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Chitosan Derivatives as Bile Acid and Cholesterol Sorbents
( Jan Tuma ),( Milan Marounek ),( Dagmar Duskova ),( Jana Opikova ),( Andriy Synytsya ) 한국키틴키토산학회 2011 한국키틴키토산학회지 Vol.16 No.4
This work is devoted to preparation of hydrophobically modified chitosans and evaluation of their sorption properties. N,N,(N)-Di(tri)methylchitosan (MC1) was prepared by the reaction of chitosan with methyl iodide; N,O-palmitoyl-chitosan (MC2) and N,N,(N)-di(tri)methyl-N,O-palmitoyl-chitosan (MC3) were prepared by the reaction of chitosan and MC1 with palmitoyl chloride, respectively. These modified chitosans were characterized by organic elemental analysis, FTIR, NMR, and DSC. The degrees of substitution were calculated from the N/C ratio and from the areas of NMR signals. The in vitro sorption of cholate and cholesterol by chitosan derivatives was studied in comparison with the original chitosan and cholestyramine, an effective synthetic sorbent of bile acids. It was found that MC2 and MC3 are able to bind cholesterol and bile acids, respectively, and thus can be used as cholestyramine supplements to improve cholesterol metabolism.
Fadhil Abass Tuma,Hussain Ali Badran,Harith Abdulrazzaq Hasan,Riyadh Chassib Abul-Hail 한국광학회 2023 Current Optics and Photonics Vol.7 No.6
This paper studies various roughness parameters, besides waviness, texture, and nonlinear parameters of Bismarck brown Y (BBY)-doped Poly(methyl methacrylate) (PMMA) films based on the computed values of optical limiting (OL) threshold power and nonlinear refractive index. The films’ morphology, grain size, and absorption spectra were investigated using atomic force microscopy in conjunction with ultraviolet-visible (UV-Vis) spectrophotometer. The particle size of the films ranged between 4.11–4.51 mm and polymer films showed good homogeneity and medium roughness, ranging from 1.11–4.58 mm.A polymer film’s third-order nonlinear optical features were carried out using the Z-scan methodology. The measurements were obtained by a continuous wave produced from a solid-state laser with a 532 nm wavelength. According to the results, BBY has a nonlinear refractive index of 10 −6 cm 2 /W that is significantly negative and nonlinear. The optical limiting thresholds are roughly 10.29, 13.52, and 18.71 mW, respectively. The shift of nonlinear optical features with the film’s concentration was found throughout the experiment Additionally, we found that the polymer samples have outstanding capabilities for restricting the amount of optical power that may be transmitted through them. We propose that these films have the potential to be used in a wide variety of optoelectronic applications, including optical photodetectors and optical switching.
유바라즈할도라이,Dian Kharismadewi,Dirk Tuma,심재진 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.8
Chitosan (CS)/iron oxide (Fe3O4) composites were prepared using a chemical precipitation method. The CS/Fe3O4 composite was characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and zeta-potential measurements. The composite was used to remove methyl orange (MO) dye from an aqueous solution. The factors affecting the adsorption capacity, such as adsorption time, absorbent dosage and solution pH were investigated. The results suggested that the composite was an effective adsorbent for the removal of MO dye from its aqueous solution. Kinetics studies showed that the adsorption process was consistent with a pseudo-second- order model. The adsorbent efficiency was unaltered, even after five cycles of reuse, and the adsorbent could be recollected easily using a magnet. In addition, the composite exhibited a superior antibacterial efficacy against Escherichia coli; 82% within 24 h, as measured by the colony forming units.
Zebire, Degife Asefa,Ayele, Tuma,Ayana, Mekonen The Ecological Society of Korea 2019 Journal of Ecology and Environment Vol.43 No.2
Background: Characterizing and describing soils and land use and make a suggestion for sustainable utilization of land resources in the Ethiopian Rift valley flat plain areas of Lake Chamo Sub-Basin (CSB) are essential. Objectives: To (1) characterize soils of experimental area according to World Reference Base Legend and assess the nature and extent of salinity problems; (2) characterize land use systems and their role in soil properties; and (3) identify best land use practices used for both environmental management and improve agricultural productivity. Methods: Twelve randomly collected soil samples were prepared from the above land uses into 120 composites and analyzed. Results: Organic carbon (OC) and total nitrogen (TN) were varied along different land uses and depleted from the surface soils. The soil units include Chernozems (41.67%), Kastanozems (25%), Solonchaks (16.67%), and Cambisols (16.67%). The identified land uses are annual crops (AA), perennial crops (PA), and natural forest (NF). Generally, organic carbon, total nitrogen, percentage base saturation (PBS), exchangeable (potassium, calcium, and magnesium), available phosphorus (P<sub>2</sub>O<sub>5</sub>), manganese, copper, and iron contents were decreased in cultivated soils. Soil salinity problem was observed in annuals. Annuals have less nutrient content compared to perennials in irrigated agriculture while it is greater in annuals under rainfed. Clay, total nitrogen, available phosphorus, and available potassium (K<sub>2</sub>O) contents were correlated positively and highly significantly with organic carbon and electrical conductivity. Conclusion: Management practices that improve soil quality should be integrated with leguminous crops when the land is used for annual crops production.
Coquet, Julia Becaria,Tumas, Natalia,Osella, Alberto Ruben,Tanzi, Matteo,Franco, Isabella,Diaz, Maria Del Pilar Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.10
A number of studies have evidenced the effect of modifiable lifestyle factors such as diet, breastfeeding and nutritional status on breast cancer risk. However, none have addressed the missing data problem in nutritional epidemiologic research in South America. Missing data is a frequent problem in breast cancer studies and epidemiological settings in general. Estimates of effect obtained from these studies may be biased, if no appropriate method for handling missing data is applied. We performed Multiple Imputation for missing values on covariates in a breast cancer case-control study of $C{\acute{o}}rdoba$ (Argentina) to optimize risk estimates. Data was obtained from a breast cancer case control study from 2008 to 2015 (318 cases, 526 controls). Complete case analysis and multiple imputation using chained equations were the methods applied to estimate the effects of a Traditional dietary pattern and other recognized factors associated with breast cancer. Physical activity and socioeconomic status were imputed. Logistic regression models were performed. When complete case analysis was performed only 31% of women were considered. Although a positive association of Traditional dietary pattern and breast cancer was observed from both approaches (complete case analysis OR=1.3, 95%CI=1.0-1.7; multiple imputation OR=1.4, 95%CI=1.2-1.7), effects of other covariates, like BMI and breastfeeding, were only identified when multiple imputation was considered. A Traditional dietary pattern, BMI and breastfeeding are associated with the occurrence of breast cancer in this Argentinean population when multiple imputation is appropriately performed. Multiple Imputation is suggested in Latin America's epidemiologic studies to optimize effect estimates in the future.
BULAKHE RAVINDRA NATHUJI,Van Quang Nguyen,Dirk Tuma,이용락,Haitao Zhang,Suojiang Zhang,심재진 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.66 No.-
Present study investigated decoration of Cu(OH)2 with different morphologies by copper precursors, on 3D nickel foam. The Cu(OH)2-A (nano flower)electrode showed an excellent capacitance of 1332 F g−1 at current density of 2 A g−1 compared to the Cu(OH)2-C (nano ribbon, 1100 F g−1) and Cu(OH)2-S (nano long leaf, 1013 F g−1) electrodes. Asymmetric supercapacitor (ASC) was fabricated, and showed maximum capacitance of 165 F g−1 at current density of 2 A g−1with high energy density of 66.7 Wh kg−1 and power density of 5698 W kg−1 with excellent stability of 80% after 10,000 cycles.
Sang-Cheol Park,심재진,Dirk Tuma,김선욱,이용록 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.1
C. I. Disperse Red 60 (DR60) was absorbed into polymer films and textile fibers in the presence of supercritical carbon dioxide at pressures between 5 and 33MPa and at temperatures between 308.2 and 423.2 K. Polystyrene (PS) and poly(methyl methacrylate) (PMMA) films and polyester (polyethylene terephthalate: PET) and Nylon 6 textiles were used as absorbents. The amount of equilibrium sorption of dye increased both with pressure and temperature. The sorption behavior was successfully analyzed with the quasi dual-mode sorption model.