Delamination Mechanics of Carbon Nanotube Micropillars.

The adhesion of carbon nanotube (CNT) forests to their growth substrate is a critical concern for many applications. Here, we measured the delamination force of CNT forest micropillars using in situ scanning electron microscopy (SEM) tensile testing. A flat tip with epoxy adhesive first established contact with the top surface of freestanding CNT pillars and then pulled the pillars in displacement-controlled tension until delamination was observed. An average delamination stress of 6.1 MPa was measured, based on the full pillar cross-sectional area, and detachment was observed to occur between catalyst particles and the growth substrate. Finite element simulations of CNT forest delamination show that force and strain are heterogeneously distributed among CNTs during tensile loading and that CNTs progressively lose adhesion with increased displacement. Based on combined experiments and simulations, an adhesion strength of approximately 350 MPa was estimated between each CNT and the substrate. These findings provide important insight into CNT applications such as thermal interfaces, mechanical sensors, and structural composites while also suggesting a potential upper limit of tensile forces allowed during CNT forest synthesis.

Precision Milling of Carbon Nanotube Forests Using Low Pressure Scanning Electron Microscopy.

A nanoscale fabrication technique appropriate for milling carbon nanotube (CNT) forests is described. The technique utilizes an environmental scanning electron microscope (ESEM) operating with a low pressure water vapor ambient. In this technique, a portion of the electron beam interacts with the water vapor in the vicinity of the CNT sample, dissociating the water molecules into hydroxyl radicals and other species by radiolysis. The remainder of the electron beam interacts with the CNT forest sample, making it susceptible to oxidation from the chemical products of radiolysis. This technique may be used to trim a selected region of an individual CNT, or it may be used to remove hundreds of cubic microns of material by adjusting ESEM parameters. The machining resolution is similar to the imaging resolution of the ESEM itself. The technique produces only small quantities of carbon residue along the boundaries of the cutting zone, with minimal effect on the native structural morphology of the CNT forest.

Diamond burr debridement vs. grid keratotomy in canine SCCED with scanning electron microscopy diamond burr tip analysis.

OBJECTIVES: (i) Compare the outcome of canine SCCED treated with grid keratotomy (GK) or diamond burr debridement (DBD); (ii) Serially evaluate morphologic and elemental composition changes to diamond burr tips. ANIMALS STUDIED: A total of 91 eyes of 88 canine SCCED patients treated at the University of Missouri (2005-2015); 75 fresh cadaver porcine globes. PROCEDURES: (i) Medical records were reviewed retrospectively. Data were analyzed for age, sex, breed, procedure performed, eye(s) on which the procedure was performed, time to healing after a single surgical procedure, performance of a second surgical procedure, contact lens placement, and postprocedural complications. (ii) Three naïve 3.5-mm medium grit burr tips were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). DBD was performed for 120 s on 8-mm porcine corneal stroma using the Algerbrush® . Manufacturer-recommended cleaning protocols were followed. SEM and EDS analyses were performed in triplicate after 10, 25, and 50 DBD, cleaning, and sterilization cycles. RESULTS: There was no statistically significant difference in healing between DBD and GK groups (P = 0.50). No diamond particle damage after 10, 25, or 50 DBDs was detected. SEM secondary electron imaging and backscatter electron imaging after repeated uses demonstrated a build-up of contamination composed of carbon, sulfur, and calcium on burr tips. CONCLUSIONS: Both DBD and GK are effective treatment options for canine SCCED. Although complications are rare after DBD, build-up of contaminants may be a contributing factor. Additional cleaning and sterilization protocols are being investigated.

What all nurses need to know about Stickler syndrome.

Stickler syndrome is one of the most common clinical syndromes in Europe although it is also one of the least known and consequently most misidentified. Because Stickler syndrome affects connective tissue, many different symptoms present, from vision to mobility difficulties. This article examines the main symptoms of the syndrome and includes an insightful personal account showing how it affects the whole family.