First-order phase transition in a 2D random-field Ising model with conflicting dynamics

The effects of locally random magnetic fields are considered in a nonequilibrium Ising model defined on a square lattice with nearest-neighbors interactions. In order to generate the random magnetic fields, we have considered random variables $\{h\}$ that change randomly with time according to a double-gaussian probability distribution, which consists of two single gaussian distributions, centered at $+h_{o}$ and $-h_{o}$, with the same width $\sigma$. This distribution is very general, and can recover in appropriate limits the bimodal distribution ($\sigma\to 0$) and the single gaussian one ($ho=0$). We performed Monte Carlo simulations in lattices with linear sizes in the range $L=32 - 512$. The system exhibits ferromagnetic and paramagnetic steady states. Our results suggest the occurence of first-order phase transitions between the above-mentioned phases at low temperatures and large random-field intensities $h_{o}$, for some small values of the width $\sigma$. By means of finite size scaling, we estimate the critical exponents in the low-field region, where we have continuous phase transitions. In addition, we show a sketch of the phase diagram of the model for some values of $\sigma$.Comment: 13 pages, 9 figures, accepted for publication in JSTA

Fatigue and functional capacity post COVID-19

Background: We explored if fatigue influenced the long-term functional capacity of patients post COVID-19. Methods: People after COVID -19, grouped by treatment setting (home - H, hospital ward - HW or intensive care unit – ICU), were studied 12 months after discharge. Fatigue-Functional Chronic Illness Assessment Questionnaire Fatigue Subscale, FACIT-F and functional capacity-6min walk test, 6MWD and 1min sit-to-stand test, 1minSTS were assessed. Groups were compared with one-way ANOVA or Kruskal-Wallis H test. Spearman’s ρ and multiple regression analyses were performed between fatigue-functional tests. Results: 148 subjects (H, n=44; HW, n=60; ICU, n=44) participated. Fatigue was clinically relevant at 12 months although not significantly different among groups [H: 41(35-49); HW: 42(33-50); ICU; 42(32-48) points; p=.979). Functional capacity was significantly higher in those treated at home (6MWD: H,626 114m, HW: 527 146m, ICU: 528 129m, p<.001; 1minSTS: H,29 11reps, HW: 23 8reps, ICU: 24 8reps, p<.002). Fatigue was significantly correlated with functional tests within each group (FACIT-F-6MWD,.317<ρ≤.550, p<.01; FACIT-F-1minSTS, .364<ρ≤.485, p<.01). Each point of FACIT-F could change 6MWD by 5-6m and 1minSTS by. 3-.5reps, explaining between 12-33% of change in 6MWD and 17-22% of change in 1minSTS (Table 1). Conclusions: Fatigue seems to influence functional capacity of patients post COVID-19. Early management of this symptom seems important for their long-term management.publishe

Development and characterization of an injectable dextrin-based hydrogel for bone regeneration

Bone is a dynamic, highly vascularized tissue that remodels itself continuously over an individual ́s lifetime. It plays several important roles in maintaining homeostasis of the body systems [ 1 , 2 ] . However, this regenerative capac ity is limited and, as in the case of large bone defects, where the template for an orchestrated regeneration is absent, surgical proce dures are needed [ 2 ] . In this respect , bone tissue engineering is a very challe nging and promising field given the need to mimic bone mechanical and biological functions and also due to the failure of current orthoped ic implants. The general concept consists in the development of three - dimensional scaffolds, from biocompatible materials (natu ral or synthetic), which confer temporary support for the regeneration of bone tissue, while the scaffold itself will be resorbed and replaced by new ly formed tissue [ 2 , 3 ] . Hydrogels are cross - linked networks made of natural or synthetic polymers, which are able to support high water contents [ 4 ] . These materials are usua lly biocompatible, have the ability to mimic physiological conditions, promote an environment that can protect cells or unstable drugs, their physical characteristics can be controlled to some extent and some can be injected in vivo . These features make th em attractive materials in the biomedical field for cell encapsulation, drug or gene delivery or to act as an interfa ce between tissue and materials [ 4 - 7 ] . Natural polymers are advantageous for this kind of applications since they are cheap raw materials, bear a great biocompatibility and are usually biodegradable [ 8 ] . Dextrin is low molecular weight carbohydrate, generally regarded as safe (GRAS), obtained from partial hydrolysis of starch or glycogen [ 9 ] . It is a glucose polymer linked by α - 1,4 glycosidic linkages with some degree of branching due to the presence of α - 1,6 bonds [ 10 ] . I t is biocompatible and non - immunogenic, degradable by α - amylases and can undergo renal clearance avoiding tissue accumulation [ 11 , 12 ] . This work describes the preparation and characterization of an injectable dextrin - bas ed hydrogel (oDex) able to incorporate nanoparticles , cells, biomolecules or Bonelike ® granules [ 13 ] . Bonelike ® is a Biosckin - molecular and cell therapies S.A. proprietary synthetic bone graft, and the outcome of the project will result in a novel injectable presentation of this product. The hydrogel was produced by dextrin oxidation with sodium periodate followed by cross - linking with a dihydrazide [ 14 ] . In vitro characterization of oDex hydrogel has shown acceptable m echanical properties, overall good biocompatibility and the ability to be combined with other materials such as a nanogel and urinary bladder matrix, without affecting its structure. The cytotoxicity of the free dihydrazide was evaluated and only a mild in hibitory effect on cell proliferation was observed for the concentration used in the hydrogel crosslinking. The biocompatibilit y of oDex hydrogels was confirmed through the encapsulation of cells, which were able to endure the gelation process. Subcutaneou s implants were performed in Sasco Sprague Dawley rats in order to evaluate the inflammatory response and systemic effects of oDex hydrogels and their combination with Bonelike ® and human mesenchymal stem cells isolated from umbilical cord’s Wharton jelly. After 3 and 15 days post - implantation, a quantitative evaluation of both responses was performed according to ISO 10993 by a scoring system leading to a classification of the implanted material as s light irritant even when associated to Bonelike ® or to the cellular system. The performance of oDex hydrogel combined with Bonelike granules and/or UBM in bone defects was investigated in New Zealand rabbits. Bone defects in several anatomical locations (t ibiae and cranium) of non - critical and critical size were filled with those materials. Histological analysis showed that oDex does not constitute a barrier for cellular colonization and proliferation since the defects that were filled with these materials presented a higher degree of regeneration and a higher amount of collagen fibers with higher organization degrees, when compared with the empty defects. Even though oDex hydrogels purpose is to act as an injectable carrier for osteoconductive materials, li ke Bonelike ® granules, the hydrogel itself seems to assists the regenerative pro cess when compared with the empty defects. This is due to the 3D supp ort conferred by hydrogels that facilitates cell migration to the defect site. Moreover, the presence of UB M strongly stimulates the bone regeneration, for levels comparable with the Bonelike ® conditions, since an increase in cellular colonization and organization in the defect site can be denoted. A sterilization protocol for oDex hydrogels by gamma and beta r adiation was investigated through irradiation of oxidized dextrin solutions. Despite b oth kinds of radiation induced slight differences in the storage modulus of the hydrogels, indicating the occurrence of chain scission/cross - linking effects on the dextri n cha in, all materials were gelable after the irradiation treatments . These effects seem to not be dose or temperature dependent and the irradiation process in liquid or solid state also does not induce major differences in the rheology of the final hydrog els. Due to its known advantages, gamma radiation seems to be a suitable sterilization method for oxidized dextrin solutions. The stability of gamma irradiated dextrin solutions was evaluated up to 8 months. Despite the increase of storage modulus of the h ydrogels over the time, this effect does not constitute a disadvantage since it improves elastic behavior of the hydrogels. oDex hydrogels provides a system that can carry and stabilize cells, nanogels, Bonelike ® granules and other biomolecules. It is a pr omising biomaterial due to its biocompatibility, and potential to promote an adequate environment for bone regeneration. Its injectability allows a minimal invasive surgical procedure with decreased patient morbidity, lower risk of infection and reduced sc ar formation. This work has been developed in the scope of an European project that allowed collaborations with research groups, which have complementary expertise. The tight collaboration between University of Minho and Bioskin S.A. company, envisioning t echnology transfer and product valorization, has resulted in a published international patent of the product ( WO2011070529A2 ) [ 15 ] . Currently, a new set of pre - clinical trials in sheep model s are being planned as well as the submission of a request for the authorization for the clinical trialsGrant SFRH/BD/64571/2009 from Fundação para a Ciência e Tecnologia (FCT), Portugal. We thank FCT funding through EuroNanoMed ENMED/0002/2

Potential of injectable dextrin-based hydrogel for biomedical applications

Bone tissue engineering is a very challenging and promising field, which handles with the limitations of bone regenerative capacity and the failure of current orthopedic implants [1]. This work describes the preparation and characterization of an injectable dextrinbased hydrogel (oDex) through dextrin oxidation followed by cross-linking with a dihydrazide [2]. In vitro and in vivo experiments allowed to conclude that this system can carry and stabilize cells, nanogels, Bonelike® granules [3] and other biomolecules. This is a promising biomaterial due to its biocompatibility, and potential to promote an adequate environment for bone regeneration, which was increased by the combined bioactive molecules. Its injectability allows a minimal invasive surgical procedure with decreased patient morbidity, lower infection risk and reduced scar formation. Furthermore, an adequate sterilization protocol for this kind of material was established. The tight collaboration between University of Minho and Bioskin S.A. company, envisioning technology transfer and product valorization, has resulted in a published international patent of the product (WO2011070529A2) [4]. Currently, the submission of a request for the authorization for the clinical trials is being planned

Development of a dextrin-based hydrogel for bone regeneration

[Excerpt] Bone tissue engineering is a very challenging and promising field, which handles with the limitations of bone regenerative capacity and the failure of current orthopedic implants [1]. This work describes the preparation and characterization of an injectable dextrin-based hydrogel (oDex) able to incorporate nanoparticles, cells, biomolecules or Bonelike~ granules [2]. (...

High-pressure phase transitions and compressibility of wolframite-type tungstates

This paper reports an investigation on the phase diagram and compressibility of wolframite-type tungstates by means of x-ray powder diffraction and absorption in a diamond-anvil cell and ab initio calculations. X-ray diffraction experiments show that monoclinic wolframite-type MgWO4 suffers at least two phase transitions, the first one being to a triclinic polymorph with a structure similar to that of CuWO4 and FeMoO4-II. The onset of each transition is detected at 17.1 and 31 GPa. In ZnWO4 the onset of the monoclinic-triclinic transition has been also found at 16.7 GPa. This transition does not involve any change in the atomic coordination as confirmed by x-ray absorption measurements. These findings are supported by density-functional theory calculations, which predict the occurrence of additional transitions upon further compression. Calculations have been also performed for wolframite-type MnWO4, which is found to have an antiferromagnetic configuration. In addition, our study reveals details of the local-atomic compression in MgWO4 and ZnWO4. In particular, below the transition pressure the ZnO6 and equivalent polyhedra tend to become more regular, whereas, the WO6 octahedra remain almost unchanged. Fitting the pressure-volume data we obtained the equation of state for the low-pressure phase of MgWO4 and ZnWO4. These and previous results on MnWO4 and CdWO4 are compared with the calculations. The compressibility of wolframite-type tungstates is also systematically discussed. Finally Raman spectroscopy measurements and lattice dynamics calculations are presented for MgWO4

Interleukin-2 as a marker for detecting asymptomatic individuals in areas where Leishmania infantum is endemic.

No field method exists for identifying asymptomatic individuals in areas where Leishmania infantum is endemic. This work reports that, 24 h after stimulating whole blood with soluble Leishmania antigen (SLA), plasma interferon-γ (IFN-γ) and interleukin-2 (IL-2) become significantly elevated in samples from asymptomatic individuals (n=47) compared with those from negative controls (n=50), all of them recruited from a blood bank. When compared with the reference test SLA-lymphoproliferative assay, IL-2 appears as a new, 100% sensitive and specific marker for asymptomatic individuals with a positive cellular response (compared with 100% and 84.78%, respectively, for IFN-γ). Further studies in other transmission areas and in other cohorts of exposed people need to be performed to confirm these results. Once validated, IFN-γ and IL-2 levels in SLA-stimulated whole blood could be reliably used in the field to estimate the prevalence of those asymptomatic individuals with Leishmania-specific cellular immune responses.We gratefully acknowledge the financial support of the Drugs for Neglected Diseases Initiative (DNDi) by the Department for International Development (DFID) , UK and the Swiss Agency for Development and Cooperation (SDC) , Swizerland; and of the Instituto de Salud Carlos III via the Tropical Diseases Research Network ( RICET RD12/0018/ 0003 and RD12/0018/0008 ) (www.ricet.es) and via the ISCIII-AES project ‘ Impact of a leishmaniasis outbreak in the southwest of Madrid in the immunosuppressed population ’ ( PI13/00440 ). EC was supported by a research contract funded via VII PN I+D+I 2013-2016 and FEDER Funds ( RICET RD12/ 0018/0003 ).S

Ising critical behavior of a non-Halmiltonian lattice system

We study steady states in d-dimensional lattice systems that evolve in time by a probabilistic majority rule, which corresponds to the zero-temperature limit of a system with conflicting dynamics. The rule satisfies detailed balance for d=1 but not for d>1. We find numerically nonequilibrium critical points of the Ising class for d=2 and 3