Prospects for Electrical Performance Tuning in Ca3Co4O9 Materials by Metallic Fe and Ni Particles Additions

This work further explores the possibilities for designing the high-temperature electrical performance of the thermoelectric Ca₃Co₄O₉ phase, by a composite approach involving separate metallic iron and nickel particles additions, and by employing two different sintering schemes, capable to promote the controlled interactions between the components, encouraged by our recent promising results obtained for similar cobalt additions. Iron and nickel were chosen because of their similarities with cobalt. The maximum power factor value of around 200 μWm⁻¹K⁻² at 925 K was achieved for the composite with the nominal nickel content of 3% vol., processed via the two-step sintering cycle, which provides the highest densification from this work. The effectiveness of the proposed approach was shown to be strongly dependent on the processing conditions and added amounts of metallic particles. Although the conventional one-step approach results in Fe- and Ni-containing composites with the major content of the thermoelectric Ca₃Co₄O₉ phase, their electrical performance was found to be significantly lower than for the Co-containing analogue, due to the presence of less-conducting phases and excessive porosity. In contrast, the relatively high performance of the composite with a nominal nickel content of 3% vol. processed via a two-step approach is related to the specific microstructural features from this sample, including minimal porosity and the presence of the Ca₂Co₂O₅ phase, which partially compensate the complete decomposition of the Ca₃Co₄O₉ matrix. The obtained results demonstrate different pathways to tailor the phase composition of Ca₃Co₄O₉-based materials, with a corresponding impact on the thermoelectric performance, and highlight the necessity of more controllable approaches for the phase composition tuning, including lower amounts and different morphologies of the dispersed metallic phases.     

Chronic adaptations of lung function in breath-hold diving fishermen

Objectives

The aim of this study was to verify and analyze the existence of chronic adaptations of lung function in free-diving fishermen whose occupation is artisanal fishing.

Material and Methods

This was a cross-sectional study involving 11 breath-hold diving fishermen and 10 non-breath-hold diving fishermen (control) from the village of Bitupitá in the municipality of Barroquinha (Ceará — Brazil). Anthropometric measurements, chest and abdominal circumferences as well as spirometric and respiratory muscle strength tests were conducted according to the specifications of the American Thoracic Society/European Respiratory Society (ATS/ERS). In order to compare the measured values versus the predicted values, Student t test was used in the case of parametric test and Wilcoxon test in the case of nonparametric test. To compare the inter-group means Student t test was used for parametric test and Mann-Whitney test for the nonparametric one. The level of significance was set at α = 5%.

Results

The forced vital capacity (FVC) (4.9±0.6 l vs. 4.3±0.4 l) and forced expiratory volume in 1 s (FEV₁) (4.0±0.5 l vs. 3.6±0.3 l) were, respectively, higher in the group of divers compared to the control group (p ≤ 0.05). Furthermore, in the group of free divers, the measured FVC, FEV₁ and FEV₁/FVC ratios were significantly greater than the predicted ones. No differences were found between the measured respiratory pressures.

Conclusions

These results indicate that breath-hold diving seems to produce chronic adaptations of the respiratory system, resulting in elevated lung volumes with no airway obstruction.     

Long-Term Lithium Treatment Reduces Glucose Metabolism in the Cerebellum and Hippocampus of Nondemented Older Adults: An [18F]FDG-PET Study

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Ambivalence in Psychotherapy Questionnaire: Development and validation studies

Research emphasizes that individuals' engagement with change process is a significant predictor of therapeutic outcomes. Ambivalence is a natural phenomenon in change processes, but when individuals cannot overcome it, their problems may intensify. Ambivalence towards change, a client variable characterized by an intrapersonal conflict between two positions of the self, one in favour of change and another one in favour of the status quo, is shown to play a determinant role in psychotherapy. Despite its importance, few empirical studies have examined this process, and the considerable methodological differences among existing studies make it difficult to generalize results. Therefore, instruments measuring ambivalence in an effective way can help broaden the understanding of the process. First, we performed a content analysis of ambivalence events identified in psychotherapy sessions from previous studies using an observational coding system. The factor structure, reliability and validity of the measure were tested using 91 and confirmed with 223 psychotherapy clients at any time during the therapeutic process. A two‐factor structure was found, suggesting two components of Ambivalence—Demoralization and Wavering. The results indicated that the Ambivalence in Psychotherapy Questionnaire exhibits good psychometric properties, including good convergent and divergent validity. The implications are discussed.     

Tobacco use and smoking cessation among third‐year dental students in southern Brazil

The aim of the present cross‐sectional study was to assess tobacco use and smoking cessation among third‐year dental students in southern Brazil. The Global Health Professions Student Survey questionnaire was used in eight dental schools in Rio Grande do Sul state, Brazil. Of the 663 eligible students, 576 (87%) participated. The prevalence of current smoking was 19.1% [95% confidence interval (CI): 12.9–25.3%], and 61.6% (95% CI: 54.9–68.3%) of students reported having smoked at least once in their lifetime. The prevalence of dental students who had smoked ≥100 cigarettes in their lifetime was 17.1% (95% CI: 12.5–21.7%). Being frequently exposed to other smokers at home or in other places (second‐hand smoke) increased the likelihood of current smoking by two‐ to threefold. Approximately 6.1% (95% CI: 3.5–8.7%) of the students reported that they currently wanted to stop smoking and 7.5% (95% CI: 5.3–9.6%) had tried to stop smoking in the last year. Friends and family were the most frequent sources of help or counselling, and only a limited proportion of students received help from health professionals. Tobacco use and exposure to second‐hand smoking is widespread among dental students in southern Brazil. Smoking‐cessation initiatives targeting health care students are urgently needed.     

Intermittent Parathyroid Hormone Administration Improves Periodontal Healing in Rats

Background: Intermittent administration of parathyroid hormone (PTH) promotes new bone formation in patients with osteoporosis and bone fractures. It was shown previously that PTH also reduces periodontitis‐related bone loss. The aim of this study is to evaluate the effect of treatment with PTH on periodontal healing in rats. Methods: Fenestration defects were created at the buccal surface of the distal root of the mandibular first molars, and both periodontal ligament (PDL) and cementum were removed. Animals were then assigned to two groups (eight animals per group): group 1: control, placebo administration; and group 2: test, human PTH (hPTH) 1‐34 administration at a concentration of 40 μg/kg. For both groups, the animals were injected every 2 days, and the animals were sacrificed at 14 and 21 days after surgery. Specimens were harvested and processed for routine decalcified histologic sections. The following parameters were assessed: 1) remaining bone defect extension (RBDE); 2) newly formed bone density (NFBD); 3) total callus area (TCA); 4) osteoclast number (ON) in the callus region; and 5) newly formed dental cementum‐like tissue (NFC). Birefringence of root PDL reattachment was also evaluated. Results: Birefringence analysis showed root PDL reattachment for both groups 21 days after treatment. Intermittent hPTH 1‐34 administration decreased RBDE (P <0.01) and increased NFBD (P <0.01), TCA (P <0.01), area of NFC (P <0.01), and ON in the callus region (P <0.01). Conclusion: Within the limits of the present study, intermittent administration of hPTH 1‐34 led to an enhanced periodontal healing process compared with non‐treated animals.     

Is There a Positive Effect of Smoking Cessation on Periodontal Health? A Systematic Review

Background: Although the detrimental effects of tobacco on the periodontal tissues have been reported extensively, little is known about the potential beneficial effect of smoking cessation on periodontal health. The aim of this systematic review is to evaluate the effect of smoking cessation on periodontitis progression and response to periodontal therapy. Methods: Two independent reviewers completed the review process through title (n = 118), abstract (n = 24), and whole‐paper selection (n = 5). Sources include Medline and EMBASE databases (up to December 2012) and a reference list of selected studies. Prospective studies comparing progression rates of periodontitis between smokers and quitters and clinical trials evaluating the effect of smoking‐cessation programs, alone or in combination with periodontal treatment, were included. At least 1 year of follow‐up was required for inclusion. Results: Of 331 potentially relevant publications, five studies fulfilled the inclusion criteria. Because of heterogeneity of the studies, a meta‐analysis could not be performed. One study reported that the progression of clinical attachment loss (AL) ≥3 mm during a 6‐year period was approximately three times higher among smokers than quitters (P <0.001). Two studies (10 and 20 years of follow‐up) observed a decrease in radiographic bone loss of ≈30% among quitters when compared with smokers. Among individuals receiving non‐surgical periodontal treatment, quitters were more likely to have periodontal probing depth reductions (P <0.05) than non‐quitters/oscillators. No differences in AL were observed. Conclusion: Based on the limited available evidence, smoking cessation seems to have a positive influence on periodontitis occurrence and periodontal healing.