Accretion regimes in the X-ray pulsar 4U 1901+03

The source 4U 1901+03 is a high-mass X-ray pulsar than went into outburst in 2003. Observation performed with the Rossi X-ray Timing Explorer showed spectral and timing variability, including the detection of flares, quasi-periodic oscillations, complex changes in the pulse profiles, and pulse phase dependent spectral variability. We re-analysed the data covering the 2003 X-ray outburst and focused on several aspects of the variability that have not been discussed so far. These are the 10 keV feature and the X-ray spectral states and their association with accretion regimes, including the transit to the propeller state at the end of the outburst. We find that 4U 1901+03 went through three accretion regimes over the course of the X-ray outburst. At the peak of the outburst and for a very short time, the X-ray flux may have overcome the critical limit that marks the formation of a radiative shock at a certain distance above the neutron star surface. Most of the time, however, the source is in the subcritical regime. Only at the end of the outburst, when the luminosity decreased below ~10^{36} (d/10 kpc)^2 erg/s, did the source enter the propeller regime. Evidence for the existence of these regimes comes from the pulse profiles, the shape of the hardness-intensity diagram, and the correlation of various spectral parameters with the flux. The 10 keV feature appears to strongly depend on the X-ray flux and on the pulse phase, which opens the possibility to interpret this feature as a cyclotron line.Comment: accepted for publication in A&A. arXiv admin note: text overlap with arXiv:astro-ph/9704084 by other author

Asymmetric copolymers: synthesis, properties, and applications of gradient and other partially segregated copolymers

This is an accepted manuscript of an article published by Wiley in Macromolecular Rapid Communications, available online: https://doi.org/10.1002/marc.201800357 The accepted version of the publication may differ from the final published version.Asymmetric copolymers are a class of materials with intriguing properties. They can be defined by a distribution of monomers within the polymer chain that is neither strictly segregated, as in the case of block copolymers, nor evenly distributed throughout each chain, as in the case of statistical copolymers. This definition includes gradient copolymers as well as block copolymers that contain segments of statistical copolymer. In this review, different methods to synthesize asymmetric copolymers are first discussed. The properties of asymmetric copolymers are investigated in comparison to those of block and random counterparts of similar composition. Finally, some examples of applications of asymmetric copolymers, both academic and industrial, are demonstrated. The aim of this review is to provide a perspective on the design and synthesis of asymmetric copolymers with useful applications.This research was financially supported by the ASYMCOPO Project, an international collaborative research project of the Deutsche Forschungsgemeinschaft (DFG, Germany) and the Agence Nationale de la Recherche (ANR, France); DFG project: GU 1685/1-1 (J. Z., C. G. S. and U. S. S.) and ANR project ANR-15-CE08-0039 (S. H.). C. G. S. and U. S. S. thank the Center for Excellence “PolyTarget” (SFB 1278, project Z01) of the Deutsche Forschungsgemeinschaft (DFG, Germany) for financial support. B. F. M. acknowledges the financial support from Consejo Nacional de Ciencia y Tecnologia (CONACyT, Mexico) to pursue her PhD.Published versio

Amphiphilic gradient copolymers of 2-methyl- and 2-phenyl-2-oxazoline: Self-organization in aqueous media and drug encapsulation

Gradient (or pseudo-diblock) copolymers were synthesized from 2-methyl-2-oxazoline and 2-phenyl-2-oxazoline monomer mixtures via cationic polymerization. The self-assembling properties of these biocompatible gradient copolymers in aqueous solutions were investigated, in an effort to use the produced nanostructures as nanocarriers for hydrophobic pharmaceutical molecules. Dynamic and static light scattering as well as AFM measurements showed that the copolymers assemble in different supramolecular nanostructures (spherical micelles, vesicles and aggregates) depending on copolymer composition. Fluorescence spectroscopy studies revealed a microenvironment of unusually high polarity inside the nanostructures. This observation is related partly to the gradient structure of the copolymers. The polymeric nanostructures were stable with time. Their structural properties in different aqueous media-PBS buffer, RPMI solution-simulating conditions used in pharmacological/medicinal studies, have been also investigated and a composition dependent behavior was observed. Finally, the hydrophobic drug indomethacin was successfully encapsulated within the gradient copolymer nanostructures and the properties of the mixed aggregates were studied in respect to the initial copolymer assemblies. The produced aggregates encapsulating indomethacin showed a significant increase of their mass and size compared to original purely polymeric ones. © 2011 Wiley Periodicals, Inc

Glucocorticoid signaling and osteoarthritis

Glucocorticoids are steroid hormones synthesized and released by the adrenal cortex. Their main function is to maintain cell homeostasis through a variety of signaling pathways, responding to changes in an organism's environment or developmental status. Mimicking the actions of natural glucocorticoids, synthetic glucocorticoids have been recruited to treat many diseases that implicate glucocorticoid receptor signaling such as osteoarthritis. In osteoarthritis, synthetic glucocorticoids aim to alleviate inflammation and pain. The variation of patients’ response and the possibility of complications associated with their long-term use have led to a need for a better understanding of glucocorticoid receptor signaling in osteoarthritis. In this review, we performed a literature search in the molecular pathways that link the osteoarthritic joint to the glucocorticoid receptor signaling. We hope that this information will advance research in the field and propose new molecular targets for the development of more optimized therapies for osteoarthritis. © 2018 Elsevier B.V

Bone morphogenetic protein signaling in musculoskeletal cancer

Purpose: Bone morphogenetic proteins (BMPs) belong to the transforming growth factor-\u3b2 (TGF-\u3b2) superfamily of proteins; they were initially named after their ability to induce ectopic bone formation. Published studies have proved BMPs\u2019 role in a variety of biological processes such as embryogenesis and patterning of body axes, and maintaining adult tissue homeostasis. Other studies have focused on BMPs properties, functions and possible involvement in skeletal diseases, including cancer. Methods: A literature search mainly paying attention to the role of BMPs in musculoskeletal tumors was performed in electronic databases. Results: This article discusses BMPs synthesis and signaling, and summarizes their prominent roles in the skeletal system for the differentiation of osteoblasts, osteocytes and chondrocytes. Conclusions: The review emphasizes on the role of BMP signaling in the initiation and progression of musculoskeletal cancer

Bedtime routines in Greek families: characteristics, barriers, and facilitators for establishing and maintaining optimal routines

Background: Bedtime routines are amongst the most common, recurrent family activities with close associations for child health, development and wellbeing especially sleep. Despite the importance of bedtime routines, no previous study has examined them within the context of a Greek family.Method: A mixed methods, stepped approach was used in this study. A cross-sectional study examined the prevalence and characteristics of bedtime routines (PRE) in families with young children and explored associations with parental mood (POMS) and child's sleep (CSHQ). A qualitative study using the Theoretical Domains Framework (TDF) examined barriers and facilitators for achieving optimal routines.Results: Total of 54 parents with a mean age of 35.9 (SD = 5.95) completed the cross-sectional study while 20 parents participated in the interviews. There were strong positive correlations between total scores on the POMS and total scores on the CSHQ r = 0.482, p < 0.001 and strong negative correlation between total scores on the POMS and total scores on the PRE, r = −0.308, p = 0.023. In terms of barriers and facilitators, social desirability, social comparison, environmental factors and resistance from children were amongst the most common barriers to establishing a good bedtime routine.Conclusion: Bedtime routines are highly prevalent in Greek families with the quality of those routines varying between households. Addressing common barriers in achieving better bedtime routines could help families benefit in the short and long-term

Bone morphogenetic protein signaling in musculoskeletal cancer

Bone morphogenetic proteins (BMPs) belong to the transforming growth factor-beta (TGF-beta) superfamily of proteins; they were initially named after their ability to induce ectopic bone formation. Published studies have proved BMPs' role in a variety of biological processes such as embryogenesis and patterning of body axes, and maintaining adult tissue homeostasis. Other studies have focused on BMPs properties, functions and possible involvement in skeletal diseases, including cancer. A literature search mainly paying attention to the role of BMPs in musculoskeletal tumors was performed in electronic databases. This article discusses BMPs synthesis and signaling, and summarizes their prominent roles in the skeletal system for the differentiation of osteoblasts, osteocytes and chondrocytes. The review emphasizes on the role of BMP signaling in the initiation and progression of musculoskeletal cancer

Harvesting, isolation and differentiation of rat adipose-derived stem cells

Background: Adipose tissue is one of the most attractive sources of stem cells because it can be easily harvested and yields a greater stromal cell density. The multilineage potential of adipose-derived stem cells (ADSCs) demonstrates their significant impact within the field of tissue engineering, with studies successfully demonstrating the ability to produce a range of tissue types. However, although a broad spectrum of applications has already been suggested, many important scientific and medical questions remain unanswered before the clinical application of ADSCs in humans. Importantly, clarification of the biology and identification of the differences of ADSCs from various areas of the body is required. In this continuous endeavor, research in rat models plays an important role in the development of new knowledge. Methods: A literature review was done to summarize all information regarding harvesting, isolation, expansion, cryopreservation and differentiation of rat ADSCs. A Wistar rat model was also used to describe harvesting sites of adipose tissue, and to characterize the ADSCs using Fourier-transform infrared (FT-IR) spectroscopy and phase contrast microscopy. Aims: To discuss all relevant considerations for harvesting, culture, differentiation and phenotypic characterization of ADSCs, to provide a comprehensive roadmap of this process, to identify the differences between ADSCs obtained from various adipose tissues of the rat, and to provide FT-IR spectroscopy marker bands that could be used as fingerprints to differentiate the types of adipose tissues. © 2018 Bentham Science Publishers