Glass transition of an epoxy resin induced by temperature, pressure and chemical conversion: a configurational entropy rationale

A comparative study is reported on the dynamics of a glass-forming epoxy resin when the glass transition is approached through different paths: cooling, compression, and polymerization. In particular, the influence of temperature, pressure and chemical conversion on the dynamics has been investigated by dielectric spectroscopy. Deep similarities are found in dynamic properties. A unified reading of our experimental results for the structural relaxation time is given in the framework of the Adam-Gibbs theory. The quantitative agreement with the experimental data is remarkable, joined with physical values of the fitting parameters. In particular, the fitting function of the isothermal tau(P) data gives a well reasonable prediction for the molar thermal expansion of the neat system, and the fitting function of the isobaric-isothermal tau(C) data under step- polymerization conforms to the prediction of diverging tau at complete conversion of the system.Comment: 16 pages, 8 figures, from the talk given at the 4th International Discussion Meeting on Relaxations in Complex Systems (IDMRCS), Hersonissos, Helaklion, Crete (Greece), 17-23 June 200

Non-Arrhenius Behavior of Secondary Relaxation in Supercooled Liquids

Dielectric relaxation spectroscopy (1 Hz - 20 GHz) has been performed on supercooled glass-formers from the temperature of glass transition (T_g) up to that of melting. Precise measurements particularly in the frequencies of MHz-order have revealed that the temperature dependences of secondary beta-relaxation times deviate from the Arrhenius relation in well above T_g. Consequently, our results indicate that the beta-process merges into the primary alpha-mode around the melting temperature, and not at the dynamical transition point T which is approximately equal to 1.2 T_g.Comment: 4 pages, 4 figures, revtex

High-performance versatile setup for simultaneous Brillouin-Raman micro-spectroscopy

This is the author accepted manuscript. The final version is available from American Physical Society via the DOI in this record.Brillouin and Raman scattering spectroscopy are established techniques for the nondestructive contactless and label-free readout of mechanical, chemical and structural properties of condensed matter. Brillouin-Raman investigations currently require separate measurements and a site-matched approach to obtain complementary information from a sample. Here we demonstrate a new concept of fully scanning multimodal micro-spectroscopy for simultaneous detection of Brillouin and Raman light scattering in an exceptionally wide spectral range, from fractions of GHz to hundreds of THz. It yields an unprecedented 150 dB contrast, which is especially important for the analysis of opaque or turbid media such as biomedical samples, and spatial resolution on a sub-cellular scale. We report the first applications of this new multimodal method to a range of systems, from a single cell to the fast reaction kinetics of a curing process, and the mechano-chemical mapping of highly scattering biological samples.S. Corezzi acknowledges financial support from MIUR-PRIN (Project No. 2012J8X57P). S. Caponi acknowledges support from PAT (Provincia Autonoma di Trento) (GP/PAT/2012) “Grandi Progetti 2012” Project “MaDEleNA.” P. S., A. M., M. P. acknowledge financial support from Centro Nazionale Trapianti (Project: “Studio di cellule per uso clinico umano, con particolare riferimento a modelli cellulari (liposomi) e linee cellulari in interazione con crioconservanti e con materiali biocompatibili”). L. C. and S. Caponi acknowledge financial support from Consiglio Nazionale delle Ricerche-Istituto Officina dei Materiali. F. P. acnowledges support from the UK Engineering and Physical Sciences Research Council (Grant No. EP/M028739/1 (F. P.)). The authors acknowledge Jacopo Scarponi for valuable help in setting up the hardware and software system for simultaneous Raman and BLS measurements

Carbon nanotubes allow capture of krypton, barium and lead for multichannel biological X-ray fluorescence imaging

The desire to study biology in situ has been aided by many imaging techniques. Among these, X-ray fluorescence (XRF) mapping permits observation of elemental distributions in a multichannel manner. However, XRF imaging is underused, in part, because of the difficulty in interpreting maps without an underlying cellular ‘blueprint’; this could be supplied using contrast agents. Carbon nanotubes (CNTs) can be filled with a wide range of inorganic materials, and thus can be used as ‘contrast agents’ if biologically absent elements are encapsulated. Here we show that sealed single-walled CNTs filled with lead, barium and even krypton can be produced, and externally decorated with peptides to provide affinity for sub-cellular targets. The agents are able to highlight specific organelles in multiplexed XRF mapping, and are, in principle, a general and versatile tool for this, and other modes of biological imaging

Interprofessional Communication Team for Caregivers of Patients Hospitalized in the COVID-19 Wards: Results From an Italian Experience

Background: During the COVID-19 pandemic, emergency restrictions did not allow clinician family meetings and relatives' visits. In Molinette Hospital, a new communication model between healthcare providers and families of COVID-19 affected patients was developed by a team of physicians and psychologists. The study's aims were to investigate caregivers' distress and to analyse their satisfaction with the communications provided. Methods: A cross-sectional study was conducted among caregivers of patients of Molinette Hospital COVID wards. Between April and June 2020, all caregivers were contacted 2 weeks after the patient's discharge/death to assess their satisfaction with the communications received through an online survey. Results: A total of 155 caregivers completed the survey. Caregivers' distress level was found to be higher in women than men (p = 0.048) and in caregivers whose relative died compared to the caregivers whose relative was discharged (p < 0.001). More than 85% of caregivers defined communication “excellent”/“very good”; being male was associated with higher satisfaction levels than women (β = −0.165, p = 0.046). Besides daily communication, 63 caregivers (40.6%) received additional support from a psychologist of the team. Conclusions: To our knowledge, this is the first study presenting, in an emergency, a new model of communication provided by a team of physicians and psychologists, and analyzing satisfaction with it. This model was highly appreciated by caregivers and it limited the discomfort caused by the restrictions on relatives' visits. It would be interesting to further evaluate the possibility of extending a communication model that includes doctors and psychologists in routine clinical practice

TEMPO-oxidized cellulose nanofibril/polyvalent cations hydrogels: a multifaceted view of network interactions and inner structure

In the last years, hydrogels from renewable biopolymers and low-cost row materials are a hot topic for biomedical applications. In this context, cellulose nanofibrils are considered suitable building blocks for the synthesis of many biocompatible products, with a variety of chemical-physical properties. Herein we report a multi-technique and multi-scale study, from the molecular to the nanometric length scale, of the sol-gel transition observed in aqueous solutions of TEMPO-oxidized nano-sized cellulose fibrils (TOCNFs), when in the presence of polyvalent cations (Mg2+ and Ca2+). We combine the data from Small Angle Neutron Scattering (SANS), which provide information about the inner structure of the nanofibril, with those from UV Resonant Raman (UVRR) spectroscopy, which is a sensitive probe of the intra- and inter-molecular interactions in the gel and the liquid state. The transition between the gel and the liquid phases is investigated as a function of the concentration of both TOCNFs and cations, the nature of the latter, and the pH at which the phenomenon is observed. SANS analysis reveals that ion concentration induces an anisotropic swelling in the nanofibrils which, at the same time, become more and more flexible. The nanofibrils flexibility is also dependent on TOCNF concentration and pH value. UVRR allows us to elucidate the structural organization and hydrogen-bonding properties of water in aqueous TOCNF dispersions and gels, showing how water molecules partially lose their typical bulk-like tetrahedral organization when ions are added, and the gel phase is formed

Maternal-foetal attachment independently predicts the quality of maternal-infant bonding and post-partum psychopathology

Purpose: The aim of this study was to evaluate the association of maternal antenatal attachment and post-partum psychopathology, maternal–infant bonding, while checking for antenatal psychopathology, for lifetime psychiatric diagnosis and for the known risk factors for peripartum depression. Methods: One hundred and six women recruited at the first month of pregnancy (T0) were evaluated with the structured interview for DSM-IV TR (SCID-I) to assess the presence of lifetime psychiatric diagnosis and with the Perinatal Depression Predictor Inventory-Revised (PDPI-R), the Edinburgh Postnatal Depression Scale (EPDS), and the State–Trait Anxiety Inventory (STAI). At the sixth month of pregnancy (T1) and at the first month post-partum (T2), all patients were evaluated with the PDPI-R, the EPDS, the STAI, at T1, with the Maternal Antenatal Attachment Scale (MAAS), and at T2 with the Maternal Postnatal Attachment Scale (MPAS). Results: Multivariate regression analyses showed that maternal–foetal attachment was the variable most significantly associated with postnatal symptoms of depression and anxiety and with quality of maternal-infant attachment. The logistic regression analyses showed that antenatal attachment may predict postnatal depressive and anxiety symptoms (respectively, OR: 0.83–IC [0.74 − 0.95], p =.005, OR: 0.88–IC [0.79 − 0.98], p =.02), and the quality of maternal postnatal attachment (OR: 1.17–IC [1.08 − 1.27], p &lt;.001), also after taking into account the known risk factors for perinatal depression, the sociodemographic variables and lifetime psychiatric diagnosis. Conclusion: The quality of maternal–foetal bonding may independently predict the quality of maternal–infant attachment and post-partum depressive and anxiety symptoms. A comprehensive assessment of maternal risk factors for perinatal psychopathology during pregnancy should include the evaluation of antenatal attachment that could be modifiable by specific interventions promoting the quality of maternal bonding

Stacking Interactions and flexibility of human telomeric multimers

G-quadruplexes (G4s) are helical four-stranded structures forming from guanine-rich nucleic acid sequences, which are thought to play a role in cancer development and malignant transformation. Most current studies focus on G4 monomers, yet under suitable and biologically relevant conditions, G4s undergo multimerization. Here, we investigate the stacking interactions and structural features of telomeric G4 multimers by means of a novel low-resolution structural approach that combines small-angle X-ray scattering (SAXS) with extremely coarse-grained (ECG) simulations. The degree of multimerization and the strength of the stacking interaction are quantitatively determined in G4 self-assembled multimers. We show that self-assembly induces a significant polydispersity of the G4 multimers with an exponential distribution of contour lengths, consistent with a step-growth polymerization. On increasing DNA concentration, the strength of the stacking interaction between G4 monomers increases, as well as the average number of units in the aggregates. We utilized the same approach to explore the conformational flexibility of a model single-stranded long telomeric sequence. Our findings indicate that its G4 units frequently adopt a beads-on-a-string configuration. We also observe that the interaction between G4 units can be significantly affected by complexation with benchmark ligands. The proposed methodology, which identifies the determinants that govern the formation and structural flexibility of G4 multimers, may be an affordable tool aiding in the selection and design of drugs that target G4s under physiological conditions