There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

PEEK Biomaterials in Trauma, Orthopedic, and Spinal Implants

Conductive polymers: towards a smart biomaterial for tissue engineering.

A range of nanocomposites containing polyethylene and montmorillonite (MMT) clay was prepared using different procedures, such that the extent of MMT dispersion varied. The interactions that occur were then studied, together with the effect of MMT dispersion on structure and short-term dielectric breakdown. When the MMT is poorly dispersed, the AC ramp breakdown strength is reduced. When the MMT is well dispersed, quenched samples with and without MMT appear to behave in an equivalent manner. However, while isothermal crystallization at 117 °C results in a significant increase in performance in the absence of MMT, no equivalent change was seen when the MMT was present. The crystallization behaviour of the polyethylene indicates that while well-dispersed MMT serves to enhance nucleation, it can also serve to inhibit crystallization. These results suggest that short-range thermodynamic interactions occur between the clay platelets and the polymer during the initial crystallization phase. The interaction zone can, however, be thought to extent throughout the material.

Polyethylene Nanodielectrics : The Influence of Nanoclays on Structure Formation and Dielectric Breakdown

Nanodielectrics - How much do we really understand?

On Additives, Morphological Evolution and Dielectric Breakdown in Low Density Polyethylene

On crystallization, morphology and radiation effects in poly(ether ether ketone)

Dilute blends of two guest monodisperse n-alkanes one, n-C 122 H 246 , shorter and one, n-C 246 H 494 , longer than the pure host, n-C 162 H 326 , have been investigated regarding the kinetics and morphology of both spherulitic growth and cellulation to clarify the related phenomena in polymers. All samples were crystallized isothermally between 118 and 124 °C. For the pure material this gave the optical textures expected of chain-extended crystallization, i.e., objects which may display circular envelopes but differ from classic spherulites in that they have domains of uniform crystallographic orientation. With increasing crystallization temperature these objects become larger and coarser to a limit when they are no more than aggregates of single crystals. Addition of 5% or 10% of a second component to n-C 162 H 326 lowers growth rates and drastically alters morphologies. When the guest is longer than the host, there is cocrystallization producing permanent cilia and finer-textured, radially symmetric spherulites. When it is shorter, it segregates with a decelerating growth rate akin to observations of cellulation in branched polyethylenes. The resulting solids have disrupted crystallographic ordering and textures with randomly oriented lamellae. In all cases, adjacent dominant lamellae splay apart by angles which increase linearly with supercooling. The rate of increase is less for blends than for the pure host and the magnitudes increase with guest concentration being greatest when there is both permanent and transient ciliation. Positive intercepts at zero supercooling may indicate a supplementary contribution from surface roughness of the embryonic lamella. The combined observations provide strong confirmation of the importance of ciliation in promoting spherulitic growth of long molecules, independent of segregation and cellulation.

Alun S. Vaughan

Papers

Polyethylene Nanodielectrics : The Influence of Nanoclays on Structure Formation and Dielectric Breakdown

Nanodielectrics - How much do we really understand?

On Additives, Morphological Evolution and Dielectric Breakdown in Low Density Polyethylene

On crystallization, morphology and radiation effects in poly(ether ether ketone)

Spherulitic Growth and Cellulation in Dilute Blends of Monodisperse Long n-Alkanes