High carrier lifetimes in UMG multicrystalline wafers after P- diffusion compatible with high-efficiency cell structures

High-quality multicrystalline Upgraded Metallurgical Grade Silicon (UMG-Si) offers significant advantages over conventional polysilicon-based PV technology, associated to lower energy budget. The aim of this study is twofold: on the one hand, to ascertain the efficiency potential of solar cells based on this material in terms of carrier lifetime; and on the other hand, to explore the adoption of high-efficiency cell architectures by establishing an effective rear-side passivation scheme for the implementation of passivated emitter rear contact (PERC) devices. The carrier lifetime and the surface passivation efficacy are investigated for different passivating layer configurations after single and double P-diffusion gettering processes. Layer stacks consisting of Al2O3, SiOxNy and a-SiNx:H capping overlayers have been optimized, on industrial size, saw-damage-etched UMG wafers and results compared to those obtained using reference iodine-ethanol (IE) passivation. Diagnosis based on minority carrier lifetime and implied V-oc (iV(oc)) measurements helped monitor the impact of parameter optimization on wafer quality, particularly after firing processes. Carrier lifetimes over 600 mu s at Delta n = 10(15) cm(-3) injection level as well as up to 790 mu s locally have been measured in UMG-Si wafers passivated with IE after a Phosphorus Diffusion Gettering (PDG), demonstrating the suitability of the material for high-efficiency cell architectures. Values higher than 300 mu s have been obtained with Al2O3-based passivation layers for gettered UMG wafers, with implied V-oc values up to 710 mV. These record-breaking lifetimes and iV(oc) figures obtained with p-type multicrystalline UMG-Si material demonstrate a significant upgrading of its electronic quality by means of industry-scalable technical processes

SEAHORSE project : Dealing with maritime workarounds and developing smarter procedures

EU funded SEAHORSE project is developing a novel approach to improve maritime SOPs. SEAHORSE Project’s ‘Smart Procedures Concept’ aims to develop a system to capture the behavioural adaptations that crew have developed in order to cope with operational demands and challenges. Initially, a detailed survey was conducted worldwide to capture seafarer’s safety attitudes as well as the common workarounds. Then, these collected workarounds will be categorised through conducting risk and benefit analysis. Accordingly, safe workarounds will be approved as Standard Operating Procedures (SOPs), on the other hand, measures will be proposed to prevent reoccurrence of unsafe workarounds. This paper will present the proposed approach to deal with maritime workarounds and report the preliminary results of the analysis

One-year prevalence and the impact of migraine and tension-type headache in Turkey: a nationwide home-based study in adults

Several studies have shown that the prevalence of migraine and tension-type headache (TTH) varied between different geographical regions. Therefore, there is a need of a nationwide prevalence study for headache in our country, located between Asia and Europe. This nationwide study was designed to estimate the 1-year prevalence of migraine and TTH and analyse the clinical features, the impact as well as the demographic and socio-economic characteristics of the participant households in Turkey. We planned to investigate 6,000 representative households in 21 cities of Turkey; and a total of 5,323 households (response rate of 89%) aged between 18 and 65 years were examined for headache by 33 trained physicians at home on the basis of the diagnostic criteria of the second edition of the International Classification of Headache Disorders (ICHD-II). The electronically registered questionnaire was based on the headache features, the associated symptoms, demographic and socio-economic situation and history. Of 5,323 participants (48.8% women; mean age 35.9 ± 12 years) 44.6% reported recurrent headaches during the last 1 year and 871 were diagnosed with migraine at a prevalence rate of 16.4% (8.5% in men and 24.6% in women), whereas only 270 were diagnosed with TTH at a prevalence rate of 5.1% (5.7% in men and 4.5% in women). The 1-year prevalence of probable migraine was 12.4% and probable TTH was 9.5% additionally. The rate of migraine with aura among migraineurs was 21.5%. The prevalence of migraine was highest among 35–40-year-old women while there were no differences in age groups among men and in TTH overall. More than 2/3 of migraineurs had ever consulted a physician whereas only 1/3 of patients with TTH had ever consulted a physician. For women, the migraine prevalence was higher among the ones with a lower income, while among men, it did not show any change by income. Migraine prevalence was lower in those with a lower educational status compared to those with a high educational status. Chronic daily headache was present in 3.3% and the prevalence of medication overuse headache was 2.1% in our population. There was an important impact of migraine with a monthly frequency of 5.9 ± 6, and an attack duration of 35.1 ± 72 h, but only 4.9% were on prophylactic treatment. The one-year prevalence of migraine estimated as 16.4% was similar or even higher than world-wide reported migraine prevalence figures and identical to a previous nation-wide study conducted in 1998, whereas the TTH prevalence was much lower using the same methodology with the ICHD-II criteria

Prevalence of headache in Europe: a review for the Eurolight project

The main aim of the present study was to do an update on studies on headache epidemiology as a preparation for the multinational European study on the prevalence and burden of headache and investigate the impact of different methodological issues on the results. The study was based on a previous study, and a systematic literature search was performed to identify the newest studies. More than 50% of adults indicate that they suffer from headache in general during the last year or less, but when asked specifically about tension-type headache, the prevalence was 60%. Migraine occurs in 15%, chronic headache in about 4% and possible medication overuse headache in 1–2%. Cluster headache has a lifetime prevalence of 0.2–0.3%. Most headaches are more prevalent in women, and somewhat less prevalent in children and youth. Some studies indicate that the headache prevalence is increasing during the last decades in Europe. As to methodological issues, lifetime prevalences are in general higher than 1-year prevalences, but the exact time frame of headache (1 year, 6 or 3 months, or no time frame stated) seems to be of less importance. Studies using personal interviews seem to give somewhat higher prevalences than those using questionnaires

Evaluation of the sealing ability of gutta-percha and thermoplastic synthetic polymer-based systems along the root canals through the glucose penetration model

Objective. To compare the sealing ability of gutta-percha and thermoplastic synthetic polymer-based systems along the root canals using a recently introduced glucose penetration model. Study design. Premolars (n = 156) instrumented to an apical size of .06/40 were divided into 12 experimental and 2 control groups. The root canals were filled with either gutta-percha (groups 1-6) or Resilon (groups 7-12) core materials combined with AH Plus (groups 1, 4, 7, 0), Ketac Endo (groups 1, 5, 8, 11), or Epiphany (groups 2, 6, 9, 12), using cold lateral compaction (groups 1-3, 7-9) or System B with Obtura 11 (groups 4-6, 10-12). The leaked glucose concentration was measured spectrophotometrically at 1, 8, 15, 22, and 30 days. Percentage leaking of each group was also Calculated. Data were recorded as mmol/L and statistically analyzed with Kruskal-Wallis and Mann-Whitney U tests (11 = 05). Results. Throughout the experimental period Resilon/Ketac-Endo/cold lateral compaction (group 8) showed the highest mean cumulative glucose penetration (mmol/L) (17.27 +/- 10.32), whereas Resilon/AH Plus/cold lateral compaction (group 7) had the least (3.36 +/- 4.65) (P < .05). At the 30(th) day, the least leaking percentage was observed in gutta-percha, Epiphany/cold lateral compaction (group 3). Glucose penetration was affected by the obturation technique in some groups. Ketac-Endo either with gutta-percha (group 2) or Resilon (group 8) indicated significantly less glucose penetration in warm technique, whereas gutta-percha/Epiphany (group 3) had significantly less glucose penetration in cold technique (P < .05). Conclusions. All material/technique combinations allowed glucose penetration. Gutta-percha/AH Plus combinations allowed similar patterns Of glucose penetration to Resilon/Epiphany combinations

A Retrospective Radiographic Study of Coronal-Periapical Status and Root Canal Filling Quality in a Selected Adult Turkish Population

&lt;b&gt;&lt;i&gt;Objective:&lt;/i&gt;&lt;/b&gt; To investigate the oral health (with regard to the periapical status, quality of root fillings and coronal restorations) in an urban adult Turkish subpopulation using digital panoramic radiographs. &lt;b&gt;&lt;i&gt;Materials and Methods:&lt;/i&gt;&lt;/b&gt; One thousand digital panoramic radiographs involving 28,000 teeth were selected from the archive of the Public Oral and Dental Health Center of Isparta. Coronal status (the type of restoration, signs of marginal leakage or decay), root filling quality (length and lateral seal) and periapical status (according to Periapical Index, PAI) were evaluated. Correlations between apical periodontitis (AP) and the quality of root fillings or coronal restorations were statistically analyzed using the &amp;#x03C7;&lt;sup&gt;2&lt;/sup&gt; test. &lt;b&gt;&lt;i&gt;Results:&lt;/i&gt;&lt;/b&gt; Of the 28,000 teeth evaluated, 22,380 (80.0%) were sound, 4,732 (16.9%) were missing, 753 (2.6%) were filled and 135 (0.5%) were decayed. Of the 753 coronal restorations, 400 (53.1%) were radiographically acceptable. Of the 23,268 teeth, 601 (2.6%) were root filled and 247 root fillings were adequate. Ninety-five (15.8%) root-filled teeth had AP (PAI 3-5). Out of the total, the AP prevalence was 0.4% in root-filled teeth and 0.8% in teeth without root fillings. The presence of AP was significantly correlated with inadequate coronal restorations and root canal fillings (p = 0.000). &lt;b&gt;&lt;i&gt;Conclusion:&lt;/i&gt;&lt;/b&gt; Tooth type, quality and type of coronal restorations, and length and homogeneity of root fillings significantly affected periapical status.</jats:p