Preliminary results in synchrotron X-ray diffraction measurements of rubber composites structure before and after exposure to hydrogen

In future years, fuel cells are expected to represent a promising technology as a source of heat and electricity in buildings and of electrical power for vehicles, since fossil fuels are exhausting and significantly degrade air quality. It is well known that, when exposed to a hydrogen environment, hydrogen embrittlerment may affect materials such as iron and steel. But these are not the only materials that are used for hydrogen equipment. In particular, the rubber materials used for O\u2013rings that seal high pressure hydrogen gas equipment show problems of internal fracture, called blister fracture, when the gas is rapidly decompressed. As many different kinds of fillers can be used, in this work we started to investigate the influence of the type of filler on the rubber composites structure, by means of X-ray diffraction measurements performed at the Elettra synchrotron radiation facility in Trieste. In this preliminary study, three kinds of samples were analyzed before and after exposure to hydrogen: Sulphur vulcanized EPDM, Peroxide vulcanized EPDM and Sulphur vulcanized NBR. While Peroxide vulcanized samples did not show significant differences in the diffraction pattern, changes could be detected in the cristalline form of Sulfure vulcanized rubber

Effects of acute and sub-chronic glucocorticoid treatments on hippocampal neurons of wild type and dystrophin-deficient DMDmdx mice: an in vitro and in vivo study

Duchenne muscular dystrophy (DMD) is a lethal X-linked disease characterized by progressive muscular wasting due to lack of full-length dystrophin (Dp427), a cytoskeletal protein expressed in muscle and selected brain regions (i.e. hippocampus). Dp427 binds to a large multi-proteic complex (Dystrophin Glycoprotein Complex, DGC), endowed with structural and functional properties, as the modulation of several intracellular signaling pathways. The presence of the dystrophin-DGC in areas involved in cognitive functions suggests that lack of Dp427 may be responsible for the neurological disturbances described in DMD patients. These could be further aggravated by the glucocorticoid (GC) therapeutic treatments of the muscular inflammation in DMD patients. As the hippocampus is one major GC target, in this study I analyzed whether in vitro (acute) and in vivo (acute and sub-chronic) treatments with either corticosterone (CORT) or dexamethasone (DEX) affected the already compromised hippocampal neuron physiology. Under any conditions we analyzed several parameters of the neuronal response to GCs: a) protein levels of the glucocorticoid receptor (GR) and of its phosphorylated (active) form pGR; b) mRNA levels of GR and GILZ; c) changes in the intensity of GR and pGR immunohistochemistry; d) protein levels of GR intracellular signaling effectors (i.e. caveolin 1, ERK 1/2); e) proliferation of hippocampal neural progenitor cells (NPC) (in vivo sub-chronic treatment only). In both in vitro and in vivo studies, mdx mouse hippocampal neurons respond differently than wild type to GC treatments. The general picture emerging is that they could be more sensitive to GCs and, therefore, more predisposed to be damaged. In fact, even acute GC administrations elicit a response similar to the more damaging chronic administration: i.e. reduction in GR levels, increase in the ration pGR/GR, possible reduction in GR gene expression, all aspects that are connotative of a chronic stress response. During high level of stress, which correspond to high and prolonged levels of secreted GCs, several physiological responses are altered, including those typical of hippocampal activity: i.e. synaptic plasticity, cognitive functions. These are accompanied by a reversal of the GC effects on hippocampal neurons: from the promotion of neuronal activity, and hence of its inhibitory control over the HPA axis, to its reduction, with consequent depression of HPA axis activity and increase in GC secretion. These are the basis for psychopathologies, as post-traumatic disorders. Therefore, the already compromised activity of the hippocampus in dystrophic subjects could be further damaged even by mild doses of GC, amplifying the risks for serious neural hilliness. Another crushing data is that sub-chronic treatments with DEX induce an increase in the proliferation of NPC in adult hippocampus, in contrast to what occurs in the wild type. This de-regulation of precursor cell cycle, responsible for of glia and neuronal self-renewal in adult brains, could further compromised hippocampal physiology. In conclusion, in the hope that new therapies could extend the life span of the young DMD patients, it is important to go deeper in the comprehension of how hippocampus and other brain areas affected by DMD, respond to anti-inflammatory (GCs) treatments

A micro-mechanical model of the elastic properties of a short fibre reinforced polyamide

n/

A possible new approach in the prediction of late gestational hypertension: The role of the fetal aortic intima-media thickness

The aim was to determine the predictive role of combined screening for late-onset gestational hypertension by fetal ultrasound measurements, third trimester uterine arteries (UtAs) Doppler imaging, and maternal history. This prospective study on singleton pregnancies was conducted at the tertiary center of Maternal and Fetal Medicine of the University of Padua during the period between January 2012 and December 2014. Ultrasound examination (fetal biometry, fetal wellbeing, maternal Doppler study, fetal abdominal aorta intima-media thickness [aIMT], and fetal kidney volumes), clinical data (mother age, prepregnancy body mass index [BMI], and parity), and pregnancy outcomes were collected. The P value <0.05 was defined significant considering a 2-sided alternative hypothesis. The distribution normality of variables were assessed using Kolmogorov–Smirnoff test. Data were presented by mean (±standard deviation), median and interquartile range, or percentage and absolute values. We considered data from 1381 ultrasound examinations at 29 to 32 weeks’ gestation, and in 73 cases late gestational hypertension developed after 34 weeks’ gestation. The final multivariate model found that fetal aIMT as well as fetal umbilical artery pulsatility index (PI), maternal age, maternal prepregnacy BMI, parity, and mean PI of maternal UtAs, assessed at ultrasound examination of 29 to 32 weeks’ gestation, were significant and independent predictors for the development of gestational hypertension after 34 weeks’ gestation. The area under the curve of the model was 81.07% (95% confidence interval, 75.83%–86.32%). A nomogram was developed starting from multivariate logistic regression coefficients. Late-gestational hypertension could be independently predicted by fetal aIMT assessment at 29 to 32 weeks’ gestation, ultrasound Doppler waveforms, and maternal clinical parameters

Dexamethasone in acute cardiopulmonary syndrome with hyperinflammatory state

Abstract Introduction Elderly patient hospitalized due to acute heart failure often have a concomitant acute lung disease (acute bronchitis, pneumonia, chronic obstructive pulmonary disease-COPD- exacerbation). Establishing the role of each disease in a clinical picture of acute cardiopulmonary syndrome can be challenging. Procalcitonin has been used as a guide to antibiotic therapy with contrasting results. A common thread of these diseases is inflammation; a hyperinflammatory response determines more serious symptoms and a worse prognosis. Purpose We evaluated the effectiveness of a treatment with dexamethasone in patients with acute cardiopulmonary syndrome and a strong inflammatory response. Materials and methods We evaluated 157 consecutive HFPEF (heart failure with preserved ejection fraction) patients ≥80 years of age, with concomitant symptoms attributable to acute bronchitis, pneumonia, or COPD exacerbation, hospitalized due to worsening dyspnoea, with an NT-proBNP ≥3,000 pg/ml, and a finding X-ray of lung congestion with or without a consolidation. Reactive C Protein was measured. Patients with SARS-CoV-2, indication to corticosteroids use for other clinical conditions or need for mechanical ventilation were excluded. The 96 patients with values&gt;20 mg/dl were randomized into 2 groups: 48 patients were treated open-label with dexamethasone at a dose of 8 mg iv/day for a maximun of ten days, in addition to the usual therapies for acute heart failure and lung disease, while the same number of patients were treated with the usual therapy. In both groups the antibiotic was administered only if the procalcitonin was≥0.25 μg/L. Clinical recovery time, length of hospitalization, in-hospital mortality, the need for a new hospitalization and mortality at one month were evaluated. Results The mean age of the patients was 88±4 years in the dexamethasone group and 87±5 in the usual therapy group. The results are shown in Table 1. Patients treated with dexamethasone experienced a faster clinical recovery and a shorter length of hospitalization. No significant differences were found regarding either in-hospital mortality or need for rehospitalization and mortality at 30 days. Conclusions Very elderly patients with acute cardiopulmonary syndrome and hyperinflammatory state associated with an excessive increase in Reactive Protein C have a favorable response to dexamethasone therapy in addition to the usual therapy in terms of clinical improvement and length of hospitalization. Our case history is small to evaluate a possible improvement in mortality. These findings need to be consolidated from double-blind randomized controlled trials Funding Acknowledgement Type of funding sources: None. Table

Heparin-induced thrombocy-topenia and COVID-19

Heparin-induced thrombocytopenia (HIT) has not been included as a possible cause of thrombocytopenia in Coronavirus Disease 2019 (COVID-19) patients. We report a case of HIT in a patient with COVID-19 treated with heparin. A 78-year-old man was admitted to our hospital for acute respiratory failure and acute renal failure due to SARS-CoV-2 infection; in intensive care unit, one 5000IU heparin dose (day 0, platelet count 305000/μL). On day 2, haemoglobin started to decrease and heparin was stopped. On day 10, platelet count was 153000/μL and 5000IU calcium heparin subcutaneously twice daily was started. The platelet further decreased, reaching 49000/μL on day 17, and the patient was investigated for suspected HIT: an IgG specific chemiluminescence test for heparin-PF4 antibodies was positive and a femoral DVT was found at ultrasound. Argatroban was started, platelet count increased without any bleeding and thrombosis complication. Our experience shows that HIT may develop in heparin treated COVID-19 patients and should be included among the possible cause of thrombocytopenia in such patients. © the Author(s), 2021

Analysis of the dependence of the tensile behaviour of a short fibre reinforced polyamide upon fibre volume fraction, length and orientation

n/

Evaluation of fibre lenght distribution in a short glass fibre reinforced PA-6

The aim of this work is to evaluate the fibre length distribution in a polyamide reinforced by short glass fibre. The fibre length and the fibre orientation distributions strongly influence the mechanical properties of short fibre reinforced composites. The sample investigated is a 30GFPA6 (polyamide-6 reinforced by 30 % by weight glass fibre), extracted from an injection-moulded plate. The digital reconstruction of the three-dimensional structure of the sample was obtained by synchrotron radiation micro-computed tomography (micro-CT), a high spatial resolution non-destructive technique. One global and one local method have been tested for the automatic evaluation of the fibre length distribution in our sample. The global method is based on the mean fibre length distribution computed from the Star Length Distribution (SLD), a morphological parameter. The local method is based on a 3D skeletonize function. The results are discussed in the light of the experimental data available in literature

Threshold Identification for Micro-Tomographic Damage Characterisation in a Short-Fibre-Reinforced Polymer

The micro-tomographic technique represents an important tool for the analysis of the internal structure in short-fibre-reinforced polymers samples. For the investigation of damage mechanisms, detection of the micro-voids within the matrix can be facilitated by applying a tensile load in-situ during the scan. The investigations here described started from two micro-CT acquisitions, at different strain levels, of the same PA6.6GF10 sample. An original procedure for micro-voids identification is proposed, based on the statistical elaboration of the matrix grey-tone range. In order to validate the suggested procedure beyond visual inspection, an independent method based on an optimisation approach, which puts to use the two available micro-tomographic sets, was developed and applied. The effect of the tensile load, which can induce a progression of the damage within the specimen, was investigated, and the relations among strain, fibre distribution and micro-voids volumetric fraction were studied. Our findings point out that the mechanisms of damage progression, even under static loading as in this case, appear to be more complex than those related to the fibre-density-induced stress concentrations alone and require further investigation