Heineke -Mikulicz Pyloroplasty - The Observer Error in the Interpretation of the Films

Barium meals done before and after Heineke-Mikulicz pyloroplasty on 29 patients undergoing surgery for duodenal ulceration ware studied. Representative views of the pre- and post-pyloroplasty examinations were arranged in a random fashion on unexposed film. Eight radiologists studied the films on 2 occasions. Five sets of films at the first view:ng and 6 sets of films at the second viewing were correctly interpreted. This observation cannot be related to the completeness or incompleteness of the vagotomy, but does appear to be related to the experience of the radiologist.S. Afr. Med. J., 45, 1375 (1971

Chemical and Physical Modification of Graphitic Materials by Oxidative Processes and Solvent Intercalation

Graphene and graphite are materials of high interest for many applications. In order to increase the possible uses of these materials, more must be understood about how their properties can be modified. One way to modify graphitic properties is by chemical functionalization, such as oxidation. This work looks at two different oxidation techniques for graphite; UV/O3 exposure and biased AFM lithography for broad and local oxidation, respectively. For the supported graphitic samples including graphene, it is important to understand how sample preparation can lead to contamination in addition to investigating how to chemically and physically manipulate the graphitic properties. Three different mechanical exfoliation sample preparations were used to create samples, and each method was investigated with biased lithography. UV/O3 exposure is able to form graphite oxide with only the exposed area undergoing oxidation. It was found that the length of exposure time could be linearly correlated to the amount of defects as determined by Raman spectroscopy. Biased AFM lithography of graphite was also able to oxidize graphite, in a localized pattern instead of entire exposed area. By controlling the lithography conditions, the extent of oxidation in an area could be manipulated. Supported graphitic materials were created via Scotch tape, thermal release tape and water soluble tape. Each tape had unique sample preparation conditions, and each of the three samples yielded single to multilayer graphene surfaces which then underwent biased lithography. Biased lithography on each of these created surfaces demonstrated the impact that sample preparation had on device creation as the samples had unique responses based on which method was used. Scotch tape samples saw growths stemming from the graphitic areas that underwent the biased lithography, thermal release tape samples formed wrinkles in the graphitic region while donuts, on the edges, and the water soluble tape showed oxidation of the graphitic region as well as the formation of bubbles. These bubbles are believed to be due to the solvent intercalation which was able to undergo electrolysis, a novel method for graphitic bubble formation

Evaporation Residue Cross Sections Measured Near the N = 126 Spherical Closed Shell in 45Sc- and 44Ca-Induced Reactions

Evaporation residue cross sections were measured for shell-stabilized nuclides near the N = 126 closed shell in ^45Sc- and ^44Ca-induced reactions on the lanthanide targets ^156-^158, ^160Gd, ^159Tb, and ^162Dy. The experiments were performed at the Texas A&M University Cyclotron Institute, with the K500 cyclotron providing the accelerated beam. The Momentum Achromat Recoil Separator was used to separate the desired evaporation residues from the other reactions products. The evaporation residue cross sections ranged between 2.7 mb and 1 μb for the reactions, and the effects of the shell stabilization and the relative neutron content of the compound nucleus on the cross sections were examined. The cross sections in the ^45Sc-induced reactions were up to four orders of magnitude smaller than ^48Ca-induced reactions on the same targets due to the relative neutron-deficiency of ^45Sc. This observation suggests that ^45Sc would be a poor projectile for synthesizing superheavy elements. The experimental data were analyzed within the framework of a theoretical model aimed at elucidating the major physical factors which determined the evaporation residue cross sections. The model describes the fusion-evaporation reaction as a series of three independent steps: capture, compound nucleus formation, and deexcitation into the cold evaporation residue. The primary factor in determining the evaporation residue cross sections was found to be the difference between the fission barrier and the neutron separation energy. The nuclear level density in the model was modified to incorporate the collective motion of the nucleons. The influence of collective effects suggests that cross sections for superheavy elements produced near the predicted N = 184 spherical closed shell may not be enhanced by the presence of the shell closure