Utilización de arenas procedentes de residuos de construcción y demolición, rcd, en la fabricación de morteros de albañilería.

En esta investigación se estudió el comportamiento y las propiedades más relevantes de los morteros de albañilería, al sustituir parte de la arena convencional por arena reciclada en diferentes porcentajes. Para ello se caracterizaron las arenas recicladas procedentes de las centrales de reciclaje y se realizaron ensayos con el fin de comparar las propiedades de los morteros tradicionales con los morteros elaborados con arena reciclada. La dosificación del mortero utilizada ha sido 1:3:0,5, y los porcentajes de sustitución de arena normalizada por arena reciclada fueron de: 10%, 15%, 25%, 35% y 45% , para los tres tipos de arenas recicladas empleadas en este estudio, dos arenas procedentes de la línea de reciclaje de hormigón y una de la línea de reciclaje cerámica. Los resultados indican un aumento en la demanda de agua para obtener morteros trabajables, siendo necesario el empleo de aditivos a partir del 10% de sustitución. Las resistencias mecánicas obtenidas en los morteros reciclados son superiores en el caso de la flexión y ligeramente inferiores en compresión. Tanto en el ensayo de adherencia como en el de retracción, los morteros reciclados presentan un peor comportamiento que los morteros tradicionales, pero sin evidenciar pérdidas significativas en dichos valores, por lo que los morteros de cemento para albañilería con dosificación 1:3:0,5 pueden incorporar hasta un 45% de árido reciclado sin que sus principales características se vean afectada

Caracterización e influencia del arido reciclado fino en las propiedades de los morteros de albañilería

This research aims to study mechanical behaviour and relevant properties of masonry mortars fabricated using fine recycled aggregate in different mixture proportions. Fine recycled aggregates samples originated from the ceramic and concrete recycling process and coming from two recycling plants of Madrid region have been used. Tests were performed using 1:3:0.5 volumetric cement-to-aggregate-to-water ratio. Standardized sand with fine recycled aggregate replacement percentages were: 10%, 15%, 25%, 35% and 45%. A continuous size distribution curve can be observed and the main crystalline phases determined have been quartz, calcite and gypsum. Compressive strength, shrinkage and bond strength tests revealed poorer performance of recycled mortars compared to the conventional mortars; however, specific values are within the limits established by the manufacturers and standards. This study shows that cement-based mortars prepared with volumetric ratio 1:3:0.5 may contain up to 45% of fine recycled aggregates, without their properties being affected and without presenting significant losses.Esta investigación estudia el comportamiento mecánico y las propiedades más relevantes de los morteros de albañilería fabricados usando arenas recicladas en diferentes proporciones. Muestras pertenecientes a la línea de reciclaje cerámica y de hormigón proceden de dos centrales de reciclaje de la Comunidad de Madrid. Los ensayos se realizaron con una dosificación 1:3:0,5. Los porcentajes de arena reciclada fueron: 10%, 15%, 25%, 35% y 45%. Se observa una línea granulométrica continua y las principales fases cristalinas encontradas son cuarzo, calcita y yeso. Los ensayos de resistencia a compresión, retracción y adherencia muestran un peor comportamiento en los morteros reciclados frente a los morteros elaborados con arena normalizada, aunque dentro de los límites establecidos por normativas y fabricantes. Se deduce que, los morteros de albañilería base cemento, pueden incorporar un 45% de arena reciclada con una dosificación 1:3:0,5 sin que las propiedades ensayadas se vean afectadas con pérdidas significativas de prestaciones

Nanoscopic surface inspection by analyzing the linear polarization degree of the scattered light

We present an optical method for the nanoscopic inspection of surfaces. The method is based on the spectral and polarization analysis of the light scattered by a probe nanoparticle close to the inspected surface. We explore the sensitivity to changes either in the probe–surface distance or in the refractive index of the surface

Exception for the zero-forward-scattering theory

Studies on single scattering of electromagnetic waves by magnetic particles were reported in the 1980s by Kerker et al. [J. Opt. Soc. Am. 73, 765 (1983)] . They obtained that very small spherical particles with electric permittivity and magnetic permeability values such that ε=(4−μ)/(2μ+1) do not produce forward scattering. We show here that this condition contains an interesting exception at ( ε=−2 , μ=−2 ) when electric and magnetic resonances are present and around which the scattered field distribution is computed and described showing a polarization-insensitive behavior at the point ( ε=−2 , μ=−2 )

Pain reduction and tolerance of type II undenatured collagen in patients with knee osteoarthritis

Background: Osteoarthritis (OA) is the most common cause of pain and disability in adults. Dietary supplements such as undenatured type II collagen (UC-II) have shown to have some benefits in OA treatment. This study aimed to assess changes in pain levels among knee OA patients treated with UC-II for 6 months. Methods: Patients with knee OA of any grade were given a daily 40 mg dose of UC-II (CondroArtil®) as a dietary supplement for 6 months. Pain levels were measured using the visual analog scale (VAS) before starting UC-II 6 months thereafter. A total of 100 patients (62/38: male/female) with a mean age of 46.3±13.8 years participated in the study. Most patients (60%) had mild to moderate OA (grade I or II). Results: The UC-II supplementation was shown to significantly reduce pain levels (p<0.001) with a negative correlation between pain reduction and age (p=0.006) and BMI (p=0.049). The OA severity also affected pain reduction (p=0.011), with grade II OA experiencing higher pain levels. Previous physical therapy and food supplements had a significant impact on pain reduction (p=0.017 and p=0.012, respectively). Conclusions: The study suggests that UC-II is an effective treatment for reducing pain in patients with knee OA

Detection of blaCTX-M-15 in an integrative and conjugative element in four extensively drug-resistant Haemophilus parainfluenzae strains causing urethritis

Haemophilus parainfluenzae is a commensal organism with rising numbers of multidrug-resistant (MDR) strains. This pathogen is of increasing clinical relevance in urogenital infection. The aim of this work was to identify and characterise the molecular mechanisms of resistance associated with four cephalosporin-resistant H. parainfluenzae strains collected from patients with urethritis. Antimicrobial resistance was determined by microdilution following European Committee on Antimicrobial Susceptibility Testing cri-teria. Strains were then analysed by whole-genome sequencing to determine clonal relationship and the molecular basis of antimicrobial resistance. Finally, a phylogenetic analysis was performed on all urogen-ital MDR strains of H. parainfluenzae previously isolated in our hospital. All strains were resistant to ,B- lactams, macrolides, tetracycline, fluoroquinolones, chloramphenicol, cotrimoxazole, and aminoglycosides. The resistance profile was compatible with the presence of an extended-spectrum ,B-lactamase (ESBL). Whole-genome sequencing detected blaCTX-M-15 that conferred high minimum inhibitory concentrations to cephalosporins in two novel integrative and conjugative elements (ICEHpaHUB6 and ICEHpaHUB7) that also harboured a blaTEM-1 ,B-lactamase. This study shows a novel bla CTX-M-15 ESBL carried in an integrative conjugative element in four extensively drug-resistant H. parainfluenzae strains. This resistance determi-nant could be transmitted to other sexually transmitted pathogens and this is a cause for concern. (c) 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/

Quantum optical response of metallic nanoparticles and dimers

The optical properties of metallic nanoparticles (NPs) can be described with analytical models based on fundamental quantum mechanical principles, of which the Drude model constitutes the classical limit. Here, we examine the plasmonic properties of silver and gold nanospheres and dimers, with radii ranging from 10 to 1 nm, extending from the classically described regime to the quantum size regime. We have studied the spectral extinction cross section by using the T-matrix method. The results indicate an increasingly substantial change in NP permittivity as the radius is reduced below 5 nm, showing a clear blueshift and weakening of the plasmon resonances for both silver and gold. As a consequence, we observe a dramatic change in the interaction of dimers, especially in the case of gold, where the introduction of quantum mechanically corrected optical properties quenches the plasmonic resonance and predicts an absence of the expected associated redshift

Light scattering by an ensemble of interacting dipolar particles with both electric and magnetic polarizabilities

We have studied the problem of light scattering by an ensemble of dipoles with both electric and magnetic polarizabilities. Using the coupled electric and magnetic dipole method as the formal base, we have generalized the eigenvector decomposition of the local dipole moments previously derived for purely electric particles to the case of both electric and magnetic dipoles. We have analyzed the properties of eigenvalues and eigenvectors in the most elementary case of two particles. In the purely electric case, the eigenvalues correspond to the resonance modes of the system due to the electromagnetic coupling of its components. For a two-dipole system with both electric and magnetic responses, purely electric, purely magnetic, and mixed states can be distinguished. The resonance spectrum is analyzed as a function of the magnetic permeability, and it is shown that the latter can be fitted quite accurately by the eigenmode decomposition