Room Temperature Organic Superconductor?

The electron--phonon coupling in fullerene C28 has been calculated from first principles. The value of the associated coupling constant lambda/N(0) is found to be a factor three larger than that associated with C60. Assuming similar values of the density of levels at the Fermi surface N(0) and of the Coulomb pseudopotential for C28-based solids as those associated with alkali-doped fullerides A3C60, one obtains Tc(C28) \approx 8 Tc(C60).Comment: 10 pages, 2 figure

Metadynamic sampling of the free energy landscapes of proteins coupled with a Monte Carlo algorithm

Metadynamics is a powerful computational tool to obtain the free energy landscape of complex systems. The Monte Carlo algorithm has proven useful to calculate thermodynamic quantities associated with simplified models of proteins, and thus to gain an ever-increasing understanding on the general principles underlying the mechanism of protein folding. We show that it is possible to couple metadynamics and Monte Carlo algorithms to obtain the free energy of model proteins in a way which is computationally very economical.Comment: Submitted to Gen

A folding inhibitor of the HIV-1 Protease

Being the HIV-1 Protease (HIV-1-PR) an essential enzyme in the viral life cycle, its inhibition can control AIDS. The folding of single domain proteins, like each of the monomers forming the HIV-1-PR homodimer, is controlled by local elementary structures (LES, folding units stabilized by strongly interacting, highly conserved, as a rule hydrophobic, amino acids). These LES have evolved over myriad of generations to recognize and strongly attract each other, so as to make the protein fold fast and be stable in its native conformation. Consequently, peptides displaying a sequence identical to those segments of the monomers associated with LES are expected to act as competitive inhibitors and thus destabilize the native structure of the enzyme. These inhibitors are unlikely to lead to escape mutants as they bind to the protease monomers through highly conserved amino acids which play an essential role in the folding process. The properties of one of the most promising inhibitors of the folding of the HIV-1-PR monomers found among these peptides is demonstrated with the help of spectrophotometric assays and CD spectroscopy

Deriving amino acid contact potentials from their frequencies of occurence in proteins: a lattice model study

The possibility of deriving the contact potentials between amino acids from their frequencies of occurence in proteins is discussed in evolutionary terms. This approach allows the use of traditional thermodynamics to describe such frequencies and, consequently, to develop a strategy to include in the calculations correlations due to the spatial proximity of the amino acids and to their overall tendency of being conserved in proteins. Making use of a lattice model to describe protein chains and defining a "true" potential, we test these strategies by selecting a database of folding model sequences, deriving the contact potentials from such sequences and comparing them with the "true" potential. Taking into account correlations allows for a markedly better prediction of the interaction potentials

Simple models of protein folding and of non--conventional drug design

While all the information required for the folding of a protein is contained in its amino acid sequence, one has not yet learned how to extract this information to predict the three--dimensional, biologically active, native conformation of a protein whose sequence is known. Using insight obtained from simple model simulations of the folding of proteins, in particular of the fact that this phenomenon is essentially controlled by conserved (native) contacts among (few) strongly interacting ("hot"), as a rule hydrophobic, amino acids, which also stabilize local elementary structures (LES, hidden, incipient secondary structures like $\alpha$--helices and $\beta$--sheets) formed early in the folding process and leading to the postcritical folding nucleus (i.e., the minimum set of native contacts which bring the system pass beyond the highest free--energy barrier found in the whole folding process) it is possible to work out a succesful strategy for reading the native structure of designed proteins from the knowledge of only their amino acid sequence and of the contact energies among the amino acids. Because LES have undergone millions of years of evolution to selectively dock to their complementary structures, small peptides made out of the same amino acids as the LES are expected to selectively attach to the newly expressed (unfolded) protein and inhibit its folding, or to the native (fluctuating) native conformation and denaturate it. These peptides, or their mimetic molecules, can thus be used as effective non--conventional drugs to those already existing (and directed at neutralizing the active site of enzymes), displaying the advantage of not suffering from the uprise of resistance

The ability of the turnaround index to assess going concern assumptions: evidence from its application to Italian listed companies.

In times of crisis, entrepreneur often must decide whether to liquidate the company and the whole business or to renew it by activating a turnaround process. A tool increasingly used in international practice is the turnaround index, which can determine whether a company can continue its activities in the future according to the going concern assumption, which is the index measured as a function of the economic and financial performance of the company. This measure can take values between 0.1, for satisfactory performance and therefore unlikely to turn around, and 0.9, for unsatisfactory performance and therefore a high propensity to turnaround. The index determines whether there is a higher or lower risk for a company to enter into crisis. The aim of this paper is to test the effectiveness of the turnaround index in assessing the turnaround urgency by choosing a sample of the Italian companies

EVIDENCE OF THE ITALIAN SPECIAL PURPOSE ACQUISITION COMPANY

In 1992 David Nussbaum with the support of the law firm Graubard Miller devised the formula of the specified purpose acquisition companies (SPAC): a financial vehicle that has the flexibility and functionality typical of the blank-check companies, which could provide investors with the right protections and guarantees in order to be a reliable instrument. The first SPAC officially debuted in 2003 through the Initial Public Offering (IPO) of Millstream Acquisition Corporation which then completed the merger with Nations Health in September 2004. In 2005 the first SPAC got listed in European Market and in 2011 the first SPAC joined in the Italian market. The aim of this research is to investigate the features of the Italian SPACs System because it\u201fs becoming a large phenomenon in Italy. This new type of investment is able to fit the needs of small-medium Italian companies, to solve crisis difficulties, to find new finance to grow, to be a good instrument for opening up venture capital and institutional investors respecting the past business history and the safeguard of corporate control. The study, then, performs an analysis on the Italian SPACs by examining their target firms, stock performance before and after the business combination and the impact of the SPACs on SME corporate governance models. These results will be compared with those of other research developed by academic literature

Evidence for using the cash conversion cycle to test the relationship with the corporate profitability an empirical analysis on a sample of textile Italian SMEs

The cash conversion cycle (CCC) is a financial index with increasing importance in recent years since analysts and investors consider it effective for financial analyses. The index provides a correct and truthful situation of the company's ability to cope with its liabilities and allows the company to monitor the cash cycle with reference to purchase operations, production, and sales of products. The CCC is an index expressed by days, so it is necessary to know the days inventory outstanding, the days sales outstanding, and the days payable outstanding to calculate it. The purpose of this research is to analyse characteristics of the CCC and differences with respect to the other liquidity ratios and its relationship with the most relevant financial ratios through empirical applications to verify if it is a reliable index for making decisions regarding a company's cash flow strategy

Designability of lattice model heteropolymers

Protein folds are highly designable, in the sense that many sequences fold to the same conformation. In the present work we derive an expression for the designability in a 20 letter lattice model of proteins which, relying only on the Central Limit Theorem, has a generality which goes beyond the simple model used in its derivation. This expression displays an exponential dependence on the energy of the optimal sequence folding on the given conformation measured with respect to the lowest energy of the conformational dissimilar structures, energy difference which constitutes the only parameter controlling designability. Accordingly, the designability of a native conformation is intimately connected to the stability of the sequences folding to them.Comment: in press on Phys. Rev.