Tephrochronology

Tephrochronology is the use of primary, characterized tephras or cryptotephras as chronostratigraphic marker beds to connect and synchronize geological, paleoenvironmental, or archaeological sequences or events, or soils/paleosols, and, uniquely, to transfer relative or numerical ages or dates to them using stratigraphic and age information together with mineralogical and geochemical compositional data, especially from individual glass-shard analyses, obtained for the tephra/cryptotephra deposits. To function as an age-equivalent correlation and chronostratigraphic dating tool, tephrochronology may be undertaken in three steps: (i) mapping and describing tephras and determining their stratigraphic relationships, (ii) characterizing tephras or cryptotephras in the laboratory, and (iii) dating them using a wide range of geochronological methods. Tephrochronology is also an important tool in volcanology, informing studies on volcanic petrology, volcano eruption histories and hazards, and volcano-climate forcing. Although limitations and challenges remain, multidisciplinary applications of tephrochronology continue to grow markedly

Use of green solvents as pre-treatment of dissolving pulp to decrease CS2 consumption from viscose production

Choline chloride-based deep eutectic solvents are widely used in biomass processing. In this work, four different green solvent mixtures were used as pre-treatment of acid sulphite dissolving pulp with the hypothesis of increasing the possibilities to produce viscose fibres and decreasing the use of the harmful and toxic carbon disulphide in the process. The experiments were performed at two different pulp to solvent mass ratios. Pulp quality parameters were also measured to determine the suitability of the pretreatment: a-cellulose, viscosity, lignin and pentosan content. In addition, X-ray diffraction analysis of pulps at the best solid to liquid ratio was performed to obtain the influence of the crystallinity index. Best results were obtained with the use of lactic acid, with reactivity values close to 94%, giving a reduction of CS2 usage of 15.83%. Furthermore, a linear relationship between the crystallinity index calculated by the XRD and reactivity with a regression factor of 0.87 was found

Commonwealth Executive Master of Business / Public Administration Degree

Background: The association between periodontal inflammation and non-fatal stroke is still controversial and limited to evidence in Western countries. The aim of this study was to investigate whether periodontitis is independently associated with non-fatal stroke in Korean adults. Methods: A case-control study was conducted on 265 non-fatal chronic stroke cases at the National Rehabilitation Center, Seoul, Korea, and 214 non-stroke population controls. Medical specialists diagnosed stroke by using brain imaging from magnetic resonance imaging and/or computerized tomography. A dentist recorded the clinical attachment level (CAL), the distance between the cemento-enamel junction and the probed base of the periodontal pocket, using a University of North Carolina-15 manual probe. An interview assessed 17 sociodemographic, behavioral, systemic/oral health–related possible confounders. Multiple logistic regression analysis was used to evaluate the association between periodontitis and stroke while controlling for age, gender, income, education, smoking, drinking, history of systemic disease, body mass index, familial cardiovascular risk factors, and oral health behaviors. Subgroup analyses were also performed. Results: Stroke was strongly associated with periodontitis (presence of CAL ≥6 mm): the odds ratio was 4.0 (95% confidence interval: 2.3 to 7.0) after controlling for all possible confounders. The association with periodontitis (tertiary percentage of CAL ≥5 mm) had a dose-response effect. The association between periodontitis and stroke was higher among adults younger than age 60 (6.0 versus 2.6) and normotensives (4.8 versus 3.2). Conclusion: Our data suggested that periodontitis is independently associated with non-fatal stroke, and its impact seems to be greater among younger or normotensive Korean adults