Synthesis and Characterization of Thermally and Chemically Gelling Injectable Hydrogels for Tissue Engineering

Novel, injectable hydrogels were developed that solidify through a dual-gelation, physical and chemical, mechanism upon preparation and elevation of temperature to 37°C. A thermogelling, poly(N-isopropylacrylamide)-based macromer with pendant epoxy rings and a hydrolyticallydegradable polyamidoamine-based diamine crosslinker were synthesized, characterized, and combined to produce in situ forming hydrogel constructs. Network formation through the epoxyamine reaction was shown to be rapid and facile, and the progressive incorporation of the hydrophilic polyamidoamine crosslinker into the hydrogel was shown to mitigate the often problematic tendency of thermogelling materials to undergo significant post-formation gel syneresis. The results suggest that this novel class of injectable hydrogels may be attractive substrates for tissue engineering applications due to the synthetic versatility of the component materials and beneficial hydrogel gelation kinetics and stability

Changing material around (2060) Chiron revealed by an occultation on December 15, 2022

Full list of authors: Ortiz, J. L.; Pereira, C. L.; Sicardy, B.; Braga-Ribas, F.; Takey, A.; Fouad, A. M.; Shaker, A. A.; Kaspi, S.; Brosch, N.; Kretlow, M.; Leiva, R.; Desmars, J.; Morgado, B. E.; Morales, N.; Vara-Lubiano, M.; Santos-Sanz, P.; Fernández-Valenzuela, E.; Souami, D.; Duffard, R.; Rommel, F. L.; Kilic, Y.; Erece, O.; Koseoglu, D.; Ege, E.; Morales, R.; Alvarez-Candal, A.; Rizos, J. L.; Gómez-Limón, J. M.; Assafin, M.; Vieira-Martins, R.; Gomes-Júnior, A. R.; Camargo, J. I. B.; Lecacheux, J.We were able to accurately predict the shadow path and successfully observe an occultation of a bright star by Chiron on December 15, 2022. The Kottamia Astronomical Observatory in Egypt did not detect the occultation by the solid body, but we found three extinction features in the light curve that had symmetrical counterparts with respect to the central time of the occultation. One of the features is broad and shallow, whereas the other two features are sharper, with a maximum extinction of ∼25% at the achieved spatial resolution of 19 km per data point. From the Wise Observatory in Israel, we detected the occultation caused by the main body and several extinction features surrounding the body. When all the secondary features are plotted in the sky plane, we find that they can be caused by a broad ∼580 km disk with concentrations at radii of 325 ± 16 km and 423 ± 11 km surrounding Chiron. At least one of these structures appears to be outside the Roche limit. The ecliptic coordinates of the pole of the disk are λ = 151° ±8 and β = 18° ±11, in agreement with previous results. We also reveal our long-term photometry results, indicating that Chiron had suffered a brightness outburst of at least 0.6 mag between March and September 2021 and that Chiron was still somewhat brighter at the occultation date than at its nominal pre-outburst phase. The outermost extinction features might be consistent with a bound or temporarily bound structure associated with the brightness increase. However, the nature of the brightness outburst is unclear, and it is also unclear whether the dust or ice released in the outburst could be feeding a putative ring structure or whether it is emanating from it. © The Authors 2023.Part of this work was supported by the Spanish projects PID2020-112789GB-I00 from AEI and Proyecto de Excelencia de la Junta de Andalucia PY20-01309. Financial support from the grant CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033 is also acknowledged. This research is partly based on observations taken with the 1.88-m telescope at the Kottamia Astronomical Observatory (KAO), operated by researchers at the National Research Institute of Astronomy and Geophysics (NRIAG), Egypt. The Egyptian team acknowledges support from Science, Technology & amp; Innovation Funding Authority (STDF) under grant number 45779. C.L.P is thankful for the support of the CAPES and FAPERJ/DSC-10 (E26/204.141/2022)

Constraints on (2060) Chiron's size, shape, and surrounding material from the November 2018 and September 2019 stellar occultations

After the discovery of rings around the largest known Centaur object, (10199) Chariklo, we carried out observation campaigns of stellar occultations produced by the second-largest known Centaur object, (2060) Chiron, to better characterize its physical properties and presence of material on its surroundings. We predicted and successfully observed two stellar occultations by Chiron. These observations were used to constrain its size and shape by fitting elliptical limbs with equivalent surface radii in agreement with radiometric measurements. Constraints on the (2060) Chiron shape are reported for the first time. Assuming an equivalent radius of R$_{equiv}$ = 105$^{+6}_{-7}$ km, we obtained a semi-major axis of a = 126 $\pm$ 22 km. Considering Chiron's true rotational light curve amplitude and assuming it has a Jacobi equilibrium shape, we were able to derive a 3D shape with a semi-axis of a = 126 $\pm$ 22 km, b = 109 $\pm$ 19 km, and c = 68 $\pm$ 13 km, implying in a volume-equivalent radius of R$_{vol}$ = 98 $\pm$ 17 km, implying a density of 1119 $\pm$ 4 kg m$^{-3}$. We determined the physical properties of the 2011 secondary events around Chiron, which may then be directly compared with those of Chariklo rings, as the same method was used. Data obtained from SAAO in 2018 do not show unambiguous evidence of the proposed rings, mainly due to the large sampling time. Meanwhile, we discarded the possible presence of a permanent ring similar to (10199) Chariklo's C1R in optical depth and extension. Using the first multi-chord stellar occultation by (2060) Chiron and considering it to have a Jacobi equilibrium shape, we derived its 3D shape. New observations of a stellar occultation by (2060) Chiron are needed to further investigate the material's properties around Chiron, such as the occultation predicted for September 10, 2023

The changing material around (2060) Chiron from an occultation on 2022 December 15

We could accurately predict the shadow path and successfully observe an occultation of a bright star by Chiron on 2022 December 15. The Kottamia Astronomical Observatory in Egypt did not detect the occultation by the solid body, but we detected three extinction features in the light curve that had symmetrical counterparts with respect to the central time of the occultation. One of the features is broad and shallow, whereas the other two features are sharper with a maximum extinction of $\sim$25$\%$ at the achieved spatial resolution of 19 km per data point. From the Wise observatory in Israel, we detected the occultation caused by the main body and several extinction features surrounding the body. When all the secondary features are plotted in the sky plane we find that they can be caused by a broad $\sim$580 km disk with concentrations at radii of 325 \pm 16 km and 423 \pm 11 km surrounding Chiron. At least one of these structures appears to be outside the Roche limit. The ecliptic coordinates of the pole of the disk are $\lambda$ = 151$^\circ~\pm$ 8$^\circ$ and $\beta$ = 18$^\circ~\pm$ 11$^\circ$, in agreement with previous results. We also show our long-term photometry indicating that Chiron had suffered a brightness outburst of at least 0.6 mag between March and September 2021 and that Chiron was still somewhat brighter at the occultation date than at its nominal pre-outburst phase. The outermost extinction features might be consistent with a bound or temporarily bound structure associated with the brightness increase. However, the nature of the brightness outburst is unclear, and it is also unclear whether the dust or ice released in the outburst could be feeding a putative ring structure or if it emanated from it.Comment: 6 pages, 4, figure

In situ biospectroscopic investigation of rapid ischemic and postmortem induced biochemical alterations in the rat brain

© 2014 American Chemical Society. Rapid advances in imaging technologies have pushed novel spectroscopic modalities such as Fourier transform infrared spectroscopy (FTIR) and X-ray absorption spectroscopy (XAS) at the sulfur K-edge to the forefront of direct in situ investigation of brain biochemistry. However, few studies have examined the extent to which sample preparation artifacts confound results. Previous investigations using traditional analyses, such as tissue dissection, homogenization, and biochemical assay, conducted extensive research to identify biochemical alterations that occur ex vivo during sample preparation. In particular, altered metabolism and oxidative stress may be caused by animal death. These processes were a concern for studies using biochemical assays, and protocols were developed to minimize their occurrence. In this investigation, a similar approach was taken to identify the biochemical alterations that are detectable by two in situ spectroscopic methods (FTIR, XAS) that occur as a consequence of ischemic conditions created during humane animal killing. FTIR and XAS are well suited to study markers of altered metabolism such as lactate and creatine (FTIR) and markers of oxidative stress such as aggregated proteins (FTIR) and altered thiol redox (XAS). The results are in accordance with previous investigations using biochemical assays and demonstrate that the time between animal death and tissue dissection results in ischemic conditions that alter brain metabolism and initiate oxidative stress. Therefore, future in situ biospectroscopic investigations utilizing FTIR and XAS must take into consideration that brain tissue dissected from a healthy animal does not truly reflect the in vivo condition, but rather reflects a state of mild ischemia. If studies require the levels of metabolites (lactate, creatine) and markers of oxidative stress (thiol redox) to be preserved as close as possible to the in vivo condition, then rapid freezing of brain tissue via decapitation into liquid nitrogen, followed by chiseling the brain out at dry ice temperatures is required

The multichord stellar occultation by the centaur Bienor on January 11, 2019

Full list of authors: Fernández-Valenzuela, E.; Morales, N.; Vara-Lubiano, M.; Ortiz, J. L.; Benedetti-Rossi, G.; Sicardy, B.; Kretlow, M.; Santos-Sanz, P.; Morgado, B.; Souami, D.; Organero, F.; Ana, L.; Fonseca, F.; Román, A.; Alonso, S.; Gonçalves, R.; Ferreira, M.; Iglesias-Marzoa, R.; Lamadrid, J. L.; Alvarez-Candal, A.; Assafin, M.; Braga-Ribas, F.; Camargo, J. I. B.; Colas, F.; Desmars, J.; Duffard, R.; Lecacheux, J.; Gomes-Júnior, A. R.; Rommel, F. L.; Vieira-Martins, R.; Pereira, C. L.; Casanova, V.; Selva, A.; Perelló, C.; Mottola, S.; Hellmich, S.; Maestre, J. L.; Castro-Tirado, A. J.; Pal, A.; Trigo-Rodriguez, J. M.; Beisker, W.; Laporta, A.; Garcés, M.; Escaned, L.; Bretton, M.-- This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Within our program of physical characterization of trans-Neptunian objects and centaurs, we predicted a stellar occultation by the centaur (54598) Bienor to occur on January 11, 2019, with good observability potential. We obtained high accuracy astrometric data to refine the prediction, resulting in a shadow path favorable for the Iberian Peninsula. This encouraged us to carry out an occultation observation campaign that resulted in five positive detections from four observing sites. This is the fourth centaur for which a multichord (more than two chords) stellar occultation has been observed so far, the other three being (2060) Chiron, (10199) Chariklo, and (95626) 2002 GZ32. From the analysis of the occultation chords, combined with the rotational light curve obtained shortly after the occultation, we determined that Bienor has an area-equivalent diameter of 150 ± 20 km. This diameter is ~30 km smaller than the one obtained from thermal measurements. The position angle of the short axis of the best fitting ellipse obtained through the analysis of the stellar occultation does not match that of the spin axis derived from long-term photometric models. We also detected a strong irregularity in one of the minima of the rotational light curve that is present no matter the aspect angle at which the observations were done. We present different scenarios to reconcile the results from the different techniques. We did not detect secondary drops related to potential rings or satellites. Nonetheless, similar rings in size to that of Chariklo's cannot be discarded due to low data accuracy. © The Authors 2023.The work leading to these results has received funding from the European Research Council under the European Community’s H2020 2014-2021 ERC Grant Agreement no. 669416 “Lucky Star”. E.F.-V. acknowledges financial support by the Space Research Initiative from State of Florida. P.S.-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 “LEO-SBNAF” (MCIU/AEI/FEDER, UE). A.P. acknowledges financial support of the Hungarian National Research, Development and Innovation Office (NKFIH) Grant K-138962. G.B.-R. acknowledges CAPES-PRINT/UNESP Process 88887.310463/2018-00, Project 88887.571156/2020-00. M.A. acknowledges financial support from CNPq grants with numbers 427700/2018-3,310683/2017-3,473002/2013-2, and FAPERJ grant no. E-26/111.488/2013. F.B.-R. acknowledges financial support from CNPq grant n° 314772/2020-0. J.I.B.C. acknowledges financial support from CNPq grants with numbers 308150/2016-3 and 305917/2019-6. R.V.-M. acknowledges financial support from CNPq grants with numbers 304544/2017-5, and 401903/2016-8. B.M. acknowledges financial support from CNPq grant no. 150612/2020-6. A.R.-G.-J. acknowledges financial support from FAPESP grant no. 2018/11239-8. J.M.T.-R. research was supported by the research Grant No. PGC2018-097374-B-I00, which is funded by FEDER/Ministerio de Ciencia e Innovación, Agencia Estatal de Investigación. This study was partly financed by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001 and the National Institute of Science and Technology of the e-Universe project (INCT do e-Universo, CNPq grant 465376/2014-2). We acknowledge financial support by the Spanish grant AYA-2017-84637-R, and the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709)”. This research has been partially funded by the Junta de Andalucía PY20_01309 and Agencia Estatal de Investigatión PID2020-112789GB-I00 projects. This research is partially based on observations collected at the Centro Astronómico Hispano-Alemán (CAHA) at Calar Alto, operated jointly by Junta de Andalucía and Consejo Superior de Investigaciones Científicas (IAA-CSIC). This research is partially based on observation carried out at the Observatorio de Sierra Nevada (OSN) operated by Instituto de Astrofísica de Andalucía (CSIC) and the Excalibur telescope at the Observatorio Astrofísico de Javalambre in Teruel, a Spanish Infraestructura Cientifico-Técnica Singular (ICTS) owned, managed and operated by the Centro de Estudios de Física del Cosmos de Aragón (CEFCA). Excalibur is funded with the Fondos de Inversiones de Teruel (FITE). This worked was partially carried out with observations from the Joan Oró Telescope (TJO) of the Montsec Observatory (OdM), which is owned by the Catalan Government and operated by the Institute for Space Studies of Catalonia (IEEC).With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S).Peer reviewe

Three-dimensional culture of human meniscal cells: Extracellular matrix and proteoglycan production

<p>Abstract</p> <p>Background</p> <p>The meniscus is a complex tissue whose cell biology has only recently begun to be explored. Published models rely upon initial culture in the presence of added growth factors. The aim of this study was to test a three-dimensional (3D) collagen sponge microenvironment (without added growth factors) for its ability to provide a microenvironment supportive for meniscal cell extracellular matrix (ECM) production, and to test the responsiveness of cells cultured in this manner to transforming growth factor-β (TGF-β).</p> <p>Methods</p> <p>Experimental studies were approved prospectively by the authors' Human Subjects Institutional Review Board. Human meniscal cells were isolated from surgical specimens, established in monolayer culture, seeded into a 3D scaffold, and cell morphology and extracellular matrix components (ECM) evaluated either under control condition or with addition of TGF-β. Outcome variables were evaluation of cultured cell morphology, quantitative measurement of total sulfated proteoglycan production, and immunohistochemical study of the ECM components chondroitin sulfate, keratan sulfate, and types I and II collagen.</p> <p>Result and Conclusion</p> <p>Meniscal cells attached well within the 3D microenvironment and expanded with culture time. The 3D microenvironment was permissive for production of chondroitin sulfate, types I and II collagen, and to a lesser degree keratan sulfate. This microenvironment was also permissive for growth factor responsiveness, as indicated by a significant increase in proteoglycan production when cells were exposed to TGF-β (2.48 μg/ml ± 1.00, mean ± S.D., vs control levels of 1.58 ± 0.79, p < 0.0001). Knowledge of how culture microenvironments influence meniscal cell ECM production is important; the collagen sponge culture methodology provides a useful in vitro tool for study of meniscal cell biology.</p

The stellar occultation by (319) Leona on 2023 September 13 in preparation for the occultation of Betelgeuse

J. L. Ortiz et al.On 2023 December 12, the star α Orionis will be occulted by asteroid (319) Leona. This represents an extraordinary and unique opportunity to analyse the brightness distribution of Betelgeuse’s photosphere with extreme angular resolution by studying light curves from different points on Earth and at different wavelengths. Here we present observations of another occultation by asteroid Leona, on 2023 September 13, whose goal was to determine Leona’s projected shape and size in preparation for the December 12th event and its interpretation. The occultation campaign was highly successful with 25 positive detections from 17 different sites and a near miss. The effective diameter in projected area derived from the positive detections was 66 ± 2 km using an elliptical fit to the instantaneous limb. The body is highly elongated, with dimensions of 79.6 ± 2.2 km × 54.8 ± 1.3 km in its long and short axis, respectively, at occultation time. This result, in combination with dense time series photometry of Leona that we recently obtained, together with archival sparse photometry, allowed us to predict the angular size of the asteroid for the Betelgeuse event and to simulate the expected brightness change. Also, an accurate position coming from the occultation is provided, to improve the orbit of Leona.Part of this work was supported by the Spanish projects PID2020-112789GB-I00 from AEI and Proyecto de Excelencia de la Junta de Andalucía PY20-01309. Financial support from the grant CEX2021-001131-S funded by MCIN/AEI/ 10.13039/501100011033 is also acknowledged. MS-G acknowledges the financial support from the Planetary Society via its ‘2023 Gene Shoemaker NEO Grant’. JM and PLLE are supported by grant PID2019-105510GB-C32/AEI/10.13039/501100011033 from the State Agency for Research of the Spanish Ministry of Science and Innovation. They also acknowledge support by Consejería de Economía, Innovación, Ciencia y Empleo of Junta de Andalucía as research group FQM- 322, as well as FEDER funds. PS-S acknowledges financial support from the Spanish I+D + i project PID2022-139555NB-I00 funded by MCIN/AEI/10.13039/501100011033. JLR acknowledges financial support by MCIN/AEI/10.13039/501100011033 and by the European Union NextGenerationEU/PRTR. We thank M. Pugnaire for observing support at Los Coloraos observatory. AR and SA acknowledge the financial support through the Europlanet Society Public Engagement Funding Scheme 2023, sponsored by the ‘Dill Faulkes Educational Trust’. This article is partly based on observations made in the Observatorios de Canarias of IAC with the Liverpool Telescope operated on the island of La Palma by the Liverpool JMU in the Observatorio del Roque de los Muchachos. This article includes observations made in the Two-metre Twin Telescope (TTT) in the Teide Observatory of the IAC, that Light Bridges operates in the Island of Tenerife, Canary Islands (Spain). The Observing Time Rights (DTO) used for this research were provided by IAC. This article includes observations made with TRAPPIST telescopes. TRAPPIST is a project funded by the Belgian Fonds (National) de la Recherche Scientifique (F.R.S.-FNRS) under grant PDR T.0120.21. TRAPPIST-North is a project funded by the University of Liége, in collaboration with the Cadi Ayyad University of Marrakech (Morocco). EJ is a F.R.S.-FNRS Senior Research Associate. FLR thanks the National Institute of Science and Technology of the e-Universe project (INCT do e-Universo) granted by CNPq grant number 465376/2014-2. PJG acknowledges financial support from project PID2021-126365NB-C21 (MCI/AEI/FEDER, UE).With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S).Peer reviewe

Coaching Models of School-Based Prevention and Promotion Programmes: A Qualitative Exploration of UK Teachers' Perceptions

There has been increased interest in recent years regarding the utility of imported universal prevention and promotion (P&P) programmes in UK schools, many of which have a coaching model attached. However, there have been relatively few studies exploring the cultural transferability and social validity of these models, even though evidence suggests that these factors are important to the successful implementation of the programmes, and thus the achievement of the intended outcomes. The aim of the current study was to explore the coaching practices that teachers report experiencing, and to further understanding of the perceived benefts of these coaching practices to teachers. The sample consisted of 33 teachers implementing one of two universal, school-based P&P programmes, Good Behavior Game and Promoting Alternative Thinking Strategies as part of large-scale, randomised controlled trials. Qualitative, semi-structured interviews were conducted, and data were analysed thematically utilising a hybrid approach. Teachers typically reported engaging in six distinct practices with their coaches. While the majority of these practices were in line with coaching literature, there were some discrepancies between intended coaching practices and teachers’ reports. The coaching practices were generally perceived to be acceptable to teachers. Two unanticipated practices, validation and motivation, appeared to be of particular value to teachers, although these are not currently a prominent feature in existing coaching models. The fndings provide implications for improving the development of socially valid coaching models for UK schools