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Biomedical subjects

E Magner

Publications and source records attributed to E Magner.

6 recordsLinked to original sources
PubMed2006

Quantitative TEM analysis of a hexagonal mesoporous silicate structure.

TEM analysis of mesoporous materials is generally undertaken to give qualitative results. Accurate quantitative analysis is demonstrated in this study. A systematic image analysis of a powder form of a hexagonal mesoporous material known as KIT-6 is conducted using a transmission electron microscope (TEM). Three types of image contrast typically appear in this material (a hexagonal honeycomb structure, wide and narrow parallel lines). The honeycomb face is used to characterise this material in terms of a conventional 2-D hexagonal structure and the d-spacings for the (100) and (110) planes are experimentally measured in varying focus conditions. A tilting experiment is conducted to determine how the angle of tilt affects the line spacing and their visibility. Tilting has very little effect on the line spacing, whereas it affects the visibility of both the wide and narrow lines by limiting an angle range of visibility. The hexagonal lattice structure parameter determined by TEM method is found to be approximately 7% lower than that calculated by low-angle X-ray diffraction. Thus we conclude that TEM data can be used to determine the geometry and dimensions of hexagonal mesoporous silica materials, with a small error in the hexagonal lattice parameter.

Computer Simulation↗
PubMed2001

Detection of ferricyanide as a probe for the effect of hematocrit in whole blood biosensors.

Measurement of the concentration of an analyte in whole blood can be influenced by a range of factors; the red cell content or hematocrit (Hct) of the sample, the distribution and rate of movement of analyte between red cells and plasma, the amount of protein in solution, the viscosity of the sample and fouling of the sensor. The effect of the red cells is the major factor that must be taken into account. Using the analyte molality rather than the analyte molarity, the theoretical response for a range of analytes which are found in plasma and in the red cells can be calculated. For an analyte which is found in plasma alone, the effect of hematocrit is significant, with a bias of -1% per %Hct; if the analyte can freely and rapidly diffuse between the red cells and plasma, this bias is reduced to zero. Using ferrocyanide as a model analyte, the effects of fouling and reduced sample viscosity were measured to be -0.2% per %Hct, giving an overall bias of -1.2% per %Hct, a level of bias which is not clinically acceptable. This bias can be negated by measuring the hematocrit separately and incorporating it into the measurement algorithm. Such a correction is essential for the correct measurement of the concentration of an analyte in whole blood.

Biosensing Techniques↗
PubMed1998

Trends in electrochemical biosensors.

The development of electrochemically based biosensors is discussed in the context of what has been learned from the successful development of glucose biosensors. Some future trends are discussed.

Biosensing Techniques↗
PubMed1989

Photochemical generation and reactions of heme cation radicals in heme proteins.

A novel approach is described for generating reactive oxidizing centers in heme proteins, with zinc hemoglobin (Zn Hb) and zinc cytochrome c (Zn cyt c) used as examples. The reaction of 3Zn* Hb with [CoIII(NH3)5 Cl]2+, and of 3Zn* cyt c with methyl viologen are described. In the case of Zn Hb the cation radical produced decays with a rate constant of k3 = 2400s-1. Using this value the rate of the reaction (formula; see text) can be calculated to be 4500s-1.

Cytochrome c Group↗