Apatite formation on calcined kaolin-white Portland cement geopolymer

In this study, calcined kaolin–white Portland cement geopolymerwas investigated for use as biomaterial. Sodiumhydroxide and sodium silicate were used as activators. In vitro test was performed with simulated body fluid (SBF) for bioactivity characterization. The formation of hydroxyapatite bio-layer on the 28-day soaked samples surface was tested using SEM, EDS and XRD analyses. The results showed that the morphology of hydroxyapatite was affected by the source material composition, alkali concentration and curing temperature. The calcined kaolin–white Portland cement geopolymer with relatively high compressive strength could be fabricated for use as biomaterial. The mix with 50% white Portland cement and 50% calcined kaolin had 28-day compressive strength of 59.0 MPa and the hydroxyapatite bio-layer on the 28-day soaked sample surface was clearly evident.This work was financially supported by the Thailand Research Fund (TRF) and Khon Kaen University under the TRF-Royal Golden Jubilee Ph.D. program (Grant No. PHD/0143/2554) and TRF-Senior Research Scholar (Grant No. RTA5780004)

Bioactivity enhancement of calcined kaolin geopolymer with CaCl2 treatment

This paper reports that surface treatment with CaCl2 enhances the bioactivity of a calcined kaolin geopolymer. Calcined kaolin, NaOH solution, sodium silicate solution, and heat curing were used to form geopolymer pastes. A soaked-treatment method was applied to the geopolymer samples using CaCl2 solution as the ion exchange agent. The bioactivity of the material was determined by the simulated body fluid (SBF) in vitro testing method. Scanning electron microscope images showed a dense apatite formation on the treated geopolymer surface after SBF immersion for only 3 days. The CaCl2 treatment promoted compressive strength and enhanced bioactivity by accelerating apatite precipitation and slowing down the rise in pH.This work was financially supported by the Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission, through the Advanced Functional Materials Cluster of Khon Kaen University; and Khon Kaen University and the Thailand Research Fund (TRF) under the TRF-Royal Golden Jubilee Ph. D. program (Grant no. PHD/0143/2554); Post-doctoral training program (Grant no. 58110), Graduate school, Khon Kaen University and TRF Senior Research Scholar Contract No. RTA5780004.info:eu-repo/semantics/publishedVersio

SIMULATION AND OPTIMIZATION STUDIES OF CATALYZED ESTERIFICATION OF PROPIONIC ANHYDRIDE WITH 2-BUTANOL: BATCH VERSUS SEMI BATCH OPERATION

ABSTRACT A model to represent the catalyzed esterification of propionic anhydride with 2-butanol has been developed and simulated. Two modes of operation i.e. batch and semi batch have been simulated and compared. The performance of both modes of operation has been compared using two performance indicators i.e. amount of conversion and process time. The effect of feed rate (semi batch) and temperature (both batch and semi batch) towards time required to achieve 97% of conversion has been carried out. Then the time required to achieve 97% conversion in semi batch operation has been optimized using Control Vector Parameterization (CVP) technique. It was observed that the highest conversion can be achieved at the lowest dynamic feed rate. For the effect of temperature, it was found that the process time of batch operation was shorter than in the semi batch if temperature is lower than 323 K, but at temperature greater than 333K, process time required by semi batch is shorter than the batch. For the optimization problem, the optimum temperature and feed rate trajectories obtained were led to shorter process time than batch operation i.e. 98 min for achieving 97% of conversion

Aurantoside J: a New Tetramic Acid Glycoside from Theonella swinhoei. Insights into the Antifungal Potential of Aurantosides

The chemical investigation of an Indonesian specimen of Theonella swinhoei afforded four aurantosides, one of which, aurantoside J (5), is a new compound. The structure of this metabolite, exhibiting the unprecedented N-α-glycosidic linkage between the pentose and the tetramate units, has been determined through detailed spectroscopic analysis. The four obtained aurantosides have been tested against five fungal strains (four Candida and one Fusarium) responsible of invasive infections in immuno-compromised patients. The non-cytotoxic aurantoside I (4) was the single compound to show an excellent potency against all the tested strains, thus providing valuable insights about the antifungal potential of this class of compounds and the structure-activity relationships

Developmental neurotoxic effects of chronic endosulfan exposure in the zebrafish larvae

Endosulfan was listed as a member of Persistent Organic Pollutants (POP) and the usage was banned, yet this pesticide is still widely used in many developing countries. The usage of this pesticide can reach aquatic system through runoff from agricultural areas. Due to their persistent characteristic in the environment, human population are posed to continuous exposure to endosulfan. Consequently, endosulfan was found in the cord blood and breast milk of pregnant women, thus may induced adverse effects to the developing nervous system. In this study, we focused to determine the developmental neurotoxicity effects of chronic embryonic exposure to endosulfan in the zebrafish larvae. The zebrafish embryos were exposed to several concentrations of endosulfan in a semi static condition, where half of the medium was renewed for every 24 h from 5 hours post fertilization (hpf) until hatching. We measured spontaneous tail coiling at 24 hpf; heart rate at 48 hpf and mortality rate at 72 hpf. We found that, endosulfan decreased the spontaneous tail coiling, heart rate and increased the total percentage of mortality as the concentration increased. At 6 days post fertilization (dpf), we measured the swimming activity of individual larva and found that endosulfan significantly decreased the swimming activity behaviour at 40nM-200nM. The zebrafish larvae exposed to endosulfan higher than 200nM were unable to survive until 6 dpf. We further evaluated anxiety behaviour in the group of 5 larvae at 6 dpf exposed to 200nM endosulfan, with and without visual stimuli. Caffeine (100mg/L) was used as an anxiogenic drug. Caffeine increased the anxiety behaviour while endosulfan decreased the anxiety behaviour in the zebrafish larvae. Our result showed that zebrafish embryos can be an alternative research model to study the developmental neurotoxicity testing at high-throughput screenings

Microparticles from patients with metabolic syndrome induce vascular hypo-reactivity via Fas/Fas-ligand pathway in mice

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Active trachoma and community use of sanitation, Ethiopia.

OBJECTIVE: To investigate, in Amhara, Ethiopia, the association between prevalence of active trachoma among children aged 1-9 years and community sanitation usage. METHODS: Between 2011 and 2014, prevalence of trachoma and household pit latrine usage were measured in five population-based cross-sectional surveys. Data on observed indicators of latrine use were aggregated into a measure of community sanitation usage calculated as the proportion of households with a latrine in use. All household members were examined for clinical signs, i.e. trachomatous inflammation, follicular and/or intense, indicative of active trachoma. Multilevel logistic regression was used to estimate prevalence odds ratios (OR) and 95% confidence intervals (CI), adjusting for community, household and individual factors, and to evaluate modification by household latrine use and water access. FINDINGS: In surveyed areas, prevalence of active trachoma among children was estimated to be 29% (95% CI: 28-30) and mean community sanitation usage was 47% (95% CI: 45-48). Despite significant modification (p < 0.0001), no pattern in stratified ORs was detected. Summarizing across strata, community sanitation usage values of 60 to < 80% and ≥ 80% were associated with lower prevalence odds of active trachoma, compared with community sanitation usage of < 20% (OR: 0.76; 95% CI: 0.57-1.03 and OR: 0.67; 95% CI: 0.48-0.95, respectively). CONCLUSION: In Amhara, Ethiopia, a negative correlation was observed between community sanitation usage and prevalence of active trachoma among children, highlighting the need for continued efforts to encourage higher levels of sanitation usage and to support sustained use throughout the community, not simply at the household level

Prediction of Low Community Sanitation Coverage Using Environmental and Sociodemographic Factors in Amhara Region, Ethiopia.

This study developed and validated a model for predicting the probability that communities in Amhara Region, Ethiopia, have low sanitation coverage, based on environmental and sociodemographic conditions. Community sanitation coverage was measured between 2011 and 2014 through trachoma control program evaluation surveys. Information on environmental and sociodemographic conditions was obtained from available data sources and linked with community data using a geographic information system. Logistic regression was used to identify predictors of low community sanitation coverage (< 20% versus ≥ 20%). The selected model was geographically and temporally validated. Model-predicted probabilities of low community sanitation coverage were mapped. Among 1,502 communities, 344 (22.90%) had coverage below 20%. The selected model included measures for high topsoil gravel content, an indicator for low-lying land, population density, altitude, and rainfall and had reasonable predictive discrimination (area under the curve = 0.75, 95% confidence interval = 0.72, 0.78). Measures of soil stability were strongly associated with low community sanitation coverage, controlling for community wealth, and other factors. A model using available environmental and sociodemographic data predicted low community sanitation coverage for areas across Amhara Region with fair discrimination. This approach could assist sanitation programs and trachoma control programs, scaling up or in hyperendemic areas, to target vulnerable areas with additional activities or alternate technologies