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The finite element method is a powerful computational technique used to solve complex problems. However, the method encounters limitations when dealing with incompressible media represented by a Poisson's ratio equal to 0.5. Because of this, mesh locking occurs as certain elements of matrices blow up as others disappear due to the nature of incompressible elasticity that leads to stress oscillations and inaccurate deformation behaviors. This study addresses these challenges by developing a stabilized and modified mixed formulation utilizing equal-order triangular elements. The proposed modified mixed formulation incorporates both displacements and pressures as degrees of freedom by treating them independently, and decoupling stresses and strains by decomposing them into their volumetric and deviatoric parts. Furthermore, the Beltrami-Michell equations are incorporated as a set of compatibility equations to close the boundary value problem. A stabilizing term based on Galerkin mixed methods is introduced to maintain the well-posedness of the problem, addressing issues such as ill-conditioning of the stiffness matrix and preventing spurious stresses. The study also emphasizes the efficiency of unstructured lower order triangular meshes, which, when stabilized, offer a balance between computational cost and accuracy. Since there is limited to no literature regarding the application of such methods in an axisymmetric case, a representative problem in the form of an infinite half-space loaded by a circular footing is presented and validated to demonstrate the effectiveness of the proposed method. The example highlights the formulation's ability to provide accurate results, validating its robustness and practical applicability in various engineering scenarios. [ABSTRACT FROM AUTHOR]

A multi‐analytical approach based on colourimetry, micro‐Raman spectroscopy, scanning electron microscopy, optical microscopy and powder X‐ray diffraction, has been applied to investigate Roman cooking ware samples dating back to imperial age (I‐II century AD). In particular, the highly distinctive production of pots coming from two different archaeological sites, 'Villa della Piscina' at Centocelle district and the so called 'Minerva Medica Temple' at Esquilino district (Rome, Italy), was studied characterising the colour, the chemical, mineralogical and petrographic distinctive properties of the investigated samples, in order to compare technological and provenance aspects. Classification of ceramic fragment by colorimetry, integrated by compositional studies with a main contribution of micro‐Raman spectroscopy, allows to discriminate between superior and inferior quality cooking ware and evaluate the compatibility of the investigated samples with some pottery realised in known manufacturing sites in Lazio. Compositional and petrographic features allow assignment of samples from 'Villa della Piscina' testifying productions in the surroundings of Rome, while an importation from outsider workshops is hypothesised for the ceramic fragments from the so called 'Minerva Medica Temple'. For these, an importation from outsider workshop is hypothesised. [ABSTRACT FROM AUTHOR]

Spike (S) glycoprotein is the largest structural protein of SARS‐CoV‐2 virus and the main one involved in anchoring of the host receptor ACE2 through the receptor binding domain (RBD). S protein secondary structure is of great interest for shedding light on various aspects, from functionality to pathogenesis, finally to spectral fingerprint for the design of optical biosensors. In this paper, the secondary structure of SARS‐CoV‐2 S protein and its constituting components, namely RBD, S1 and S2 regions, are investigated at serological pH by measuring their amide I infrared absorption bands through Attenuated Total Reflection Infrared (ATR‐IR) spectroscopy. Experimental data in combination with MultiFOLD predictions, Define Secondary Structure of Proteins (DSSP) web server and Gravy value calculations, provide a comprehensive understanding of RBD, S1, S2, and S proteins in terms of their secondary structure content, conformational order, and interaction with the solvent. [ABSTRACT FROM AUTHOR]

ABSTRACT Manganese oxides/oxyhydroxides (MnOx) are based on Mnn+O6 and Mnn+O4 polyhedra arranged such as to form compact, channel or layered structures. In geology, they are precious archives of past redox conditions for palaeoclimatic reconstructions; in material sciences, they are used for a variety of applications, from pigments to environmental remediation and energy storage. Thus, the fast, remote and non‐destructive identification of MnOx is critical in several disciplines. Micro‐Raman spectroscopy is often used for this purpose, although a systematic characterization of their stability under the laser beam is still lacking. In this work, we present our results on the behaviour of the most common MnOx having compact and channel structures when a 532‐nm laser with intensity between ~23 μW/μm2 and ~36.8 mW/μm2 is used. The compact structures of manganosite (NaCl‐like) and hausmannite (spinel‐like) are stable up to ~36.8 mW/μm2. The stability of oxides with channel structures depends on channel size, charge of channel cations and valence state of Mn. Hausmannite is the final degradation product of all MnOx with channel structures, irrespective of the starting phase. Pyrolusite, manganite, hollandite and romanéchite are relatively stable under the laser beam, and the transition to the spinel structure occurs above 2.5 mW/μm2 while the degradation of cryptomelane and todorokite starts ~226 μW/μm2. The analysis of MnOx thus needs very accurate experimental conditions to avoid misleading and incorrect phase identifications. Based on our data, we propose an analytical protocol for a proper characterization of these minerals via Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Elucidating the high-temperature behavior of rock-forming minerals such as amphiboles (AB2C5 T8O22W2) is critical for the understanding of large-scale geological processes in the lithosphere and, in particular, the development of high conductivity in the Earth's interior. Recently, we have shown that at elevated temperatures, CFe-bearing amphiboles with a vacant A site develop two types of charge carriers: (1) small polarons and (2) delocalized H+ ions. To elucidate the effect of A-site cations on the formation and stability of charge carriers within the amphibole structure, here we analyzed synthetic potassic-ferro-richterite as a model Fe-rich amphibole with a fully occupied A site via in situ temperature-dependent Raman spectroscopy. We further compare the results from in situ time-dependent Raman-scattering experiments on pre-heated and rapidly quenched potassic-ferro-richterite and riebeckite as a model Fe-rich amphibole with a vacant A site. We show that the presence of A-site cations (1) reduces the activation temperature of mobile polarons and delocalized H+ cations; (2) decreases the magnitude of the polaron dipole moment; (3) slows down the process of re-localization of electrons on cooling; and (4) makes the electrons inert to rapid change in external conditions, supporting the persistence of a metastable state of pre-activated delocalized electrons even at room temperature. Our results have important geological implications demonstrating that the A-site cations may control the depth of development of high conductivity in subducted amphibole-bearing rocks. Moreover, from the viewpoint of mineral-inspired materials science, our results suggest that the amphibole-structure type has great potential for designing functional materials with tunable anisotropic-conductivity properties. [ABSTRACT FROM AUTHOR]

Microbial colonization can lead to various biodeterioration phenomena in outdoor stone monuments. To prevent these issues and mitigate the negative effects of chemical control, recent research has focused on encapsulating biocides in nanostructures. We tested the antifouling efficiency of the new multifunctional coating through in situ experiments performed on the Aurelian Walls in Rome. We selected two different biocides (2-mercaptobenzothiazole and zosteric sodium salt) and loaded them into two different silica nanocontainers (nanocapsules and mesoporous particles), which were dispersed in TEOS coatings. These coatings were applied to four common lithotypes (marble, travertine, mortar, and brick). Subsequently, we accelerated the colonization by inoculating microorganisms onto half of the samples, subjecting all samples to aging cycles. We conducted colorimetric, infrared spectroscopy, and other microscopic analyses to assess their durability and antimicrobial action. Our 3-year survey indicates that the coatings demonstrated antifoulant efficiency across all samples, with higher effectiveness observed on brick and mortar compared to travertine and marble. Among the nanostructures, nanocapsules exhibited greater efficiency than mesoporous particles, and regarding the biocides, the commercial one outperformed the natural one. These findings highlighted the potential of such systems in preserving cultural heritage; however, further research and product development is imperative for practical implementation. [ABSTRACT FROM AUTHOR]