Properties Of Esterified Κ-Carrageenan And Esterified Κ-Carrageenan-Zirconia Composite Material

A new method which does not involve the use of water as solvent for esterification of carrageenan, was developed to synthesize κ-carrageenan esters. Pyridine was used as solvent and catalyst in this synthesis. The effect of temperature and amount of decanoyl chloride to the esterification process was studied systematically in this work. Characterisation by Fourier Transforms Infra-Red Spectrometer (FTIR) and Nuclear Magnetic Resonances Spectrometer (NMR) techniques revealed the formation of ester bond in all samples. The glass transition temperatures, Tg of κ-carrageenan esters which were studied using Differential Scanning Calorimetry (DSC) and the result revealed that all the κ-carrageenan esters synthesized have lower glass transition temperature than the κ-carrageenan. By using 1H-NMR spectra, the degree of substitution of acyl group was determined to be highest at 90 oC reaction temperature. The optimum amount of acyl chloride used to prepared κ-carrageenan ester with the highest degree of substitution was determined to be 0.175 mol. All κ-carrageenan esters show good solubility in toluene but not in water. Further purification of the esters using sodium bicarbonate and toluene yield a purer κ-carrageenan ester. κ-carrageenan ester synthesized without further purification was used in the preparation of κ-carrageenan ester and zirconia composite using the sonication technique. The composite which is insoluble in water and toluene, showed better thermal properties as compared to κ-carrageenan esters

Green synthesis of Fe3O4 nanoparticles stabilized by a Garcinia mangostana fruit peel extract for hyperthermia and anticancer activities

Fe3O4 nanoparticles (Fe3O4 NPs) with multiple functionalities are intriguing candidates for various biomedical applications. Materials and Methods: This study introduced a simple and green synthesis of Fe3O4 NPs using a low-cost stabilizer of plant waste extract rich in polyphenols content with a well-known antioxidant property as well as anticancer ability to eliminate colon cancer cells. Herein, Fe3O4 NPs were fabricated via a facile co-precipitation method using the crude extract of Garcinia mangostana fruit peel as a green stabilizer at different weight percentages (1, 2, 5, and 10 wt.%). The samples were analyzed for magnetic hyperthermia and then in vitro cytotoxicity assay was performed. Results: The XRD planes of the samples were corresponding to the standard magnetite Fe3O4 with high crystallinity. From TEM analysis, the green synthesized NPs were spherical with an average size of 13.42±1.58 nm and displayed diffraction rings of the Fe3O4 phase, which was in good agreement with the obtained XRD results. FESEM images showed that the extract covered the surface of the Fe3O4 NPs well. The magnetization values for the magnetite samples were ranging from 49.80 emu/g to 69.42 emu/g. FTIR analysis verified the functional groups of the extract compounds and their interactions with the NPs. Based on DLS results, the hydrodynamic sizes of the Fe3O4 nanofluids were below 177 nm. Furthermore, the nanofluids indicated the zeta potential values up to −34.92±1.26 mV and remained stable during four weeks of storage, showing that the extract favorably improved the colloidal stability of the Fe3O4 NPs. In the hyperthermia experiment, the magnetic nanofluids showed the acceptable specific absorption rate (SAR) values and thermosensitive performances under exposure of various alternating magnetic fields. From results of in vitro cytotoxicity assay, the killing effects of the synthesized samples against HCT116 colon cancer cells were mostly higher compared to those against CCD112 colon normal cells. Remarkably, the Fe3O4 NPs containing 10 wt.% of the extract showed a lower IC50 value (99.80 μg/mL) in HCT116 colon cancer cell line than in CCD112 colon normal cell line (140.80 μg/mL). Discussion: This research, therefore, introduced a new stabilizer of Garcinia mangostana fruit peel extract for the biosynthesis of Fe3O4 NPs with desirable physiochemical properties for potential magnetic hyperthermia and colon cancer treatment

Clinical outcomes of pneumococcal pneumonia caused by antibiotic-resistant strains in Asian countries: a study by the Asian network for surveillance of resistant pathogens

To evaluate the clinical outcomes of pneumococcal pneumonia caused by antibiotic-resistant strains in Asian countries, we performed a prospective observational study of 233 cases of adult pneumococcal pneumonia in 9 Asian countries from January 2000 to June 2001. Among 233 isolates, 128 (55%) were not susceptible to penicillin (25.3% were intermediately susceptible, and 29.6% were resistant). Clinical severity of pneumococcal pneumonia was not significantly different between antibiotic-resistant and antibiotic-susceptible groups. Mortality rates among patients with pneumococcal pneumonia caused by penicillin-, cephalosporin-, or macrolide-resistant strains were not higher than those with antibiotic-susceptible pneumococcal pneumonia. Bacteremia and mechanical ventilation were significant risk factors for death, but any kind of antibiotic resistance was not associated with increased mortality due to pneumococcal pneumonia. Outcome of pneumococcal pneumonia was not significantly affected by drug resistance, and current antimicrobial regimens are mostly effective in the treatment of pneumococcal pneumonia, despite the widespread emergence of in vitro resistance

Macrolide resistance and genotypic characterization of Streptococcus pneumoniae in Asian countries: a study of the Asian Network for Surveillance of Resistant Pathogens (ANSORP)

Objectives: To characterize mechanisms of macrolide resistance among Streptococcus pneumoniae from 10 Asian countries during 1998-2001. Methods: Phenotypic and genotypic characterization of the isolates and their resistance mechanisms. Results: Of 555 isolates studied, 216 (38.9%) were susceptible, 10 (1.8%) were intermediate and 329 (59.3%) were resistant to erythromycin. Vietnam had the highest prevalence of erythromycin resistance (88.3%), followed by Taiwan (87.2%), Korea (85.1%), Hong Kong (76.5%) and China (75.6%). Ribosomal methylation encoded by erm(B) was the most common mechanism of erythromycin resistance in China, Taiwan, Sri Lanka and Korea. In Hong Kong, Singapore, Thailand and Malaysia, efflux encoded by mef(A) was the more common in erythromycin-resistant isolates. In most Asian countries except Hong Kong, Malaysia and Singapore, erm(B) was found in >50% of pneumococcal isolates either alone or in combination with mef(A). The level of erythromycin resistance among pneumococcal isolates in most Asian countries except Thailand and India was very high with MIC90s of >128 mg/L. Molecular epidemiological studies suggest the horizontal transfer of the erm(B) gene and clonal dissemination of resistant strains in the Asian region. Conclusion: Data confirm that macrolide resistance in pneumococci is a serious problem in many Asian countries

Case study of load-bearing precast wall system subject to low seismic intensity by linear and nonlinear analyses

This paper investigates the behaviour of load-bearing precast wall system (namely the HC Precast System − HCPS) subject to seismicity in Malaysia. Recent tremors felt across the country heeded the call for the need of seismic design guidelines to be implemented. For this study, the design ground acceleration for Malaysia has not been finalized. Throughout the years, several schools of thought that occurred among different researchers pertaining to the value of design ground acceleration, ranging from 0.05 g to 0.1 g. The implications of the selected values can be great especially in designing new buildings or retrofitting existing ones. Thus, linear analysis using Modal Response Spectrum Analysis (MRSA) and nonlinear pushover analysis of representative HCPS were performed for this study. The finite element (FE) model focused particularly on the nonlinear behaviour of the interface between a precast wall and cast in-situ column. Prior to the modal and pushover analyses, the FE model was validated against quasi-static cyclic test results of identical precast system obtained from literature. Differences between the MRSA and pushover approaches are presented and discussed. Performance levels of the structural system were subjected to three levels of design ground acceleration (0.05, 0.075 and 0.1 g) have been included.Published versio

Semi-automating abstract screening with a natural language model pretrained on biomedical literature

Abstract We demonstrate the performance and workload impact of incorporating a natural language model, pretrained on citations of biomedical literature, on a workflow of abstract screening for studies on prognostic factors in end-stage lung disease. The model was optimized on one-third of the abstracts, and model performance on the remaining abstracts was reported. Performance of the model, in terms of sensitivity, precision, F1 and inter-rater agreement, was moderate in comparison with other published models. However, incorporating it into the screening workflow, with the second reviewer screening only abstracts with conflicting decisions, translated into a 65% reduction in the number of abstracts screened by the second reviewer. Subsequent work will look at incorporating the pre-trained BERT model into screening workflows for other studies prospectively, as well as improving model performance

Additional file 1 of Semi-automating abstract screening with a natural language model pretrained on biomedical literature

Additional file 1. Search criteria and strategy. Appendix 1. Study eligibility criteria. Appendix 2. Search strategy