Simulation of Co-Rotating Twin Screw Extrusion Process Subject to Pressure-Dependent Wall Slip at Barrel and Screw Surfaces: 3D FEM Analysis for Combinations of Forward- and Reverse-Conveying Screw Elements

Mathematical modeling and simulation of the coupled flow, deformation, heat and mass transfer, and rate of reactions occurring in the twin screw extruder allow the optimization of process parameters and the screw and barrel geometries. In mathematical modeling of the twin screw extrusion process the conventional flow boundary condition at the screw and barrel walls is the no-slip condition. However, most complex fluids, including polymers, polymeric suspensions and blends, exhibit wall slip, with the slip behavior depending on the intrinsic properties of the materials being processed, the operating conditions, the geometries of the barrel, screw and the die, and the properties of the solid surfaces. Typically, the slip velocity is specified to be a function of temperature, stress condition at the wall and the materials of construction. However, recent investigations have further revealed that the wall slip behavior can also be significantly affected by pressure. With an objective of considering the effects of wall slip on the dynamics of twin screw extrusion, fully-intermeshing co-rotating twin screw extrusion of a concentrated suspension is analyzed using three-dimensional finite element method, FEM, subject to the wall slip boundary condition. The wall slip boundary condition is first applied systematically to barrel and screw surfaces individually followed by the application of wall slip to both surfaces simultaneously. In an integrated fashion both the forward-conveying (pressure-generating) and reverse-conveying (pressure-losing) screw sections are considered. The effects of pressure on wall slip are also analyzed and elucidated.

The challenges of publishing on health informatics in developing countries

The Journal of Health Informatics in Developing Countries was established to meet a perceived need for Health Informaticians in developing countries to be able to share the results of their research in an affordable and easy-to-access online publication. The journal was developed using the open source platform "Open Journal System," and has now published 67 articles across 13 issues. A collaborative editorial approach has been established to address the problems of limited research budgets, difficulties with translating to English and other problems specific to authors from developing countries. The journal faces many challenges including ensuring future financial sustainability and inclusion in journal indexing systems. However, the continuing support of an international body of Associate Editors and Editorial Board Members has enabled a wide range of useful and informative health informatics research to be disseminated across the developing world.

Reproducibility and validity of a quantitative food frequency questionnaire in an urban and rural area of northern India

Background. Food frequency questionnaires (FFQs) have been used in epidemiological studies across the world to capture the usual food intake of individuals. As food habits vary in different population groups, FFQs should be validated before use. Hence, we determined the reproducibility and validity of FFQs designed for urban and rural populations of northern India. Methods. Separate FFQs, designed for urban and rural populations using standard methods, were administered to a sample of 200 subjects (100 urban and 100 rural) in the age group of 35-70 years in the beginning (baseline FFQ) of the study and after an interval of 1 year (1-year FFQ) to assess their reproducibility. Six 24-hour dietary-recalls, taken at an interval of 2 months over a period of 1 year, were used as a reference method to test the validity. Crude and energy- adjusted nutrient intakes estimated from FFQs and 24-hour dietary-recalls were compared using Pearson correlation coefficients. Bland and Altman plots were also used to test the agreement between the two methods. Results. Nutrient intakes were found to be similar at the baseline and 1-year FFQs in urban and rural areas. The unadjusted Pearson correlation between 24-hour dietary- recalls and 1-year FFQ ranged from 0.22 for vitamin C to 0.63 for iron in the urban area. It ranged from 0.06 for vitamin C to 0.74 for energy in the rural area. The correlations lowered after adjusting for energy and there was a minimal increase after de-attenuation. Conclusion. The FFQs were reproducible and valid for assessing nutrient intakes except for some micronutrients.

The state of hepatitis B and C in the Mediterranean and Balkan countries: report from a summit conference

The burden of disease due to chronic viral hepatitis constitutes a global threat. In many Balkan and Mediterranean countries, the disease burden due to viral hepatitis remains largely unrecognized, including in high-risk groups and migrants, because of a lack of reliable epidemiological data, suggesting the need for better and targeted surveillance for public health gains. In many countries, the burden of chronic liver disease due to hepatitis B and C is increasing due to ageing of unvaccinated populations and migration, and a probable increase in drug injecting. Targeted vaccination strategies for hepatitis B virus (HBV) among risk groups and harm reduction interventions at adequate scale and coverage for injecting drug users are needed. Transmission of HBV and hepatitis C virus (HCV) in healthcare settings and a higher prevalence of HBV and HCV among recipients of blood and blood products in the Balkan and North African countries highlight the need to implement and monitor universal precautions in these settings and use voluntary, nonremunerated, repeat donors. Progress in drug discovery has improved outcomes of treatment for both HBV and HCV, although access is limited by the high costs of these drugs and resources available for health care. Egypt, with the highest burden of hepatitis C in the world, provides treatment through its National Control Strategy. Addressing the burden of viral hepatitis in the Balkan and Mediterranean regions will require national commitments in the form of strategic plans, financial and human resources, normative guidance and technical support from regional agencies and research.

An Integrated Approach for Numerical Analysis of Coupled Flow and Heat Transfer in Co-rotating Twin Screw Extruders

The co-rotating twin screw extrusion process is widely employed in chemical industries for the processing of complex fluids including various polymers, suspensions, emulsions and gels. Here we propose a new integrated modeling strategy that is based on the numerical analysis of pressure-generating extrusion elements concomitantly with the pressure-losing extrusion elements of the co-rotating twin screw extrusion process for non-Newtonian fluids under nonisothermal conditions. The numerical analysis undertakes three-dimensional (3-D) finite element simulations of any multiple combinations of forwarding and reversing fully-flighted screw elements with other types of elements including kneading discs staggered in the forward or reverse configurations and the die. The abilities of the methodologies in simulating the coupled flow and heat transfer in industrially-relevant mixing sections or pressurization/die shaping are demonstrated with predictions of the degree of fill and typical velocity, deformation rate, stress magnitude, pressure distributions as functions of various operating parameters and basic twin screw extrusion geometries for a viscoplastic type generalized Newtonian fluid.

Infection prevention and control measures for acute respiratory infections in healthcare settings: an update

Viruses account for the majority of the acute respiratory tract infections (ARIs) globally with a mortality exceeding 4 million deaths per year. The most commonly encountered viruses, in order of frequency, include influenza, respiratory syncytial virus, parainfluenza and adenovirus. Current evidence suggests that the major mode of transmission of ARls is through large droplets, but transmission through contact (including hand contamination with subsequent self-inoculation) and infectious respiratory aerosols of various sizes and at short range (coined as "opportunistic" airborne transmission) may also occur for some pathogens. Opportunistic airborne transmission may occur when conducting highrisk aerosol generating procedures and airborne precautions will be required in this setting. General infection control measures effective for all respiratory viral infections are reviewed and followed by discussion on some of the common viruses, including severe acute respiratory syndrome (SARS) coronavirus and the recently discovered novel coronavirus.

Proarrhythmic safety of repeat doses of mirabegron in healthy subjects: a randomized, double-blind, placebo-, and active-controlled thorough QT study

Potential effects of the selective β(3)-adrenoceptor agonist mirabegron on cardiac repolarization were studied in healthy subjects. The four-arm, parallel, two-way crossover study was double-blind and placebo- and active (moxifloxacin)-controlled. After 2 baseline ECG days, subjects were randomized to one of eight treatment sequences (22 females and 22 males per sequence) of placebo crossed over with once-daily (10 days) 50, 100, or 200 mg mirabegron or a single 400-mg moxifloxacin dose on day 10. In each period, continuous ECGs were recorded at two baselines and on the last drug administration day. The lower one-sided 95% confidence interval for moxifloxacin effect on QTcI was >5 ms, demonstrating assay sensitivity. According to ICH E14 criteria, mirabegron did not cause QTcI prolongation at the 50-mg therapeutic and 100-mg supratherapeutic doses in either sex. Mirabegron prolonged QTcI interval at the 200-mg supratherapeutic dose (upper one-sided 95% CI >10 ms) in females, but not in males.

[Breast cancer centres in North Rhine-Westphalia - case volume trends 2004-2010]

BACKGROUND

To improve quality of breast cancer care, in 2004 the state of North Rhine-Westphalia (NRW), Germany, began to appoint 51 breast cancer centres. These centres comprise 91 hospitals performing breast cancer surgery which have - amongst other things - to fulfill minimum volume standards. The aim of our study was to analyse if the intended regionalisation of care from 252 hospitals performing breast cancer surgery formerly to the appointed hospitals had taken place by the year 2010.

METHODS

We used data for the years 2004-2010 from the agency for quality assurance in North Rhine-Westphalia concerning breast cancer care and analysed trends concerning the number of hospitals performing breast cancer surgery, case volumes, and achievement of minimum volume standards by performing descriptive and inferential statistics.

RESULTS

Between 2004 and 2010 the number of breast cancer cases increased by 36.6% from 12 975 to 17 724 cases (p<0.001, Wilcoxon test). Simultaneously, the number of hospitals performing breast cancer surgery decreased from 252 to 208 whereby more than double the number of planned hospitals still performed breast cancer surgery. The case volumes of the 71 appointed hospitals for which we had individual data over the entire period of time increased by 49.4% from 8 103 cases in year 2004 to 12 105 cases in 2010. Assuming that case volume trends of those 20 appointed hospitals of which we did not have individual data developed uniformly to all other appointed hospitals, the proportion of cases that were operated in not appointed hospitals decreased from 20% in year 2004 to 12.5% in 2010 (p<0.001, χ2 test). Simultaneously, the proportion of cases that were operated in hospitals not achieving minimum volume standards decreased from 42.7% in year 2004 to 12.1% in 2010 (p<0.001, χ2 test).

CONCLUSION

The establishment of breast cancer centres in NRW regionalised breast cancer surgery. In fact, in 2010 breast cancer surgery still took place in more than 100 not appointed hospitals. However, these hospitals were responsible for only a small proportion of breast cancer surgery.

Bacteriological Profile Of Ear Discharge And Their Antibiotic Sensitivity In Chronic Suppurative Otitis Media In Kashmir,India

The objective of the study was to study the microflora and the antibiograms of patients with chronic suppurative otitis media (CSOM) in Kashmir,in order to provide a guidelines for making a protocol for empirical antibiotic therapy. Study design:Prospective study Material and methods: This study was conducted on OPD basis in Department of Ear, Nose and Throat and HNS Government medical college Srinagar kashmir from july 2010 to june 1011 and one hundred twenty five(125) patients with unilateral or bilateral active chronic suppurative otitis media were prospectively studied.They had chronic ear discharge and had not received antibiotics for the previous five days. Swabs were taken from discharging ear's and sent to microbiological section of hospital were culture for bacteria was done Antibiotic sensitivity testing was done with standard antibiotic discs using Kirby-bauer disk diffusion method.4 Results:From the Clinical specimens off the 125 patients microbiological culture was positive in 110 specimens. The most common causal organisms isolated were Staphylococcus aureus (48%) including 8% of methcillin resistant staph aureus and Pseudomonas aeruginosa (16%) followed by coagulase negative.Antibiotic sensitivities of staph aureus (other than MRSA) showed that 72% isolates were sensitivity to gentamicin,55% to ciprofloxacin followed by 36% to cephalosporins (cetazidime,ceftriaxone) .For pseudomonas aeruginosa 72% isolates were sensitive to piperacillin/tazobactum 48% to ciprofloxacin and 32% to ceftazidime/ceftriaxone. Of the three antibiotics commonly available as topical eardrops,ciprofloxacin and gentamicin has the highest susceptibility rate. DOI: http://dx.doi.org/10.3329/bjms.v11i3.11731 Bangladesh Journal of Medical Science Vol. 11 No. 03 July’12