166 research outputs found
EXPERIMENTAL EVALUATION OF A CONICAL-SCREW BRIQUETTING MACHINE FOR THE BRIQUETTING OF CARBONIZED COTTON STALKS IN SUDAN
Briquetting of the carbonized agricultural residues represents one of the possible solutions to the local energy shortages in many developing countries. It constitutes a positive solution to the problem of increasing rates of desertification in many areas worldwide. Agricultural residues are not attractive as a household fuel source for urban areas because they are very bulky and have low energy intensity. Also, to eliminate the smoke generation when burning agricultural residues requires processing it by carbonization before being used as a house-hold indoor fuel. Previously investigated, briquetting machines lacked high productivity and were of complicated designs. The present study puts forward a machine of simple design which could be manufactured locally in Sudan and of much higher productivity. The local Sudanese briquetting experience was overviewed, studying all the alternative available options and the market potential. The study presents a detailed design study of the new briquetting machine. The prototype was made and tested in the field at Al-Gazeera area in Sudan. The investigation results show that the new machine has a production rate better than all the previous alternatives. This low pressure screw briquetting machine was found to have a production rate equivalent to about eight times better than the production rate of the best local competitor. The production cost was found to be lower due to the lower binder requirement for the new machine, which is lower by about 65%. The initial moisture content of the feed stock required for this machine is lower by about 30 % compared to the best alternative, which results in shorter drying time for the fuel briquettes produced. The quality of the produced briquettes was found to be better and of lower smoke generation when burned due to the lower binder content
The effects of external disturbances on the performance and chaotic behaviour of industrial FCC units
The dynamic behaviour of an industrial Type IV fluid catalytic cracking for the production of gasoline unit is investigated for a case where the air feed temperature is periodically forced. The investigation concentrates on the behaviour of the system for a case of bistability for the autonomous system with special emphasis on the effect of forcing on the periodic attractor of the autonomous system. When the centre of forcing is very close to the homoclinical termination point of the autonomous periodic attractor, period-doubling mechanism and Type 1 intermittency have been identified as the routes to chaos for this six-dimensional (6D) system. Chaotic behaviour occurs at very low forcing amplitudes which simulate small disturbances that are unavoidable in the operation of any industrial unit. While in certain ranges of the values of the forcing amplitudes the output amplitudes of the forced system are higher than their counterparts in the autonomous system, other regions show the opposite behaviour. Average gasoline yield in the bistability region for the attractor resulting from the forcing of the autonomous periodic attractor is much higher than that resulting from forcing the autonomous static attractor. This yield is very close to that obtained with the optimum steady state which is unstable and requires prohibitively high values of controller gains to be stabilized
Recommended from our members
Highly Selective Syngas/H2 Production via Partial Oxidation of CH4 Using (Ni, Co and Ni–Co)/ZrO2–Al2O3 Catalysts: Influence of Calcination Temperature
In this study, Ni, Co and Ni–Co catalysts supported on binary oxide ZrO2–Al2O3 were synthesized by sol-gel method and characterized by means of various analytical techniques such as XRD, BET, TPR, TPD, TGA, SEM, and TEM. This catalytic system was then tested for syngas respective H2 production via partial oxidation of methane at 700 °C and 800 °C. The influence of calcination temperatures was studied and their impact on catalytic activity and stability was evaluated. It was observed that increasing the calcination temperature from 550 °C to 800 °C and addition of ZrO2 to Al2O3 enhances Ni metal-support interaction. This increases the catalytic activity and sintering resistance. Furthermore, ZrO2 provides higher oxygen storage capacity and stronger Lewis basicity which contributed to coke suppression, eventually leading to a more stable catalyst. It was also observed that, contrary to bimetallic catalysts, monometallic catalysts exhibit higher activity with higher calcination temperature. At the same time, Co and Ni–Co-based catalysts exhibit higher activity than Ni-based catalysts which was not expected. The Co-based catalyst calcined at 800 °C demonstrated excellent stability over 24 h on stream. In general, all catalysts demonstrated high CH4 conversion and exceptionally high selectivity to H2 (~98%) at 700 °C
Irrational prescribing of over-the-counter (OTC) medicines in general practice: testing the feasibility of an educational intervention among physicians in five European countries
Background: Irrational prescribing of over-the-counter (OTC) medicines in general practice is common in Southern Europe. Recent findings from a research project funded by the European Commission (FP7), the “OTC SOCIOMED”, conducted in seven European countries, indicate that physicians in countries in the Mediterranean Europe region prescribe medicines to a higher degree in comparison to physicians in other participating European countries. In light of these findings, a feasibility study has been designed to explore the acceptance of a pilot educational intervention targeting physicians in general practice in various settings in the Mediterranean Europe region.
Methods: This feasibility study utilized an educational intervention was designed using the Theory of Planned Behaviour (TPB). It took place in geographically-defined primary care areas in Cyprus, France, Greece, Malta, and Turkey. General Practitioners (GPs) were recruited in each country and randomly assigned into two study groups in each of the participating countries. The intervention included a one-day intensive training programme, a poster presentation, and regular visits of trained professionals to the workplaces of participants. Reminder messages and email messages were, also, sent to participants over a 4-week period. A pre- and post-test evaluation study design with quantitative and qualitative data was employed. The primary outcome of this feasibility pilot intervention was to reduce GPs’ intention to provide medicines following the educational intervention, and its secondary outcomes included a reduction of prescribed medicines following the intervention, as well as an assessment of its practicality and acceptance by the participating GPs.
Results: Median intention scores in the intervention groups were reduced, following the educational intervention, in comparison to the control group. Descriptive analysis of related questions indicated a high overall acceptance and perceived practicality of the intervention programme by GPs, with median scores above 5 on a 7-point Likert scale.
Conclusions: Evidence from this intervention will estimate the parameters required to design a larger study aimed at assessing the effectiveness of such educational interventions. In addition, it could also help inform health policy makers and decision makers regarding the management of behavioural changes in the prescribing patterns of physicians in Mediterranean Europe, particularly in Southern European countries
Public knowledge and behaviours relating to antibiotic use in Gulf Cooperation Council countries: A systematic review
© 2018 The Authors The aim of this review was to assess public knowledge and behaviours in relation to antibiotic use in GCC countries. A systematic review was performed using MEDLINE, EMBASE and other relevant databases. Cross-sectional studies published from January 2000 to June 2017 relating to public knowledge and behaviours towards antibiotic use were included. Overall nine studies met the inclusion criteria for this systematic review. Nearly half of general public respondents in the GCC region reported a lack of knowledge about antibiotic use and showed negative attitudes towards antibiotic utilisation. Penicillin was the most frequently misused antibiotic, particularly for self-medication. Most respondents declared that they obtained information on antibiotics from pharmacists. Pharmacies were the major source of antibiotics used for self-medication. A multi-disciplinary approach must be put in place to educate the public on appropriate antibiotic use, to improve policies regarding the rational prescription of antimicrobials and to increase regulation enforcement
Recent progress in ceria-based catalysts for the dry reforming of methane: a review
The mitigation of CO2 and CH4 emissions is feasible by transforming them into valuable syngas via the dry
reforming of methane (DRM). However, the problem of catalyst deactivation has restricted its industrial
application. Therefore, the development of catalysts for an effective reforming process has been attracted
enormous attention. Ceria has a high potential as it can serve as both catalyst support and metal active
site for adsorption and dissociation of CO2 and CH4. Material properties, such as redox and acid/base
properties, and oxygen storage capacity, greatly affect catalytic behavior and performance, as well as coke
inhibition in the DRM. This review aims to provide an up-to-date summary on the DRM over ceria-based
catalysts, including aspects of the catalysts, reaction mechanism, deactivation, and regeneration studies.
This review also proposes governing factors and new ways for improving the process, to provide a more
rational to designing an ideal ceria-based catalyst for DRM
How chip size impacts steam pretreatment effectiveness for biological conversion of poplar wood into fermentable sugars
Taste and Smell Alterations in Patients undergoing Hematopoietic Stem Cell Transplantations (HSCT)
Thesis (Master's)--University of Washington, 2015Background: Alterations in the chemosensory functions of taste and smell are common side effects experienced by patients undergoing standard oncology treatment. However, minimal data exists in patients undergoing hematopoietic stem cell transplantation (HSCT). Furthermore, most HSCT studies have focused solely on gustatory function and have been conducted only following completion of treatment. Aim: This study aimed to assess the magnitude and characteristics of gustatory and olfactory (chemosensory) function in patients receiving HSCT at the Seattle Cancer Care Alliance (SCCA) using objective and subjective chemosensory testing methods. We examined the relationship between chemosensory function and Quality of Life (QOL). Methods: In a prospective cohort study, patients aged 18+; scheduled to undergo HSCT at the SCCA were tested for gustatory and olfactory function at three time points: pre-transplant (baseline) and then on day 30 and day 80 post HSCT. Gustatory function was assessed following the procedures of the Rapid Screening test used by the Monell-Jefferson Taste and Smell Clinic, modified to use the general Labeled Magnitude Scale for response. Olfactory testing was conducted using the NIH Toolbox Odor Identification Test. Self-assessment of taste and smell function was performed using two different survey instruments: the Taste and Smell survey (Heald et al., 1998) and the EORTC QLQ-C30 & EORTC QLQ – H&N35. QOL was also assessed using the EORTC QLQ-C30 & EORTC QLQ – H&N35. Results: Twenty-nine patients were enrolled in the study between August 2014 and March 2015. A total of twenty-three patients were included in the analysis after exclusion of patients who were not tested at day 30 post-HSCT. Sixteen participants were tested at baseline, day 30 and day 80. The primary finding of this study is the decreased sensitivity (hypoguesia) for citric acid on day 30 and day 80 following HSCT; citric acid intensity was partially recovered by day 80. Increased sensitivity (hyperguesia) to a single concentration of sucrose at day 30 and a single concentration of NaCl at day 80 were also observed. Olfactory identification scores were unchanged from baseline to day 30. Results of the QOL data analysis indicated that most patients quality of life was reduced at 30 days post-transplant, however, quality of life was restored to an acceptable level of functioning and symptoms by 80 days after HSCT. Notably, some areas remain impaired, such as social functioning and dry mouth. Conclusion: Patient reports of altered taste function were collaborated by objective testing. Taste was not reduced across the board, however. Rather specific declines in sour (citric acid) perception were noted. Selective hypersensitivity was seen for some taste solutions. No obvious issues were found with olfactory function in relation to HSCT. It would be helpful if future investigations confirm our results with a larger number of patients. That would aid in developing food products and/or nutritional supplements that appeal to patients experiencing altered taste functions post HSCT
Analysis of the Use of Antibiotics in the United Arab Emirates
Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Social and Clinical Pharmacy Candidate PharmDr. Abobakr Abasaeed Elhag Supervisor prof. RNDr. Jiří Vlček, CSc. Title of Doctoral Thesis Analysis of the Use of Antibiotics in the United Arab Emirates Introduction and Aims: The misuse of antibiotics for viral infections (for which they are of no value) and the immoderate use of broad spectrum antibiotics instead of narrower spectrum antibiotics have been well-documented and reported. Therefore the inappropriate use of antibiotics is getting a global problem, mainly in the developing countries. Emergence of antibiotics resistance is often a result of irrational prescribing patterns, misuse of the antibiotics as well as self-medication. Although the United Arab Emirates (UAE]) antimicrobial policy restricts dispensing of antibiotics without prescription , studies revealed the wide availability of these agents over the counter (OTC), their over prescribing pattern and the high prevalence of self-medication with antibiotics, unfortunately and regardless of this results, there is a lack and paucity in studies that tracking the prevalence of antibiotics resistance. The aim of our research was to evaluate the attitude of the community towards the use of antibiotics, estimate..
Modeling, Simulation and Bifurcation Analysis of a Mutating Autocatalytic Reaction
In this paper, we present a conceptual model for autocatalytic reactions in which the autocatalyst undergoes a mutation process in a continuous stirred tank reactor. Three cases with different mutation coefficient (a) have been considered. The analysis of these cases shows the importance of this parameter and the qualitative and quantitative differences in the resulting bifurcation diagrams. Generally speaking, selectivity towards main product increases with decreasing substrate conversion. Co-existence of a mushroom and an isola has been determined for one of the cases. The isola portion is a low main product yield solution and is to be avoided. Keywords: Autocatalytic reactions, mutation, bifurcation, selectivit
- …