Spatial and temporal spectra of noise driven stripe patterns

Spatial and temporal noise power spectra of stripe patterns are investigated, using as a model a Swift-Hohenberg equation with a stochastic term. In particular, the analytical and numerical investigations show: 1) the temporal noise spectra are of 1/f^alpha form, where alpha=1+(3-D)/4 with D the spatial dimension of the system; 2) that the stochastic fluctuations of the stripe position are sub-diffusive.Comment: Submitted to PR

Local deformation in a hydrogel induced by an external magnetic field

The aim of this study is to prove the feasibility of a system able to apply local mechanical loading on cells seeded in a hydrogel for tissue engineering applications. This experimental study is based on a previously developed artificial cartilage model with different concentrations of poly(vinyl alcohol) (PVA) that simulates the cartilage extracellular matrix (ECM). Poly(l-lactic acid) (PLLA) microspheres with dispersed magnetic nanoparticles (MNPs) were produced with an emulsion method. These microspheres were embedded in aqueous PVA solutions with varying concentration to resemble increased viscosity of growing tissue during regeneration. The ability to induce a local deformation in the ECM was assessed by applying a steady or an oscillatory magnetic field gradient to different PVA solutions containing the magnetic microparticles, similarly as in ferrogels. PLLA microparticle motion was recorded, and the images were analyzed. Besides, PVA gels and PLLA microparticles were introduced into the pores of a polycaprolactone scaffold, and the microparticle distribution and the mechanical properties of the construct were evaluated. The results of this experimental model show that the dispersion of PLLA microparticles containing MNPs, together with cells in a supporting gel, will allow applying local mechanical stimuli to cells during tissue regeneration. This local stimulation can have a positive effect on the differentiation of seeded cells and improve tissue regeneration.The authors gratefully acknowledge the financial support from the Spanish Ministry of Economy and Competitiveness through the MAT2013-46467-C4-1-R project, including the Feder funds. CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program. CIBER Actions are financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund. The authors thank "Servicio de Microscopia Electronica" of Universitat Politecnica de Valencia for their invaluable help. The translation of this paper was funded by the Universitat Politecnica de Valencia, Spain.Vikingsson, L.; Vinals Guitart, Á.; Valera Martínez, A.; Riera Guasp, J.; Vidaurre Garayo, AJ.; Gallego Ferrer, G.; Gómez Ribelles, JL. (2016). Local deformation in a hydrogel induced by an external magnetic field. Journal of Materials Science. 51(22):9979-9990. https://doi.org/10.1007/s10853-016-0226-8S997999905122Eyre D (2002) Collagen of articular cartilage. Arthritis Res 4:30–35Roughley PJ, Lee ER (1994) Cartilage proteoglycans: structure and potential functions. Microsc Res Tech 28:385–397Gillard GC, Reilly HC, Bell-Booth PG, Flint MH (1979) The influence of mechanical forces on the glycosaminoglycan content of the rabbit flexor digitorum profundus tendon. Connect Tissue Res 7:37–46Quinn TM, Grodzinsky AJ, Buschmann MD, Kim YJ, Hunziker EB (1998) Mechanical compression alters proteoglycan deposition and matrix deformation around individual cells in cartilage explants. J Cell Sci 111:573–583Banes AJ, Tsuzaki M, Yamamoto J, Fischer T, Brigman B, Brown T, Miller L (1995) Mechanoreception at the cellular level: the detection, interpretation, and diversity of responses to mechanical signals. Biochem Cell Biol 73:349–365Appelman T, Mizrahi J, Elisseeff J, Seliktar D (2011) The influence of biological motifs and dynamic mechanical stimulation in hydrogel scaffold systems on the phenotype of chondrocytes. Biomaterials 32:1508–1516Mow VC, Ratcliffe A, Poole AR (1992) Cartilage and diarthrodial joints as paradigms for hierarchical materials and structures. Biomaterials 13:67–97Mow VC, Huiskes R (2005) Basic orthopaedic biomechanics and mechano-biology. Lippincott Williams and Wilkins, PhiladelphiaBrady MA, Waldman SD, Ethier CR (2015) The application of multiple biophysical cues to engineer functional neocartilage for treatment of osteoarthritis. Part I: cellular response. Tissue Eng Part B Rev 21:1–19Valhmu WB, Stazzone EJ, Bachrach NM, Saed-Nejad F, Fischer SG, Mow VC, Ratcliffe A (1998) Load-controlled compression of articular cartilage induces a transient stimulation of aggrecan gene expression. Arch Biochem Biophys 353:29–36Ingber DE (1997) Tensegrity: the architectural basis of cellular mechanotransduction. Ann Rev Physiol 59:575–599Khan S, Sheetz MP (1997) Force effects on biochemical kinetics. Ann Rev Biochem 66:785–805Hutmacher DW (2000) Scaffolds in tissue engineering bone and cartilage. Biomaterials 21:2529–2543Crick FHC, Hughes AFW (1950) The physical properties of cytoplasm: a study by means of the magnetic particle method. Exp Cell Res 1:37–80Valberg PA, Albertini DF (1985) Cytoplasmic motions, rheology, and structure probed by a novel magnetic particle method. J Cell Biol 101:130–140Valberg PA, Feldman HA (1987) Magnetic particle motions within living cells. Measurement of cytoplasmic viscosity and motile activity. Biophys J 52:551–561Wang N, Ingber DE (1995) Probing transmembrane mechanical coupling and cytomechanics using magnetic twisting cytometry. Biochem Cell Biol 73:327–335Pommerenke H, Schreiber E, Durr F, Nebe B, Hahnel C, Moller W, Rychly J (1996) Stimulation of integrin receptors using a magnetic drag force device induces an intracellular free calcium response. Eur J Cell Biol 70:157–164Bausch AR, Hellerer U, Essler M, Aepfelbacher M, Sackmann E (2001) Rapid stiffening of integrin receptor-actin linkages in endothelial cells stimulated with thrombin: a magnetic bead microrheology study. Biophys J 80:2649–2657Li L, Yang G, Li J, Ding S, Zhou S (2014) Cell behaviors on magnetic electrospun poly-d, l-lactide nano fibers. Mater Sci Eng, C 34:252–261Fuhrer R, Hofmann S, Hild N, Vetsch JR, Herrmann IK, Grass RN, Stark WJ (2013) Pressureless mechanical induction of stem cell differentiation is dose and frequency dependent. PLoS One 8:e81362Cezar CA, Roche ET, Vandenburgh HH, Duda GN, Walsh CJ, Mooney DJ (2016) Biologic-free mechanically induced muscle regeneration. Proc Natl Acad Sci USA 113:1534–1539Vikingsson L, Gallego Ferrer G, Gómez-Tejedor JA, Gómez Ribelles JL (2014) An in vitro experimental model to predict the mechanical behaviour of macroporous scaffolds implanted in articular cartilage. J Mech Behav Biomed Mater 32:125–131Vikingsson L, Gomez-Tejedor JA, Gallego Ferrer G, Gomez Ribelles JL (2015) An experimental fatigue study of a porous scaffold for the regeneration of articular cartilage. J Biomech 48:1310–1317Vikingsson L, Claessens B, Gómez-Tejedor JA, Gallego Ferrer G, Gómez Ribelles JL (2015) Relationship between micro-porosity, water permeability and mechanical behavior in scaffolds for cartilage engineering. J Mech Behav Biomed Mater 48:60–69Li F, Su YL, Shi DF, Wang CT (2010) Comparison of human articular cartilage and polyvinyl alcohol hydrogel as artificial cartilage in microstructure analysis and unconfined compression. Adv Mater Res Trans Tech Publ 87:188–193Grant C, Twigg P, Egan A, Moody A, Eagland D, Crowther N, Britland S (2006) Poly(vinyl alcohol) hydrogel as a biocompatible viscoelastic mimetic for articular cartilage. Biotechnol Prog 22:1400–1406Weeber R, Kantorovich S, Holm C (2015) Ferrogels cross-linked by magnetic nanoparticles—Deformation mechanisms in two and three dimensions studied by means of computer simulations. J Magn Magn Mater 383:262–266Lebourg M, Suay Antón J, Gómez Ribelles JL (2008) Porous membranes of PLLA–PCL blend for tissue engineering applications. Eur Polym J 44:2207–2218Santamaría VA, Deplaine H, Mariggió D, Villanueva-Molines AR, García-Aznar JM, Gómez Ribelles JL, Doblaré M, Gallego Ferrer G, Ochoa I (2012) Influence of the macro and micro-porous structure on the mechanical behavior of poly (l-lactic acid) scaffolds. J Non Cryst Solids 358:3141–3149Panadero JA, Vikingsson L, Gomez Ribelles JL, Lanceros-Mendez S, Sencadas V (2015) In vitro mechanical fatigue behaviour of poly-ε-caprolactone macroporous scaffolds for cartilage tissue engineering. Influence of pore filling by a poly(vinyl alcohol) gel. J Biomed Mater Res Part B Appl Biomater 103:1037–1043Hassan CM, Peppas NA (2000) Structure and applications of poly(vinyl alcohol) hydrogels produced by conventional crosslinking or by freezing/thawing methods. Adv Polym Sci 153:37–65Labet M, Thielemans W (2009) Synthesis of polycaprolactone: a review. Chem Soc Rev 38:3484–3504Mano JF, Gómez Ribelles JL, Alves NM, Salmerón Sanchez M (2005) Glass transition dynamics and structural relaxation of PLLA studied by DSC: influence of crystallinity. Polymer 46:8258–8265Eckstein F, Lemberger B, Gratzke C, Hudelmaier M, Glaser C, Englmeier KH, Reiser M (2005) In vivo cartilage deformation after different types of activity and its dependence on physical training status. Ann Rheum Dis 64:291–295Garlotta D (2001) A literature review of poly(lactic acid). J Polym Eng 9:63–84Kovacs AJ, Aklonis JJ, Hutchinson JM, Ramos AR (1979) Isobaric volume and enthalpy recovery of glasses. II. A transparent multiparameter theory. J Polym Sci Polym Phys 17:1097–1162Hernández F, Molina Mateo J, Romero Colomer F, Salmerón Sánchez M, Gómez Ribelles JL, Mano J (2005) Influence of low-temperature nucleation on the crystallization process of poly(l-lactide). 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Coulomb excitation of 222Rn

The nature of quadrupole and octupole collectivity in 222Rn was investigated by determining the electricquadrupole (E2) and octupole (E3) matrix elements using subbarrier, multistep Coulomb excitation. The radioactive 222Rn beam, accelerated to 4.23 MeV/u, was provided by the HIE-ISOLDE facility at CERN. Data were collected in the Miniball gamma -ray spectrometer following the bombardment of two targets, 120Sn and 60Ni. Transition E2 matrix elements within the ground-state and octupole bands were measured up to 10 h over bar and the results were consistent with a constant intrinsic electric-quadrupole moment, 518(11) e fm2. The values of the intrinsic electric-octupole moment for the 0+ -> 3- and 2+ -> 5- transitions were found to be respectively -210 e fm3 and 2300+300-500 e fm3 while a smaller value, 1200+500-900 e fm3, was found for the 2+ -> 1- transition. In addition, four excited non-yrast states were identified in this work via gamma -gamma coincidences.Peer reviewe

First beta-decay spectroscopy of In-135 and new beta-decay branches of In-134

The beta decay of the neutron-rich In-134 and In-135 was investigated experimentally in order to provide new insights into the nuclear structure of the tin isotopes with magic proton number Z = 50 above the N = 82 shell. The beta-delayed gamma-ray spectroscopy measurement was performed at the ISOLDE facility at CERN, where indium isotopes were selectively laser-ionized and on-line mass separated. Three beta-decay branches of In-134 were established, two of which were observed for the first time. Population of neutron-unbound states decaying via. rays was identified in the two daughter nuclei of In-134, Sn-134 and Sn-133, at excitation energies exceeding the neutron separation energy by 1 MeV. The beta-delayed one- and two-neutron emission branching ratios of In-134 were determined and compared with theoretical calculations. The beta-delayed one-neutron decay was observed to be dominant beta-decay branch of In-134 even though the Gamow-Teller resonance is located substantially above the two-neutron separation energy of Sn-134. Transitions following the beta decay of In-135 are reported for the first time, including. rays tentatively attributed to Sn-135. In total, six new levels were identified in Sn-134 on the basis of the beta.. coincidences observed in the In-134 and In-135 beta decays. A transition that might be a candidate for deexciting the missing neutron single-particle 13/2(+) state in Sn-133 was observed in both beta decays and its assignment is discussed. Experimental level schemes of Sn-134 and Sn-135 are compared with shell-model predictions. Using the fast timing technique, half-lives of the 2(+), 4(+), and 6(+) levels in Sn-134 were determined. From the lifetime of the 4(+) state measured for the first time, an unexpectedly large B(E2; 4(+)-> 2(+)) transition strength was deduced, which is not reproduced by the shell-model calculations.Peer reviewe

Competition between allowed and first-forbidden β decays of at 208 and expansion of the Po 208 level scheme

The structure of Po208 populated through the EC/β+ decay of At208 is investigated using γ-ray spectroscopy at the ISOLDE Decay Station. The presented level scheme contains 27 new excited states and 43 new transitions, as well as a further 50 previously observed γ rays which have been (re)assigned a position. The level scheme is compared to shell model calculations. Through this analysis approximately half of the β-decay strength of At208 is found to proceed via allowed decay and half via first-forbidden decay. The first-forbidden transitions predominantly populate core excited states at high excitation energies, which is qualitatively understood using shell model considerations. This mass region provides an excellent testing ground for the competition between allowed and first-forbidden β-decay calculations, important for the detailed understanding of the nucleosynthesis of heavy elements

208Po populated through EC/β+decay

The structure of 208Po resulting from the EC/β + decay of 208At was studied at CERN’s ISOLDE Decay Station (IDS). The high statistics afforded by the high yield of 208At and the high efficiency HPGe clusters at the IDS allowed for greater insight into lower intensity transitions and thus significant expansion of the 208Po level scheme. Furthermore, investigation into the isomeric state yielded a new half life 377(9) ns in addition to uncovering new transitions populating the state.The research leading to these results has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 654002. As well as the Science and Technology Facilities Council (UK) through grants ST/P005314/1, ST/L005743/1, ST/J000051/1, ST/L005670/1, and ST/P004598/1 and (PHR) by the UK Department of Business, Energy and Industrial Strategy (BEIS) via the National Measurement System. Further funding was provided by the German BMBF under contract 05P18PKCIA and ”Verbundprojekt 05P2018” as well as the Spanish MINECO grant FPA2015-65035-P.Peer reviewe

Receptor Complementation and Mutagenesis Reveal SR-BI as an Essential HCV Entry Factor and Functionally Imply Its Intra- and Extra-Cellular Domains

HCV entry into cells is a multi-step and slow process. It is believed that the initial capture of HCV particles by glycosaminoglycans and/or lipoprotein receptors is followed by coordinated interactions with the scavenger receptor class B type I (SR-BI), a major receptor of high-density lipoprotein (HDL), the CD81 tetraspanin, and the tight junction protein Claudin-1, ultimately leading to uptake and cellular penetration of HCV via low-pH endosomes. Several reports have indicated that HDL promotes HCV entry through interaction with SR-BI. This pathway remains largely elusive, although it was shown that HDL neither associates with HCV particles nor modulates HCV binding to SR-BI. In contrast to CD81 and Claudin-1, the importance of SR-BI has only been addressed indirectly because of lack of cells in which functional complementation assays with mutant receptors could be performed. Here we identified for the first time two cell types that supported HCVpp and HCVcc entry upon ectopic SR-BI expression. Remarkably, the undetectable expression of SR-BI in rat hepatoma cells allowed unambiguous investigation of human SR-BI functions during HCV entry. By expressing different SR-BI mutants in either cell line, our results revealed features of SR-BI intracellular domains that influence HCV infectivity without affecting receptor binding and stimulation of HCV entry induced by HDL/SR-BI interaction. Conversely, we identified positions of SR-BI ectodomain that, by altering HCV binding, inhibit entry. Finally, we characterized alternative ectodomain determinants that, by reducing SR-BI cholesterol uptake and efflux functions, abolish HDL-mediated infection-enhancement. Altogether, we demonstrate that SR-BI is an essential HCV entry factor. Moreover, our results highlight specific SR-BI determinants required during HCV entry and physiological lipid transfer functions hijacked by HCV to favor infection

Carbon Dioxide Utilisation -The Formate Route

UIDB/50006/2020 CEEC-Individual 2017 Program Contract.The relentless rise of atmospheric CO2 is causing large and unpredictable impacts on the Earth climate, due to the CO2 significant greenhouse effect, besides being responsible for the ocean acidification, with consequent huge impacts in our daily lives and in all forms of life. To stop spiral of destruction, we must actively reduce the CO2 emissions and develop new and more efficient “CO2 sinks”. We should be focused on the opportunities provided by exploiting this novel and huge carbon feedstock to produce de novo fuels and added-value compounds. The conversion of CO2 into formate offers key advantages for carbon recycling, and formate dehydrogenase (FDH) enzymes are at the centre of intense research, due to the “green” advantages the bioconversion can offer, namely substrate and product selectivity and specificity, in reactions run at ambient temperature and pressure and neutral pH. In this chapter, we describe the remarkable recent progress towards efficient and selective FDH-catalysed CO2 reduction to formate. We focus on the enzymes, discussing their structure and mechanism of action. Selected promising studies and successful proof of concepts of FDH-dependent CO2 reduction to formate and beyond are discussed, to highlight the power of FDHs and the challenges this CO2 bioconversion still faces.publishersversionpublishe

Inborn errors of OAS-RNase L in SARS-CoV-2-related multisystem inflammatory syndrome in children

Multisystem inflammatory syndrome in children (MIS-C) is a rare and severe condition that follows benign COVID-19. We report autosomal recessive deficiencies of OAS1, OAS2, or RNASEL in five unrelated children with MIS-C. The cytosolic double-stranded RNA (dsRNA)-sensing OAS1 and OAS2 generate 2'-5'-linked oligoadenylates (2-5A) that activate the single-stranded RNA-degrading ribonuclease L (RNase L). Monocytic cell lines and primary myeloid cells with OAS1, OAS2, or RNase L deficiencies produce excessive amounts of inflammatory cytokines upon dsRNA or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) stimulation. Exogenous 2-5A suppresses cytokine production in OAS1-deficient but not RNase L-deficient cells. Cytokine production in RNase L-deficient cells is impaired by MDA5 or RIG-I deficiency and abolished by mitochondrial antiviral-signaling protein (MAVS) deficiency. Recessive OAS-RNase L deficiencies in these patients unleash the production of SARS-CoV-2-triggered, MAVS-mediated inflammatory cytokines by mononuclear phagocytes, thereby underlying MIS-C

New ß-decaying state in 214Bi

A new β-decaying state in 214Bi has been identified at the ISOLDE Decay Station at the CERN-ISOLDE facility. A preferred Iπ = (8−) assignment was suggested for this state based on the β-decay feeding pattern to levels in 214Po and shell-model calculations. The half-life of the Iπ = (8−) state was deduced to be T1/2 = 9.39(10) min. The deexcitation of the levels populated in 214Po by the β decay of this state was investigated via γ -γ coincidences and a number of new levels and transitions was identified. Shell-model calculations for excited states in 214Bi and 214Po were performed using two different effective interactions: the H208 and the modified Kuo-Herling particle interaction. Both calculations agree on the interpretation of the new β-decaying state as an Iπ = 8− isomer and allow for tentative assignment of shell-model states to several high-spin states in 214Po.peerReviewe