74 research outputs found

    Cement equivalence factor evaluations for fluid catalytic cracking catalyst residue

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    Fluid catalytic cracking catalyst residue (FC3R) is a waste material that can be used as a Portland cement replacement in pastes, mortars, and concrete. The flow table results show that FC3R is a water demanding addition; nevertheless, this effect can be compensated with the use of superplasticizers. The pozzolanic activity of FC3R was studied observing the mechanical strength evolution with time. Pastes and mortars with FC3R incorporated show higher mechanical strengths than control specimens, indicating the pozzolanic activity of the waste. Cement equivalence factor (k-factor) evaluations were carried out. The k-factor values for the FC3R pastes and mortars were always greater than one, indicating that in order to maintain the same compressive mechanical strength of the control specimen it is sufficient to replace cement with a smaller amount of catalyst residue, due to the high pozzolanic activity of FC3R. There is a strong agreement between the k-factor values obtained in pastes and mortars.This work was supported by Ministerio de Ciencia y Tecnologia, Spain (Project MAT 2001-2694).Paya Bernabeu, JJ.; MonzĂł Balbuena, JM.; Borrachero Rosado, MV.; Velazquez Rodriguez, S. (2013). Cement equivalence factor evaluations for fluid catalytic cracking catalyst residue. Cement and Concrete Composites. 39:12-17. https://doi.org/10.1016/j.cemconcomp.2013.03.011S12173

    Costs and Effects of Abdominal versus Laparoscopic Hysterectomy: Systematic Review of Controlled Trials

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    Objective: Comparative evaluation of costs and effects of laparoscopic hysterectomy (LH) and abdominal hysterectomy (AH). Data sources: Controlled trials from Cochrane Central register of controlled trials, Medline, Embase and prospective trial registers. Selection of studies: Twelve (randomized) controlled studies including the search terms costs, laparoscopy, laparotomy and hysterectomy were identified. Methods: The type of cost analysis, perspective of cost analyses and separate cost components were assessed. The direct and indirect costs were extracted from the original studies. For the cost estimation, hospital stay and procedure costs were selected as most important cost drivers. As main outcome the major complication rate was taken. Findings: Analysis was performed on 2226 patients, of which 1013 (45.5%) in the LH group and 1213 (54.5%) in the AH group. Five studies scored >= 10 points (out of 19) for methodological quality. The reported total direct costs in the LH group (63,997)were6.163,997) were 6.1% higher than the AH group (60,114). The reported total indirect costs of the LH group (1,609)werehalfofthetotalindirectintheAHgroup(1,609) were half of the total indirect in the AH group (3,139). The estimated mean major complication rate in the LH group (14.3%) was lower than in the AH group (15.9%). The estimated total costs in the LH group were 3,884versus3,884 versus 3,312 in the AH group. The incremental costs for reducing one patient with major complication(s) in the LH group compared to the AH group was $35,750. Conclusions: The shorter hospital stay in the LH group compensates for the increased procedure costs, with less morbidity. LH points in the direction of cost effectiveness, however further research is warranted with a broader costs perspective including long term effects as societal benefit, quality of life and survival

    Durability of Mortar Incorporating Ferronickel Slag Aggregate and Supplementary Cementitious Materials Subjected to Wet–Dry Cycles

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    This paper presents the strength and durability of cement mortars using 0–100% ferronickel slag (FNS) as replacement of natural sand and 30% fly ash or ground granulated blast furnace slag (GGBFS) as cement replacement. The maximum mortar compressive strength was achieved with 50% sand replacement by FNS. Durability was evaluated by the changes in compressive strength and mass of mortar specimens after 28 cycles of alternate wetting at 23 °C and drying at 110 °C. Strength loss increased by the increase of FNS content with marginal increases in the mass loss. Though a maximum strength loss of up to 26% was observed, the values were only 3–9% for 25–100% FNS contents in the mixtures containing 30% fly ash. The XRD data showed that the pozzolanic reaction of fly ash helped to reduce the strength loss caused by wet–dry cycles. Overall, the volume of permeable voids (VPV) and performance in wet–dry cycles for 50% FNS and 30% fly ash were better than those for 100% OPC and natural sand

    Polymer-modified glass fibre reinforced gypsum

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    Total laparoscopic hysterectomy versus abdominal hysterectomy in the treatment of patients with early stage endometrial cancer:A randomized multi center study

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    BACKGROUND: Traditionally standard treatment for patients with early stage endometrial cancer (EC) is total abdominal hysterectomy and bilateral salpingo oophorectomy (TAH+BSO) with or without lymph node dissection through a vertical midline incision. While TAH is an accepted effective treatment, it is highly invasive, visibly scarring and associated with morbidity. An alternative treatment is the same operation by laparoscopy. Though in several studies total laparoscopic hysterectomy (TLH+ BSO) seems a safe and feasible alternative approach in early stage endometrial cancer patients, there are no randomized data available yet. Furthermore, a randomized controlled trial with surgeons trained in laparoscopy is warranted in order to implement this technique in a safe manner. The aim of this study is to compare the treatment related morbidity, cost-effectiveness and quality of life in early stage endometrial cancer patients treated by laparoscopy versus the standard open approach.METHODS: A multi centre randomized clinical phase 3 trial, including 5 university hospitals and 15 regional hospitals in the Netherlands. Only gynecologists trained in performing a TLH are allowed to participate.INCLUSION CRITERIA: Patients with a clinical stage I endometrioid adenocarcinoma or complex atypical hyperplasia are randomized in a 2:1 allocation to receive TLH or TAH. The main outcome measure is the rate of major complications, as assessed by an independent clinical review board. In total, 275 patients are required to have 80% power at alpha-0.05 to detect a significant difference of 15% complication rate. Secondary outcome measures are 1) costs and cost-effectiveness, 2) minor complications, and 3) quality of life. All data from this multi center study are reported using case record forms. Data regarding quality of life, pain, body Image, sexuality and additional homecare are assessed with self reported questionnaires.DISCUSSION: A randomized multi center study in early stage endometrial cancer patients with inclusion criteria for patients and surgeons is designed and ongoing. Results will be presented at the end of 2009.TRIAL REGISTRATION: Dutch trial register number NTR821.</p
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