Comparative Microstructural Study of the Diffusion Zone Between Ni-Cr Alloy and Different Dental Ceramics

Detailed knowledge of bonding mechanisms, between the metal and ceramic parts in conventional dental systems, can help the development of new, improved systems and the optimisation of recent technologies. Despite their allergic potential, the NiCr alloys are still amongst the most often used dental materials so their investigation is important. The aim of the study was to carry out a detailed microstructural investigation and to compare the reaction layer developed between three different dental ceramics and NiCr alloy under different firing conditions. For the measurements six identical samples were cast from WIRON 99 (Bego, Konstantz, Germany) alloy. Ceramic opaquers were fired on the polished surface using Vision (Wohlwend AG), Vita VMK 95 (Vita) and Carat(DeTrey/Dentsplay) materials. Two samples were produced from each type of opaquers by different firing conditions. The TEM investigations were performed by using a 2000FX-II microscope with a Link-lsis EDS system. Similar growth processes of the phases were observed in all of the investigated systems in the sense that an amorphous phase was formed on the metal-ceramic interface producing bubble like inclusions on the metal surface. The main component of this phase is silicon oxide in the case of Carat and Vita ceramics, while in the case of Vision potassium and nickel oxides were observed after the normal firing process. In all systems and at all firing conditions a nanocrystalline Cr2O3 layer (with about 50 nm grain size) was commonly observed. This investigation was supported in part by ETT Grant 2001-3

Response of a catalytic reaction to periodic variation of the CO pressure: Increased CO_2 production and dynamic phase transition

We present a kinetic Monte Carlo study of the dynamical response of a Ziff-Gulari-Barshad model for CO oxidation with CO desorption to periodic variation of the CO presure. We use a square-wave periodic pressure variation with parameters that can be tuned to enhance the catalytic activity. We produce evidence that, below a critical value of the desorption rate, the driven system undergoes a dynamic phase transition between a CO_2 productive phase and a nonproductive one at a critical value of the period of the pressure oscillation. At the dynamic phase transition the period-averged CO_2 production rate is significantly increased and can be used as a dynamic order parameter. We perform a finite-size scaling analysis that indicates the existence of power-law singularities for the order parameter and its fluctuations, yielding estimated critical exponent ratios $\beta/\nu \approx 0.12$ and $\gamma/\nu \approx 1.77$. These exponent ratios, together with theoretical symmetry arguments and numerical data for the fourth-order cumulant associated with the transition, give reasonable support for the hypothesis that the observed nonequilibrium dynamic phase transition is in the same universality class as the two-dimensional equilibrium Ising model.Comment: 18 pages, 10 figures, accepted in Physical Review

Use of thyroid hormones in hypothyroid and euthyroid patients: A survey of members of the Endocrine Society of Australia

\ua9 2024 The Authors. Clinical Endocrinology published by John Wiley & Sons Ltd.Objective: Hypothyroidism is a common endocrine condition usually managed with levothyroxine (LT4). However, controversy remains around the use of liothyronine (LT3). We aimed to investigate the practices of Australian endocrinologists when managing patients with hypothyroidism, their use of LT3 + LT4 combination therapy and use of thyroid hormones in euthyroid patients. Design and Participants: Members of the Endocrine Society of Australia (ESA) were invited to participate in an online questionnaire. Measurements: We analysed questionnaires that had complete demographic data. Results: Eighty-seven questionnaires fulfilled the criteria. LT4 was used as first line treatment for hypothyroidism by all respondents. Only 45% reported that their patients were dispensed the brand of LT4 that they recommend. LT3 (alone or in combination) was prescribed by 44% in their clinical practice. Although 49% of respondents would consider LT3 + LT4 in patients with normal TSH who had ongoing symptoms of hypothyroidism, the inability of LT4 to restore normal physiology was ranked the least likely explanation for persistent symptoms and only 32% would consider it for themselves if they were diagnosed with hypothyroidism. The majority (55%), in accordance with evidence, would not prescribe thyroid hormone to euthyroid individuals but 39% would consider use in euthyroid female infertility with high levels of thyroid antibodies and 11% in euthyroid patients with a simple goitre growing over time. LT4 use in pregnancy was variable among members. Conclusions: Australian endocrinologists mostly follow international guidelines when prescribing thyroid hormone therapy and many prescribe combination LT3 and LT4 therapy, particularly for patients who remain symptomatic on LT4 monotherapy. Prescribing practices are largely similar to other countries who have completed similar questionnaires

Hypothyroidism and type d personality:Results from E-MPATHY, a cross-sectional international online patient survey

ContextBetween 10% and 15% of people with hypothyroidism experience persistent symptoms, despite achieving biochemical euthyroidism.The underlying causes are unclear. Type D personality (a vulnerability factor for general psychological distress) is associated with poor healthstatus and symptom burden but has not been studied in people with hypothyroidism.ObjectiveTo investigate type D personality in hypothyroidism and explore associations with other characteristics and patient-reported outcomes.DesignMultinational, cross-sectional survey.SettingOnline.ParticipantsIndividuals with self-reported, treated hypothyroidism.InterventionQuestionnaire.Main Outcome MeasuresType D personality and associations with baseline characteristics, control of the symptoms of hypothyroidism bymedication, satisfaction with care and treatment of hypothyroidism, impact of hypothyroidism on everyday living.ResultsA total of 3915 responses were received, 3523 of which were valid. The prevalence of type D personality was 54.2%. Statisticallysignificant associations were found between type D personality and several respondent characteristics (age, marital status, ethnicity,household income, comorbidities, type of treatment for hypothyroidism, most recent TSH level), anxiety, depression, somatization, poorcontrol of the symptoms of hypothyroidism by medication, dissatisfaction with care and treatment of hypothyroidism, and a negative impactof hypothyroidism on everyday living).DiscussionOur study found a high prevalence of type D personality among people with hypothyroidism who responded to the survey. Type Dpersonality may be an important determinant of dissatisfaction with treatment and care among people with hypothyroidism. Our findings requireindependent confirmation. Close collaboration between the disciplines of thyroidology and psychology is likely to be key in progressing ourunderstanding in this area

Barriers to the development of palliative care in Western Europe

The Eurobarometer Survey of the <i>EAPC Task Force on the Development of Palliative Care in Europe</i> is part of a programme of work to produce comprehensive information on the provision of palliative care across Europe. Aim: To identify barriers to the development of palliative care in Western Europe. Method: A qualitative survey was undertaken amongst boards of national associations, eliciting opinions on opportunities for, and barriers to, palliative care development. By July 2006, 44/52 (85%) European countries had responded to the survey; we report here on the results from 22/25 (88%) countries in Western Europe. Analysis: Data from the Eurobarometer survey were analysed thematically by geographical region and by the degree of development of palliative care in each country. Results: From the data contained within the Eurobarometer, we identified six significant barriers to the development of palliative care in Western Europe: (i) Lack of palliative care education and training programmes (ii) Lack of awareness and recognition of palliative care (iii) Limited availability of/knowledge about opioid analgesics (iv) Limited funding (v) Lack of coordination amongst services (vi) Uneven palliative care coverage. Conclusion: Findings from the EAPC Eurobarometer survey suggest that barriers to the development of palliative care in Western Europe may differ substantially from each other in both their scope and context and that some may be considered to be of greater significance than others. A number of common barriers to the development of the discipline do exist and much work still remains to be done in the identified areas. This paper provides a road map of which barriers need to be addressed