90 research outputs found

    First order transitions by conduction calorimetry: Application to deuterated potassium dihydrogen phosphate ferroelastic crystal under uniaxial pressure

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    The specific heat c and the heat power W exchanged by a Deuterated Potassium Dihydrogen Phosphate ferroelectric-ferroelastic crystal have been measured simultaneously for both decreasing and increasing temperature at a low constant rate (0.06 K/h) between 175 and 240 K. The measurements were carried out under controlled uniaxial stresses of 0.3 and 4.5±0.1 bar applied to face (110). At Tt=207.9 K, a first order transition is produced with anomalous specific heat behavior in the interval where the transition heat appears. This anomalous behavior is explained in terms of the temperature variation of the heat power during the transition. During cooling, the transition occurs with coexistence of phases, while during heating it seems that metastable states are reached. Excluding data affected by the transition heat, the specific heat behavior agrees with the predictions of a 2-4-6 Landau potential in the range of 4–15 K below Tt while logarithmic behavior is obtained in the range from Tt to 1 K below Tt. Data obtained under 0.3 and 4.5 bar uniaxial stresses exhibit the same behavior.Dirección General de Investigación Científica y Técnica. Gobierno de España-PB91-60

    Phase coexistence in highly deuterated ferroelectric triglycine selenate: Landau description

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    The phase transition in a 90% deuterated sample of TGSe has been investigated by calorimetric and dielectric measurements. As a consequence of the presence of an internal crack in the sample, the transition takes place in two stages separated by an interval where the paraelectric and the ferroelectric phases coexist without latent heat contribution. From the latent heat, the specific heat excess and the Curie law for the dielectric constant, it is shown that the transition follows a 2-4-6 Landau potential, whose coefficients are determined. This potential describes completely all the data, including those corresponding to the coexistence interval.Dirección General de Investigación Científica y Técnica (DGICYT) FIS2005-0244

    Deuteration effect on tricritical phase transition of triglycine selenate: Calorimetric and dielectric measurements analyzed in the framework of Landau theory

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    The ferroelectric phase transition of three single crystals of TGSe1−x DTGSex has been described by using specific heat, latent heat, and dielectric permittivity measurements. Pure, half-deuterated, and highly-deuterated TGSe single crystals were analyzed. Transition temperature and latent heat increase with increasing deuteration. Irrespective of the degree of deuteration, a 2-4-6 Landau model is suitable to describe the phase transition. The fourth-rank prefactor in Landau potential is found to be very sensitive to deuteration while the second-rank and the sixth-rank prefactors smoothly change with composition. The pyroelectric figure of merit for these materials has also been derived from the theoretical model.Gobierno de España-FIS2006-0404

    Memory effect in triglycine sulfate induced by a transverse electric field: specific heat measurement

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    The influence of a transverse electric field on the specific heat of triglycine sulfate (TGS) has been studied. The specific heat of TGS has been measured on heating the sample from the ferroelectric to the paraelectric phase after prolonged application of transverse electric field (i.e. perpendicular to the ferroelectric axis). It is shown that the specific heat of TGS can 'remember' the temperature T(s) at which the transverse field was previously applied.España, Gobierno de España IS-2006-0404

    Bilateral neurotrophic corneal ulcers associated with trigeminal neuralgia

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    La patología corneal es una de las afecciones oculares a nivel de la población que más afectan a la calidad visual (Whitcher et al 2001)). Entre las patologías que mayor alteración producen en la anatomía y fisiología ocular encontramos aquellas que van a afectar al trofismo corneal. Para mantener dicho trofismo corneal, es necesario que las estructuras que integran la superficie ocular, como son el epitelio conjuntival y corneal, glándulas lagrimales accesorias, así como la unidad funcional que constituyen junto con la película lagrimal, párpados y arcos neurales reflejos (cuya vía aferente principal, está vehiculizada por la rama oftálmica del trigémino), tengan un funcionamiento correcto e integrado. La alteración de cualquiera de estos elementos puede conducir a la aparición de una lesión corneal. Así, existen patologías como las úlceras neurotróficas que se producen como resultado de una disminución de la sensibilidad corneal por una lesión del nervio trigémino, especialmente de sus ramas nasociliar y nervios ciliares largos, encargados de la inervación sensitiva corneal

    Complex multidisciplinary intervention to improve Initial Medication Adherence to cardiovascular disease and diabetes treatments in primary care (the IMA-cRCT study) : mixed-methods process evaluation protocol

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    Medication non-initiation, or primary non-adherence, is a persistent public health problem that increases the risk of adverse clinical outcomes. The initial medication adherence (IMA) intervention is a complex multidisciplinary intervention to improve adherence to cardiovascular and diabetes treatments in primary care by empowering the patient and promoting informed prescriptions based on shared decision-making. This paper presents the development and implementation strategy of the IMA intervention and the process evaluation protocol embedded in a cluster randomised controlled trial (the IMA-cRCT) to understand and interpret the outcomes of the trial and comprehend the extent of implementation and fidelity, the active mechanisms of the IMA intervention and in what context the intervention is implemented and works. We present the protocol for a mixed-methods process evaluation including quantitative and qualitative methods to measure implementation and fidelity and to explore the active mechanisms and the interactions between the intervention, participants and its context. The process evaluation will be conducted in primary care centres and community pharmacies from the IMA-cRCT, and participants include healthcare professionals (general practitioners, nurses and community pharmacists) as well as patients. Quantitative data collection methods include data extraction from the intervention operative records, patient clinical records and participant feedback questionnaires, whereas qualitative data collection involves semistructured interviews, focus groups and field diaries. Quantitative and qualitative data will be analysed separately and triangulated to produce deeper insights and robust results. Ethical approval has been obtained from the Research Ethics Comittee (CEIm) at IDIAP Jordi Gol (codeCEIm 21/051 P). Findings will be disseminated through publications and conferences, as well as presentations to healthcare professionals and stakeholders from healthcare organisations.

    Isotopic labelling-based analysis elucidates biosynthesis pathways in Saccharomyces cerevisiae for Melatonin, Serotonin and Hydroxytyrosol formation

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    Yeasts can synthetise bioactive compounds such as Melatonin (MEL), Serotonin (SER) and Hydroxytyrosol (HT). Deciphering the mechanisms involved in their formation can lead to exploit this fact to increase the bioactive potential of fermented beverages. Quantitative analysis using labelled compounds, 15-N2 l-tryptophan and 13-C tyrosine, allowed tracking the formation of the above-mentioned bioactive compounds during the alcoholic fermentation of synthetic must by two different Saccharomyces cerevisiae strains. Labelled and unlabelled MEL, SER and HT were undoubtedly identified and quantified by High Resolution Mass Spectrometry (HRMS). Our results prove that there are at least two pathways involved in MEL biosynthesis by yeast. One starts with tryptophan as precursor being known for the vertebrates’ pathway. Additionally, MEL is produced from SER which in turn is consistent with the plants’ biosynthesis pathway. Concerning HT, it can be formed both from labelled tyrosine and from intermediates of the Erlich pathway.Ministerio de Economía y Competitividad AGL2016-77505-C3-2-RMinisterio de Ciencia, Innovación y Universidades PID2019-108722RB-C32Junta de Andalucía, Consejería de Economía y Conocimiento P18-RT-309

    Dentist´s knowledge, attitudes and determining factors of the conservative approach in teeth with reversible pulpitis and deep caries lesions

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    The aim of this study was to investigate dentists` knowledge, attitudes and factors regarding the conservative approach in the management of deep caries lesions (DCLs) in teeth with reversible pulpitis. 187 dentists were contacted directly or by mail, and 125 (67%) were finally included in the study. Dentists were requested to answer an open/discursive questionnaire about the routine approach to the diagnosis and treatment of DCLs, including knowledge-related attitudinal items. Total caries excavation was the preferred treatment option for more than 80% of dentists in case of DCL with reversible pulpitis. Only a small percentage (8%) chose partial caries removal, leaving some carious dentin close to the pulp to avoid pulp exposure. More than a half (51%) of respondents considered that cariogenic microorganisms must be removed or caries would progress. Dentists teaching at the University strongly disagreed with this statement (OR = 4.6; 95% C.I. = 1.3 ? 15.8; p = 0.017). Good clinical result was the most chosen reason (83%) to choose a specific treatment. Patient?s oral health (84%) and patient?s age (70%) were the two patient-related factors most taken into account for the choice of treatment. Total caries excavation is still the most frequently chosen treatment in teeth with DCL and reversible pulpitis. The joint assessment of the answers given by respondents allows to conclude that the new knowledge and concepts about caries lesions and the more conservative approach to DCLs have not still been incorporated by dentists into their usual clinical practice

    Criteria and treatment decisions in the management of deep caries lesions : is there endodontic overtreatment?

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    The aim of this study was to investigate the diagnostic criteria and treatment decisions in the management of deep caries lesions (DCLs). The null hypothesis tested was that DCLs are managed according to the current scientific evidence. A total of 288 dentists were contacted directly or by mail, and 125 (43%) were included in the study. Dentists were requested to answer a questionnaire about the routine approach to the diagnosis and treatment of DCLs. Logistic regression analyses were carried out to calculate odds ratios (OR). Pulp sensitivity tests were used by 65% of dentists when assessing pulpal health in cases of DCLs, particularly those who had followed courses in cariology (OR = 3.8; p = 0.005). Dentine hardness was the most frequent criterion used during DCLs excavation (98%). Two thirds of the respondents (65%) removed carious tissue until they felt hard dentine, and feeling hard dentine correlated with caries removal even at the risk of pulpal exposure (OR = 15.8; p = 0.0000). Acute transient pain or sensitivity to cold or heat (reversible pulpitis) were considered by 58% of respondents as a reason to provide endodontic therapy. The null hypothesis tested is rejected. The evidence-based more conservative approach on the management of DCLs is not being translated to clinical dentistry. Root canal treatment is being indicated in cases of DCLs in which the diagnosis is reversible pulpitis. Likewise, it can be concluded that non-conservative management of DCLs, with endodontic overtreatment, could be occurring

    Long-Term in vivo Evaluation of Orthotypical and Heterotypical Bioengineered Human Corneas

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    Purpose: Human cornea substitutes generated by tissue engineering currently require limbal stem cells for the generation of orthotypical epithelial cell cultures. We recently reported that bioengineered corneas can be fabricated in vitro from a heterotypical source obtained from Wharton’s jelly in the human umbilical cord (HWJSC). Methods: Here, we generated a partial thickness cornea model based on plastic compression nanostructured fibrin-agarose biomaterials with cornea epithelial cells on top, as an orthotypical model (HOC), or with HWJSC, as a heterotypical model (HHC), and determined their potential in vivo usefulness by implantation in an animal model. Results: No major side effects were seen 3 and 12 months after implantation of either bioengineered partial cornea model in rabbit corneas. Clinical results determined by slit lamp and optical coherence tomography were positive after 12 months. Histological and immunohistochemical findings demonstrated that in vitro HOC and HHC had moderate levels of stromal and epithelial cell marker expression, whereas in vivo grafted corneas were more similar to control corneas. Conclusion: These results suggest that both models are potentially useful to treat diseases requiring anterior cornea replacement, and that HHC may be an efficient alternative to the use of HOC which circumvents the need to generate cornea epithelial cell cultures.Spanish Plan Nacional de Investigacion Cientifica, Desarrollo e Innovacion Tecnologica (I CD Ci) from the Spanish Ministry of Science and Innovation: Instituto de Salud Carlos III FIS PI17/0391 FIS PI14/0955European Union (EU)Spanish Plan Nacional de Investigacion Cientifica, Desarrollo e Innovacion Tecnologica (I CD Ci) from the Spanish Ministry of Science and Innovation: Ministry of Science, Innovation and Universities of Spain PGC2018-101904-A-I00 RTC-2017-6696-
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