15 research outputs found

    Advancing Compressive Strength Prediction in Self-Compacting Concrete via Soft Computing: A Robust Modeling Approach

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    Self-Compacting Concrete (SCC) is a unique type of concrete that can flow and fill spaces without the need for vibrating compaction, resulting in a dense and uniform material. This article focuses on predicting the compressive strength of SCC using Artificial Neural Networks. Specifically, the study employs multilayer perceptrons with back-propagation learning algorithms, which are commonly used in various problem-solving scenarios. The study covers essential components such as structure, algorithm, data preprocessing, over-fitting prevention, and sensitivity analysis in MLPs. The input variables considered in the research include cement, limestone powder, fly ash, ground granulated blast furnace slag, silica fume, rice husk ash, coarse aggregate, fine aggregate, water, super-plasticizer, and viscosity-modifying admixtures. The target variable is the compressive strength. Through a sensitivity analysis, the study evaluates the relative importance of each parameter. The results demonstrate that the AI-based model accurately predicts the compressive strength of self-compacting concrete

    Amino acid-mPEGs: Promising excipients to stabilize human growth hormone against aggregation

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    Objective(s): Today, the non-covalent PEGylation methods of protein pharmaceuticals attract more attention and possess several advantages over the covalent approach. In the present study, Amino Acid-mPEGs (aa-mPEGs) were synthesized, and the human Growth Hormone (hGH) stability profile was assessed in their presence and absence.Materials and Methods: aa-mPEGs were synthesized with different amino acids (Trp, Glu, Arg, Cys, and Leu) and molecular weights of polymers (2 and 5 KDa). The aa-mPEGs were analyzed with different methods. The physical and structural stabilities of hGH were analyzed by SEC and CD spectroscopy methods. Physical stability was assayed at different temperatures within certain intervals. Molecular dynamics (MD) simulation was used to realize the possible mode of interaction between protein and aa-mPEGs. The cell-based method was used to evaluate the cytotoxicity.Results: HNMR and FTIR spectroscopy indicated that aa-mPEGs were successfully synthesized. hGH as a control group is known to be stable at 4 °C; a pronounced change in monomer degradation is observed when stored at 25 °C and 37 °C. hGH:Glu-mPEG 2 kDa with a molar ratio of 1:1 to the protein solution can significantly increase the physical stability. The CD spectroscopy method showed that the secondary structure of the protein was preserved during storage. aa-mPEGs did not show any cytotoxicity activities. The results of MD simulations were in line with experimental results.Conclusion: This paper showed that aa-mPEGs are potent excipients in decreasing the aggregation of hGH. Glu-mPEG exhibited the best-stabilizing properties in a harsh environment among other aa-mPEGs

    Prioritizing of Strategy Implementation Obstacles among Energy sector's Contractors Using Fuzzy TOPSIS Method

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    The main purpose of this practical survey is devoted to identify the obstacles of strategic plan implementation among energy sector's contractors and then, to present a classification of identified obstacles on the basis of their priorities. In order to achieve this purpose, 8 factors were chosen as the obstacles of strategic plans in energy sector following the literature review and experts comments, and then applied to 87 managers and senior experts of strategic planning in contracting firms by a questionnaire. The Fuzzy TOPSIS technique is assumed as a well-known Multiple-criteria Decision Making (MCDM) approach. Results showed that organizational structure was received the most priority as an obstacle in implementing strategic plan in contracting industry and operational planning, resource allocation, quality of strategy, communication, strategy executors, control and commitment got subsequent ranks. So, findings of this survey could improve the efficiency of contracting firm's managers to direct the process of strategy implementation and to overcome on identified obstacle

    Impact of Dialysis on Open Cardiac Surgery

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    Background: Dialysis patients frequently have coronary artery disease but are regarded as high risk patients for coronary artery bypass grafting (CABG). Methods: Between February 2002 and September 2006, seventeen dialysis-dependent patients underwent isolated CABG at our center. CABG was performed under cardiopulmonary bypass (CPB) for all the patients. All cases had been maintained on hemodialysis and the duration of preoperative hemodialysis ranged from 6 to 24 months (mean 13.4±6.4). The patients’ characteristics, clinical and operative data as well as perioperative and mid-term outcome were reviewed. Results: All patients were men with a mean age of 53±8.4 years. Mean preoperative ejection fraction was 45.5%±10.4% (range 25 to 60 %). One internal mammary graft was used in 16 (94.1%) patients. Cardiopulmonary bypass and aortic cross-clamp times were 71.3±18.7 and 40.5±8.3 minutes respectively. The more frequent complication was prolonged mechanical ventilation in 2 (11.7%), there was no perioperative mortality. In mid-term follow-up (mean time: 11.8±9.5 months) the mid-term mortality rate was 20% (3 patients). Conclusion: CABG in chronic renal dialysis patients can be accomplished with acceptable short and mid-term morbidity and mortality
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