Early discovery of individual firm insolvency

Email: wxding{at}uic.edu Received on 11 January 2006. Accepted on 21 November 2006. This paper proposes a new methodology for the early discoveryof individual firm insolvency without employing any other firm'sdata. The proposed individual-level model can be applied todifferent firms, regardless of industry type or asset size,and thereby overcomes the sample selection problem commonlyfound in aggregate-level prediction models. Unlike many previousstudies, which assume that the distributions of variables involveddo not change over time and that the variables follow a singleknown distribution, the proposed model can capture each individualfirm's potential multiple data-generating processes and determinethe actual distributions exhibited in its own data. Thus, itcaptures each individual firm's intrinsic heterogeneity. Anempirical study illustrates the greater predictive power ofthis model compared with the current conventional methods. Specifically,the predictive accuracy of the proposed model is 92.65% and77.45% for 2 and 5 years prior to actual bankruptcy, respectively.Moreover, the proposed model is adaptive and simple to implement.     

Influence of chelate substituents on the structure and spin state of unsaturated [N(SiMe2CH2PtBu2)2]Ru-X

Density functional theory calculations on the conformational preferences in the two fused five-membered rings of anionic N(SiR2CH2PR'2)2 chelated to RuX+ are compared to several experimental structures (X=halide). The calculations consider the structures of both singlet and triplet states and reveal that both the four tBu groups and the crowded juncture (N(SiMe2)2) of the two rings must be included computationally to understand the observed structures. Computational experiments with different substituents R and R' show the reality of N-->Ru pi donation. The cases where X=H and CH3 are also studied.     

Radical (NO) and nonradical (N(2)O) reagents convert a ruthenium(IV) nitride to the same nitrosyl complex

The ruthenium(IV) nitride complex (PNP)RuN (PNP = (tBu2PCH2-SiMe2)2N-) reacts rapidly with 2NO to form (PNP)Ru(NO) and N2O, via no detectable intermediate. The linear nitrosyl complex has a planar structure. In a slower reaction, (PNP)RuN reacts with N2O by O-atom transfer (established by 15N labeling) to give the same nitrosyl complex and N2. Density functional theory (B3LYP) calculations show both reactions to be very thermodynamically favorable. Analysis of possible intermediates in each reaction shows that radical (PNP)RuN(NO) has much spin density on nitride N (hence, N2-), while one 2 + 3 metallacycle, (PNP)RuN3O, has the wrong connectivity to form a product. Instead, an intermediate with a doubly bent N2O (hence, a two-electron reduced N-nitrosoimide form) brings the O atom in proximity to the nitride N on the path to a product.     

Cu-ATSM: a radiopharmaceutical for the PET imaging of hypoxia

Copper(II)-diacetyl-bis(N(4)-methylthiosemicarbazone), Cu-ATSM, labeled with a positron emitting isotope of copper ((60)Cu, (61)Cu, (62)Cu or (64)Cu) has been shown, in vitro and in vivo, to be selective for hypoxic tissue. In silico studies have explored the mechanism of its hypoxia selectivity, and clinical studies with this agent have shown non-invasive imaging data that is predictive of a cancer patients' response to conventional therapy. This Perspective discusses the evolution of Cu-ATSM, how its selectivity can be improved upon, and where this metal-ligand platform could be taken in the future.     

Kinetic separation of propene and propane in metal-organic frameworks: controlling diffusion rates in plate-shaped crystals via tuning of pore apertures and crystallite aspect ratios

A series of isostructural, noncatenated, zinc-pillared-paddlewheel metal-organic framework materials has been synthesized from 1,2,4,5-tetrakis(carboxyphenyl)benzene and trans-1,2-dipyridylethene struts. Substantial kinetic selectivity in the adsorption of propene over propane can be observed, depending on the pore apertures and the rectangular-plate morphology of the crystals.     

Site-directed methyl group labeling as an NMR probe of structure and dynamics in supramolecular protein systems: applications to the proteasome and to the ClpP protease

Methyl groups are powerful reporters of structure, motion, and function in NMR studies of supramolecular protein assemblies. Their utility can be hindered, however, by spectral overlap, difficulties with assignment or lack of probes in biologically important regions of the molecule studied. Here we show that (13)CH(3)-S- labeling of Cys side chains using (13)C-methyl-methanethiosulfonate ((13)C-MMTS) (IUPAC name: methylsulfonylsulfanylmethane) provides a convenient probe of molecular structure and dynamics. The methodology is demonstrated with an application focusing on the gating residues of the Thermoplasma acidophilum proteasome, where it is shown that the (13)CH(3)-S- label reports faithfully on the conformational heterogeneity and dynamics in this region of the complex. A second and related application involves labeling with (13)C-MMTS at the N-termini of the subunits comprising the E. coli ClpP protease that reveals multiple conformations of gating residues in this complex as well. These N-terminal residues adopt a single conformation upon gate opening.     

Synthesis and characterization of sodium vanadium oxide gels: the effects of water (n) and sodium (x) content on the electrochemistry of Na(x)V2O5·nH2O

Sodium vanadium oxide gels, Na(x)V(2)O(5)·nH(2)O, of varying sodium content (0.12 < x < 0.32) were prepared by careful control of an ion exchange process. The water content (0.23 > n > 0.01) and interlayer spacing were found to be inversely proportional to the sodium level (x), thus control of sodium (x) content provided a direct, chimie douce approach for control of hydration level (n) and interlayer spacing, without the need for high temperature treatment to affect dehydration. Notably, the use of high temperatures to modify hydration levels can result in crystallization and collapse of the interlayer structure, highlighting the distinct advantage of our novel chimie douce synthesis strategy. Subsequent to synthesis and characterization, results from an electrochemical study of a series of Na(x)V(2)O(5)·nH(2)O samples highlight the significant impact of interlayer water on delivered capacity of the layered materials. Specifically, the sodium vanadium oxide gels with higher sodium content and lower water content provided higher capacities in lithium based cells, where capacity delivered to 2.0 V under C/20 discharge ranged from 170 mAh/g for Na(0.12)V(2)O(5)·0.23H(2)O to 300 mAh/g for Na(0.32)V(2)O(5)·0.01H(2)O. The capacity differences were maintained as the cells were cycled.