Insights into molecular recognition from the crystal structures of p-tert-butylcalix[6]arene complexed with different solvents

Calixarenes are host molecules that can form complexes with one or more guest molecules, and molecular recognition in calixarenes can be affected by many factors. With a view to establishing molecular recognition rules, the host p-tert-butylcalix[6]arene (TBC6) was crystallized with different guest molecules (cyclohexane, anisole, heptane, toluene, benzene, methyl acetate, ethyl acetate, dichloromethane, tetrahydrofuran and pyridine) and the obtained structures were characterized by X-ray diffraction. With most solvents, 1:1 and/or 1:3 host–guest complexes were formed, although other stoichiometries were also observed with small guest molecules, and crystallization from ethyl acetate produced the unsolvated form. The calculated fill percentage of the TBC6 cavity was ∼55% for apolar guests and significantly lower for polar solvents, indicating that polar molecules can bind to apolar cavities with significantly lower packing coefficients. The most stable crystals were formed by 1:1 host–guest inclusion complexes. The ratio between the apolar surface area and the volume was used to predict the formation of inclusion versus exclusion complexes, with inclusion complexes observed at ratios <40. These findings allow the binding of potential guest molecules to be predicted and a suitable crystal packing for the designed properties to be obtained.

Routing simulation of brain network topology.

The incessant search to understand human cognitive functions has led to the hypothesis that the brain works similar to a packet switched network such as the Internet [28]. In this thesis, I have developed a top-down simulator of brain-like networks which uses prob- ability routing to route data and a distance vector routing algorithm [21] to propagate feedback to varying depths. I investigate the impact of the feedback depth on routing table metrics. The results indicate that important performance metrics are affected by the feedback depth of the routing algorithm but also, to a large extent, by the topological features of such networks [17, 44]. The results indicate feedback depths from 25 to 30 fill the routing table most efficiently in terms of routing table fill percentage, routing table fill time and packet rejection ratio. There is also a strong correlation between the macaque monkey brain and sparse topologies.

Routing simulation of brain network topology.

The incessant search to understand human cognitive functions has led to the hypothesis that the brain works similar to a packet switched network such as the Internet [28]. In this thesis, I have developed a top-down simulator of brain-like networks which uses prob- ability routing to route data and a distance vector routing algorithm [21] to propagate feedback to varying depths. I investigate the impact of the feedback depth on routing table metrics. The results indicate that important performance metrics are affected by the feedback depth of the routing algorithm but also, to a large extent, by the topological features of such networks [17, 44]. The results indicate feedback depths from 25 to 30 fill the routing table most efficiently in terms of routing table fill percentage, routing table fill time and packet rejection ratio. There is also a strong correlation between the macaque monkey brain and sparse topologies.

Anisotropy Evaluation of Different Raster Directions, Spatial Orientations, and Fill Percentage of 3D Printed PETG Tensile Test Specimens

In this paper, the mechanical properties of Polyethylene terephthalate-glycol (PETG) tensile test specimens have been investigated. The test pieces were prepared using fused deposition modelling (FDM) 3D printing technology. Three print settings were examined which are: raster direction angles, print orientations, and infill percentage and patterns in order to evaluate the anisotropy of objects when employing FDM print method. The variations in stress-strain curves, tensile strength values and elongation at break among the tested samples were studied and compared. Illustration for the broken specimens after the tensile test was accomplished to know how the test pieces printed with various parameters were fractured. A comparison with some previous results regarding the elongation at break has been carried out.

Detection of Voids in Tungsten Interconnect Vias Using Laser-Induced Surface Acoustic Waves

Test wafers were prepared under different process conditions of barrier and seed film deposition, in order to study the effects on tungsten plug filling. Tungsten fill percentage was measured using laser-induced surface acoustic wave metrology on plug arrays of varying plug diameter and the results were verified by SEM cross-section. The data show that, for via diameters of 0.12 micron or less, the seed deposition process is a critical factor in effective (void free) plug filling. Seed deposition by ALD and low-temperature CVD were found to be far more effective than conventional CVD. Changing the thickness of the TiN barrier layer was found to have minimal effect on the occurrence of voids. For via diameters greater than 0.12 microns, all of the seed processes led to relatively little voiding.

Bronzing of Pecan Foliage

The influence of pecan [Carya illinoinensis (Wangenh.) K. Koch] leaflet bronzing, a discoloration of the lower surface, on foliar physiology and nut-meat yield is unknown. Field investigations indicate that bronzing can adversely affect foliage by reducing net photoassimilation (A), stomatal conductance (sgw), and transpiration (E) while also altering stomatal aperture and cellular structure, and increasing temperature. Kernel weight and fill percentage are also reduced. Research indicated that foliar A declined in proportion to degree of bronze coloration, with negative A exhibited by heavily bronzed foliage. A by bronzed foliage did not increase as light levels exceeded ≈250 μmol·m-2·s-1. Within the same compound leaf, nonbronzed leaflets adjacent to bronzed leaflets exhibited greater than normal A. Bronzed leaflets also exhibited lower sgw to water vapor, less transpirational H2O loss, and higher afternoon leaf temperature. Light micrographs of bronzed foliage indicated abnormal epidermal and spongy mesophyll cells. Weight and percentage of kernel comprising the nut declined on shoots supporting foliage bronzing in July to August, but was unaffected when bronzing occurred in September to October. Bronzing of pecan foliage can therefore be of both physiological and economic significance.