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

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

Crystal engineering, the ability to predict and control the packing of molecular building units in the solid state, has attracted much attention over the past three decades owing to its potential exploitation for the synthesis of technologically important materials. We present here the development of crystal-engineering strategies toward the synthesis of noncentrosymmetric infinite coordination networks for use as second-order nonlinear optical (NLO) materials. Work performed mainly in our laboratory has demonstrated that noncentrosymmetric solids based on infinite networks can be rationally synthesized by combining unsymmetrical bridging ligands and metal centers with well-defined coordination geometries. Specifically, coordination networks based on 3D diamondoid and 2D grid structures can be successfully engineered with a high degree of probability and predictability to crystallize in noncentrosymmetric space groups. We have also included noncentrosymmetric solids based on 1D chains and related helical structures for comparison.

Crystal engineering of NLO materials based on metal-organic coordination networks

Physical Review B

1: Magnetic Particles: Preparation, Properties and Applications: M. Ozaki. 2: Maghemite (gamma-Fe2O3): A Versatile Magnetic Colloidal Material C.J. Serna, M.P. Morales. 3: Dynamics of Adsorption and Oxidation of Organic Molecules on Illuminated Titanium Dioxide Particles Immersed in Water M.A. Blesa, R.J. Candal, S.A. Bilmes. 4: Colloidal Aggregation in Two-Dimensions A. Moncho-Jorda, F. Martinez-Lopez, M.A. Cabrerizo-Vilchez, R. Hidalgo Alvarez, M. Quesada-PMerez. 5: Kinetics of Particle and Protein Adsorption Z. Adamczyk.

Surface and Colloid Science

We study closely packed crystalline structures formed by slow lateral compression of a colloidal suspension of hard spheres in a thin wedge. In addition to the known sequence of structural transitions, a buckling mechanism was recently proposed to maximize the packing fraction F between one and two layers. We here confirm this prediction experimentally and present the first evidence that for more than two layers, buckling, in this case of prism shaped arrays of particles, also takes place. This efficient mechanism may enhance F by up to 4% and dominates in major regions of the phase diagram. [S0031-9007(97)04068-4]

/pdf/finite-size-effects-on-the-closest-packing-of-hard-spheres-3fo9zjmhbx.pdf

Finite-size effects on the closest packing of hard spheres

Colloidal spheres interacting via a purely repulsive potential provide an excellent model system to study the kinetics of solidification from the melt. Such systems are readily accessible by comparably simple yet powerful optical methods like time resolved static light scattering and microscopy, reviewed in the first part of this paper. We then present results from our own recent studies within a framework of data available from literature. In particular we investigated nucleation and growth of hard sphere crystals using combined Bragg and small angle light scattering and of charged sphere crystals using Bragg microscopy. Special attention is given to the range of validity of classical nucleation theory and of Wilson Frenkel growth and a discussion of kinetic prefactors for both processes.

http://iopscience.iop.org/article/10.1088/0953-8984/11/28/201/pdf

Crystallization kinetics of repulsive colloidal spheres

Colloidal model systems allow studying crystallization kinetics under fairly ideal conditions, with rather well-characterized pair interactions and minimized external influences. In complementary approaches experiment, analytic theory and simulation have been employed to study colloidal solidification in great detail. These studies were based on advanced optical methods, careful system characterization and sophisticated numerical methods. Over the last decade, both the effects of the type, strength and range of the pair-interaction between the colloidal particles and those of the colloid-specific polydispersity have been addressed in a quantitative way. Key parameters of crystallization have been derived and compared to those of metal systems. These systematic investigations significantly contributed to an enhanced understanding of the crystallization processes in general. Further, new fundamental questions have arisen and (partially) been solved over the last decade: including, for example, a two-step nucleation mechanism in homogeneous nucleation, choice of the crystallization pathway, or the subtle interplay of boundary conditions in heterogeneous nucleation. On the other hand, via the application of both gradients and external fields the competition between different nucleation and growth modes can be controlled and the resulting microstructure be influenced. The present review attempts to cover the interesting developments that have occurred since the turn of the millennium and to identify important novel trends, with particular focus on experimental aspects.

http://iopscience.iop.org/article/10.1088/0953-8984/26/33/333101/pdf

Crystallization kinetics of colloidal model suspensions: recent achievements and new perspectives.

Many important properties of colloidal dispersions are directly or indirectly determined by the electric charge of the colloidal particles. Phase stability is provided by the repulsive interaction between like charges, while the details of the static and dynamic behavior are the result of the interplay between electrostatic interactions between macroions, counterions, and added salt ions, the dielectric response of the solvent, and the solvent hydrodynamics. Depending on whether the concentration of the background electrolyte (relative to that of the “native” counterions) is large or small, one must expect quite different behavior both with respect to statics and dynamics. The salt-dominated regime (high salt concentration) has been studied extensively both for static [1] and dynamic properties [2, 3, 4, 5]. In this case, the large reservoir of salt ions results in a strong Debye screening of the electrostatic interactions between the macroions, such that the net charge density is essentially zero throughout the dispersion except for narrow ionic atmospheres around the colloids. An external electric field will therefore exert forces only within these layers, such that hydrodynamic interactions are also strongly screened in a system subjected to electrophoresis [6, 7]. Therefore, the problems both of ion cloud structure and of electrophoresis can be treated within a single-macroion framework [8], and the dependence of the electrophoretic mobility � = v/E (v denoting the colloid drift velocity and E the driving

https://arxiv.org/pdf/cond-mat/0601588.pdf

Electrophoresis of colloidal dispersions in the low-salt regime.

Colloidal model systems allow studying crystallization kinetics under fairly ideal conditions with rather well characterized pair interactions and minimized external influences. In complementary approaches therefore experiment, analytic theory and simulation have been employed to study colloidal solidification in great detail. These studies were based on advanced optical methods, careful system characterization and sophisticated numerical methods. Both the effects of the type, strength and range of the pair-interaction between the colloidal particles and those of the colloid-specific polydispersity were addressed in a quantitative way. Key parameters of crystallization were derived and compared to those of metal systems. These systematic investigations significantly contributed to an enhanced understanding of the crystallization processes in general. Further, new fundamental questions have arisen and (partially) been solved over the last decade including e.g. a two step nucleation mechanism in homogeneous nucleation, choice of the crystallization pathway or the subtle interplay of boundary conditions in heterogeneous nucleation. On the other side, via the application of both gradients and external fields the competition between different nucleation and growth modes can be controlled and the resulting micro-structure be influenced. The present review attempts an account of the interesting developments occurred since the turn of the millennium and an identification of important novel trends with particular focus on experimental aspects.

Thomas Palberg

Papers

Finite-size effects on the closest packing of hard spheres

Crystallization kinetics of repulsive colloidal spheres

Crystallization kinetics of colloidal model suspensions: recent achievements and new perspectives.

Electrophoresis of colloidal dispersions in the low-salt regime.

Crystallization kinetics of colloidal model suspensions: recent achievements and new perspectives