is the determining parameter in the formation and stability of the mesophases and that the other parameters are secondary and less significant. Accordingly, salts can be divided into 3 categories: Type I salts (such as LiCl, LiBr, LiI, LiNO3, LiClO4, CaCl2, Ca(NO3)(2), MgCl2, and some transition metal nitrates) have low %DRH and form stable salt-surfactant LLC mesophases in the presence of a small amount of water, type II salts (such as some sodium and potassium salts) that are moderately hygroscopic form disordered stable mesophases, and type III salts that have high %DRH values, do not form stable LLC mesophases and leach out salt crystals. To illustrate this effect, a large group of salts from alkali and alkaline earth metals were investigated using XRD, POM, FTIR, and Raman techniques. Among the different salts investigated in this study, the LiX (where X is Cl-, Br-, I-, NO3-, and ClO4-) and CaX2 (X is Cl-, and NO3-) salts were more prone to establish LLC mesophases because of their lower %DRH values. The phase behavior with respect to concentration, stability, and thermal behavior of Li(I) systems were investigated further. It is seen that the phase transitions among different anions in the Li(I) systems follow the Hofmeister series. (C) 2014 Elsevier Inc. All rights reserved
Molten-Salt-Assisted Self-Assembly (MASA)-Synthesis Mesoporous Metal Titanate-Titania, Metal Sulfide-Titania, and Metal Selenide-Titania Thin Films
Cataloged from PDF version of article.New synthetic strategies are needed for the assembly of porous metal titanates and metal chalcogenite-titania thin films for various energy applications. Here, a new synthetic approach is introduced in which two solvents and two surfactants are used. Both surfactants are necessary to accommodate the desired amount of salt species in the hydrophilic domains of the mesophase. The process is called a molten-salt-assisted self-assembly (MASA) because the salt species are in the molten phase and act as a solvent to assemble the ingredients into a mesostructure and they react with titania to form mesoporous metal titanates during the annealing step. The mesoporous metal titanate (meso-Zn2TiO4 and meso-CdTiO3) thin films are reacted under H2S or H2Se gas at room temperature to yield high quality transparent mesoporous metal chalcogenides. The H2Se reaction produces rutile and brookite titania phases together with nanocrystalline metal selenides and H2S reaction of meso-CdTiO3 yields nanocrystalline anatase and CdS in the spatially confined pore walls. Two different metal salts (zinc nitrate hexahydrate and cadmium nitrate tetrahydrate) are tested to demonstrate the generality of the new assembly process. The meso-TiO2-CdSe film shows photoactivity under sunlight
Fabrication of Mesoporous Metal Chalcogenide Nanoflake-Silica Thin Films and Spongy Mesoporous CdS and CdSe
Cataloged from PDF version of article.Mesoporous silica metal oxide (ZnO and CdO) thin films have been used as metal ion precursors to produce the first examples of mesoporous silica metal sulfide (meso-SiO2@ZnS, meso-SiO2@CdS) or silica metal selenide (meso-SiO2@ZnSe, meso-SiO2@CdSe) thin films, in which the pore walls are made up of silica and metal sulfide or metal selenide nanoflakes, respectively. A gentle chemical etching with a dilute HF solution of the meso-SiO2@CdS (or meso-SiO2@CdSe) produces mesoporous cadmium sulfide (meso-CdS) (or cadmium selenide, meso-CdSe). Surface modified meso-CdS displays bright blue photoluminescence upon excitation with a UV light. The mesoporous silica metal oxides are formed as metal oxide nanoislands over the silica walls through a self-assembly process of a mixture of metal nitrate salt-two surfactants-silica source followed by calcination step. The reactions, between the H2S (or H2Se) gas and solid precursors, have been carried out at room temperature and monitored using spectroscopy and microscopy techniques. It has been found that these reactions are: 1) taking place through the diffusion of sulfur or selenium species from the top metal oxide layer to the silica metal oxide interface and 2) slow and can be stopped at any stage to obtain mesoporous silica metal oxide metal sulfide or silica metal oxide metal selenide intermediate thin films
Assembly of Molten Transition Metal Salt-Surfactant in a Confined Space for the Synthesis of Mesoporous Metal Oxide-Rich Metal Oxide-Silica Thin Films
Cataloged from PDF version of article.ABSTRACT: Uniform and homogeneous coating of mesoporous
materials with an active (catalytically, photonic, electrical)
nanostructure can be very useful for a number of applications.
Understanding chemical reactions in a confined space is important
in order to design new advanced materials. In this work,
we demonstrate that an extensive amount (as high as 53 mol
percent) of transition metal salts can be confined between silica
walls and two surfactant domains (cetyltrimethylammonium
bromide, CTAB, and lauryl ether, C12H25(OCH2CH2)10OH,
C12EO10) as molten salts and then converted into sponge-like
mesoporous silica metal oxides by thermal annealing. This
investigation has been carried out using two different salts, namely, zinc nitrate hexahydrate, [Zn(H2O)6](NO3)2, and cadmium
nitrate tetrahydrate, [Cd(H2O)4](NO3)2, in a broad range of salt concentrations. The ZnO (or CdO) layers are as thin as about
∼1.6 nm and are homogenously coated as crystalline nano-islands over the silica pore walls
The effect of cationic surfactant and some organic/inorganic additives on the morphology of mesostructured silica templated by pluronics
Cataloged from PDF version of article.Tri-block copolymers (poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide), represented as EOxPOyEOx), pluronics (F127=EO106PO70EO106, P65=EO20PO30EO20, P85=EO27PO39EO27, P103= EO17PO55EO17, and P123 = EO20PO70EO20) and cationic surfactants (cethyltrimethylammonium bromide (CTAB)), two surfactant systems, form complex micelles that self-assemble into mesostructured particles with distinct morphology depending on the pluronic type, the concentration of the cationic surfactant and the organic-inorganic ingredients in a siliceous reaction media under acidic conditions. The CTAB-P65 and CTAB-P85 systems form spheres, CTAB-P103 and CTAB-P123 systems form wormlike particles, and CTAB-F127 system form single crystals of mesostructured silica particles under very similar conditions. However addition of various salts (such as KCI and NaNO3) into a CTAB-P103 or CTAB-P123 solution system and cyclohexane and KCI into a CTAB-P85 solution system produces the mesostructured silica spheres and wormlike particles, respectively. By controlling the hydrophilic-hydrophobic character of the pluronics, core-corona interface, by means of additives, such as small organic molecules or salts, one could obtain the desired morphology that is dictated by the shape of the micelles of the pluronic-cationic surfactant complex. The effects of the additives and the formation mechanism of those morphologies have been discussed using spectroscopy (FT-IR and Raman), diffraction (XRD) and microscopy (POM and SEM) data. (c) 2008 Elsevier Inc. All rights reserved
Half-metallic properties of atomic chains of carbon-transition metal compounds
We found that magnetic ground state of one-dimensional atomic chains of
carbon-transition metal compounds exhibit half-metallic properties. They are
semiconductors for one spin-direction, but show metallic properties for the
opposite direction. The spins are fully polarized at the Fermi level and net
magnetic moment per unit cell is an integer multiple of Bohr magneton. The
spin-dependent electronic structure can be engineered by changing the number of
carbon and type of transition metal atoms. These chains, which are stable even
at high temperature and some of which keep their spin-dependent electronic
properties even under moderate axial strain, hold the promise of potential
applications in nanospintronics.Comment: 11 pages, 3 figures, 1 table
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