Lateral structure

P. Miiller-Buschbaum, M. Tolan, W. Press, F. Brinkop, J. P. Kotthaus. Wetting of laterally structured surfaces. Ber Bunsenges Phys Chem 95 413—414, 1994. 

This area of research is still at its beginning and many aspects are not resolved. This includes in particular the structure and conformation of polymers at an interface as well as the modification of polymer dynamics by the interface. We have given several examples of the potential of surface and interface analytical techniques. They provide information on surface roughness, surface composition, lateral structure, depth profiles, surface-induced order and interfacial mixing of polymers on a molecular and sometimes subnanometer scale. They thus offer a large variety of possible surface and interface studies which will help in the understanding of polymer structure and dynamics as it is modified by the influence... 

Other lateral structures that are bound to the microtubules of cilia and flagella are filamentous interdoublet links composed of nexin, radial spokes directed to the central pair of microtubules, and a central sheath that is attached to the walls of the central pair (Figure 1). 

Today the successful application of TOF-SIMS in chemistry and material sciences covers all kinds of organic and inorganic materials—functionalized surfaces as well as mono-molecular or multilayer coatings with lateral structures down to the 50 nm range. TOF-SIMS is here applied in the... 

In nanotechnology, dimensions of interest are shrinking from the fiva to the nm range. For many microelectronic devices, such as laterally structured surfaces, particles, sensors, their physical as well as their chemical properties are decisively determined by their chemical composition. Its knowledge is mandatory for understanding their behavior, as well as for their successful and reliable technical application. This presents a challenge for TOF-SIMS, because of its demand for the unique combination of spatial resolution and sensitivity. 

The foregoing examples give initial impressions of how DNA can be nsed to fnnctionalize solid supports with respect to applications, for instance, in the field of microelectronics. In the following, the use of laterally structured substrates is addressed. In particnlar, the generation and applications of microstrnctnred snpports fnnctionalized with nncleic acid molecules will be discussed. 

The lateral structure was studies by optical microscopy, and contrast arises from the fact that after irradiation of the samples with the ion beam in the TOF-ERDA apparatus, the PBrxS-rich structures appear darker than those rich in dPS, giving an excellent contrast (Figure 4.30). 

Lateral structures were observed after 40 min of annealing, when typical spinodally decomposed structures were apparent. After 315 min the mean diameter of the dPS particles has reached the film thickness, and for larger times, two-dimensional domain growth takes place. 

Vascular changes include thickening of pulmonary vessels that may lead to endothelial dysfunction of the pulmonary arteries. Later, structural changes increase pulmonary pressures, especially during exercise. In severe COPD, secondary pulmonary hypertension leads to right-sided heart failure (cor pulmonale). 

Fig. 9.13 a) Preparation of laterally structured SAMs by the microcontact printing (pCP) technique. A structured PDMS stamp is inked with self-assembling molecules (hexa-decanethiols HDT) and placed onto a planar substrate (gold). SAM formation occurs within seconds at the areas of contact (I). The structure can be further processed by etching (II) or deposition of a second SAM (III) onto... 

The later structure might explain why trans- disubstituted ethylenes form more stable complexes than their cis- isomers (see following section). 

X-ray reflectivity, AFM and optical microscopy have been used to probe lateral structure in a thin film of a symmetric PS-PMMA diblock that formed islands at the surface (Cai et al. 1993). The step height obtained from beating of fringes in the X-ray reflectivity profile was found to be in good agreement with a direct... 

The application of methods of multivariate statistics (here demonstrated with examples of cluster analysis, multivariate analysis of variance and discriminant analysis, and principal components analysis) enables clarification of the lateral structure of the types of feature change within a test area. 

On reaction with xenon hexafluoride (53) NOF forms the adduct 2NOF XeFs. Infrared and Raman measurements suggested the ionic formulation NOj2 TXeF8]2 for the solid, and later structural work... 

In another study, Fourcroy is cast as the historian of the chemical revolution, a role he fulfils admirably as he was both spectator and participant in the most important chemical events of the period.230 The importance of the language of chemistry has been stressed by Trevor Levere231 and by Pierre Laszlo.232 It has also been contended that the new chemistry contained the seeds of later structural concepts.233 This may be pushing the potential of Lavoisier s anti-phlogistic chemistry and its revised nomenclature too far, yet without all these main components, the fundamental reorganization of chemistry could not have been achieved. Fresh interest was also stimulated in Lavoisier s collaborators and contemporaries. For example, the... 

Fig. 14.1 The life cycle of coxsackievirus B3. CVB3 starts its life cycle by attaching to its receptor CAR and coreceptor DAF. Internalized virus releases its viral RNA, which can be used as the template for translation of polyprotein or transcription by RNA-dependent RNA polymerase 3D to replicate its genome. The polyprotein is self-cleaved by virus-encoded proteases to release structural proteins and nonstructural proteins. Later, structural proteins and viral RNA will assemble into progeny virions to be released from infected cell. Abbreviations CVB3, coxsackievirus B3 DAF, decay accelerating factor CAR, coxsackievirus and adenovirus receptor 3Dpo1, RNA-dependent RNA polymerase.

Many ESR studies (see Section 3.3.6) using different systems have shown that phase separation in lipid layers may lead to a domain-like lateral structure. The area of domain formation can be extended over several hundred angstroms. In this context, charge-induced domain formation in biomembranes is of special interest for the medicinal chemist. In particular, the addition of Ca2+ to negatively charged lipids leads to domain formation [106]. Each lipid component is expected to have a characteristic spontaneous curvature. The Ca2+-induced domains lead to protrusions in the... 

The helical hand of the individual stems in chiral but racemic polymers is a very severe and therefore critical criterion in the crystallization process. The constraints apply for each stem and are dictated by the symmetry of the unit-cell. Contrary to the stem length (which, if incorrect, can be healed or adjusted by later structural reorganization), helix chirality involves a flip of a coin type of decision - right- or left-handedness. 

The more recent neutron reflectivity studies have established that flattened surface micelle or fragmented bilayer structure in more detail and with more certainty, using contrast variation in the surfactant and the solvent [24, 31]. However, the extent of the lateral dimension (in the plane of the surface) and the detailed structure in that direction is less certain. From those neutron reflectivity measurements [24, 31] and related SANS data on the adsorption of surfactants onto colloidal particles [5], it is known that the lateral dimension is small compared with the neutron coherence length, such that averaging in the plane is adequate to describe the data. The advent of the AFM technique and its application to surfactant adsorption [15] has provided data that suggest that there is more structure and ordering in the lateral direction than implied from other measurements. This will be discussed in more detail in a later section of the chapter. At the hydrophobic interface, although the thickness of the adsorbed layer is now consistent with a monolayer, the same uncertainties about lateral structure exist. 

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