| 1. |
- Ademuyiwa, Adesoji O., et al.
(författare)
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Determinants of morbidity and mortality following emergency abdominal surgery in children in low-income and middle-income countries
- 2016
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Ingår i: BMJ Global Health. - : BMJ Publishing Group Ltd. - 2059-7908. ; 1:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Child health is a key priority on the global health agenda, yet the provision of essential and emergency surgery in children is patchy in resource-poor regions. This study was aimed to determine the mortality risk for emergency abdominal paediatric surgery in low-income countries globally.Methods: Multicentre, international, prospective, cohort study. Self-selected surgical units performing emergency abdominal surgery submitted prespecified data for consecutive children aged <16 years during a 2-week period between July and December 2014. The United Nation's Human Development Index (HDI) was used to stratify countries. The main outcome measure was 30-day postoperative mortality, analysed by multilevel logistic regression.Results: This study included 1409 patients from 253 centres in 43 countries; 282 children were under 2 years of age. Among them, 265 (18.8%) were from low-HDI, 450 (31.9%) from middle-HDI and 694 (49.3%) from high-HDI countries. The most common operations performed were appendectomy, small bowel resection, pyloromyotomy and correction of intussusception. After adjustment for patient and hospital risk factors, child mortality at 30 days was significantly higher in low-HDI (adjusted OR 7.14 (95% CI 2.52 to 20.23), p<0.001) and middle-HDI (4.42 (1.44 to 13.56), p=0.009) countries compared with high-HDI countries, translating to 40 excess deaths per 1000 procedures performed.Conclusions: Adjusted mortality in children following emergency abdominal surgery may be as high as 7 times greater in low-HDI and middle-HDI countries compared with high-HDI countries. Effective provision of emergency essential surgery should be a key priority for global child health agendas.
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| 2. |
- Thomas, HS, et al.
(författare)
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- 2019
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swepub:Mat__t
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| 3. |
- Abrahamsson, K, et al.
(författare)
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Application of heat pump systems for energy conservation in paper drying
- 1997
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Ingår i: International Journal of Energy Research. - 0363-907X. ; 21:7, s. 631-642
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Tidskriftsartikel (refereegranskat)abstract
- Drying is one of the most energy intensive and common operations in the chemical and process industries. Scope for energy recovery is substantial, particularly from the latent heat of the exhaust moist air. Using real operating data from a major Swedish mill, optimal energy conservation strategies were investigated using different heat pump systems in paper drying. Simulation results are compared for compressor-driven and absorption heat pump systems. An absorption heat transformer was also investigated. A CH3OH-LiBr double-lift cycle would have a low COP value due to the low temperature of the moist air stream and the restricted temperature of the cooling water available. A total of 30 MW thermal equivalent is currently needed in the mill at a temperature of 75 degrees C for mixing-pits, district heating and a log store. Exhaust humid air at a temperature of 54 degrees C from only three of the paper machines was used in this study. SHPUMP simulations revealed that installing a mechanical heat pump unit using HFC 134a would result in a recovery of 22 MW due to the temperature level of this application. On the other hand, 12 MW can be recovered with an absorption heat pump. To optimize the operating conditions, H2O-NaOH was selected as the best of three based on exergy index criteria. Assuming a steam cost of 22 $/MW h and an electricity cost of 32 $/MW h, the pay-off periods would be 3.3 and 2.9 years for compressor-driven and absorption heat pump alternatives, respectively. (C) 1997 by John Wiley & Sons, Ltd.
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| 4. |
- Aly, Gharib, et al.
(författare)
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Denickling of fatty acid pitch
- 1993
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Ingår i: Journal of the American Oil Chemists Society. - 0003-021X. ; 70:2, s. 193-197
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Tidskriftsartikel (refereegranskat)abstract
- Unsaturated fatty acids are usually hydrogenated with a nickel catalyst. As a side reaction, nickel dissolves in the fatty acids and forms nickel soaps. On refining the crude fatty acid feedstock by distillation, these nickel soaps are enriched in the bottom fraction (pitch) to a concentration range of 2,500-5,500 ppm. With a heat value comparable to heavy fuel oil, the pitch has been used as fuel. However, due to new environmental restrictions, the nickel concentration must be considerably reduced to limit gas emission of nickel. In this study, solvent extraction was investigated as a separation method for denickling of this valuable oleochemical by-product. At a temperature of 80-degrees-C, the nickel content in the pitch was reduced from 2,900 ppm to 4 ppm in three extraction steps by means of 1 wt% citric acid in water. Based on experimental results, a preliminary process flowsheet is presented consisting of extraction, stripping, acid washing and electrolysis. An economic analysis, performed on the extraction process and a process based on direct combustion followed by electrostatic precipitation revealed that direct combustion is economically more advantageous. However, the compatibility of the extraction alternative can be considerably improved by process optimization. The type and concentration of the stripping and acid washing agents, phase ratios, temperature, ionic strength and the equilibrium pH of the aqueous and acid phases are important process parameters that should be considered in the optimization process.
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| 5. |
- Aly, Gharib, et al.
(författare)
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Dynamical behavior of mixer settlers II: Models and identification
- 1972
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Ingår i: Journal of Applied Chemistry and Biotechnology. - : Wiley. - 0375-9210. ; 22:11, s. 1165-1184
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Tidskriftsartikel (refereegranskat)abstract
- Mathematical models explaining the dynamics of the mixer-settler unit are investigated. It is shown that the static model is inadequate in this context and a two-part dynamic model is proposed.
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| 6. |
- Aly, Gharib, et al.
(författare)
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Simulation and design of distillation units for treatment of sulphite pulping condensates to recover methanol and furfural. Part II: Applicability of multi-effect distillation using live steam
- 1979
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Ingår i: Canadian Journal of Chemical Engineering. - : Wiley. - 0008-4034 .- 1939-019X. ; 57:3, s. 316-320
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Tidskriftsartikel (refereegranskat)abstract
- A distillation unit has been designed for a capacity of 73 t/h of condensate and for at least 90% recovery of the contaminating organics. This unit consists of three columns: a primary stripper to remove volatile organics and two upgrading columns to purify the methanol and furfural byproducts. Three different energy-saving alternatives for satisfying the energy requirements have been studied: utilisation of secondary steam from the evaporation plant, and application of the principle of multi-effect distillation in one-stripper and in two-stripper configurations. Investment cost needed in all alternatives amounts to 5.5–6.0 MCr (millions of Swedish Crowns) while operating cost varies between 0.8–3.1 MCr. The first design alternative has a payoff period of 2.3 years while the two multi-effect distillation alternatives have a payoff period of about 3 years.
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| 7. |
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| 8. |
- Stenström, Stig, et al.
(författare)
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Extraction of cadmium from phosphoric acid solutions with amines Part I. Extractant selection, stripping, scrubbing and effects of other components
- 1985
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Ingår i: Hydrometallurgy. - 0304-386X. ; 14:2, s. 231-255
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Tidskriftsartikel (refereegranskat)abstract
- Cadmium can be effectively removed from wet-process phosphoric acid (WPA) by solvent extraction using long-chain amines, preferably tertiary amines, as extractants. Stripping can be performed either with water or with acids such as phosphoric or sulphuric acid depending on the final conversion of the cadmium waste. Scrubbing could be necessary in some cases and can be performed with alkali. A factorial design experiment was performed to determine the effects of four different components (H2SO4, HCl, HF, H2SiF6) in WPA on cadmium extraction with Alamine 336. The largest influence on cadmium extraction is seen for the hydrochloric acid, drastically increasing the distribution coefficient. Variations of the concentrations of H3PO4, HCl, HF, Fe and Al were also studied. The extraction of cadmium was seen to be strongly dependent on phosphoric acid concentration. A simple extraction model is proposed indicating that CdCl42− ions are extracted.
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| 9. |
- Stenström, Stig, et al.
(författare)
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Extraction of cadmium from phosphoric acid solutions with amines Part II. Diluent selection, flow-sheet configuration, pilot plant operation
- 1985
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Ingår i: Hydrometallurgy. - 0304-386X. ; 14:2, s. 257-276
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Tidskriftsartikel (refereegranskat)abstract
- A large number of diluents were screened to determine the optimum combination between diluent and extractant. Combinations of a C8 tertiary amine and aromatic diluents or of a C12 tertiary amine and aliphatic diluents do not lead to third-phase formation. A flow-sheet for a solvent-extraction process for treatment of various qualities of wet-process phosphoric acid solutions is proposed. Based on a cadmium purification level of 1 mg/kg, extraction, stripping and scrubbing sections of the process would contain two, two and one stages, respectively. A solvent pre-treatment stage may be necessary in some cases. Co-extraction of acids such as H3PO4, H2SO4, HCI, HF and H2SiF6 can be decreased to very low values by manipulating process variables such as pre-equilibration, phase ratios, diluent and amine concentration. Co-extraction of cations other than cadmium was also investigated. Iron, aluminium and magnesium are not co-extracted while zinc and calcium are co-extracted to some extent. The proposed process can be used either for pollution abatement or in combination with other purification processes to recover some of the valuable cations such as uranium, or to produce more refined phosphoric acid streams.
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| 10. |
- Stenström, Stig, et al.
(författare)
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Solvent Extraction of Phosphoric Acid with Long Chain Tertiary Amines
- 1986
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Ingår i: Solvent Extraction and Ion Exchange. - : Informa UK Limited. - 0736-6299 .- 1532-2262. ; 4:5, s. 883-905
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Tidskriftsartikel (refereegranskat)abstract
- Solvent extraction of phosphoric acid with Alamine 336 and tri-n-octylamine in toluene has been investigated. The activity of phosphoric acid is expressed as a polynomial of ionic strength and Bromley's model for electrolyte solutions is employed for calculation of ionic activity coefficients. Three species R3N (H3P04) n with n = 1, 2 and 3 in the organic phase are taken into account for explanation of the distribution equilibria. The extraction constants have been determined as log K11 = 2.05, log K12 = 3.61 and log K13 = 3.84 respectively. Aggregation and other non-ideal behaviour in the organic phase are described by letting the corresponding activity coefficient quotients be a function of the total concentration of acid in the organic phase.
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