16 research outputs found
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Investigation of hard-burn and soft-burn lime kiln dust as alternative materials for alkali-activated binder cured at ambient temperature
Copyright © 2020 The Author(s). As climate change becomes a severe concern, the development of green technology becomes a goal for many sectors, including the construction material sector. Ordinary Portland cement (OPC), the main constituent of concrete production, is a primary contributor to releasing carbon dioxide (CO2) into the atmosphere. Some alternative cementitious materials have been studied to reduce the massive amount of OPC consumption. Lime kiln dust (LKD), a by-product of quicklime production, is produced in abundance worldwide and mostly disposed of in landfills. The two types of LKD, soft-burn and hard-burn, are high-potential wastes that can be developed as alternative cementitious binders using the alkali-activated binder (AAB) technology. This study investigates the mixture designation and properties of LKD-based AAB when cured at ambient temperature. The results show that an ambient-cured soft-burn LKD-AAB achieved practical workability with an 8 M NaOH solution, 1.50 of sodium silicate-to-sodium hydroxide ratio (SS/SH), and 0.60 of liquid alkaline-to-binder ratio (L/B). A rapid setting behavior and an excellent compressive strength of 10.89 MPa at 28 days were revealed at room temperature curing. The ambient-cured hard-burn LKD-AAB could not provide the appropriate properties. However, the mixture of 20% hard-burn LKD and 80% soft-burn LKD resulted in an LKD-AAB mixture that meets the minimum requirement for low-strength cement applications. The positive outcome of this study may be the solution for of LKD wastes utilization in Thailand that addresses the challenge of developing ambient-cured AAB for in-field applications.Partially supported by Chiang Mai University; the fifth author would like to acknowledge the financial support of the Thailand Research Fund (TRF) under the TRF Distinguished Research Professor Grant No. DPG6180002; financial support and the raw materials for these experiments from Chememan Public Company Limited, Thailand
Effect of different factors on sporulation of Colletotrichum coffeanum
Abstract The effect of different factors on sporulation of Colletotrichum coffeanum was investigated. Result showed that V8 and PDA media were suitable for the growth of C. coffeanmum. On the contrary, the content of the media gave a significant impact on sporulation. The media content increased then it would greatly increase the sporulation. 12 h light/dark photoperiod (12:12 L:D; 10000 lux, fluorescent lamp) was the most suitable light condition for C. coffeanmum sporulation, compared with constant darkness (continuous darkness; CD) and constant illumination (continuous light; CL; 10000 lux, fluorescent lamp). Moreover, the growth rate in the 28 th day showed the fastest growing culture. It is concluded 10 ml PDA medium and incubated 28 days under natural light conditions was the best time of sporulation
Eugenol, α-pinene and β-caryophyllene from Plectranthus barbatus essential oil as eco-friendly larvicides against malaria, dengue and Japanese encephalitis mosquito vectors
Mosquito-borne diseases represent a deadly threat for millions of people worldwide. Eco-friendly mosquitocides are a priority. In Ayurvedic medicine, Plectranthus species have been used to treat heart disease, convulsions, spasmodic pain and painful urination. In this research, we evaluated the acute toxicity of essential oil from Plectranthus barbatus and its major constituents, against larvae of the malaria vector Anopheles subpictus, the dengue vector Aedes albopictus and the Japanese encephalitis vector Culex tritaeniorhynchus. The chemical composition of P. barbatus essential oil was analyzed by gas chromatography–mass spectroscopy. Nineteen components were identified. Major constituents were eugenol (31.12 %), α-pinene (19.38 %) and β-caryophyllene (18.42 %). Acute toxicity against early third-instar larvae of An. subpictus, Ae. albopictus and Cx. tritaeniorhynchus was investigated. The essential oil had a significant toxic effect against larvae of An. subpictus, Ae. albopictus and Cx. tritaeniorhynchus, with 50 % lethal concentration (LC50) values of 84.20, 87.25 and 94.34 μg/ml and 90 % lethal concentration (LC90) values of 165.25, 170.56 and 179.58 μg/ml, respectively. Concerning major constituents, eugenol, α-pinene and β-caryophyllene appeared to be most effective against An. subpictus (LC50 = 25.45, 32.09 and 41.66 μg/ml, respectively), followed by Ae. albopictus (LC50 = 28.14, 34.09 and 44.77 μg/ml, respectively) and Cx. tritaeniorhynchus (LC50 = 30.80, 36.75 and 48.17 μg/ml, respectively). Overall, the chance to use metabolites from P. barbatus essential oil against mosquito vectors seems promising, since they are effective at low doses and could be an advantageous alternative to build newer and safer mosquito control tools