Quantum correlation dynamics in photosynthetic processes assisted by molecular vibrations

During the long course of evolution, nature has learnt how to exploit quantum effects. In fact, recent experiments reveal the existence of quantum processes whose coherence extends over unexpectedly long time and space ranges. In particular, photosynthetic processes in light-harvesting complexes display a typical oscillatory dynamics ascribed to quantum coherence. Here, we consider the simple model where a dimer made of two chromophores is strongly coupled with a quasi-resonant vibrational mode. We observe the occurrence of wide oscillations of genuine quantum correlations, between electronic excitations and the environment, represented by vibrational bosonic modes. Such a quantum dynamics has been unveiled through the calculation of the negativity of entanglement and the discord, indicators widely used in quantum information for quantifying the resources needed to realize quantum technologies. We also discuss the possibility of approximating additional weakly-coupled off-resonant vibrational modes, simulating the disturbances induced by the rest of the environment, by a single vibrational mode. Within this approximation, one can show that the off-resonant bath behaves like a classical source of noise

Novel achromatic single reflection quarter-wave retarder: design and measurement

In this work, we present an achromatic quarter-wave retarder whose design is based upon the reflection properties of an isotropic-anisotropic interface. In theory, it is possible to obtain a π/2 phase shift by means of a total internal reflection at an isotropic-isotropic interface. However, in order to achieve such a phase shift, it is necessary to use a medium with a particularly high refractive index. We have previously shown that these phase shifts can be achieved by means of a total internal reflection in an isotropic-uniaxial interface, which allows the use of smaller refractive index media. By means of this property, we designed, built, and characterized a novel quarter-wave retarder that makes it possible to obtain circularly polarized light from a linear polarization state. We developed some guidelines that allowed us to obtain a device of competitive performance, low cost, and manageable manufacture.Fil: Veiras, Francisco Ezequiel. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Raffa, G.. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física; ArgentinaFil: Caré, D.. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física; ArgentinaFil: Perez, Liliana Ines. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Garea, María Teresa. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Física; Argentin

Protein adsorption onto Fe3O4 nanoparticles with opposite surface charge and its impact on cell uptake

Nanoparticles (NPs) engineered for biomedical applications are meant to be in contact with protein-rich physiological fluids. These proteins are usually adsorbed onto the NP surface, forming a swaddling layer called protein corona that influences cell internalization. We present a study on protein adsorption onto different magnetic NPs (MNPs) when immersed in cell culture medium, and how these changes affect the cellular uptake. Two colloids with magnetite cores of 25 nm, same hydrodynamic size and opposite surface charge were in situ coated with (a) positive polyethyleneimine (PEI-MNPs) and (b) negative poly(acrylic acid) (PAA-MNPs). After few minutes of incubation in cell culture medium the wrapping of the MNPs by protein adsorption resulted in a 5-fold size increase. After 24 h of incubation large MNP-protein aggregates with hydrodynamic sizes 1500 to 3000 nm (PAA-MNPs and PEI-MNPs respectively) were observed. Each cluster contained an estimated number of magnetic cores between 450 and 1000, indicating the formation of large aggregates with a "plum pudding" structure of MNPs embedded into a protein network of negative surface charge irrespective of the MNP_core charge. We demonstrated that PEI-MNPs are incorporated in much larger amounts than the PAA-MNPs units. Quantitative analysis showed that SH-SY5Y cells can incorporate 100 per cent of the added PEI-MNPs up to about 100 pg per cell, whereas for PAA-MNPs the uptake was less than 50 percent. The final cellular distribution showed also notable differences regarding partial attachment to the cell membrane. These results highlight the need to characterize the final properties of MNPs after protein adsorption in biological media, and demonstrate the impact of these properties on the internalization mechanisms in neural cells.Comment: 32 pages, 10 figure

Postoperative pain surveys in Italy from 2006 and 2012. (POPSI and POPSI-2)

OBJECTIVE: Despite established standards, effective treatments, and evidence-based guidelines, postoperative pain control in Italy and other parts of the world remains suboptimal. Pain control has been recognized as a fundamental human right. Effective treatments exist to control postsurgical pain. Inadequate postoperative analgesia may prolong the length of hospital stays and may adversely impact outcomes. MATERIALS AND METHODS: The same multiple-choice survey administered at the SIAARTI National Congress in Perugia in 2006 (n=588) was given at the SIAARTI National Congress in Naples, Italy in 2012 (n=635). The 2012 survey was analysed and compared to the 2006 results. RESULTS: Postoperative pain control in Italy was less than optimal in 2006 and showed no substantial improvements in 2012. Geographical distinctions were evident with certain parts of Italy offering better postoperative pain control than other. Fewer than half of hospitals represented had an active Acute Pain Service (APS) and only about 10% of postsurgical patients were managed according to evidence-based guidelines. For example, elastomeric pumps for continuous IV infusion are commonly used in Italy, although patient-controlled analgesia systems are recommended in the guidelines. The biggest obstacles to optimal postoperative pain control reported by respondents could be categorized as organizational, cultural, and economic. CONCLUSIONS: There is considerable room for improvement in postoperative pain control in Italy, specifically in the areas of clinical education, evidence-based treatments, better equipment, and implementation of active APS departments in more hospitals. Two surveys taken six years apart in Italy reveal, with striking similarity, that there are many unmet needs in postoperative pain control and that Italy still falls below European standards for postoperative pain control

Synthesis and solution properties of poly(p,α dimethylstyrene-co-maleic anhydride):The use of a monomer potentially obtained from renewable sources as a substitute of styrene in amphiphilic copolymers

The use of p,α-dimethylstyrene, potentially obtainable from renewable sources, as a substitute for styrene in the synthesis of amphiphilic copolymers is reported in this work. A series of novel poly(p,α-dimethylstyrene-co-maleic anhydride) (SMA) copolymers was synthesized, characterized, and studied as potential polymeric surfactants. After hydrolysis, the copolymers solution properties were compared to the similar and very well-known styrene-maleic acid copolymers. Both series of copolymers were synthesized using reversible addition-fragmentation chain transfer-mediated polymerization (RAFT), and a sample of poly(p,α-dimethylstyrene-co-maleic anhydride) was synthesized via classical free radical polymerization. The synthesized copolymers were studied from the point of view of their solution properties, with particular attention to the influence of the macromolecular and chemical structure on the surface tension of their aqueous solutions. Our results suggest that p,α-dimethylstyrene can be employed in copolymers with maleic anhydride, the resulting material being a valid alternative to SMA copolymers for various applications, such as emulsifiers and dispersants. Furthermore, the DMSMA series seems to be slightly more surface active than SMA

Atlas-Based Evaluation of Hemodynamic in Ascending Thoracic Aortic Aneurysms

Atlas-based analyses of patients with cardiovascular diseases have recently been explored to understand the mechanistic link between shape and pathophysiology. The construction of probabilistic atlases is based on statistical shape modeling (SSM) to assess key anatomic features for a given patient population. Such an approach is relevant to study the complex nature of the ascending thoracic aortic aneurysm (ATAA) as characterized by different patterns of aortic shapes and valve phenotypes. This study was carried out to develop an SSM of the dilated aorta with both bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV), and then assess the computational hemodynamic of virtual models obtained by the deformation of the mean template for specific shape boundaries (i.e., ±1.5 standard deviation, σ). Simulations demonstrated remarkable changes in the velocity streamlines, blood pressure, and fluid shear stress with the principal shape modes such as the aortic size (Mode 1), vessel tortuosity (Mode 2), and aortic valve morphologies (Mode 3). The atlas-based disease assessment can represent a powerful tool to reveal important insights on ATAA-derived hemodynamic, especially for aneurysms which are considered to have borderline anatomies, and thus challenging decision-making. The utilization of SSMs for creating probabilistic patient cohorts can facilitate the understanding of the heterogenous nature of the dilated ascending aorta

Regional biomechanical characterization of human ascending aortic aneurysms: Microstructure and biaxial mechanical response

: The ascending thoracic aortic aneurysm (ATAA) is a permanent dilatation of the vessel with a high risk of adverse events, and shows heterogeneous properties. To investigate regional differences in the biomechanical properties of ATAAs, tissue samples were collected from 10 patients with tricuspid aortic valve phenotype and specimens from minor, anterior, major, and posterior regions were subjected to multi-ratio planar biaxial extension tests and second-harmonic generation (SHG) imaging. Using the data, parameters of a microstructure-motivated constitutive model were obtained considering fiber dispersion. SHG imaging showed disruptions in the organization of the layers. Structural and material parameters did not differ significantly between regions. The non-symmetric fiber dispersion model proposed by Holzapfel et al. [25] was used to fit the data. The mean angle of collagen fibers was negatively correlated between minor and anterior regions, and the parameter associated with collagen fiber stiffness was positively correlated between minor and major regions. Furthermore, correlations were found between the stiffness of the ground matrix and the mean fiber angle, and between the parameter associated with the collagen fiber stiffness and the out-of-plane dispersion parameter in the posterior and minor regions, respectively. The experimental data collected in this study contribute to the biomechanical data available in the literature on human ATAAs. Region-specific parameters for the constitutive models are fundamental to improve the current risk stratification strategies, which are mainly based on aortic size. Such investigations can facilitate the development of more advanced finite element models capable of capturing the regional heterogeneity of pathological tissues. STATEMENT OF SIGNIFICANCE: Tissue samples of human ascending thoracic aortic aneurysms (ATAA) were collected. Samples from four regions underwent multi-ratio planar biaxial extension tests and second-harmonic generation imaging. Region-specific parameters of a microstructure-motivated model considering fiber dispersion were obtained. Structural and material parameters did not differ significantly between regions, however, the mean fiber angle was negatively correlated between minor and anterior regions, and the parameter associated with collagen fiber stiffness was positively correlated between minor and major regions. Furthermore, correlations were found between the stiffness of the ground matrix and the mean fiber angle, and between the parameter associated with the collagen fiber stiffness and the out-of-plane dispersion parameter in the posterior and minor regions, respectively. This study provides a unique set of mechanical and structural data, supporting the microstructural influence on the tissue response. It may facilitate the development of better finite element models capable of capturing the regional tissue heterogeneity

Transcatheter heart valve implantation in bicuspid patients with self-expanding device

Bicuspid aortic valve (BAV) patients are conventionally not treated by transcathether aortic valve implantation (TAVI) because of anatomic constraint with unfavorable outcome. Patient-specific numerical simulation of TAVI in BAV may predict important clinical insights to assess the con-formability of the transcathether heart valves (THV) implanted on the aortic root of members of this challenging patient population. We aimed to develop a computational approach and virtually simulate TAVI in a group of n.6 stenotic BAV patients using the self-expanding Evolut Pro THV. Specif-ically, the structural mechanics were evaluated by a finite-element model to estimate the deformed THV configuration in the oval bicuspid anatomy. Then, a fluid–solid interaction analysis based on the smoothed-particle hydrodynamics (SPH) technique was adopted to quantify the blood-flow patterns as well as the regions at high risk of paravalvular leakage (PVL). Simulations demonstrated a slight asymmetric and elliptical expansion of the THV stent frame in the BAV anatomy. The contact pressure between the luminal aortic root surface and the THV stent frame was determined to quantify the device anchoring force at the level of the aortic annulus and mid-ascending aorta. At late diastole, PVL was found in the gap between the aortic wall and THV stent frame. Though the modeling framework was not validated by clinical data, this study could be considered a further step towards the use of numerical simulations for the assessment of TAVI in BAV, aiming at understanding patients not suitable for device implantation on an anatomic basis

Growth factor choice is critical for successful functionalization of nanoparticles

Nanoparticles (NPs) show new characteristics compared to the corresponding bulk material. These nanoscale properties make them interesting for various applications in biomedicine and life sciences. One field of application is the use of magnetic NPs to support regeneration in the nervous system. Drug delivery requires a functionalization of NPs with bio-functional molecules. In our study, we functionalized self-made PEI-coated iron oxide NPs with nerve growth factor (NGF) and glial cell-line derived neurotrophic factor (GDNF). Next, we tested the bio-functionality of NGF in a rat pheochromocytoma cell line (PC12) and the bio-functionality of GDNF in an organotypic spinal cord culture. Covalent binding of NGF to PEI-NPs impaired bio-functionality of NGF, but non-covalent approach differentiated PC12 cells reliably. Non-covalent binding of GDNF showed a satisfying bio-functionality of GDNF:PEI-NPs, but turned out to be unstable in conjugation to the PEI-NPs. Taken together, our study showed the importance of assessing bio-functionality and binding stability of functionalized growth factors using proper biological models. It also shows that successful functionalization of magnetic NPs with growth factors is dependent on the used binding chemistry and that it is hardly predictable. For use as therapeutics, functionalization strategies have to be reproducible and future studies are needed

Hepatitis B virus DNA integration in tumour tissue of a non-cirrhotic HFE-haemochromatosis patient with hepatocellular carcinoma.

Co-existence of multiple causes of liver injury increases the risk of hepatocellular carcinoma (HCC) development. HCC usually develops in patients with cirrhosis although it may also occur in individuals with no or mild liver disease, in particular in cases with hepatitis B virus (HBV) infection. Here we report the case of a 43year-old man with HFE-haemochromatosis, seronegative for hepatitis B and C infections, who developed HCC in the absence of severe liver damage. Both tumoural and non-tumoural liver DNA extracts were tested by nested-PCR and primers specific for four different HBV genomic regions in order to evaluate the presence of occult HBV infection. Only X gene sequences were detected in tumour (but not in non-tumour) DNA extracts. HBV-Alu PCR showed a HBV integration involving a 5'-deleted X gene with an intact enhancer-II/basal-core promoter region. The viral-host junction sequencing revealed that this integrant was located upstream of the partitioning-defective-6-homolog-gamma gene (PARD6G) and real time-PCR quantification demonstrated that PARD6G was overexpressed in tumour compared to non-tumour liver tissues. In conclusion, the combination of HFE-haemochromatosis and occult HBV infection in this patient might have led to a sequel of cellular events that determined the development of HCC even in the absence of cirrhosis