Transverse flow under oscillating stimulation in helical square ducts with cochlea-like geometrical curvature and torsion

The cochlea, situated within the inner ear, is a spiral-shaped, liquid-filled organ responsible for hearing. The physiological significance of its shape remains uncertain. Previous research has scarcely addressed the occurrence of transverse flow within the cochlea, particularly in relation to its unique shape. This study aims to investigate the impact of the geometric features of the cochlea on fluid dynamics by characterizing transverse flow induced by harmonically oscillating axial flow in square ducts with curvature and torsion resembling human cochlear anatomy. We examined four geometries to investigate curvature and torsion effects on axial and transverse flow components. Twelve frequencies from 0.125 Hz to 256 Hz were studied, covering infrasound and low-frequency hearing, with mean inlet velocity amplitudes representing levels expected for normal conversation or louder situations. Our simulations show that torsion contributes significantly to transverse flow in unsteady conditions, and that its contribution increases with increasing oscillation frequency. Curvature alone has a small effect on transverse flow strength, which decreases rapidly with increasing frequency. Strikingly, the combined effect of curvature and torsion on transverse flow is greater than expected from a simple superposition of the two effects, especially when the relative contribution of curvature alone becomes negligible. These findings may be relevant to understanding physiological processes in the cochlea, including metabolite transport and wall shear stress. Further studies are needed to investigate possible implications for cochlear mechanics.</p

Laser-driven resonance of dye-doped oil-coated microbubbles: A theoretical and numerical study

Microbubbles are used to enhance the contrast in ultrasound imaging. When coated with an optically absorbing material, these bubbles can also provide contrast in photoacoustic imaging. This multimodal aspect is of pronounced interest to the field of medical imaging. The aim of this paper is to provide a theoretical framework to describe the physical phenomena underlying the photoacoustic response. This article presents a model for a spherical gas microbubble suspended in an aqueous environment and coated with an oil layer containing an optically absorbing dye. The model includes heat transfer between the gas core and the surrounding liquids. This framework is suitable for the investigation of both continuous wave and pulsed laser excitation. This work utilizes a combination of finite difference simulations and numerical integration to determine the dependancy on the physical properties, including composition and thickness of the oil layer on the microbubble response. A normalization scheme for a linearized version of the model was derived to facilitate comparison with experimental measurements. The results show that viscosity and thickness of the oil layer determine whether or not microbubble resonance can be excited. This work also examines the use of non-sinusoidal excitation to promote harmonic imaging techniques to further improve the imaging sensitivity

US velocimetry in participants with aortoiliac occlusive disease

The accurate quantification of blood flow in aortoiliac arteries is challenging but clinically relevant because local flow patterns can influence atherosclerotic disease. To investigate the feasibility and clinical application of two-dimensional blood flow quantification using high-frame-rate contrast-enhanced US (HFR-CEUS) and particle image velocimetry (PIV), or US velocimetry, in participants with aortoiliac stenosis. In this prospective study, participants with a recently diagnosed aortoiliac stenosis underwent HFR-CEUS measurements of the pre- and poststenotic vessel segments. Two-dimensional quantification of blood flow was achieved by performing PIV analysis, which was based on pairwise cross-correlation of the HFR-CEUS images. Visual inspection of the entire data set was performed by five observers to evaluate the ability of the technique to enable adequate visualization of blood flow. The contrast-to-background ratio and average vector correlation were calculated. In two participants who showed flow disturbances, the flow complexity and vorticity were calculated. Results: 35 participants were included. Visual scoring showed that flow quantification was achieved in 41 of 42 locations. In 25 locations, one or multiple issues occurred that limited optimal flow quantification, including loss of correlation during systole, shadow regions, a short vessel segment in the image plane, and loss of contrast during diastole. In the remaining 16 locations, optimal quantification was achieved. The contrast-to-background ratio was higher during systole than during diastole, whereas the vector correlation was lower. Flow complexity and vorticity were high in regions with disturbed flow. Blood flow quantification with US velocimetry is feasible in patients with an aortoiliac stenosis, but several challenges must be overcome before implementation into clinical practice

Sonoprinting liposomes on tumor spheroids by microbubbles and ultrasound

Ultrasound-triggered drug-loaded microbubbles have great potential for drug delivery due to their ability to locally release drugs and simultaneously enhance their delivery into the target tissue. We have recently shown that upon applying ultrasound, nanoparticle-loaded microbubbles can deposit nanoparticles onto cells grown in 2D monolayers, through a process that we termed "sonoprinting". However, the rigid surfaces on which cell monolayers are typically growing might be a source of acoustic reflections and aspherical microbubble oscillations, which can influence microbubble-cell interactions. In the present study, we aim to reveal whether sonoprinting can also occur in more complex and physiologically relevant tissues, by using free-floating 3D tumor spheroids as a tissue model. We show that both monospheroids (consisting of tumor cells alone) and cospheroids (consisting of tumor cells and fibroblasts, which produce an extracellular matrix) can be sonoprinted. Using doxorubicin-liposome-loaded microbubbles, we show that sonoprinting allows to deposit large amounts of doxorubicin-containing liposomes to the outer cell layers of the spheroids, followed by doxorubicin release into the deeper layers of the spheroids, resulting in a significant reduction in cell viability. Sonoprinting may become an attractive approach to deposit drug patches at the surface of tissues, thereby promoting the delivery of drugs into target tissues

Estudios geoquímicos de Tierras Raras e Itrio en rocas de la Formación El Cortijo, Sierras Septentrionales de la provincia de Buenos Aires

Geochemical studies of Rare Earth Elements and Yttrium in rocks of the El Cori&amp; Formation, Sierras Septentrionales de la Provincia de Buenos Aires. El Cortijo Formation (NO Tana city) has contrasting mineralogical, structural and metamorphic features with those of the rest the Sierras Septentrionales de la Provincia de Buenos Ai-res basement. It comprises mylonitized low grade metamorphic rocks preliminarily classified, in former time, as metacherts, metabasalts and metawakes. Detailed analysis of rare earth elements (REE) in gray-whitish (GB) and gray-green-bluish (GVA) them samples allowed a certain classification of these rocks. The obtained multielement diagram, normalized to Post-Archean Australian Shale (PAAS), shows a flat distribution in light rare earth element (LREE) and depleted contents of heavy rare earth element (HREE) for OVA. The GB presents a different design, similar to that of a Greenstone Belt them of 3.71-3.81 Ga, characterized by very positive anomalies in La (1.29), Eu (3.87) and Y (Y/Ho 68.66), and LREE/HREE and MREE/HREE relationships of 0.89 and 1.14, respectively. These characteristics indicate that GB them corresponds to C-Cheri sensustricto, while GVA chert is comparable with S-Chert due to Y/Ho ratios — 31, and Eu anomalous contents between 1.2 and 1.4. This new geochemical evidence allows confirming the presence of cherts in the El Cortijo Formation that have been formed in an ocean basin before to the collision of Tandilia with the Rio de la Plata Craton

Formación El Cortijo: una secuencia tipo OPS (Ocean Plate Stratigraphy) en el basamento paleoproterozoico del sistema de Tandilia

El Cortijo Formation: an OPS (ocean plate stratigraphy) type sequence in the Palaeoproterozoic basement of the Tandilia System. El Cortijo Formation is exposed near the Tandil city, within an isoclinal fold and vertical fault system, with an E-W general orientation. It is constituted by an intercalation of low metamorphic grade metabasites, metacherts and metawackes. Structural, petrological and geochemical characteristics of the aforementioned rocks could be interpreted as an OPS (ocean plate stratigraphy) type sequence. This new interpretation of El Cortijo Formation genesis provides reliable evidences to the collisional theory of Tandilia System basement evolution

Hydrocarbon-bearing sulphate-polymetallic deposits at the Colipilli area, Neuquén Basin, Argentina: Implications in the petroleum system modeling

This work deals with the hydrocarbon-bearing barite-polymetallic mineralizations of the Colipilli area, located in the western sector of the Agrio Fold and Thrust Belt (Neuqu´en Basin, Argentina). The mineralizations consist of bed- and vein-type deposits mainly composed of barite (barite96.99%–celestine2.93%) with minor amounts of Feoxyhydroxides and sulfides. The bed-type deposits have zebra texture and are emplaced along the contact between Late Cretaceous–Paleocene igneous rocks (Naunauco Group) and their Early Cretaceous sedimentary host rocks (e.g., Huitrín Formation). In contrast, the vein-type deposits have breccia texture and are crosscutting the Mulichinco, Agrio and Huitrín formations or the andesitic/dioritic stocks and sills of the Naunauco Group. Different types and families of primary fluid inclusions (FI) were identified in the barite crystals. Fluorescence techniques with UV incident light and Raman spectroscopy allowed FI from completely aqueous to completely organic, including all the intermediate terms, to be identified. The organic FI have blue fluorescence and contain liquid hydrocarbons. The blue fluorescence is correlated with medium to high API gravity values (ca. 40◦), indicating the presence of light hydrocarbons of advanced maturity related with the window for the generation of liquid/gaseous hydrocarbons. Microthermometry studies carried out on aqueous FI revealed that vein-type deposits formed at higher temperatures and salinities (249.7 ◦C and 0.5–9.3 wt % NaCl equivalent) than bed-type deposits (162.2 ◦C and 0.2–7.2 wt % NaCl equivalent). The heat influx provided by the Late Cretaceous– Paleocene magmatism promoted the circulation of inorganic and organic fluids of connate origin and the leaching of metallic and non-metallic elements from the sedimentary pile. During its crystallization, barite trapped fluids with variable hydrocarbon contents. The thermal anomaly associated with the magmatic activity could also have contributed with the maturation of the nearby source rocks and to the development of an atypical petroleum system.Instituto de Recursos Minerale

Faja milonítica El Cortijo: puesta en valor de su patrimonio geominero y propuesta de un nuevo sitio de interés geológico en Tandil, Buenos Aires

El basamento del Sistema de Tandilia reúne a las rocas más antiguas de la Argentina, las cuales guardan una valiosa información de los procesos geológicos ocurridos hace aproximadamente 2.200 Ma. Entre estas rocas ígneo-metamórficas (Complejo Buenos Aires) se encuentran las que integran la Formación El Cortijo, que contrastan notoriamente con el resto por sus características mineralógicas, metamórficas y estructurales. Esta Formación está constituida por rocas típicas de una cuenca oceánica desarrollada durante el lapso Neoarqueano - Paleoproterozoico, fuertemente milonitizadas. Aflora en las cercanías de la ciudad de Tandil, a lo largo de una faja de 3 kilómetros con rumbo este-oeste (aquí denominada Faja milonítica El Cortijo), a la que se accede por la Ruta Nacional 226. Tandil es una ciudad reconocida por su origen minero, actualmente con una fuerte impronta turística y una infraestructura óptima para ofrecer diversos circuitos geomineros. Esta contribución tiene como objetivo presentar un nuevo sitio de interés geológico en Tandil, que junto con los otros circuitos geoturísticos urbanos, manifieste el valor geológico de la región. Esto conduciría a su protección y podría impulsar la creación de un futuro Parque Geológico, producto de la integración de todos los geositios conocidos además del aquí propuesto. El trabajo realizado incluyó un relevamiento del área mediante imágenes satelitales y actividades de campo que permitieron seleccionar un conjunto de canteras labradas en la faja milonítica que constituye el geositio propuesto. Este sector de la provincia de Buenos Aires reúne todos los atributos necesarios para establecer un sitio de interés geológico como el sugerido, considerando sus riquezas paisajísticas y geológicas relacionadas con la evolución geológica y tectónica del basamento de Tandilia