First results of the CAKE experiment

We present the preliminary results of the cosmic abundances below the knee energies (CAKE) experiment for the study of the primary cosmic-ray composition and for the search of exotic particles in the primary cosmic radiation. CAKE uses CR39^® and Lexan nuclear track detectors, which were calibrated with beams of 158 AGeV Pb ions and 1 AGeV Fe ions at the CERN and BNL accelerators, respectively. Results based on the analysis of a first data sample are shown.     

New hybrid zirconium aminophosphonates containing piperidine and bipiperidine groups

The reaction of N-(phosphonomethyl)piperidine and N,N'-bis(phosphonomethyl)bipiperidine with zirconium(IV) in hydrofluoric acid media led to the preparation of two new zirconium fluoride phosphonate derivatives with 1D and 2D structure, respectively. Their structures were solved ab initio from laboratory powder X-ray diffraction (PXRD) data. The monophosphonate derivative, with formula ZrF(2)(HF)(O(3)PCH(2)NC(5)H(10)), has a 1D structure (triclinic, space group P ?1, a = 6.6484(3) ?, b = 7.1396(3) ?, c = 12.2320(6) ?, α = 77.932(4)°, β = 87.031(6)°, γ = 78.953(5)°, V = 557.22(4) ?(3), and Z = 2) made of inorganic chains constituted from the connection of zirconium octahedra and phosphorus tetrahedra with the piperidine groups bonded on their external part. The diphosphonate derivative, with formula Zr(2)F(4)(HF)(2)(O(3)PCH(2))NC(10)H(18)N(CH(2)PO(3)), has a 2D structure (triclinic, space group P ?1, a = 6.6243(3) ?, b = 7.2472(4) ?, c = 12.2550(7) ?, α = 102.879(4)°, β = 100.29(1)°, γ = 101.287(7)°, V = 547.03(4) ?(3), and Z = 1) composed of the packing of covalent layers whose structure may be ideally obtained by the joining of adjacent chains of the 1D compound. In these hybrid layers, inorganic regions made of the connectivity of zirconium octahedra and phosphorus tetrahedra alternate with organic regions represented by the bipiperidine moieties. A section dedicated to vibrational spectroscopy analysis is also included, mainly devoted to clarify some issues not easily deducible on the basis of PXRD data and to describe the fluorine environment inside zirconium phosphonate structures.     

Competitive Boolean function evaluation: Beyond monotonicity, and the symmetric case

We study the extremal competitive ratio of Boolean function evaluation. We provide the first non-trivial lower and upper bounds for classes of Boolean functions which are not included in the class of monotone Boolean functions. For the particular case of symmetric functions our bounds are matching and we exactly characterize the best possible competitiveness achievable by a deterministic algorithm. Our upper bound is obtained by a simple polynomial time algorithm.     

Exact solution of the 1D Hubbard model with NN and NNN interactions in the narrow-band limit

In this paper, we propose a family of weighted extended Koch networks based on a class of extended Koch networks. They originate from a r-complete graph, and each node in each r-complete graph of current generation produces mr-complete graphs whose weighted edges are scaled by factor h in subsequent evolutionary step. We study the structural properties of these networks and random walks on them. In more detail, we calculate exactly the average weighted shortest path length (AWSP), average receiving time (ART) and average sending time (AST). Besides, the technique of resistor network is employed to uncover the relationship between ART and AST on networks with unit weight. In the infinite network order limit, the average weighted shortest path lengths stay bounded with growing network order (0 < h < 1). The closed form expression of ART shows that it exhibits a sub-linear dependence (0 < h < 1) or linear dependence (h = 1) on network order. On the contrary, the AST behaves super-linearly with the network order. Collectively, all the obtained results show that the efficiency of message transportation on weighted extended Koch networks has close relation to the network parameters h, m and r. All these findings could shed light on the structure and random walks of general weighted networks.     

On maximum additive Hermitian rank-metric codes

Journal of Algebraic Combinatorics - Inspired by the work of Zhou (Des Codes Cryptogr 88:841–850, 2020) based on the paper of Schmidt (J Algebraic Combin 42(2):635–670, 2015), we...     

On the intersection problem for linear sets in the projective line

The aim of this paper is to investigate the intersection problem between two linear sets in the projective line over a finite field. In particular, we analyze the intersection between two clubs with possibly different maximum fields of linearity. We also consider the intersection between a certain linear set of maximum rank and any other linear set of the same rank. The strategy relies on the study of certain algebraic curves whose rational points describe the intersection of the two linear sets. Among other geometric and algebraic tools, function field theory and the Hasse–Weil bound play a crucial role. As an application, we give asymptotic results on semifields of BEL-rank two.     

Synthesis and Pharmacological Screening of Pyridopyrimidines as Effective Anti-Diarrheal Agents through the Suppression of Cyclic Nucleotide Accumulation

The increased levels of cyclic nucleotides (cGMP and cAMP) in enterocytes trigger intracellular mechanisms of ion and fluid secretion into the lumen, causing secretory diarrhea. Twelve novel pyridopyrimidines derived from 5-(3,5-bistrifluoromethylphenyl)-1,3-dimethyl-5,11-dihydro-1H-indeno[2,1 : 5,6]pyrido[2,3-d]pyrimidine-2,4,6-trione (FPIPP) were synthesized and evaluated on intracellular cyclic nucleotide accumulation. All compounds had no effect on either cyclic nucleotide basal levels or on pre-contracted aortic rings. The metabolic activity and viability in T84 cells, assessed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) and the LDH (lactate dehydrogenase) assays, respectively, were not affected by incubation with the compounds (50 μM). Compound VI almost abolished cGMP accumulation (94 % inhibition) induced by STa toxin in T834 cells and significantly reduced (69 %) forskolin-induced cAMP accumulation in Jurkat cells. Compound VI was active in an in vivo model for diarrhea in rabbits. These results prompted us to perform a microscopic histopathological analysis of intestinal tissues, showing that only compound VI preserves the intestine without significant pathological changes and with a decreased inflammatory pattern in comparison to FPIPP. In vitro stability test revealed that compound VI is resistant to oxidation promoted by atmospheric oxygen.     

Structural homologies in benzylamino-N,N-bis methylphosphonic acid and its layered zirconium derivative

A new layered zirconium diphosphonate fluoride, ZrF(O₃PCH₂)₂NHCH₂C₆H₅ has been prepared and its structure determined ab initio by X-ray powder data and refined with the Rietveld method (orthorhombic, , , , space group Pbca, , Z=8, R_wp=0.080). Both phosphonic groups of each diphosphonate building block are bonded to zirconium atoms on the same side of each layer. Benzyl groups from adjacent layers are interdigitated in the interlayer region, with probable π-π stacking interactions. The structure of the free benzylamino-N,N-bis methylphosphonic acid has been determined by single crystal X-ray data (monoclinic, space group P2₁, , , , β=92.930(3)°, , Z=2, R₁=0.072, wR₂=0.150). As in the zirconium derivative, benzyl groups from adjacent layers are interdigitated and create a regular alternation of polar and non-polar regions.     

Finite element incremental analysis of elastoplastic plate bending

Summary The paper discusses the numerical solution of the elastoplastic bending of plates with any polygonal boundary subject to a generic load and to distributed dislocations.For the discretization of the plate Herrmann's and Hellan's constant moment triangular equilibrium model has been chosen. Compatibility is imposed through a minimum principle, proposed by Capurso and Maier, which can be considered a generalization of the minimum complementary energy principle for elastoplastic workhardening continua allowing for distributed dislocations.By means of a completely automatic computation program, the cases of simply supported and clamped square plate under uniformly distributed load and under central concentrated load are solved. Present results are partly compared with existing solutions.

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Sommario Viene studiato il problema della flessione di una piastra a contorno poligonale qualsiasi costituita da materiale elastico-incrudente e sottoposta ad un carico generico e a distorsioni diffuse. Per la discretizzazione della piastra viene scelto il modello triangolare equilibrato a momento costante di Herrmann e Hellan. La congruenza viene imposta attraverso un principio di minimo proposto da Capurso e Maier che può essere riguardato come la generalizzazione del principio della minima energia complementare per materiali elastico-incrudenti in presenza di distorsioni diffuse.Viene sviluppato un programma di calcolo automatico, che stende sulla piastra un reticolo di densità prefissata, numera e collega fra di loro nodi, lati e triangoli. In tal modo il programma genera le condizioni di equilibrio nodale e costruisce la funzione dell'energia da minimizzare. Vengono risolti, per il confronto con le soluzioni esistenti i casi di piastra quadrata semplicemente appoggiata e incastrata al contorno sottoposte a carico uniforme e ad una forza concentrata nel centro.

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This study forms part of a research program supported by the National (Italian) Research Council (C.N.R. Gruppo Problemi avanzati di ingegneria strutturale).