Trabecular scaffolds created using micro CT guided fused deposition modeling

Free form fabrication and high resolution imaging techniques enable the creation of biomimetic tissue engineering scaffolds. A 3D CAD model of canine trabecular bone was produced via micro CT and exported to a fused deposition modeler, to produce polybutylene terephthalate (PBT) trabeculated scaffolds and four other scaffold groups of varying pore structures. The five scaffold groups were divided into subgroups (n=6) and compression tested at two load rates (49 N/s and 294 N/s). Two groups were soaked in a 25 °C saline solution for 7 days before compression testing. Micro CT was used to compare porosity, connectivity density, and trabecular separation of each scaffold type to a canine trabecular bone sample. At 49 N/s the dry trabecular scaffolds had a compressive stiffness of 4.94±1.19 MPa, similar to the simple linear small pore scaffolds and significantly more stiff (p<0.05) than either of the complex interconnected pore scaffolds. At 294 N/s, the compressive stiffness values for all five groups roughly doubled. Soaking in saline had an insignificant effect on stiffness. The trabecular scaffolds matched bone samples in porosity; however, achieving physiologic connectivity density and trabecular separation will require further refining of scaffold processing.     

GaN single crystals grown on HVPE seeds in alkaline supercritical ammonia

Ammonothermal growth (synthesis in supercritical (sc) ammonia fluid) has the promise of producing large low defect gallium nitride crystals through the application of techniques similar to those used in hydrothermal growth. Retrograde solubility of GaN greater than 5% by weight using group I amides as mineralizers is demonstrated in high nickel content autoclaves at pressures of one to three kilobars and temperatures between 300 to 600°C. The above conditions were optimized to grow single-crystal GaN at rates up to 40 μm per day on one cm² seeds. Gallium nitride Hydride Vapor Phase Epitaxy (HVPE) seeds are placed in the higher temperature zone below the nutrient basket employing the same configurations used in reverse gradient hydrothermal growth of berlinite (AlPO₄). GaN single crystals grown by the ammonothermal technique were characterized by X-ray diffraction, photoluminescence, scanning electron microscopy (SEM), atomic force microscopy (AFM), and chemical etching. The nitrogen-terminated face tends to exhibita flatter surface morphology than the gallium-terminated face, which is made up of a series of hexagonal columns. Major impurities in the crystal include potassium from the mineralizer, metals from the autoclave, and oxygen. The nitrogen-terminated face incorporated a lower level of metallic impurities in comparison with the gallium-terminated face. Finally, several process phenomena such as ammonia decomposition, parasitic nucleation of GaN on the autoclave walls, impurity incorporation, and defect generation in single-crystal GaN layers grown on HVPE seeds are identified and their possible mechanisms are discussed.     

Fire Performance of Selected IT-Equipment

The results from a series of large scale tests are presented to establish the fire performance of a number of common pieces of IT equipment including: computer monitors, printers and CPUs. The monitors have been tested in a fully furnished scenario in the ISO 9705 room arranged in a typical bedroom setting and in a specially constructed 4 m × 5 m room arranged in a typical classroom setting. The other pieces of equipment have been tested directly under the furniture calorimeter. This paper presents HRR for the various tests and discusses the significance of the results in terms of fire safety. A discussion of available statistical and anecdotal information is presented in this context.     

Electron diffraction analysis and techniques for studying polypeptides and other polymers

A review of electron diffraction studies of polypeptide structures is given together with a discussion of the methods for obtaining diffraction patterns without serious specimen damage by electrons. Electron diffraction studies of poly-β-benzyl-L-aspartate show that diffraction intensities can be used quantitatively to determine polypeptide structures and the advantages of these studies in observing high angle meridional reflections are shown up by the observation of a novel structure in the unheated left handed helical form of the polypeptide. A large catalogue of techniques for preparing orientated films of polypeptides suitable for electron diffraction investigations makes the technique a powerful one for studying these structures. Polypeptides are shown to be useful for studying electron beam damage in protein-like materials.     

Resisting temptations to smoke: Results from within-subjects analyses.

Within-subjects analyses were used to examine differences between resisted temptations to smoke (either a specific close call or the most common temptation) and smoking lapses among 130 participants lapsing within 1 month after a self-initiated quit attempt. Participants were more likely to report coping during resisted temptations than during lapses; those who reported coping in both were more likely to report using multiple strategies and combining cognitive and behavioral strategies during the resisted temptation. Participants were more likely to report that the lapse was precipitated by others smoking, but this difference was not significant when the sample was restricted to those reporting a specific close call. No other statistically significant differences were found. Results support previous findings that the use or nonuse of coping strategies during a temptation to smoke is the variable most strongly associated with its outcome. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The social climate of alcoholism treatment programs

The social climate of four residential alcoholism treatment programs was assessed with the Community-Oriented Programs Environment Scale (COPES). The programs differed in terms of their treatment orientations (aversion-conditioning, milieu therapy) and the sociodemographic characteristics of the patients admitted. Results showed that (1) COPES profiles distinguished between the four alcoholism programs in ways that were consistent with their respective treatment orientations; (2) the type of patient admitted to these programs did not systematically affect their treatment environment; and (3) changes occurring within an alcoholism program resulted in corresponding changes in relevant dimensions of the treatment environment. We also discuss the practical utility of the COPES for assessing alcoholism programs.     

Efficacy of oxibendazole against adult and larval nematodes of cattle

Calves which were artificially infected with Haemonchus, Ostertagia, Trichostrongylus, Cooperia, and Oesophagostomum but which were also carrying natural infections of Nematodirus and Trichuris were treated with 15.0 mg of oxibendazole (methyl-5-n-propoxy-2-benzimidazole-carbamate)/kg of body weight at 3 days, 7 days, and 42 days after exposure to the infective trichostrongylid and strongylid larvae. Efficacies against adult populations of these genera treated on day 42, except Trichostrongylus, exceeded 98%. The chemical was highly effective against immature nematodes of the genera, except Oesophagostomum (0%). Data were not obtained on Trichostrongylus. The oxibendazole premix was palatable, and toxicosis due to the chemical was not seen in these calves.