Oxidation of Carbon Nanotubes in an Ionizing Environment

In this work, we present systematic studies on how an illuminating electron beam which ionizes molecular gas species can influence the mechanism of carbon nanotube oxidation in an environmental transmission electron microscope (ETEM). We found that preferential attack of the nanotube tips is much more prevalent than for oxidation in a molecular gas environment. We establish the cumulative electron doses required to damage carbon nanotubes from 80 keV electron beam irradiation in gas versus in high vacuum. Our results provide guidelines for the electron doses required to study carbon nanotubes within or without a gas environment, to determine or ameliorate the influence of the imaging electron beam. This work has important implications for in situ studies as well as for the oxidation of carbon nanotubes in an ionizing environment such as that occurring during field emission

Additional file 2: of Neurocognitive sparing of desktop microbeam irradiation

Supplementary Method. (DOCX 16 kb

Additional file 1: of Neurocognitive sparing of desktop microbeam irradiation

Pretest results. (DOCX 754 kb

Infarcted volumes calculated as a percentage of the total left ventricle wall volume.

<p>Legend: Percent of infarcted tissue as derived from computed tomography images and from TTC-stained histological slices.</p><p>Infarcted volumes calculated as a percentage of the total left ventricle wall volume.</p

Micro-CT images of the ischemia reperfusion murine model.

<p>Images acquired an average of 13 (a) and 30 (b) minutes after administration of Iohexol display delayed contrast enhancement within regions of infarcted tissue.</p

Calculated ejection fractions for ischemia reperfusion mice and controls.

<p>N = 7 for IR mice and N = 7 for controls. Error bars indicate one standard deviation.</p

The contrast administration and imaging protocol.

<p>Four micro-CT images were acquired using two iodinated contrast agents, Iohexol 300 mg I/mL and Fenestra VC. Images were acquired during either diastole (on r-wave) or systole (55 msec delay from r-wave). Acquisition of each gated micro-CT image required 10 to 15 minutes. After successful completion each stage of the protocol, the next immediately commenced. </p

CT slices showing delayed contrast and LV volume, and matching histology.

<p>Areas of delayed iodine contrast enhancement in the infarcted myocardium are visible in micro-CT images (4A) due to contrast agent retention in fibrotic tissue. These portions of infarcted myocardial tissue appear on stained histological slices (4B). Indicators for infarcted myocardium are comparable in location, shape, and volume in both CT grayscale images and stained histological slices. At bottom, CT images of the same subject after administration of an iodinated lipid blood pool contrast agent. Images acquired during diastole (4C) and systole (4D) were used to calculate the ejection fraction.</p

CT contrast (in Hounsfield units) with Iohexol for materials-of-interest plotted over time.

<p>During the first image acquisition (average 13 minutes after administration), CT numbers for the blood, infarcted region, and myocardium were 411 ± 56 HU, 431 ± 111 HU, and 182 ± 29.4, respectively. During the second image acquisition (average 30 minutes after administration), CT numbers for the blood, infarcted region, and myocardium were 245 ± 59, 281 ± 108, and 139 ± 28, respectively.</p