Bioresorbable microspheres as devices for the controlled release of paclitaxel

The release of the anti-cancer drug paclitaxel (PTX) from microspheres of both a bioresorbable poly(ε-caprolactoneoxyethylene- ε-caprolactone) tri-block copolymer and of polyurethanes containing either copolymers with the same composition and different molecular weights or poly(ε-caprolactone) diol as soft segments was studied. The microspheres, both loaded and not with PTX, were prepared by emulsion-evaporation technique, then characterized by SEM and DSC. The quantities of PTX released were measured by HPLC. The results showed slow and very regular releases, which fit very well the Peppas equation, Mt/M? = k · tn, where Mt is the amount of solute released at the time t, M? is the amount of drug released at the plateau condition, k represents the Peppas kinetic constant and n the diffusion order. Most n values are consistent with non-Fickian release mechanisms, with the exceptions of two less hydrophilic polyurethanes

Chitosan-Based Macromolecular Biomaterials for the Regeneration of Chondroskeletal and Nerve Tissue

The use of materials, containing the biocompatible and bioresorbable biopolymer poly()-2-amino-2-deoxy--D-glucan, containing some N-acetyl-glucosamine units (chitosan, CHI) and/or its derivatives, to fabricate devices for the regeneration of bone, cartilage and nerve tissue, was reviewed. The CHI-containing devices, to be used for bone and cartilage regeneration and healing, were tested mainly for in vitro cell adhesion and proliferation and for insertion into animals; only the use of CHI in dental surgery has reached the clinical application. Regarding the nerve tissue, only a surgical repair of a 35 mm-long nerve defect in the median nerve of the right arm at elbow level with an artificial nerve graft, comprising an outer microporous conduit of CHI and internal oriented filaments of poly(glycolic acid), was reported. As a consequence, although many positive results have been obtained, much work must still be made, especially for the passage from the experimentation of the CHI-based devices, in vitro and in animals, to their clinical application

Targeting cancer cells overexpressing folate receptors with new terpolymer-based nanocapsules: Toward a novel targeted dna delivery system for cancer therapy

Chemotherapeutics represent the standard treatment for a wide range of cancers. However, these agents also affect healthy cells, thus leading to severe off-target effects. Given the non-selectivity of the commonly used drugs, any increase in the selective tumor tissue uptake would represent a significant improvement in cancer therapy. Recently, the use of gene therapy to completely remove the lesion and avoid the toxicity of chemotherapeutics has become a tendency in oncotherapy. Ideally, the genetic material must be safely transferred from the site of administration to the target cells, without involving healthy tissues. This can be achieved by encapsulating genes into non-viral carriers and modifying their surface with ligands with high selectivity and affinity for a relevant receptor on the target cells. Hence, in this work we evaluate the use of terpolymer-based nanocapsules for the targeted delivery of DNA toward cancer cells. The surface of the nanocapsules is decorated with folic acid to actively target the folate receptors overexpressed on a variety of cancer cells. The nanocapsules demonstrate a good ability of encapsulating and releasing DNA. Moreover, the presence of the targeting moieties on the surface of the nanocapsules favors cell uptake, opening up the possibility of more effective therapies

Cretaceous intraplate contraction in Southern Patagonia: A far-field response to changing subduction dynamics?

The origin, extent, and timing of intraplate contraction in Patagonia are among the least understood geological processes of southern South America. Particularly, the intraplate Deseado fold-thrust belt (FTB), located in the Patagonian broken foreland (47°–48°300 S), is one of the most enigmatic areas. In this belt, time constraints on tectonic events are limited and synorogenic deposits have not been documented so far. Furthermore, the driving mechanism for intraplate contraction remains unknown. In this study, we carried out a structural and sedimentological analysis. We report the first syntectonic deposits in this area in the Baqueró (Aptian) and Chubut (Cenomanian/Campanian) groups and a newly found unit referred to as the Albian beds (109.9 ± 1.5 Ma). Thus, several contractional stages in late Aptian, Albian, and Cenomanian-Campanian are then inferred. We suggest that the Deseado FTB constituted the southernmost expression of the early Patagonian broken foreland in Cretaceous times. Additionally, we analyzed the spatiotemporal magmatic arc behavior as a proxy of dynamic changes in the Andean subduction during determined stages of intraplate contraction. We observe a significant arc broadening from ~121 to 82 Myr and magmatic quiescence after ~67 Ma. This is interpreted as a slab shallowing to flattening process. Far-field tectonic forces would have been produced by increased plate coupling linked to the slab flattening as indirectly indicated by the correlation between Cretaceous arc expansion and intraplate contraction. Finally, the tectonic evolution of the Deseado FTB favors studies supporting inception of Andean shortening since Cretaceous times.Fil: Gianni, Guido Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; ArgentinaFil: Navarrete Granzotto, César Rodrigo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Liendo, Ingrid Florencia. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Díaz, Marianela Ximena Yasmin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geología; ArgentinaFil: Gimenez, Mario Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Geofísico Sismológico Volponi; ArgentinaFil: Encinas, Alfonso. Universidad de Concepción; ChileFil: Folguera Telichevsky, Andres. 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"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentin

Optimal trajectories for range resolution improvement in multi-PCL SAR

In this paper the problem of multiple passive coherent location (PCL) radar systems mounted on moving platforms for range resolution improvement is addressed. Specifically, enabling them to be also used for imaging purposes. Constellations of low-cost ultra-light platforms constitute an extremely appealing solution for future surveillance and reconnaissance systems. These platforms exploit a common transmitter of opportunity, but they observe the area of interest with slightly different incident angles. As a consequence, the corresponding ground echo signals result shifted in the K-space, thus enabling a range resolution improvement. In this paper it is shown how the relative shift of these echo signals varies (in general) during the synthetic aperture and it is also described how this varying shift impedes proper imaging. In addition, optimal trajectories for the different platforms are derived which guarantee a constant K-space signal occupancy during their motion. Finally, an analysis is performed to assess the effects of non-ideal flown trajectories

Joint monostatic and bistatic STAP for improved SAR-GMTI capabilities

This paper proposes a novel simultaneous monostatic and bistatic ground moving target indication (GMTI) mode for improved target detection and imaging capability. The mode uses an airborne multichannel radar system and a stationary transmitter. Both systems transmit simultaneously on adjacent frequency bands, and the airborne multichannel system receives both its monostatic echoes and the bistatic returns. Geometrical diversity between the monostatic and bistatic measurements enhances moving target detection capabilities. Moreover, for movers detected in both data sets, an estimation of the target velocity vector (i.e., velocity and direction of motion) can be performed. By simply extracting a single-channel data set, this also allows correct focusing of moving targets both in monostatic and bistatic data sets, if synthetic aperture radar GMTI capability is required. Consequently, situational awareness over the observed area is greatly improved. The effectiveness of the proposed technique is analyzed both from a theoretical point of view and by means of an ad hoc experiment conducted by the Fraunhofer Institute for High Frequency Physics and Radar Techniques (FHR) in fall 2013

A robust direct data domain approach for STAP

In this paper, a novel approach for direct data domain space time adaptive processing (STAP) is presented. As already described in past literature, direct data domain STAP (also known as deterministic STAP) has several advantages compared to traditional stochastic STAP. In particular, being implicitly a single snapshot interference cancellation technique, deterministic STAP generally outperforms stochastic STAP in fast varying interference scenarios. On the other hand, in its classical derivation, target detection performances of deterministic STAP are severely deteriorated in case of uncertainty in the knowledge of exact target parameters as direction of arrival (DOA) and Doppler frequency. To overcome this problem, we propose a robust implementation of deterministic STAP in order to take into account a possible mismatch between the nominal and the actual target parameters. The proposed approach reformulates the deterministic STAP problem in the context of convex probl em optimization. A detailed analysis of the maximum acceptable target parameters error is conducted, which ensures the existence of a numerical solution for the convex problem optimization. The proposed robust deterministic approach is defined for both the one dimensional (spatial-only) and the two dimensional (space-time) case. The effectiveness of the proposed approach is shown both in simulated scenarios and by direct application to real data taken from the experimental multichannel radar system PAMIR developed at Fraunhofer FHR

Maritime target imaging via simultaneous DVB-T and DVB-S passive ISAR

This work presents an analysis of passive inverse synthetic aperture radar images obtained exploiting simultaneously digital video broadcasting-Terrestrial (DVB-T) and digital video broadcasting-satellite (DVB-S) as illuminators of opportunity (IOs) over a cooperative maritime target with known motion. The combined exploitation of these two IOs is extremely appealing for passive imaging purposes, given their complementary characteristics. The analysis is first conducted in a simulated environment, to show the different expected outcomes from the two considered bistatic geometries and operating bandwidths. Subsequently, the same analysis is repeated over real data acquired during a field trial, by exploiting experimental setups developed at Fraunhofer FHR. In particular, DVB-T and DVB-S data are focused by means of back projection, which enables an easier comparison of the different ISAR products. Real data results show good match with simulated ones. Target size can be estimated with good accuracy in both DVB-T and DVB-S cases, and dominant scatterers can also be identified. DVB-S also enables target-shape recognition, given its higher signal bandwidth

DVB-S based passive radar imaging of ship targets

This work investigates the potentialities of DVB-S based passive ISAR for maritime surveillance applications. Specifically, in order to characterize the bound on the achievable performance, a knowledge based approach is adopted: Assuming known the target motion, the image is focused in both the range/Doppler domain and the x-y plane via backprojection. The approach is applied to experimental data acquired during a field trial by exploiting an experimental system developed at Fraunhofer FHR. Obtained results clearly demonstrate the potentialities of DVB-S based passive ISAR at providing output products suitable for the extraction of the length/width of the ship and of its shape