Single Stage (single + stage)

Distribution by Scientific Domains


Selected Abstracts


Single stage and double absorption heat transformers used to recover energy in a distillation column of butane and pentane

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2003
W. Rivera
This paper presents the theoretical analysis of the use of single stage and double absorption heat transformers operating with the water,lithium bromide mixture coupled to a butane and pentane distillation column in a Mexican refinery. A mathematical model of the heat transformers was developed in FORTRAN and integrated as a user model to the Aspen Plus simulation code. Both components coupled to the column were modelled on steady-state conditions. The results show that it is theoretically possible to reduce the energy consumed in the reboiler between 26 and 43% by the use of single stage heat transformer at specific conditions, and between 28 and 33% with double absorption heat transformers for a wide range of operating conditions. Copyright © 2003 John Wiley & Sons, Ltd. [source]


Comparison of the microbial population dynamics and phylogenetic characterization of a CANOXIS reactor and a UASB reactor degrading trichloroethene

JOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2005
O. Tresse
Abstract Aims:, To understand the microbial ecology underlying trichloethene (TCE) degradation in a coupled anaerobic/aerobic single stage (CANOXIS) reactor oxygenated with hydrogen peroxide (H2O2) and in an upflow anaerobic sludge bed (UASB) reactor. Methods and Results:, The molecular study of the microbial population dynamics and a phylogenetic characterization were conducted using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). In both reactors, TCE had a toxic effect on two uncultured bacterial populations whereas oxygen favoured the growth of aerobic species belonging to Rhizobiaceae and Dechloromonas. No methanotrophic bacteria were detected when targeting 16S rRNA gene with universal primers. Alternatively, pmo gene encoding the particulate methane monooxygenase of Methylomonas sp. LW21 could be detected in the coupled reactor when H2O2 was supplied at 0·7 g O2 l day,1. Conclusions:,Methylomonas sp. LW21 that could be responsible for the aerobic degradation of the TCE by-products is not among the predominant bacterial populations in the coupled reactor. It seems to have been outcompeted by heterotrophic bacteria (Rhizobiaceae and Dechloromonas sp.) for oxygen. Significance and Impact of the Study:, The results obtained show the limitations of the coupled reactor examined in this study. Further investigations should focus on the operating conditions of this reactor in order to favour the growth of the methanotrophs. [source]


Mitral Valve Replacement with the Beating Heart Technique in a Patient with Previous Bypass Graft from Ascending to Descending Aorta due to Aortic Coarctation

JOURNAL OF CARDIAC SURGERY, Issue 2 2008
Ferit Cicekcioglu M.D.
In this case, MVR was performed with on-pump beating heart technique without cross-clamping the aorta because of the diffuse adhesion around the ascending aorta, and tube graft presence between ascending and descending aortas. Methods: A 47-year-old female patient had aorto-aortic bypass graft from ascending aorta to descending aorta with median sternotomy and left thoracotomy in single stage because of aortic coarctation 2 years ago in our cardiac center. She was admitted to the hospital with palpitation and dyspnea on mild exertion. Transthoracic echocardiography revealed 4th degree mitral insufficiency. Results: MVR was carried out through remedian sternotomy with on-pump beating heart technique without cross-clamping the aorta. Conclusions: MVR with on-pump beating heart technique offers a safe approach when excessive dissection is required to place cross-clamp on the ascending aorta. [source]


Ward reduction of gastroschisis in a single stage without general anaesthesia may increase the risk of short-term morbidities: Results of a retrospective audit

JOURNAL OF PAEDIATRICS AND CHILD HEALTH, Issue 6 2009
Shripada C Rao
Background: Ward reduction of gastroschisis in a single stage without the need for general inhalational anaesthesia (ward reduction) has been reported by some authors to be effective and safe. We introduced this practice to our neonatal unit 2 years ago. Aim: To compare the short-term outcomes of this new practice with the standard procedure of reduction under general anaesthesia (GA). Methods: Retrospective case series of all infants with gastroschisis between January 2004 and January 2008. Results: Twenty-seven infants were managed with the traditional approach and 11 infants underwent ward reduction without GA. Infants in the ward reduction group had an increased frequency for all the three major adverse events (ischemic necrosis of bowel: 27.3% vs. 3.7%, odds ratio (OR) 10.72, 95% confidence interval (CI): 0.72, 159.6; need for total parenteral nutrition (TPN) more than 60 days: 18% vs. 3.7%, OR 4.13, 95% CI: 0.28, 61.55; and unplanned return to theatre: 27.3% vs. 7.4%, OR 3.88, 95% CI: 0.44, 34.08), although none of these events reached statistical significance. There were no significant differences between the groups for the outcomes of time to reach full feeds, duration of hospital stay and number of days on antibiotics. Conclusions: These results raise concerns over the role of ward reduction of gastroschisis in a single sitting without the use of GA. Randomised trials with appropriate design and sample size are needed before embracing this method as a standard practice. [source]


Ion imprinted polymer particles for separation of yttrium from selected lanthanides

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 9 2006
Ramakrishnan Kala
Abstract Lanthanide(III) (Dy, Gd, Tb and Y) ion imprinted polymer (IIP) materials were synthesized via single pot reaction by mixing lanthanide imprint ion with 5,7-dichloroquinoline-8-ol, 4-vinylpyridine, styrene, divinylbenzene and 2,2,-azobisisobutyronitrile in 2-methoxyethanol porogen. The imprint ion was removed by stirring the above materials (after powdering) with 6 mol/L HCl to obtain the respective lanthanide IIP particles. Y-Dy, Y-Gd and Dy-Gd polymer particles were obtained by physically mixing equal amounts of the respective leached individual lanthanide(III) particles. Control polymer (CP) particles were similarly prepared without imprint ion. Application of the above synthesized polymer particles was tested for separation of Y from Dy, Gd and Tb employing batch and column SPE methods using inductively coupled plasma atomic emission spectrometry for the determination. Optimization studies show that Y present in 500 mL can be preconcentrated using Dy-Gd IIP particles and eluted with 20 mL of 1.0 mol/L of HCl, providing an enrichment factor of , 25. Dy-Gd IIP particles offer higher selectivity coefficients for Y over other lanthanides compared to other IIP particles and commercial liquid,liquid extractants. Selectivity studies for Y over other coexisting inorganic species (other than lanthanides) were also conducted and the results obtained show a quantitative separation of Y from other inorganics other than Cu(II) and Fe(III). Furthermore, both batch and column studies indicate the purification of yttrium concentrate from 55.0 ± 0.2 to 65.2 ± 0.2% in a single stage of operation. [source]


One-stage reconstruction of the complex midfoot defect with a multiple osteotomized free fibular osteocutaneous flap: Case report and literature review

MICROSURGERY, Issue 1 2010
Efstathios G. Lykoudis M.D., Ph.D.
Complex midfoot defects represent a reconstructive challenge since midfoot plays a key role in standing and gait. We report the case of a 27-year-old patient with a complex midfoot defect due to a high-energy gun shot injury. The defect included the tarsometatarsal complex, all three arches of the foot, and the overlying dorsal skin of the foot. Reconstruction was achieved in a single stage with a free fibular osteocutaneous flap. The fibula was osteotomized into three segments, which were used to reconstruct the bone defects, while the skin paddle of the flap was used for stable soft tissue coverage of the reconstructed bony skeleton. Early and late postoperative periods were uneventful. Bone incorporation was radiographically evident at 12 weeks, and full weight bearing was possible at 6 months postop. Final follow up, at 2 years postop, showed a very good functional and esthetic outcome. © 2009 Wiley-Liss, Inc. Microsurgery, 2010. [source]


Microsurgical treatment for bilateral thumb defect: Five case reports

MICROSURGERY, Issue 6 2003
Lei Xu M.D., Ph.D.
The authors present a new and efficient treatment for reconstruction of bilateral defective thumbs by different configured toe-tissuestransplantations in a single stage, including bilateral second-toe transfer in 2 cases, bilateral hallux wrap-around flap transfer in 1 case, bilateral modified hallux wrap-around flap transfer in 1 case, and combined second toe with island flap with neurovascular pedicles from the proximal and dorsal aspect of the index finger transfer in 1 case. In total, eight transferred tissues survived uneventfully after circulation monitor and medicine administration according to the rules of microsurgery, and in two other transferred toe tissues, temporary circulation crises occurred. Over a 1-year follow-up, the satisfactory appearance and excellent function of the reconstructed bilateral thumbs were noted. For ensuring the success of the procedure, the authors emphasize the establishment of a double artery supply and venous return-flow systems and the modification of the hallux wrap-around flap dissection and tendon repair. Meanwhile, three-stage systemically functional rehabilitations also improved functional restoration of reconstructed thumbs. © 2003 Wiley-Liss, Inc. MICROSURGERY 23:547,554 2003 [source]


Continuous accumulation games on discrete locations

NAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 1 2002
Kensaku Kikuta
Abstract In an accumulation game, a HIDER attempts to accumulate a certain number of objects or a certain quantity of material before a certain time, and a SEEKER attempts to prevent this. In a continuous accumulation game the HIDER can pile material either at locations $1, 2, ,, n, or over a region in space. The HIDER will win (payoff 1) it if accumulates N units of material before a given time, and the goal of the SEEKER will win (payoff 0) otherwise. We assume the HIDER can place continuous material such as fuel at discrete locations i = 1, 2, ,, n, and the game is played in discrete time. At each time k > 0 the HIDER acquires h units of material and can distribute it among all of the locations. At the same time, k, the SEEKER can search a certain number s < n of the locations, and will confiscate (or destroy) all material found. After explicitly describing what we mean by a continuous accumulation game on discrete locations, we prove a theorem that gives a condition under which the HIDER can always win by using a uniform distribution at each stage of the game. When this condition does not hold, special cases and examples show that the resulting game becomes complicated even when played only for a single stage. We reduce the single stage game to an optimization problem, and also obtain some partial results on its solution. We also consider accumulation games where the locations are arranged in either a circle or in a line segment and the SEEKER must search a series of adjacent locations. © 2002 John Wiley & Sons, Inc. Naval Research Logistics, 49: 60,77, 2002; DOI 10.1002/nav.1048 [source]


Genesis and Age Constraints on Gold Deposits of the Daerae Mine, Sangju Area, Central-Northern Sobaegsan Massif, Korea

RESOURCE GEOLOGY, Issue 3 2001
Seong, Taek YUN
Abstract: Gold mineralization of the Daerae mine represents the first recognized example of the Jurassic gold mineralization in the Sangju area, Korea. It occurs as a single stage of quartz veins that fill fault fractures in Precambrian gneiss of the central-northern Sobaegsan Massif. The mineralogical characteristics of quartz veins, such as the simple mineralogy and relatively gold-rich (65,72 atomic % Au) nature of electrum, as well as the CO2,rich and low salinity nature of fluid inclusions, are consistent with the ,mesothermal-type' gold deposits previously recognized in the Youngdong area (about 50 km southwest of the Sangju area). Ore fluids were evolved mainly through CO2 immiscibility at temperatures between about 250 and 325 C. Vein sulfides characteristically have negative sulfur isotopic values (,1.9 to +0.2 %), which have been very rarely reported in South Korea, and possibly indicate the derivation of sulfur from an ilmenite-series granite melt. The calculated O and H isotopic compositions of hydrothermal fluids at Daerae (,18Owater = +5.2 to +5.9 %; ,Dwater = ,59 to ,67 %) are very similar to those from the Youngdong area, and indicate the important role of magmatic water in gold mineralization. The 40Ar,39Ar age dating of a pure alteration sericite sample yields a high-temperature plateau age of 188.3 0.1 Ma, indicating an early Jurassic age for the gold mineralization at Daerae. The lower temperature Ar-Ar plateau defines an age of 158.4 2.0 Ma (middle Jurassic), interpreted as reset by a subsequent thermal effect after quartz vein formation. The younger plateau age is the same as the previously reported K-Ar ages (145,171 Ma) for the other ,mesothermal,type' gold deposits in the Youngdong and Jungwon areas, Korea, which are too young in view of the new Jurassic Ar-Ar plateau age (around 188 Ma). [source]


Outcomes of dental implants placed in a surgical training programme

AUSTRALIAN DENTAL JOURNAL, Issue 4 2009
LP Smith
Abstract Background:, This study evaluates surgical outcomes and survival rates of implants placed in a multidisciplinary implant teaching programme. Methods:, A retrospective review of all implant surgery performed over a 6-year period by accredited oral and maxillofacial surgery trainees at the Royal Dental Hospital of Melbourne was undertaken. Patients were reviewed for a minimum of 6 months post-implant placement. Implant survival was defined as those implants which were not removed, were clinically integrated as assessed by torque testing and in an appropriate position to receive a subsequent prosthesis. Kaplan-Meier analysis was used to assess overall survival and univariate factors affecting survival. Multivariate analysis used Cox proportional hazards models. Results:, Over 6 years, 127 patients were treated. Follow-up data were present for 105 patients with 236 implants placed. Survival of implants at 1 and 5 years was 94 per cent and 92.8 per cent, respectively. The only univariate and multivariate factor which affected implant survival was perioperative bone grafting. All failed implants were single stage. Other factors such as patient age, smoking status, implant site, anaesthetic type, immediate or delayed placement, implant length and diameter, and medical comorbidities did not significantly affect implant survival. Conclusions:, A satisfactory implant survival rate was found in a tertiary teaching centre. Perioperative bone grafting significantly increased the risk of implant failure. [source]


Efficiency Optimization and Prediction in High-Gradient Magnetic Centrifugation

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 8 2010
J. Lindner
Abstract In order to separate small magnetizable particles down to the micro- and nanometer scale, high-gradient magnetic separation is a well-established process. The superposition of magnetic filtration with centrifugation, called magnetic field-enhanced centrifugation, permits continuous separation. The separation efficiency of magnetic filters and the prediction of the efficiency is described. The separation efficiency of one single stage could be enhanced from 51 to 78,% by increasing the wire number and improving the wire cross section. The separation efficiency on different particle sizes at different filter stage numbers and comparison to the prediction of separation efficiency based on magnetic forces and the fluid drag force is demonstrated. [source]


Enhance Cyanide Recovery by UsingAir-Sparged Hydrocyclone

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 4 2003
J.R. Parga Torres
Abstract Human health and environmental concerns dictate that industrial processes be improved or replaced. Recovery or recycling is an important activity that allows cyanide residue from the industrial processes to be re-used, reducing its production cost and disposal problems. In this regard, the air-sparged hydrocyclone (ASH) has been used as a reactor for the treatment of cyanide solutions for cyanide recycling by acidification/volatilization using the Mexican modification of the Mills-Crowe process. Aqueous cyanide-ion concentration can be reduced from 250 ppm to below 20 ppm in the ASH with recoveries greater than 80 % in a single stage. [source]