Tailored freestanding multilayered membranes based on chitosan and alginate

Engineering metabolically demanding tissues requires the supply of nutrients, oxygen, and removal of metabolic byproducts, as well as adequate mechanical properties. In this work, we propose the development of chitosan (CHIT)/alginate (ALG) freestanding membranes fabricated by layer-by-layer (LbL) assembly. CHIT/ALG membranes were cross-linked with genipin at a concentration of 1 mg· mL−1 or 5 mg·mL−1. Mass transport properties of glucose and oxygen were evaluated on the freestanding membranes. The diffusion of glucose and oxygen decreases with increasing cross-linking concentration. Mechanical properties were also evaluated in physiological-simulated conditions. Increasing cross-linking density leads to an increase of storage modulus, Young modulus, and ultimate tensile strength, but to a decrease in the maximum hydrostatic pressure. The in vitro biological performance demonstrates that cross-linked films are more favorable for cell adhesion. This work demonstrates the versatility and feasibility of LbL assembly to generate nanostructured constructs with tunable permeability, mechanical, and biological properties.The authors acknowledge the financial support by the Portuguese Foundation for Science and Technology (FCT) through the doctoral and Postdoctoral grants with the reference numbers SFRH/BD/81372/2011 (JMS) and SFRH/BPD/96797/2013 (SGC), respectively. This work was financially supported by the FCT, by the project PTDC/FIS/115048/2009, and by the European Commission/FP7 programme (ERC Starting Grant, GA 259370 to C.P.). The authors would also like to acknowledge the project novel smart and biomimetic materials for innovative regenerative medicine approaches (ref.: RL1 - ABMR - NORTE-01-0124-FEDER-000016) cofinanced by the North Portugal Regional Operational Programme (ON.2 0 Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF)

Study of flavor dependence of the baryon-to-meson ratio in proton-proton collisions at s=13 TeV

The production cross sections of D0 and Λ+c hadrons originating from beauty-hadron decays (i.e., nonprompt) were measured for the first time at midrapidity (|y|<0.5) by the ALICE Collaboration in proton-proton collisions at a center-of-mass energy √s=13 TeV. They are described within uncertainties by perturbative QCD calculations employing the fragmentation fractions of beauty quarks to baryons measured at forward rapidity by the LHCb Collaboration. The b ̄b production cross section per unit of rapidity at midrapidity, estimated from these measurements, is dσb ̄b/dy||y|<0.5=83.1±3.5(stat)±5.4(syst)+12.3−3.2(extrap) μb. The baryon-to-meson ratios are computed to investigate the hadronization mechanism of beauty quarks. The nonprompt Λ+c/D0 production ratio has a similar trend to the one measured for the promptly produced charmed particles and to the p/π+ and Λ/K0S ratios, suggesting a similar baryon-formation mechanism among light, strange, charm, and beauty hadrons. The pT -integrated nonprompt Λ+c/D0 ratio is found to be significantly higher than the one measured in e+e− collisions

Energy dependence of coherent photonuclear production of J/ψ mesons in ultra-peripheral Pb-Pb collisions at s NN sNN \sqrt{{\textrm{s}}_{\textrm{NN}}} = 5.02 TeV

Abstract The cross section for coherent photonuclear production of J/ψ is presented as a function of the electromagnetic dissociation (EMD) of Pb. The measurement is performed with the ALICE detector in ultra-peripheral Pb-Pb collisions at a centre-of-mass energy per nucleon pair of s NN $$\sqrt{{\textrm{s}}_{\textrm{NN}}}$$ = 5.02 TeV. Cross sections are presented in five different J/ψ rapidity ranges within |y| < 4, with the J/ψ reconstructed via its dilepton decay channels. In some events the J/ψ is not accompanied by EMD, while other events do produce neutrons from EMD at beam rapidities either in one or the other beam direction, or in both. The cross sections in a given rapidity range and for different configurations of neutrons from EMD allow for the extraction of the energy dependence of this process in the range 17 < W γ Pb,n < 920 GeV, where W γ Pb,n is the centre-of-mass energy per nucleon of the γPb system. This range corresponds to a Bjorken-x interval spanning about three orders of magnitude: 1.1 × 10 −5 < x < 3.3 × 10 −2. In addition to the ultra-peripheral and photonuclear cross sections, the nuclear suppression factor is obtained. These measurements point to a strong depletion of the gluon distribution in Pb nuclei over a broad, previously unexplored, energy range. These results, together with previous ALICE measurements, provide unprecedented information to probe quantum chromodynamics at high energies

Inclusive photon production at forward rapidities in pp and p–Pb collisions at sNN=5.02\sqrt{{{s}}_{\textrm{NN}}}={5.02} s NN = 5.02 TeV

Abstract A study of multiplicity and pseudorapidity distributions of inclusive photons measured in pp and p–Pb collisions at a center-of-mass energy per nucleon–nucleon collision of $$\sqrt{s_{\textrm{NN}}}~=~5.02$$ s NN = 5.02  TeV using the ALICE detector in the forward pseudorapidity region 2.3  $$<~\eta _\textrm{lab} ~<$$ < η lab <  3.9 is presented. Measurements in p–Pb collisions are reported for two beam configurations in which the directions of the proton and lead ion beam were reversed. The pseudorapidity distributions in p–Pb collisions are obtained for seven centrality classes which are defined based on different event activity estimators, i.e., the charged-particle multiplicity measured at midrapidity as well as the energy deposited in a calorimeter at beam rapidity. The inclusive photon multiplicity distributions for both pp and p–Pb collisions are described by double negative binomial distributions. The pseudorapidity distributions of inclusive photons are compared to those of charged particles at midrapidity in pp collisions and for different centrality classes in p–Pb collisions. The results are compared to predictions from various Monte Carlo event generators. None of the generators considered in this paper reproduces the inclusive photon multiplicity distributions in the reported multiplicity range. The pseudorapidity distributions are, however, better described by the same generators