Search results for: alkalinization

Authors: Mochamad Chalid, Imam Prabowo

Abstract:

The pollution due to non-degradable material such as plastics, has led to studies about the development of environmental-friendly material. Because of biodegradability obtained from natural sources, polylactid acid (PLA) and ijuk fiber are interesting to modify into a composite. This material is also expected to reduce the impact of environmental pollution. Surface modification of ijuk fiber through alkalinization with 0.25 M NaOH solution for 30 minutes, was aimed to enhance it’s compatibility to PLA, in order to improve properties of the composite such as the mechanical properties. Alkalinization of the ijuk fibers annihilates some surface components such as lignin, wax and hemicelloluse, so the pore on the surface clearly appeared, decreasing of the density and diameter of the ijuk fibers. The change of the ijuk fiber properties leads to increase the mechanical properties of PLA composites reinforced the ijuk fibers through strengthening of the mechanical interlocking with the PLA matrix. An addition to enhance the distribution of the fibers in the PLA matrix, the stirring during DCM solvent evaporation from the mixture of the ijuk fibers and the dissolved-PLA can reduce amount of the trapped-voids and fibers pull-out phenomena, which can decrease the mechanical properties of the composite.

Keywords: polylactic acid, Arenga pinnata, alkalinization, compatibility, adhesion, morphology, mechanical properties, volume fraction, distributiom

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Authors: J. S. S. Neto, R. A. A. Lima, D. K. K. Cavalcanti, J. P. B. Souza, R. A. A. Aguiar, M. D. Banea

Abstract:

In the last decade, investments in sustainable processes and products have gained space in several segments, such as in the civil, automobile, textile and other industries. In addition to increasing concern about the development of environmentally friendly materials that reduce, energy costs and reduces environmental impact in the production of these products, as well as reducing CO2 emissions. Natural fibers offer a great alternative to replace synthetic fibers, totally or partially, because of their low cost and their renewable source. The purpose of this research is to study the effect of surface chemical treatment on the thermal properties of hybrid fiber reinforced natural fibers (NFRC), jute + ramie, jute + sisal, jute + curauá, and jute fiber in polymer matrices. Two types of chemical treatment: alkalinization and silanization were employed, besides the condition without treatment. Differential scanning calorimetry (DSC), thermogravimetry (TG) and dynamic-mechanical analysis (DMA) were performed to explore the thermal stability and weight loss in the natural fiber reinforced composite as a function of chemical treatment.

Keywords: chemical treatment, hybrid composite, jute, thermal

Procedia PDF Downloads 285

Authors: Leili Iranirad, Mohammad Saleh Sadeghi, Seyed Fakhreddin Hejazi, Negar Vakili Razlighi

Abstract:

Objective: Contrast-induced nephropathy (CIN) or contrast-induced acute kidney injury (CI-AKI) is an unknown acute kidney injury (AKI) occurring after exposure to contrast media (CM). Contrast agents are most often used for diagnostic procedures or therapeutic angiographic interventions. Recently, Na/K citrate as a urine alkalinization has been evaluated for the prevention of CIN. We conducted this experiment to evaluate the efficiency of Na/K citrate on CIN in high-risk patients treated with cardiac catheterization. Methods: A prospective randomized clinical trial was conducted on 400 patients having moderate to high-risk factors for CIN treated with elective percutaneous coronary intervention (PCI) and were assigned randomly to the control group or the Na/K citrate group. The Na/K citrate group (n=200) received 5 g Na/K citrate solution, which was diluted in 200 mL water two h before and four hours after the first administration and intravenous hydration for two h prior to and six h after the procedure, while the control group (n=200) only received intravenous hydration. Serum creatinine (SCr) was calculated prior to the contrast exposure and after 48 h. CIN was described as a 25% increase in creatinine of serum (SCr) or >0.5 mg/dl 48 h after contrast administration. Results: CIN was observed in 33 patients (16.5%) in the control group and in 6 patients (3%) in the Na/K citrate group. A significant variation was recorded in the CIN incidence between the two groups 48 h after the radiocontrast agent administration (p < 0.001). Conclusion: Our results show that Na/K citrate is useful and substantially reduces the incidence of CIN.

Keywords: contrast media, citrate, PCI

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