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•Starch hydrogel nanocomposites responding to pH and magnetic field were proposed.•The hydrogels were formed by polymerizing vinylated starch under ultrasound.•Water transport ...properties were studied by applying swelling-based kinetic models.•Swelling changes in response to an applied magnetic field and pH were observed.•Hydrogels with pharmacological potential for application in biological systems.
This work reports the preparation of starch-based hydrogel nanocomposites that undergo changes in swelling behavior in response to both pH and a remotely applied magnetic field. The hydrogels were formed by ultrasound-induced radicalar cross-linking/polymerization of vinyl-modified starch with N′,N′-dimethylacrylamide (DMAAm) and acrylic acid (AAc) in the presence of CoFe2O4 nanoparticles (average diameter of 365.5±2.1nm). Water transport properties were studied by applying swelling-based kinetic models. The effect of the magnetic field on the swelling potential was more prominent at pH 2 for hydrogel without AAc and the ionic nature of the polymer network was more important at pH 10 for hydrogel with AAc. At pH 2, the swelling mechanism for all hydrogels is described by a pseudo-Fickian transport, and is independent of the applied magnetic field. At pH 7 and pH 10, the hydrogels containing AAc showed anomalous mechanism, attributed to the anion–anion electrostatic repulsion forces. These hydrogels showed an increase in the swelling rate at higher pH. A significant increase in the swelling rate was also observed when the magnetic field is on, but this was verified only at pH 2. The hydrogels made of starch (0.5%), DMAAm (0.25%), and CoFe2O4 (0.125% or 0.250%) underwent changes in swelling rate in response to an applied magnetic field, independently of pH. For these hydrogels, the magnetic properties of the nanoparticles were more important than their physical–chemical characteristics. Cytotoxicity research showed that the hydrogels have a great pharmacological potential for application in biological systems.
Context.
Most stars from in groups which with time disperse, building the field population of their host galaxy. In the Milky Way, open clusters have been continuously forming in the disk up to the ...present time, providing it with stars spanning a broad range of ages and masses. Observations of the details of cluster dissolution are, however, scarce. One of the main difficulties is obtaining a detailed characterisation of the internal cluster kinematics, which requires very high-quality proper motions. For open clusters, which are typically loose groups with tens to hundreds of members, there is the additional difficulty of inferring kinematic structures from sparse and irregular distributions of stars.
Aims.
Here, we aim to analyse internal stellar kinematics of open clusters, and identify rotation, expansion, or contraction patterns.
Methods.
We use
Gaia
Early Data Release 3 (EDR3) astrometry and integrated nested Laplace approximations to perform vector-field inference and create spatio-kinematic maps of 1237 open clusters. The sample is composed of clusters for which individual stellar memberships were already known, thus minimising contamination from field stars in the velocity maps. Projection effects were corrected using EDR3 data complemented with radial velocities from
Gaia
Data Release 2 and other surveys.
Results.
We report the detection of rotation patterns in eight open clusters. Nine additional clusters display possible rotation signs. We also observe 14 expanding clusters, with 15 other objects showing possible expansion patterns. Contraction is evident in two clusters, with one additional cluster presenting a more uncertain detection. In total, 53 clusters are found to display kinematic structures. Within these, elongated spatial distributions suggesting tidal tails are found in five clusters. These results indicate that the approach developed here can recover kinematic patterns from noisy vector fields, as those from astrometric measurements of open clusters or other stellar or galactic populations, thus offering a powerful probe for exploring the internal kinematics and dynamics of these types of objects.
Remotely Piloted Aircrafts (RPAs) are commonly used as a platform for collecting images which can be processed with Structure from Motion-Multi View Stereo (SfM-MVS) to generate 3D models. However, ...mobile applications for mapping planning are not designed for image acquisition of vertical surfaces, such as quarry walls or large cliffs, leaving the user to a manual flight operation, which does not ensure optimal overlap between images. Here we describe a workflow, based on the Litchi App, for automated RPA missions designed to acquire images of vertical surfaces or structures.•An easy-to-follow 8 steps method to survey vertical surfaces using a Remotely Piloted Aircraft.•It can be applied to outcrops, quarry walls, high cliffs and virtually any other type of vertical surface.•The workflow is flexible and can be adapted to a variety of target configurations and user-defined parameters.
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This work presents a 1:10,000 geomorphological mapping of an area in southeastern Brazil, based on morphometric analysis of Digital Elevation Models (DEMs), while classical methods focus on photo ...interpretation. Data derived from the DEM include elevation, slope gradient, slope aspect, vertical and horizontal curvatures, amplitude, elongation and wavelength of landforms. These parameters were used along with slope shape and drainage patterns to classify the landforms according to the Land Systems method, in which portions of the landscape that presents similar terrains attributes are grouped from regional (low detail) to local (high detail) scales, respectively, Land Systems, Land Units and Land Elements. The São Paulo State geomorphological map at 1:1,000,000 scale is considered the best reference source, and was compared with the results obtained in this project. Two Land Systems, four Land Units and twelve Land Elements were identified in the study area. In this area, karst terrains are common and easily identified due their characteristics drainage patterns, amplitude and slope gradient. Karst terrain boundaries defined in this study do overlap with those defined in the state map, however the morphometric analysis allowed a better description of the terrain attributes used to define them. The terrain attributes derived automatically from the DEM enabled an accurate geomorphological classification of the study area. The methodology presented in this paper is considered effective for mapping landforms at a detailed scale and can be employed in regional scale mapping using coarser resolution DEMs.
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•A geomorphological map was created based on DEM-extracted terrain attributes.•Attributes were grouped from low to high detail in Land Systems, Units and Elements.•The same Land Systems and Units of a map based on traditional methods were identified.•Land Elements were defined by attributes unavailable from aerial imagery.•Automatic identification of karst areas produced fair results to existing maps.
This work describes the drug release profile and the initial burst release from covalent hydrogel nanocomposites composed of pectin, hydroxyethyl methacrylate (HEMA) and titania (TiO
2
). Vitamin B12 ...(Vit-B
12
), a highly water-soluble substance, was used as a model drug. We studied the water transport profiles over a wide pH range, the moduli of elasticity (
E
), the morphological properties and the Vit-B
12
release kinetics from these hydrogels. The initial release burst was reduced by crosslinking titania with vinylated pectin and HEMA. A reduction of up to
ca.
60% was observed when compared with pure pectin/HEMA hydrogel. To gain insight into the burst release phenomenon, the experimental data were adjusted to diffusive-based models that include a rate constant of release (
k
). A decrease in the values of
k
was related to a reduction in the burst effect. The release mechanism of Vit-B
12
from the pure hydrogels was governed by both Fickian diffusion and macromolecular relaxation, which are the driving forces for release. Upon addition of titania, the contribution of macromolecular relaxation to the release was minimized, suggesting a tendency towards Fickian diffusion. Furthermore, titania played a significant role in improving mechanical properties. Hydrogel nanocomposites showed a marked increase in
E
compared with pure hydrogels. This increase was found to be the result of an apparent increment in the cross-linking density, owing to chemical bonds of titania with the hydrogel. The proposed materials were demonstrated to be biocompatible with cells, showing good pharmacological potential.
Hydrogel nanocomposites of pectin, HEMA and titania for Vit-B
12
controlled release with reduced initial release burst were prepared. A reduction of up to
ca.
60% was observed.
Sand dunes are commonly regarded as a challenge to traditional photogrammetry due their homogeneous texture and spectral response. In this work we present an evaluation of Structure from Motion-Multi ...View Stereo (SfM-MVS) to obtain high-resolution elevation data of coastal sand dunes based on images acquired by Remotely Piloted Aircraft (RPA). A Digital Elevation Model (DEM) of a dunefield in Southern Brazil was generated from 810 photos captured by an RPA at 100 m above the takeoff point in February 2019. Image matching was successful in all areas of the survey due the presence of superficial features (footprints and sandboard tracks) and visibility of the sedimentary stratification, highlighted by heavy minerals. Altimetric accuracy of the SfM-MVS DEM was validated by comparison with Terrestrial LiDAR (TLS) data collected during the same fieldwork campaign of the RPA flights. The SfM-MVS DEM was then compared to an Airborne LiDAR (ALS) DEM from October 2010. While the SfM-MVS and TLS DEMs are very similar, without any major difference in elevation or in the reconstruction of topographic features, the SfM-MVS DEM presents a small scale surface roughness not visible in the TLS DEM. The Feature Preserving DEM Smoothing (FPD) algorithm was applied to the SfM-MVS DEM with good results in terms of surface smoothing, but without any significant changes in descriptive statistics and error metrics, with an RMSE of 0.08 m and MAE of 0.06 m for both the original and the FPD-filtered DEM. Displacement of dune crest lines from the ALS and SfM-MVS DEMs resulted in a migration rate of ≈5 m/year between 2010 and 2019, in good agreement with rates derived from satellite images and historical aerial photographs of the same area. Sand volume change in the same period showed a decrease of only 0.2%, which can be related to the installation of sand fences to promote dune stabilization and sand removal from the front of the dune field to keep a road open to vehicles. ALS can cover large areas in little time but its high cost still remains a barrier to wider usage, especially by researchers in developing countries. TLS has an intermediate cost but demands more fieldwork and more processing time. In our case we needed three days for the TLS survey and around three weeks to produce a DEM of ≈80 400m2. On the other hand, we were able to cover ≈740 900m2 with six flight missions in under three hours, with ≈13 h processing time in a medium-range workstation. This makes SfM-MVS a low-cost solution with fast and reliable results for 3D modelling and continuous monitoring of coastal dunes.
•Comparison of SfM-MVS, Terrestrial and Airborne LiDAR DEMs for dune modelling.•SfM-MVS DEM validated by comparison with TLS DEM, with RMSE of 0.08 m.•Dune migration 5m/year, stable volume (-0.2%) in 9 years (2010–2019).•SfM-MVS successful due visibility of footprints, tracks and stratification in photos.•“Bad” weather (cloudy sky, light rain) favoured SfM-MVS results.
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A facile and reproducible route that can lead to two-dimensional arrays of nanopores in thin polymer films is demonstrated. The formation of the pores in the polymer films involves ...breath figure phenomenon and occurs during the film deposition by spin coating. The formation of nanoporous thin films takes only few seconds, and the method does not require complex equipment or expensive chemicals. This method also constitutes a straightforward approach to control the size of the pores formed in thin films. Besides allowing control over the average pore size of the porous films, the use of dynamic deposition with the breath figure phenomenon causes the reduction in the pore size to nanometer scale. The nanoporous arrays obtained by the breath figure are applied as substrates for cell growth, and the effect of their nanopore size on cell growth was evaluated. Notably, it is found that cell viability is related to pore size, where 2D nanoporous structure is more beneficial for cell culture than 2D microporous structures. The change in the average pore size of the polymer films from 1.22μm to 346nm results in a threefold increase in cell viability.
•Largest Brazilian study analyzing post-transplant outcomes in HCC patients.•Post-transplant overall survival in HCC patients was 63% over five years.•HCC recurrence was observed in 8% of patients ...submitted to liver transplantation.•Patients within Brazilian expanded criteria had lower survival than Milan Criteria.•Brazilian criteria was inferior to Milan Criteria to predict tumor recurrence.
Hepatocellular carcinoma (HCC) is one of the main indications for orthotopic liver transplantation (OLT). In Brazil, selection criteria for HCC is an expanded version of the Milan Criteria (MC), the so-called "Brazilian Milan Criteria" (BMC). Our aims were to evaluate post-OLT outcomes in patients with HCC and analyze the BMC performance.
We conducted a multicenter, retrospective cohort study, analyzing medical records of 1,059 liver transplant recipients with HCC. Tumor was staged according to MC and BMC and correlated with overall survival (OS) and disease-free survival (DFS). We compared the ability of MC and BMC to predict OS and DFS using Delta C-statistic.
Post-OLT OS were 63% in five years and HCC recurrence was observed in 8% of patients. At diagnosis, 85% of patients were within MC. Patients within MC at diagnosis and in the explant showed a higher OS and DFS than patients outside MC and within BMC and patients outside both criteria (p < 0.001). Patients outside MC in the explant had an increased risk of tumor recurrence (HR: 3.78; p < 0.001) and poor survival (HR:1.77; p = 0.003). The BMC presented a lower performance than MC in properly classifying patients regarding recurrence risk.
In a large Brazilian cohort of HCC patients submitted to liver transplantation, we observed satisfactory overall survival and recurrence rates. However, patients transplanted within the Brazilian expanded criteria had lower OS and DFS when compared to patients within MC, which may generate future discussions regarding the criteria currently used.
This paper describes the synthesis and characterization of a hydrogel nanocomposite based on starch and Co-doped zinc ferrite nanoparticles (Co0.50Zn0.50Fe2O4) that underwent drug release changes in ...response to an external magnetic field. The material was prepared using vinylated starch together with N′,N′-dimethylacrylamide (DMAAm) and Co0.50Zn0.50Fe2O4 (CZ) via an ultrasound-assisted radical cross-linking/polymerization reaction. CZ was synthesized by an adapted sol–gel method that uses water as solvent, from which nanoparticles with an average crystallite size of 13nm were obtained. The drug release profile of the hydrogels was obtained by fitting the experimental data to power law equation, using prednisolone as a model drug. In the hydrogel without CZ, the prednisolone release was driven by an anomalous transport, contributions of macromolecular relaxation and the Fickian diffusion. With addition of CZ, the drug release tended towards the Fickian diffusion. In such a case, the macromolecular relaxation is minimized and the Fickian mechanism begins to prevail. When the magnetic field was applied, the anomalous mechanism became more important, which makes the release more favorable. It was shown that, under magnetic field, 90% of initial prednisolone load is released at early times. On the other hand, the more densely cross-linked hydrogels showed irrelevant release changes in response to magnetic field, owing to their tighter polymer structure. Cytotoxicity research showed that both the hydrogels and CZ have great pharmacological potential and an appropriate level of security for use in the biological systems.
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•A hydrogel showing magnetic field-responsive prednisolone release changes was made.•The hydrogel was made of starch and Co-doped zinc ferrite under ultrasound.•The particles were made by an adapted sol–gel method that uses water as solvent.•The prednisolone release was more favorable with an applied magnetic field.•Under magnetic field, 90% of initial prednisolone load is released at early times.
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