Thiolated-polymer-based nanoparticles as an avant-garde approach for anticancer therapies—Reviewing thiomers from chitosan and hyaluronic acid

Thiomers (or thiolated polymers) have broken through as avant-garde approaches in anticancer therapy. Their distinguished reactivity and properties, closely linked to their final applications, justify the extensive research conducted on their preparation and use as smart drug-delivery systems (DDSs). Multiple studies have demonstrated that thiomer-rich nanoformulations can overcome major drawbacks found when administering diverse active pharmaceutical ingredients (APIs), especially in cancer therapy. This work focuses on providing a complete and concise review of the synthetic tools available to thiolate cationic and anionic polymers, in particular chitosan (CTS) and hyaluronic acid (HA), respectively, drawing attention to the most successful procedures. Their chemical reactivity and most relevant properties regarding their use in anticancer formulations are also discussed. In addition, a variety of NP formation procedures are outlined, as well as their use in cancer therapy, particularly for taxanes and siRNA. It is expected that the current work could clarify the main synthetic strategies available, with their scope and drawbacks, as well as provide some insight into thiomer chemistry. Therefore, this review can inspire new research strategies in the development of efficient formulations for the treatment of cancer

Light scattering from a rough metal surface: theory and experiment

There is still great interest in the determination of microtopographic properties of rough metallic surfaces from light scattering measurements. According to Beckmann–Kirchhoff theory a clear relationship is established between the in-plane angular scattered light intensity and the statistical properties of the surface. We discuss one way to invert this relationship, and we introduce a new iterative procedure to retrieve the height autocorrelation function even for a very rough metallic surface (rms surface roughness of the same order of the optical wavelength). The procedure is eventually applied to the experimental data of a known metallic surface for validation

The Marine Environment: Hazards, Resources and the Application of Geoethics Principles

Oceans cover three quarters of the Earth surface and represent a fundamental component of the global climate system. Life on Earth is closely tied to the climate system and thus to the oceans. Marine regions are subjected to numerous submarine natural hazards such as earthquakes, volcanic eruptions and landslides, in many cases producing tsunamis that threaten coastal areas and many onshore and offshore man-made facilities. On the other hand, as society and technological needs progressively increase, the impact of human activities on coastal and deep waters become more severe, with consequences that include global warming and sea-level rise, coastal erosion, pollution, ocean acidification, damage to marine resources and ecosystem degradation. Nevertheless, humankind seems not to be adequately conscious about the different kind of hazards threatening the marine environment. The challenge for marine geoscientists is to be conscious of the geoethical compromise in order to alert society, industries and policy makers about the needs to minimize the risks of natural and human impacts in the ocean system.Fil: Violante, Roberto Antonio. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval. Departamento Oceanografía; ArgentinaFil: Bozzano, Graziella. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval. Departamento Oceanografía; ArgentinaFil: Rovere, Elizabeth Ivonne. Secretaría de Industria y Minería. Servicio Geológico Minero Argentino; Argentin

The Argentine Continental Margin: A Potential Paleoclimatic-Paleoceanographic Archive for the Southern Ocean

The Argentina Continental Margin, located in the Southwestern Atlantic Ocean, is inserted in a key region of the World Ocean due to its significance in the global oceanographic-climatic interaction, and because it is the only place where Antarctic- and Equator-sourced water-masses interact in mid-latitudes. On the other hand, the geotectonic history of the region imprints it with significant geological characteristics. As a result, the climatically-, oceanographically- and physically-driven sedimentary processes occurred in the region originated particular and almost unique morphosedimentary features, which constitute complete records of the processes involved in its evolution. Those features contain different kinds of proxies, tracers and records (biological, geochemical, sedimentological, morphological and structural) which provide valuable quantitative and qualitative evidences for detailed paleoceanographic, paleoclimatic and paleoenvironmental reconstructions. Therefore, the Argentine margin potentially behaves as a complete archive for understanding most of the unique oceanographic and climatic characteristics that occur in the region and impact in the rest of the Southern Hemisphere.Fil: Violante, Roberto Antonio. No especifíca;Fil: Laprida, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: García Chapori, Natalia Luz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentin

Pyroclasts of the first phases of the explosive-effusive PCCVC volcanic eruption: physicochemical analysis

The morphology, texture, grain size and other physicochemical characteristics of pyroclastic material from the first phases of the Puyehue-Cordon Caulle volcanic complex (PCCVC) eruption, (Southern Andes, Chile), can be associated to the model recently reported for the magma storage and its ascent conditions. The eruption started June 4th 2011, and the studied volcanic material corresponds to that collected in Argentine territory at different distances from the source, between 4 and 12 June 2011. The explosive-effusive volcanic process of the first days occurred with the simultaneous emplacement of lava flows and the venting of pyroclastic material, ejecting two well differentiated types of particles. The more abundant was constituted by rhyolitic and light color pumice fragments, characterized by a typical vesicular texture, easy fragmentation and absence of occluded crystalline phases. Particles found in minor proportion were dark color, different in shape and texture and rich in Fe and Ti. They seemed to be more effective for the interaction with emitted gases in the upper part of the column, for this reason, they appeared partially covered by condensation products. The ascent conditions of the magma affected its rheological behavior through variations in the degassing, viscosity and fragmentation. On the other hand, distance to the source, depositional time, volcanic evolution and environmental conditions are factors that affect the chemical composition of collected ash. So, the SiO2/FeO ratio not only increases with the distance but also with the deposition time and volcanic activity. The work was done with the aid of several techniques such as a laser-sediment analyzer, X-ray diffraction (XRD), chemical analysis (bulk and surface), SEM microscopy and Raman “microprobe” spectroscopy. On the other hand, the physicochemical behavior of the pyroclastic material allows us to suggest eventual applications

Sediment dynamics and geohazards offshore Uruguay and northern Argentina: first results from the multi-disciplinary Meteor-cruise M78-3

About 90% of the sediments generated by weathering and erosion on land get finally deposited at the ocean margins. The sediment distribution processes and landscape evolution on land are relatively well understood, but comparably little is known about the role and relative importance of marine sediment dynamics in controlling the architectural evolution of ocean margins. Important players include hemi-pelagic settling, down-slope and current-controlled along-slope sediment transport, depositional and post-depositional sedimentary processes (e.g. consolidation and diagenesis), as well as the destabilization of sediment bodies and their erosion. Submarine landslides in this context thus may represent an important sediment transport process, but also a major geo-hazard due to the increasing number of offshore constructions as well as their potential to instantaneously displace large water masses triggering waves in densely populated coastal areas. Here we present first results from a seagoing expedition that aimed at investigating the interaction processes of sediment redistribution, partitioning, deposition and diagenesis from the coast to the deep-sea along the western South-Atlantic passive continental margin. During RV Meteor Cruise M78/3 in May-July 2009 the shelf, slope and rise offshore Argentina and Uruguay have been investigated by means of hydroacoustic and seismic mapping as well as geological sampling with conventional coring tools as well as the new MARUM seafloor drill rig (MeBo) that revealed recovery of geological strata sampled from up to 50m below seafloor. The working area is characterized by a high amount of fluvial input by the Rio de la Plata river. The continental slope is relatively wide and shows average slope gradients between 1 and 2.5 but locally higher slope gradients may occur (>5). The transition for the continental rise with low slope gradients is found in ~3000 m water depth. The working area is located in a highly dynamic oceanographic regime. Cold Antarctic water masses of the northward flowing Malvina current meet warm water masses of the southward flowing Brazil current in the working area. Various types of sediment instabilities have been imaged in geophysical and core data, documenting particularly the continental slope offshore Uruguay to be locus of frequent submarine landslides. Apart from individual landslides, however, gravitational downslope sediment transport along the continental slope is restricted to the prominent Mar del Plata Canyon and possibly to smaller canyons indentified in the bathymetric data. The location of the canyons might be controlled by tectonics. In contrast, many morphological features (e.g. progradational terraces and slope parallel scarps with scour-geometries) reveal that sediment transport is predominantly influenced/controlled by strong contour bottom currents. This suggests a significant impact of the western boundary currents on the overall architectural evolution of the margin. Future studies using the acquired geophysical, sedimentological, physical property and geochemical data will (i) quantify the relative contribution of gravitational down-slope vs. along-slope processes through time in shaping this ocean margin and how it relates to the global ocean circulation pattern and sea-level change through time, (ii) investigate depositional and post-depositional processes and how they control submarine slope stability and submarine landslide initiation and (iii) explore the interaction and relative contribution of the various processes in controlling margin evolution, sediment dynamics and geohazard off Uruguay and Northern Argentina

The submarine canyons of the Argentine Continental Margin: a review of their formation and sedimentary dynamics

Los cañones submarinos son los mayores rasgos erosivos de los márgenes continentales tanto activos como pasivos. Desde los albores del siglo XX, representan un fructífero tema de debate e investigación por su gran relevancia como agentes de transferencia de sedimento y materia orgánica de continente a océano, por ser lugar de surgencia de aguas profundas, elevada producción primaria y riqueza en biodiversidad, y por ser potenciales factores de riesgo en las rupturas de infraestructuras submarinas. El presente trabajo comprende una revisión de las principales teorías de formación y evolución de los cañones submarinos así como de los procesos de interacción entre dinámica oceanográfica, flujos sedimentarios y morfologías asociadas a los cañones. El objetivo es presentar una síntesis del estado del conocimiento sobre los cañones del Margen Continental Argentino (MCA), discutir su formación y evolución en el marco de los modelos genéticos más aceptados en la actualidad así como proponer una hipótesis de trabajo vinculada a la dinámica sedimentaria del Cañón Mar del Plata (MdP), el más estudiado del margen. Este cañón, como la mayoría de los del MCA, por un lado se desarrolla exclusivamente en el talud (cañón ciego) y por el otro interrumpe un gran sistema depositacional contornítico relacionado con la circulación oceanográfica regional. De aquí que su génesis en principio se explicaría por el modelo de erosión retrogradante a partir de fenómenos de inestabilidad del talud, pero además podría funcionar como trampa de sedimento captando el material transportado por el Agua Antártica Intermedia a lo largo del talud medio. Se propone que en la Terraza Ewing, donde el cañón tiene su cabecera, podrían generarse corrientes turbidíticas que afectarían a la evolución y dinámica del cañón. Estas corrientes se encauzarían cañón abajo contribuyendo a profundizar su valle y a conformar su trazado en parte sinuoso. En los sistemas de cañones Patagonia otros factores podrían activar la génesis de los cañones submarinos. Se ha sugerido la posibilidad que irregularidades morfológicas provocadas por la acción erosiva de las corrientes contorníticas sobre el fondo puedan dar origen a los cañones de esta zona. Este mecanismo podría no limitarse exclusivamente al sistema Patagonia sino aplicarse a los demás sistemas de cañones argentinos ya que el MCA está intersectado por intensas corrientes de contorno que operan a diferentes profundidades.Submarine canyons are the most outstanding geomorphologic features of continental margins. They play a fundamental role in transferring sediment and organic matter from shallow to deep waters. Also, they influence oceanographic and sedimentary processes, interact with productivity and benthic ecosystems, and pose a serious threat to seafloor infrastructures. Submarine canyons have been described as steep-walled, sinuous valleys with V-shaped cross sections, axes sloping outward as continuously as river-cut land canyons and relief comparable to even the largest of land canyons. The understanding of the origin and evolution of submarine canyons has been matter of intense debate since the first geologists observed them characterizing both passive and active margins. Canyons have been interpreted as (1) the off-shore prolongation of river systems that during low sealevel stages migrated seaward; (2) the product of the erosion caused by gravity dense flows- called turbidity currents- produced at the shelf-slope transition; (3) the deepening of pre-existing tectonic structures (e.g. faults) and (4) the result of slope instability combined with headward erosion. The first model only explains the genesis of the breaching-shelf canyons that connect with river systems, but does not resolve the formation of those that are unrelated to fluvial input. Turbidity currents take place at the shelf break when sufficient amount of sediment is injected into the water column by (re) suspension, resulting in a flow with higher density than the surrounding waters. These high-density flows, moving down-slope under the effect of gravity, cut the valleys that finally evolve into submarine canyons. Turbidity currents, though effective agents of erosion, do not account for the formation of slopeconfined canyons. From the other side, tectonic control can apply for limited examples of canyons, which are located in specific geological contexts. Continental slopes often show scars that are left behind by instability events. Mass wasting processes may arise from fluid escape, sediment over pressure and steepening or be triggered by seismic shocks. These initial scars would evolve into rills and then into valleys by a process that combines localized slope failures, sediment funneling and headward erosion. According to this genetic model, slope-confined and shelf-breaching canyons are, respectively, the early and mature stages in the evolution of canyons, which starts with a pre-canyon rill that advances upslope by retrogressive failure and ends with the canyon cutting the shelf break. The objective of this contribution is to review the knowledge on the submarine canyons from the Argentine Continental Margin and to suggest a working hypothesis concerning the sedimentary dynamics of the Mar del Plata Canyon, by far the best known canyon of this margin. Four main systems have been described: La Plata River, Colorado-Negro (or Bahía Blanca), Ameghino (or Chubut) and Patagonia (or Deseado). Mar del Plata Canyon, belonging to the first of these systems, cuts the slope between ~1000 m (Ewing Terrace, middle slope) and ~3900 m (lower slope-continental rise transition) as a deep valley with steep walls. In its proximal sector, between 1100 and 3000 m, it shows a sinuous path whereas the thalweg is mostly linear between 3000 an 3900 m. Seismic profiles, obtained during the Meteor research cruise M78/3a, demonstrate no evidences of incisions that could suggest past fluvial connections with the canyon head. For this reason, the origin of this canyon has been explained as an example of headward erosion. During the Holocene, the sedimentation rate inside the canyon is much higher than outside. This occurs because the large amount of sediment mobilized by bottom currents along the Ewing Terrace is intercepted by the canyon. In contrast, during the Late Glacial and deglaciation phase, turbidite accumulation has been attributed to slope instability of the drift deposits at the southern flank of the canyon. In this study, we put forward the following working hypothesis: the canyon most probably generated from slope instability and retrogressive erosion. However, when the valley moved upslope and etched the Ewing Terrace (middle slope), turbidity currents might have been produced at this water depth (1000-1200 meters) by the peculiar oceanographic dynamics driven by the interaction between bottom currents and seafloor. If confirmed by future investigations, this hypothesis would account both for the turbidite deposition and the sinuous path of the canyon in its proximal sector, which is more typical, although not exclusive, for canyons routed by turbidity currents. The detailed morphological investigations, performed in the Patagonia Canyons system by a Spanish research group in 2011, add a stimulating source of discussion about canyon formation in the Argentine Margin. These authors have proposed that topographic irregularities shaped by scars resulting from the sea-floor erosion under strong contour currents and the step separating terraces located at different water depths, might be the precursors for a pre-canyon incision. This hypothesis, of great relevance in a continental margin where downslope and along-slope sedimentary processes often coexist and interact, probably apply not only to the Patagonia but also to the other, less investigated, canyons systems of the Argentine Margin.Fil: Bozzano, Graziella. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Martín de Nascimento, Jacobo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Spoltore, Daniela V.. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; ArgentinaFil: Violante, Roberto Antonio. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentin

Estudios geológicos en el margen continental argentino

El Margen Continental Argentino tiene un enorme potencial para estudios científicos y aplicados en el área de las geociencias marinas, por sus características geotectónicas y oceanográficas que le imprimen condiciones casi únicas entre las cuencas oceánicas del mundo. Sin embargo la investigación en geología submarina es incompleta, principalmente por las limitaciones tecnológicas sobre un territorio oceánico tan vasto. En las últimas décadas han habido avances muy significativos en su conocimiento, que abren las puertas a nuevas líneas de investigación a las cuales el país debería dedicarle importantes esfuerzos.Fundación Museo de La Plat

Estudios geológicos en el margen continental argentino

El Margen Continental Argentino tiene un enorme potencial para estudios científicos y aplicados en el área de las geociencias marinas, por sus características geotectónicas y oceanográficas que le imprimen condiciones casi únicas entre las cuencas oceánicas del mundo. Sin embargo la investigación en geología submarina es incompleta, principalmente por las limitaciones tecnológicas sobre un territorio oceánico tan vasto. En las últimas décadas han habido avances muy significativos en su conocimiento, que abren las puertas a nuevas líneas de investigación a las cuales el país debería dedicarle importantes esfuerzos.Fundación Museo de La Plat

Estudios geológicos en el margen continental argentino

El Margen Continental Argentino tiene un enorme potencial para estudios científicos y aplicados en el área de las geociencias marinas, por sus características geotectónicas y oceanográficas que le imprimen condiciones casi únicas entre las cuencas oceánicas del mundo. Sin embargo la investigación en geología submarina es incompleta, principalmente por las limitaciones tecnológicas sobre un territorio oceánico tan vasto. En las últimas décadas han habido avances muy significativos en su conocimiento, que abren las puertas a nuevas líneas de investigación a las cuales el país debería dedicarle importantes esfuerzos.Fundación Museo de La Plat