Mixing and recirculation characteristics of gas-liquid Taylor flow in microreactors

The effects of operating parameters (capillary and Reynolds numbers) and microchannel aspect ratio (α = w/h = [1; 2.5; 4]) on the recirculation characteristics of the liquid slug in gas-liquid Taylor flow in microchannels have been investigated using 3-dimensional VOF simulations. The results show a decrease in the recirculation volume in the slug and an increase in recirculation time with increasing capillary number, which is in good agreement with previous results obtained in circular and square geometries (Thulasidas et al., 1997). In addition, increasing the aspect ratio of the channel leads to a slight decrease in recirculating volumes but also a significant increase in recirculation times

An integrated approach of multiple correspondences analysis (MCA) and fuzzy AHP method for occupational health and safety performance evaluation in the land cargo transportation

Land cargo transportation is one of the components of the logistics chain with high impact on economic and social development worldwide. However, problems such as top logistics costs, deficiencies in transportation infrastructure and the failure to adopt good operating practices in aspects such as quality, environment, and occupational safety and health affect the ability of companies to comply with the agreements, requirements, and regulations of the clients and other interested parties. One of the most relevant problems for the sector is associated with the high accident rates that make this medium less advantageous compared to other means of transport with impact on operational costs, on logistics indicators, on compliance with legal regulations and customer satisfaction. However, although there are legal standards and management standards in occupational safety and health, evaluating performance can become a difficult and subjective process, due to the complexity of the land cargo transportation and the different interest groups involved. Besides, there is little information in the literature that provides solutions for the industry. Therefore, this document presents an integrated approach between multi-criterion decision making models (MCDM) and the Multiple Correspondences Analysis (MCA) to facilitate the evaluation and improvement of occupational health and safety performance, with a logical process, objective, robust and using both qualitative and quantitative techniques, with real application in the land cargo transportation sector. First, the multivariate method of Multiple Correspondences Analysis (MCA) was used for the evaluation of a sample of companies in the industry, considering the factors and sub-factors identified in the first stage and performing correlational analyzes among the variables. Subsequently, a multicriteria decision-making model was designed to determine the factors and sub-factors that affect occupational health and safety performance through the technique of the Fuzzy Analytic Hierarchy Process (FAHP). Finally, improvement strategies are proposed based on the approaches suggested in this document

Dynamic Control of Nanoprecipitation in a Nanopipette

Studying the earliest stages of precipitation at the nanoscale is technically challenging but quite valuable as such phenomena reflect important processes such as crystallization and biomineralization. Using a quartz nanopipette as a nanoreactor, we induced precipitation of an insoluble salt to generate oscillating current blockades. The reversible process can be used to measure both kinetics of precipitation and relative size of the resulting nanoparticles. Counter ions for the highly water-insoluble salt zinc phosphate were separated by the pore of a nanopipette and a potential applied to cause ion migration to the interface. By analyzing the kinetics of pore blockage, two distinct mechanisms were identified: a slower process due to precipitation from solution, and a faster process attributed to voltage-driven migration of a trapped precipitate. We discuss the potential of these techniques in studying precipitation dynamics, trapping particles within a nanoreactor, and electrical sensors based on nanoprecipitation

Extrusion of Endodontic Filling Materials: Medico-Legal Aspects. Two Cases

The Authors describe two cases of alleged malpractice due to overfilling. The aim of this article is to underline some medico-legal aspects regarding the quantity of extruded material which may be considered acceptable and the consequent damage to the patient

Reference isotherms for water vapor sorption on nanoporous carbon: results of an interlaboratory study

This paper reports the results of an international interlaboratory study sponsored by the Versailles Project on Advanced Materials and Standards (VAMAS) and led by the National Institute of Standards and Technology (NIST) on the measurement of water vapor sorption isotherms at 25 °C on a pelletized nanoporous carbon (BAM-P109, a certified reference material). Thirteen laboratories participated in the study and contributed nine pure water vapor isotherms and four relative humidity isotherms, using nitrogen as the carrier gas. From these data, reference isotherms, along with the 95% uncertainty interval (Uk=2), were determined and are reported in a tabular format

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

Adult attention deficit hyperactivity disorder is associated with migraine headaches

Attention deficit hyperactivity disorder (ADHD) is now recognized as a common disorder both in child and adult psychiatry. Adult patients with a diagnosis of ADHD (n = 572) and community controls (n = 675) responded to auto-questionnaires rating past and present symptoms of ADHD, co-morbid conditions, including migraine, treatment history and work status. The prevalence of migraine was significantly higher in the patient group compared to the controls (28.3% vs. 19.2%, P < 0.001, OR = 1.67, CI 1.28–2.17). The difference from controls was particularly marked for men (22.5% vs. 10.7%, P < 0.001, OR = 2.43, CI 1.51–3.90) but was also significant for women (34.4% vs. 24.9%, P = 0.008, OR = 1.58, CI 1.13–2.21). In both patients and controls, migraine was associated with symptoms of mood and anxiety disorders. These findings point to a co-morbidity of migraine with ADHD, and it is possible that these patients represent a clinical and biological subgroup of adult patients with ADHD

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

Migraine and psychiatric comorbidity: a review of clinical findings

Migraine is an extremely common disorder. The underlying mechanisms of this chronic illness interspersed with acute symptoms appear to be increasingly complex. An important aspect of migraine heterogeneity is comorbidity with other neurological diseases, cardiovascular disorders, and psychiatric illnesses. Depressive disorders are among the leading causes of disability worldwide according to WHO estimation. In this review, we have mainly considered the findings from general population studies and studies on clinical samples, in adults and children, focusing on the association between migraine and psychiatric disorders (axis I of the DSM), carried over after the first classification of IHS (1988). Though not easily comparable due to differences in methodology to reach diagnosis, general population studies generally indicate an increased risk of affective and anxiety disorders in patients with migraine, compared to non-migrainous subjects. There would also be a trend towards an association of migraine with bipolar disorder, but not with substance abuse/dependence. With respect to migraine subtypes, comorbidity mainly involves migraine with aura. Patients suffering from migraine, however, show a decreased risk of developing affective and anxiety disorders compared to patients with daily chronic headache. It would also appear that psychiatric disorders prevail in patients with chronic headache and substance use than in patients with simple migraine. The mechanisms underlying migraine psychiatric comorbidity are presently poorly understood, but this topic remains a priority for future research. Psychiatric comorbidity indeed affects migraine evolution, may lead to chronic substance use, and may change treatment strategies, eventually modifying the outcome of this important disorder