Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

The growth of high-quality indium (In)-rich InXGa1−XN alloys is technologically important for applications to attain highly efficient green light-emitting diodes and solar cells. However, phase separation and composition modulation in In-rich InXGa1−XN alloys are inevitable phenomena that degrade the crystal quality of In-rich InXGa1−XN layers. Composition modulations were observed in the In-rich InXGa1−XN layers with various In compositions. The In composition modulation in the InXGa1−XN alloys formed in samples with In compositions exceeding 47%. The misfit strain between the InGaN layer and the GaN buffer retarded the composition modulation, which resulted in the formation of modulated regions 100 nm above the In0.67Ga0.33N/GaN interface. The composition modulations were formed on the specific crystallographic planes of both the {0001} and {0114} planes of InGaN.

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

The Environmental Scanning Electron Microscope (ESEM) was used to study film-formation in vinyl latices polymerised in the presence of varying amount and type of starch. An understanding of the effect of native biopolymers on film forming mechanisms in latex has technological and industrial relevance because it can lead to the creation of novel latices with potentially lower cost and improved biosustainability.

Film formation studies were carried out on a range of samples selected by ICI Paints as the most promising candidates for the novel latices. These included vinyl latices polymerised with 2 - 15% of potato and waxy maize starch, taken either in native or modified. Normally, no surfactants were used during latex polymerisation; a few samples were prepared for comparative purposes when polymerisation was carried out both with and without the addition of surfactant. Latex films were spun-cast on glass slides before insertion into the microscope.

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Conventional scanning electron microscopy permits the use of cryogenic techniques, which has led to the examination of ice-containing samples (eg ice cream) at temperatures of -80°C and below. At these temperatures moderate etching of the ice crystals occurs which helps to identify the crystals in the surrounding glassy matrix. However, imaging at higher temperatures - equivalent to those at which most ice-containing systems are actually utilised - is impossible because of rapid sublimation. We have set out to develop a system which will enable us to examine ice crystals at temperatures of -20°C and below, corresponding much more closely to realistic conditions of use.

In the environmental scanning electron microscope (ESEM), a gas can be maintained around the sample. Not only can this be used to maintain the sample in its native state, but the gas is actively involved in the imaging process through its role in signal amplification.

Most endosymbionts remain separated from their host cell by a derivative of the phagocytic membrane. This membrane and its contents have been defined as a novel “organelle-like” structure called a symbiosome. However, in the case of many cnidarian-dinoflagellate symbioses the putative symbiosome is composed of multiple layers of apparent membranes (Fig. 1). In the past the origin of these membranes has been assigned to host and/or symbiont with very little experimental evidence to support either view; however, several interesting hypotheses have been proposed to explain the origin of the “membranes”. Trench and Blank suggest that occasionally the outer most layer of the vegetative symbiont's cell wall is sloughed off the surface of the cell. They concede that the outer most layer of “membranes” must be the host vacuolar membrane, but believe that it simply prevents the sloughed layer from moving away from the cell, (as would happen in culture), and that, over time, multiple sloughed layers accumulate beneath the host vacular membrane.

We are using the term "Industrial Polymers" to refer to polymers [plastics] that are produced by the ton or (in the case of films) by the mile. For example, in descending order of world-wide use (tonnage), the top eight of these polymers are polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), styrene polymers (including polystyrene - PS, and acrylonitrile-butadienestyrene/ styrene-acrylonitrile - ABS/SAN), polyesters (PETP), polyurethane (PU), phenolics and aminoplastics.

Industrial polymers, which have been produced by the millions of tons for the last five decades and are of obvious social and economic importance, have been exhaustively characterized. Structural features which affect physical properties and indicate process variables have been studied by many techniques other than microscopy (x-ray diffraction, thermal analysis, rheology, chromatographies, etc.). Microscopy techniques for polymer characterization have been well documented. Our motivation to apply field emission (high resolution) scanning electron microscopy to the study of polymers is: (1) The application of low voltage, high resolution SEM to biological materials is well characterized.

The nuclear envelope (NE) physically separates the genetic machinery residing in the nucleus from protein synthesis taking place in the cytoplasm. Bidirectional transport of proteins, RNAs and RNP particles between these two compartments is mediated by the nuclear pore complexes (NPCs), large (-120 MDa) supramolecular assemblies embedded in the NE and being built of -100 different polypeptides, called nucleoporins. Extensive structural studies have revealed the 3D architecture of NPCs, and epitopes of several nucleoporins have been localized within their 3D structure.

In an attempt to go beyond the current consensus model of the NPC (Fig. lc, inset), we have embarked on a more systematic structural analysis of the molecular architecture of native NPCs. This is achieved by field-emission (FETEM; Fig. la) or energy-filtering (EFTEM; Fig. lb) TEM of completely unfixed and unstained Xenopus oocyte NEs embedded in thick (i.e. -200 nm) amorphous ice so that the 3D organization of the cytoplasmic and nuclear periphery of the NPCs (i.e. the cytoplasmic fibrils and nuclear baskets) is fully preserved (Fig. lb).

The physical properties of crystalline materials are dependent on the presence and nature of planar defects such as grain boundaries within the crystalline lattice. A comprehensive understanding of a material's properties requires a detailed knowledge of the atomic structure and chemistry of such defects. In general, the crystal orientation relationship at grain boundaries and related planar defects are described in geometric terms, such as the coincidence-site lattice (CSL) model. However, geometric models do not take account of the atomic bonding across grain boundaries whose characteristics differ from that in the bulk. In general, defect structures may relax from the exact CSL orientation in order to minimize the energy of the interface. Lattice relaxations can manifest as a local rearrangement of the atoms close to the boundary and/or rigid-body lattice translations which perturb the relative positions of the grains far from the interface.