Point-Coupling Models from Mesonic Hypermassive Limit and Mean-Field Approaches

In this work we show how nonlinear point-coupling models, described by a Lagrangian density that presents only terms up to fourth order in the fermion condensate $(\bar{\psi}\psi)$, are derived from a modified meson-exchange nonlinear Walecka model. The derivation can be done through two distinct methods, namely, the hypermassive meson limit within a functional integral approach, and the mean-field approximation in which equations of state at zero temperature of the nonlinear point-coupling models are directly obtained.Comment: 18 pages. Accepted for publication in Braz. J. Phy

Recycled steel fibre reinforced concrete failing in bending and in shear

Recent research is showing that the addition of Recycled Steel Fibres (RSF) from wasted tyres can decrease significantly the brittle behaviour of cement based materials, by improving its toughness and post-cracking resistance. In this sense, Recycled Steel Fibre Reinforced Concrete (RSFRC) seems to have the potential to constitute a sustainable material for structural and non-structural applications. To assess this potential, experimental and numerical research was performed on the use of RSFRC in elements failing in bending and in beams failing in shear. The values of the fracture mode I parameters of the developed RSFRC were determined by performing inverse analysis with test results obtained in three point notched beam bending tests. To assess the possibility of using RSF as shear reinforcement in Reinforced Concrete (RC) beams, three point bending tests were executed with three series of RSFRC beams flexurally reinforced with a relatively high reinforcement ratio of longitudinal steel bars in order to assure shear failure for all the tested beams. By performing material nonlinear simulations with a computer program based on the finite element method (FEM), the applicability of the fracture mode I crack constitutive law derived from the inverse analysis is assessed for the prediction of the behaviour of these beams. The performance of the formulation proposed by RILEM TC 162 TDF and CEB-FIP 2010 for the prediction of the shear resistance of fibre reinforced concrete elements was also evaluated.The present study is part of the activities carried out by the Authors within the "EnCoRe" Project (FP7-PEOPLE-2011-IRSES no. 295283; www.encore-fp7-unisa.it) funded by the European Union within the Seventh Framework Programme. The authors wish also to acknowledge the support provided by Civitest and BioSafe companies

An optimization-based rigid block modeling approach to seismic assessment of dry-joint masonry structures subjected to settlements

A rigid block modeling approach is presented for rocking dynamics and nonlinear static analysis of dry-joint masonry structures subjected to settlements and earthquake excitations. For the different types of analysis, a unified optimization-based formulation is adopted, which is equivalent to the system governing the static and dynamic structural response. Sequential solution procedures are used for time integration and for pushover analysis which take into account the effects of large displacements under the combined action of support movements and lateral loads. No-tension elastic contacts with finite shear strength are considered at block in-terfaces for time-history analysis and to obtain the elastic branch of pushover curves in nonlinear static analysis. A unilateral rigid contact behavior is also considered to obtain the descending post-peak branch of pushover curves corresponding to the activation of the rigid-body rocking motion, according to displacement-based assessment methods of failure mechanisms adopted in the standards. Comparisons with numerical models and experimental tests on a rocking block and on a buttressed arch are presented to show the accuracy of the developed approach. Simple tests on dry-joint tuff panels on the tilting table were also carried out to show the effects of imposed movements at support on the response to lateral loads. Finally, an application is presented to a full-scale triumphal arch subjected to the combined action of support movements and earthquake excitation to discuss, on the basis of the developed model, the effects of settlement-induced damage on seismic performance. The numerical analyses showed that the lateral force, the displacement capacity and the rocking response can be significantly affected by support movements, pointing out the relevance of the current building condition in the seismic safety assessment.- The financial support of the research project DPC-ReLUIS 2022-2024: Work Package 5 "Integrated and low-impact strengthening interventions" funded by the Civil Protection Department IT (Grant no. 897-01/04/2022) is acknowledged. The authors are grateful to Prof. Chiara Calderini from the University of Genova for providing data from the experimental tests on the arch-pillars system investigated in the manuscript. The authors are also grateful to Mr. Domenico Imperatrice from the Department of Structures for Engineering and Architecture for his assistance and support throughout the experimental investigation on the wall panels subjected to support movement and lateral loads

Canonical Analysis of the Jackiw-Teitelboim Model in the Temporal Gauge. I. The Classical Theory

As a preparation for its quantization in the loop formalism, the 2-dimensional gravitation model of Jackiw and Teitelboim is analysed in the classical canonical formalism. The dynamics is of pure constraints as it is well-known. A partial gauge fixing of the temporal type being performed, the resulting second class constraints are sorted out and the corresponding Dirac bracket algebra is worked out. Dirac observables of this classical theory are then calculated.Comment: 15 pages, Latex. Misprint correction

Effect of Agrobacterium rhizogenes infection on in vitro rooting of Vitis vinifera

Agrobacterium rhizogenes is known to induce the proliferation of rapid growing, highly branching roots (hairy roots) in most dicotyledonous plants. We report here the effect of in vitro infection of Vitis vinifera with two A. rhizogenes strains (b-glucuronidase transgenic A4 and wild type LBA), with regard to an increase of root mass. In vitro-grown V. vinifera explants were infected with two A. rhizogenes strains. Both strains induced a significant increase in the number of the developed roots, and of their weight and length. Root number was increased by a factor of 2.9 (strain A4) and 2.7 (strain LBA), length increased 1.9 and 1.6 times (strains A4 and LBA, respectively), while the root weight was more affected by strain A4 (2.8 times increasing) than by LBA strain (1.9 times increasing). The transformation status of the developed roots was assessed by two different methods: PCR detection of rolB gene in LBA strain-derived roots and quantification of â-glucuronidase activity in A4 strain-derived roots.

New HDPE/MCM41 nanocomposites with improved mechanical performance: synthesis and characterizatio

Ordered mesoporous silicas with a channel structure of well-defined geometries and dimensions at nanometer scale are excellent candidates to host intercalation reactions. In recent years, our research group has shown that mesoporous silicas of the M41S class combined with metallocene complexes give rise to excellent supported catalysts for ethylene polymerisation. Due to the support characteristics, the reaction is allowed to occur in the channels and in this way hybrid organic-inorganic materials can be prepared within a large range of nanofiller concentration. These HDPE/MCM-41 nanocomposites exhibit an improved mechanical performance and an easier degradability due to the additional role of MCM-41 as a promoter for PE degradation