On a nonlocal Cahn--Hilliard equation with a reaction term

We prove existence, uniqueness, regularity and separation properties for a nonlocal Cahn- Hilliard equation with a reaction term. We deal here with the case of logarithmic potential and degenerate mobility as well an uniformly lipschitz in u reaction term g(x, t, u)

Density-functional perturbation theory goes time-dependent

The scope of time-dependent density-functional theory (TDDFT) is limited to the lowest portion of the spectrum of rather small systems (a few tens of atoms at most). In the static regime, density-functional perturbation theory (DFPT) allows one to calculate response functions of systems as large as currently dealt with in ground-state simulations. In this paper we present an effective way of combining DFPT with TDDFT. The dynamical polarizability is first expressed as an off-diagonal matrix element of the resolvent of the Kohn-Sham Liouvillian super-operator. A DFPT representation of response functions allows one to avoid the calculation of unoccupied Kohn-Sham orbitals. The resolvent of the Liouvillian is finally conveniently evaluated using a newly developed non-symmetric Lanczos technique, which allows for the calculation of the entire spectrum with a single Lanczos recursion chain. Each step of the chain essentially requires twice as many operations as a single step of the iterative diagonalization of the unperturbed Kohn-Sham Hamiltonian or, for that matter, as a single time step of a Car-Parrinello molecular dynamics run. The method will be illustrated with a few case molecular applications

Turbo charging time-dependent density-functional theory with Lanczos chains

We introduce a new implementation of time-dependent density-functional theory which allows the \emph{entire} spectrum of a molecule or extended system to be computed with a numerical effort comparable to that of a \emph{single} standard ground-state calculation. This method is particularly well suited for large systems and/or large basis sets, such as plane waves or real-space grids. By using a super-operator formulation of linearized time-dependent density-functional theory, we first represent the dynamical polarizability of an interacting-electron system as an off-diagonal matrix element of the resolvent of the Liouvillian super-operator. One-electron operators and density matrices are treated using a representation borrowed from time-independent density-functional perturbation theory, which permits to avoid the calculation of unoccupied Kohn-Sham orbitals. The resolvent of the Liouvillian is evaluated through a newly developed algorithm based on the non-symmetric Lanczos method. Each step of the Lanczos recursion essentially requires twice as many operations as a single step of the iterative diagonalization of the unperturbed Kohn-Sham Hamiltonian. Suitable extrapolation of the Lanczos coefficients allows for a dramatic reduction of the number of Lanczos steps necessary to obtain well converged spectra, bringing such number down to hundreds (or a few thousands, at worst) in typical plane-wave pseudopotential applications. The resulting numerical workload is only a few times larger than that needed by a ground-state Kohn-Sham calculation for a same system. Our method is demonstrated with the calculation of the spectra of benzene, C$_{60}$ fullerene, and of chlorofyll a.Comment: 15 pages, 7 figures, to be pdflatex + bibte

turboTDDFT - A code for the simulation of molecular spectra using the Liouville-Lanczos approach to time-dependent density-functional perturbation theory

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Identification of G-quadruplex DNA/RNA binders: Structure-based virtual screening and biophysical characterization

Background Recent findings demonstrated that, in mammalian cells, telomere DNA (Tel) is transcribed into telomeric repeat-containing RNA (TERRA), which is involved in fundamental biological processes, thus representing a promising anticancer target. For this reason, the discovery of dual (as well as selective) Tel/TERRA G-quadruplex (G4) binders could represent an innovative strategy to enhance telomerase inhibition. Methods Initially, docking simulations of known Tel and TERRA active ligands were performed on the 3D coordinates of bimolecular G4 Tel DNA (Tel2) and TERRA (TERRA2). Structure-based pharmacophore models were generated on the best complexes and employed for the virtual screening of ~ 257,000 natural compounds. The 20 best candidates were submitted to biophysical assays, which included circular dichroism and mass spectrometry at different K+ concentrations. Results Three hits were here identified and characterized by biophysical assays. Compound 7 acts as dual Tel2/TERRA2 G4-ligand at physiological KCl concentration, while hits 15 and 17 show preferential thermal stabilization for Tel2 DNA. The different molecular recognition against the two targets was also discussed. Conclusions Our successful results pave the way to further lead optimization to achieve both increased selectivity and stabilizing effect against TERRA and Tel DNA G4s. General significance The current study combines for the first time molecular modelling and biophysical assays applied to bimolecular DNA and RNA G4s, leading to the identification of innovative ligand chemical scaffolds with a promising anticancer profile. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio

Time-dependent density functional theory study of squaraine dye-sensitized solar cells

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Applicazione della classificazione National Health Service Breast Screening Pathology (NHSBSP) nella comparazione cito-istologica dei tumori mammari della cagna = NHSBSP classification use in the correlation of canine mammary tumour cytology and histopathology

Canine mammary tumours (CMT) are the most common neoplasia in bitches. Fine needle aspiration cytology (FNAC) is a fast and inexpensive technique well-tolerated by animals. Few reports have shown how difficult cytological diagnosis of CMT is and how difficult benign or malignant tumours are to classify using FNAC. Cytological diagnosis has often been inconclusive in veterinary pathology. In the diagnosis of human breast cancer, FNAC efficacy is beyond doubt due to its high specificity. In this preliminary study, our aim is to evaluate the efficacy of NHSBSP classification, applied to CMT. Secondly, we wish to test the usefulness of H&H stain in FNAC for CMT diagnosis. 75 FNAC specimens, from 41 dogs with mammary tumours were examined. 72/75 underwent the NHSBSP classification Histological examination of the tumours was performed in each case for comparison purposes. All the CMTs fell under the five categories: C1 (3 cases), C2 (7 cases), C3 (38 cases), C4 (15 cases), C5 (9 cases). As regards H&H staining in our view it was more efficacious than M.G.G. staining in distinguishing morphological cell details. Our results showed that the NHSBSP classification gave a 94.4% correspondence level between cytological and histological findings

Un Caso di linfoma a grandi linfociti granulosi (LGL) in un cavallo: caratterizzazione istochimica ed immunofenotipica = Large granular lymphoma (LGL) in a horse: histochemical and immunophenotype characterization

The aim of this study is to confirm lymphoma diagnosis, characterize the neoplasia immunophenotype and observe cell typologies by histochemical staining

Efficacy of risedronate in a post-menopausal woman affected by osteoporosis and inflammatory bowel disease

Post-menopausal osteoporosis is a skeletal disease that can be asymptomatic and is sometimes underdiagnosed and undertreated. Post-menopausal osteoporosis can be associated with fractures and consequent impaired quality of life and increase of health care costs. Bisphosphonates are a therapeutic choice, because they proved to be effective in preventing bone loss. The current case report shows the efficacy of six-month risedronate administration in a post-menopausal woman affected by osteoporosis and inflammatory bowel disease in reducing biochemical bone turnover markers and increasing bone mineral density

Osservazioni istochimiche e immunoistochimiche sull'ipofisi anteriore di un cane affetto da malattia di Cushing

Gli adenomi del lobo anteriore dell'ipofisi sono neoplasie benigne piuttosto frequenti. Essi mostrano aspetto circoscritto e accrescimento non invasivo nei confronti dei tessuti circostanti. Il tumore a cellule secernenti ACTH, che colpisce le cellule cromofobe della pars anteriore dell'ipofisi, è uno di questi e viene associato alla sindrome di Cushing, causando evidente ipercortisolemia per stimolazione della corteccia surrenale. Un cane meticcio, femmina, di 7 anni, in terapia per sospetta Sindrome di Cushing e pervenuto a morte, è stato sottoposto ad accurato esame necroscopico, durante il quale si procedeva tra l'altro a prelevare ghiandole surrenali, polmone, fegato, cute, muscoli e intera ghiandola pituitaria. Su detti organi veniva eseguito l'esame istopatologico per la ricerca delle lesioni tipiche determinate dalla sindrome. Sulla ghiandola pituitaria, aumentata notevolmente di volume, venivano eseguite indagini istopatologiche specifiche, mediante colorazione OFG, per differenziare gli istotipi costituenti la pars anteriore. Tale colorazione ha consentito di riscontrare e identificare tra le cellule pituitarie gli elementi acidofili, basofili e cromofobi; queste ultime cellule, aumentate di numero, erano d'aspetto omogeneo e formavano un nucleo compatto e con scarso stroma al centro della ghiandola. La caratterizzazione cromatica e la differenziazione dai restanti istotipi ha reso possibile identificare la neoplasia come adenoma ipofisario di tipo "diffuso", caratterizzato per l'appunto da cellule disposte a strati, con scarso stroma e debole vascolarizzazione. Per verificare l'ormonoattività  delle cellule neoplastiche si è proceduto all'esame immunoistochimico per la ricerca dell'ACTH. Il risultato di tale indagine ha dato esito positivo, confermando l'intensa attività secernente delle cellule oggetto di studio