Modeling and Design of Multi-Stable Composite Structures

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Full characterization of the quantum linear-zigzag transition in atomic chains

A string of repulsively interacting particles exhibits a phase transition to a zigzag structure, by reducing the transverse trap potential or the interparticle distance. The transition is driven by transverse, short wavelength vibrational modes. Based on the emergent symmetry Z_2 it has been argued that this instability is a quantum phase transition, which can be mapped to an Ising model in transverse field. We perform an extensive Density Matrix Renormalization Group analysis of the behaviour at criticality and evaluate the critical exponents and the central charge with high precision. We thus provide strong numerical evidence confirming that the quantum linear-zigzag transition belongs to the critical Ising model universality class. These results show that structural instabilities of one-dimensional interacting atomic arrays can simulate quantum critical phenomena typical of ferromagnetic systems.Comment: 5 pages, 4 figure

A static analysis of three-dimensional sandwich beam structures by hierarchical finite elements modelling

A static analysis of three-dimensional sandwich beam structures using one-dimensional modelling approach is presented within this paper. A family of several one-dimensional beam elements is obtained by hierarchically expanding the displacements over the cross-section and letting the expansion order a free parameter. The finite element approximation order over the beam axis is also a formulation free parameter (linear, quadratic and cubic elements are considered). The principle of virtual displacements is used to obtain the problem weak form and derive the beam stiffness matrix and equivalent load vectors in a nuclear, generic form. Displacements and stresses are presented for different load and constraint configurations. Results are validated towards three-dimensional finite element solutions and experimental results. Sandwich beams present a three-dimensional stress state and higher-order models are necessary for an accurate description. Numerical investigations show that fairly good results with reduced computational costs can be obtained by the proposed finite element formulation

Hierarchical one-dimensional finite elements for the thermal stress analysis of three-dimensional functionally graded beams

In this work, the thermoelastic response of functionally graded beams is studied. To this end, a family of advanced one-dimensional finite elements is derived by means of a Unified Formulation that is not dependent on the order of approximation of the displacements upon the beam cross-section. The temperature field is obtained via a Navier-type solution of Fourier’s heat conduction equation and it is considered as an external load within the mechanical analysis. The stiffness matrix of the elements is derived via the Principle of Virtual Displacements. Numerical results in terms of temperature, displacements and stresses distribution are provided for different beam slenderness ratios and type of material gradation. Linear, quadratic and cubic elements are used. Results are validated through comparison with three-dimensional finite elements solutions obtained by the commercial software ANSYS. It is shown that accurate results can be obtained with reduced computational costs

The Coexistence of asthma and Chronic Ostructive Pulmonary Disease (COPD): prevalence and risk factors in young, middle-aged and elderly people from the general population

Background: The joint distribution of asthma and chronic obstructive pulmonary disease (COPD) has not been well described. This study aims at determining the prevalence of self-reported physician diagnoses of asthma, COPD and of the asthma-COPD overlap syndrome and to assess whether these conditions share a common set of risk factors. Methods: A screening questionnaire on respiratory symptoms, diagnoses and risk factors was administered by mail or phone to random samples of the general Italian population aged 20–44 (n = 5163) 45–64 (n = 2167) and 65–84 (n = 1030) in the frame of the multicentre Gene Environment Interactions in Respiratory Diseases (GEIRD) study. Results: A physician diagnosis of asthma or COPD (emphysema/chronic bronchitis/COPD) was reported by 13% and 21% of subjects aged &lt;65 and 65–84 years respectively. Aging was associated with a marked decrease in the prevalence of diagnosed asthma (from 8.2% to 1.6%) and with a marked increase in the prevalence of diagnosed COPD (from 3.3% to 13.3%). The prevalence of the overlap of asthma and COPD was 1.6% (1.3%–2.0%), 2.1% (1.5%–2.8%) and 4.5% (3.2%–5.9%) in the 20–44, 45–64 and 65–84 age groups. Subjects with both asthma and COPD diagnoses were more likely to have respiratory symptoms, physical impairment, and to report hospital admissions compared to asthma or COPD alone (p&lt;0.01). Age, sex, education and smoking showed different and sometimes opposite associations with the three conditions. Conclusion: Asthma and COPD are common in the general population, and they coexist in a substantial proportion of subjects. The asthma-COPD overlap syndrome represents an important clinical phenotype that deserves more medical attention and further research.</br

Thermodynamic Solution Properties of a Biodegradable Chelant (L-glutamic-N,N-diacetic Acid, L-GLDA) and Its Sequestering Ability toward Cd2+

The thermodynamics of the interaction of L-glutamic-N,N-diacetic acid (GLDA) with protons was studied potentiometrically at different temperatures, ionic strengths and ionic media. Four protonation constants and corresponding enthalpy changes occurred at infinite dilution together with temperature and ionic strength coefficients. The medium effect was also interpreted in terms of the formation of weak complexes between the ligand and the cations of supporting electrolytes, resulting in a greater tendency of GLDA to chemically interact with Na+ rather than K+ and, in turn, (CH3)4N+. Formation constants of GLDA with Cd2+ were determined in NaCl(aq) at different ionic strength values. Five complex species were found, namely CdL2−, CdHL−, CdH2L0(aq), Cd2L0(aq), and Cd(OH)L3−, whose formation constant values at infinite dilution were log β = 12.68, 17.61, 20.76, 17.52, and 1.77, respectively. All the species results were relevant in the pH range of natural waters, although the Cd2L0(aq) was observed only for CCd ≥ CGLDA and concentrations of >0.1 mmol dm−3. The sequestering ability of GLDA toward Cd2+, evaluated by means of pL0.5, was maximum at pH~10, whereas the presence of a chloride containing a supporting electrolyte exerted a negative effect. Among new generation biodegradable ligands, GLDA was the most efficient in Cd2+ sequestration.The authors C.B., P.C., A.I., G.L. and C.D.S. thank the University of Messina for the Research and Mobility 2017 Project (cod. 009041). Authors thank COST action CA18202—Network for Equilibria and Chemical Thermodynamics Advanced Research for the support to this study. O.G.-L. is grateful to the project IT-742-13 for Consolidated Research Groups, funded by the Basque Country Government, for her post-doctoral contract

Clinical characteristics and prognostic impact of atrial fibrillation in patients with chronic heart failure

AIMS: To assess the prevalence, clinical characteristics and independent prognostic impact of atrial fibrillation (AF) in chronic heart failure (CHF) patients, and the potential protective effect of disease-modifying medications, particularly beta-blockers (BB). METHODS: We retrospectively reviewed the charts of patients referred to our center since January 2004, and collected all clinical information available at their first visit. We assessed mortality to the end of June 2015. We compared patients with and without AF, and assessed the association between AF and all-cause mortality by multivariate Cox regression and Kaplan-Meyer analysis, particularly accounting for ongoing treatment with BB. RESULTS: A total of 903 patients were evaluated (mean age 68\ub112 years, 73% male). Prevalence of AF was 19%, ranging from 10% to 28% in patients 6460 and 6577 years, respectively. Besides the older age, patients with AF had more symptoms (NYHA II-III 60 vs. 44%), lower prevalence of dyslipidemia (23 vs. 37%), coronary artery disease (28 vs. 52%) and left bundle branch block (9 vs. 16%). On the contrary, they more frequently presented with an idiopathic etiology (50 vs. 24%), a history of valve surgery (13 vs. 4%) and received overall more devices implantation (31% vs. 21%). The use of disease-modifying medications (i.e. BB and ACE inhibitors/angiotensin receptor blockers) was lower in patients with AF (72 vs. 80% e 71 vs. 79%, respectively), who on the contrary were more frequently treated with symptomatic and antiarrhythmic drugs including diuretics (87 vs. 69%) and digoxin (51 vs. 11%). At a mean follow-up of about 5 years, all-cause mortality was significantly higher in patients with AF as compared to those in sinus rhythm (45% vs. 34%, p value &lt;0.05 for all previous comparisons). However, in a multivariate analysis including the main significant predictors of all-cause mortality, the univariate relationship between AF and death (HR 1.49, 95% CI 1.15-1.92) became not statistically significant (HR 0.98, 95% CI 0.73-1.32). Nonetheless, patients with AF not receiving BB treatment were found to have the worst prognosis, followed by patients with sinus rhythm not receiving BB therapy and patients with AF receiving BB therapy, who both had similarly worse survival when compared to patients with sinus rhythm receiving BB therapy. CONCLUSIONS: AF was highly prevalent and associated with older age, worse clinical presentation and underutilization of disease-modifying medications such as BB in a population of elderly patients with CHF. AF had no independent impact on mortality, but the underutilization of BB in this group of patients was associated to a worse long-term prognosis

CD4+CD25+ lymphocyte subsets in chronic graft versus host disease patients undergoing extracorporeal photochemotherapy.

Extracorporeal photochemotherapy (ECP) has been used successfully for the treatment of chronic Graft versus Host Disease (cGvHD). However, the mechanism by which ECP exerts its protective effects remains elusive. Some recent observations have suggested a possible role of certain subsets of T lymphocytes with immunosuppressive properties (T-regulatory cells) that coexpress CD4 and high levels of the interleukin-2 receptor chain: CD4+CD25+ T lymphocytes. We studied whether ECP affects the percentage of these cells in the peripheral blood of patients with cGvHD. The study population consisted of 14 patients with cGvHD refractory to systemic steroids. On enrolment in each cycle of ECP, patients underwent clinical examination, blood chemistry analysis and other instrumental procedures to document and assess involvement of the various organs and systems. For cytofluorimetric identification and phenotyping of CD4+CD25+ T lymphocytes, peripheral blood samples were collected in EDTA anticoagulant before ECP, after 48 hours, and after 6 and 12 months from the start of treatment. The 14 patients in this study received a total of more than 300 cycles of ECP, with only minor side effects. The clinical outcome was negative in 2 patients and positive in 12 patients. Within-subject analysis indicated that the percentage of CD4+CD25+ T lymphocytes before ECP and after 12 months of treatment was significantly increased. Our study confirms that changes in the percentage of CD4+CD25+ T cells induced by ECP could be a central aspect in the cascade of immune events leading to the immunological and clinical effects of this treatment in patients with cGvHD

The Genetics of Non-Syndromic Primary Ovarian Insufficiency: A Systematic Review

Several causes for primary ovarian insufficiency (POI) have been described, including iatrogenic and environmental factor, viral infections, chronic disease as well as genetic alterations. The aim of this review was to collect all the genetic mutations associated with non-syndromic POI. All studies, including gene screening, genome-wide study and assessing genetic mutations associated with POI, were included and analyzed in this systematic review. Syndromic POI and chromosomal abnormalities were not evaluated. Single gene perturbations, including genes on the X chromosome (such as BMP15, PGRMC1 and FMR1) and genes on autosomal chromosomes (such as GDF9, FIGLA, NOBOX, ESR1, FSHR and NANOS3) have a positive correlation with non-syndromic POI. Future strategies include linkage analysis of families with multiple affected members, array comparative genomic hybridization (CGH) for analysis of copy number variations, next generation sequencing technology and genome-wide data analysis. This review showed variability of the genetic factors associated with POI. These findings may help future genetic screening studies on large cohort of women

O Modelo Molecular Adaptado e o desenvolvimento da noção da Tridimensionalidade

O material didático pode contribuir para a compreensão dos conteúdos químicos. Entretanto, é fundamental que este tenha potencial inclusivo, garantindo igualdade de oportunidades educacionais para os indivíduos. Neste sentido, para que um material seja considerado adaptado, este deve trazer significados aos alunos com necessidades educacionais especiais, respeitando seu referencial perceptual. Uma destas necessidades é a baixa visão, que é definida atualmente como a perda parcial da visão, requerendo a utilização de auxílios ópticos e/ou não ópticos. Desta forma, numa abordagem qualitativa, buscou-se elaborar um modelo molecular com potencial inclusivo para o ensino de Química e avaliar a sua contribuição no processo de aprendizagem. O modelo molecular adaptado foi produzido e avaliado por especialistas em educação inclusiva, professores universitários de química e alunos videntes e não videntes. Posterior a esta avaliação o modelo foi utilizado em uma sala de aula para verificação de sua contribuição para a aprendizage