Browsing by Subject "Sedimentation"

Now showing 1 - 4 of 4

Open Access
Dating of Black sea sediments from Romanian coast using natural 210Pb and fallout 137CS
(Akademiai Kiado Rt., 2004) Ayçık, G. A.; Çetaku, D.; Erten, H. N.; Salihoǧlu, İ.
The sediment samples collected near the shore from Romania were used for the determination of levels of natural 210Pb, 226Ra and fallout 137Cs radionuclides. The sediment samples were dried and ground to a fine powder. Airtight sealed samples were counted by gamma-spectrometer with 110 cm3 well-type HPGe detector for one week each. By using the isotopic analysis results, sediment accumulation rate was determined. A sedimentation rate of 0.20±0.01 cm·y-1 was determined using 210Pb method and 0.15±0.03 cm·y-1 using 137Cs isotope. Fallout peak from Chernobyl reactor accident, as well as the peaks due to nuclear tests, act as time markers.
Open Access
A microfluidic erythrocyte sedimentation rate analyzer using rouleaux formation kinetics
(Springer Verlag, 2017-03) Isiksacan, Z.; Asghari, M.; Elbuken, C.
Red blood cell aggregation is an intrinsic property of red blood cells that form reversible stacked structures, also called rouleaux, under low shear rates. Erythrocyte sedimentation rate (ESR), commonly performed in clinics, is an indirect inflammation screener and a prognostic test for diseases. We have recently developed a microfluidic system for rapid measurement of ESR from 40 µl whole blood employing the aggregation dynamics. In this work, we propose the use of an aggregation inducer, dextran polyglucose, for the preparation of multiple blood samples with differing aggregation dynamics. Using these samples, we characterized the performance of the system with three aggregation indices and under varying experimental conditions. Additionally, using the same underlying principle, we improved the system for ESR measurement using both venipuncture and fingerprick whole blood samples depending on the user needs. The results demonstrate that the system performs equally well with both samples, which validates the compatibility of the system for both laboratory and point-of-care applications where venous and capillary blood are the primary samples, respectively. The detailed characterization presented in this study legitimates the feasibility of the system for ultrafast and facile measurement of ESR in clinics and diverse off-laboratory settings.
Open Access
Microfluidic measurement of erythrocyte sedimentation rate and monitoring of erytrocyte aggregation
(Chemical and Biological Microsystems Society, 2016) Isiksacan, Ziya; Elbuken, Çağlar
We developed a novel microfluidic opto-electro-mechanical system and performed ultrafast, cheap, and low-sample volume measurement of erythrocyte sedimentation rate (ESR) from erythrocyte aggregation (EA). We also showed EA dynamics in real-time during measurements.
Open Access
Mixing challenges for SiO2/polystyrene nanocomposites
(SAGE Publications, 2018) Kourki, H.; Famili, M. H. N.; Mortezaei, M.; Malekipirbazari, M.
Morphology of a nanocomposite, which has indisputable effects on its properties, is determined by its dynamic and thermodynamic conditions. While physical properties of the components of a nanocomposite as well as the interaction between them are the parameters controlling the morphology thermodynamically, their dynamic condition is related to the issues like intensity of mixing and geometry of mixer. In this research, we investigate the mixing process of solution casting method by studying the effects of mixing intensity on the dynamics of the particle structure and hereby its morphology using sedimentation test. In these experiments, mixing is performed at various durations, input energies, and energy types for suspensions containing different particle sizes and concentrations as well as diverse polymer concentrations. We found that increasing mixing time and input energy along with using ultrasonic wave decrease the size of aggregates. Sedimentation test revealed improvements of dispersion and distribution states of suspension by using ultrasonic waves and high shear mixing, respectively. Finally, particle-particle interaction data show increase in the probability of restructuring after mixing with reduction in particle size and increase in particle volume fraction.