Papers in the Appendix were published in electronic format as Volume 1534

http://journals.cambridge.org/issue_MRS Online Proceedings Library/OPL1534no-1

A molecular dynamics simulation was performed to study the polymer filling process in nanoimprint lithography for a bi-layered resist. The bi-layered resist consisted of PMMA resins with different molecular weights. When the mold cavity size became smaller than the polymer size of the top layer resist, the required force to fill the cavity became large. The molecular weight of the top layer dominated the filling characteristics in the bi-layered resist process.

In this work we compare two different detection schemes that are sensitive to the focus shift of a probe beam due to induced surface curvature. The technique on which both detection schemes are based is called ThERM (Thermal Expansion-Recovery Microscopy) and allows the retrieval of the thermal diffusivity at microscopic levels, hence mapping such magnitude over a sample surface. The induced thermal expansion defocuses the probe beam due to the surface deformation (curvature). The dependence of the defocusing with the pump modulation frequency yields the thermal diffusivity of the sample at the impinging location. The explored depth is controlled by the pump beam size. By scanning both beams, a complete map of the thermal diffusivity can be retrieved.

Microporous-macroporous carbononaceous monolith-type materials, prepared through a hard template method using silica as exo-templating matrices, have been impregnated by an etheric solution of LiBH4 to prepare LiBH4@Carbon samples. It has been shown that the amorphous character of LiBH4 is largely favoured when developing the carbon microporosity (pores smaller than 2 nm) and that LiBH4 dehydrogenation is strongly enhanced at low temperatures. The onset temperature of dehydrogenation can be decreased to 200°C and hydrogen capacity reaching 4.0 wt.% is obtained at 300°C with the carbon having the largest microporous volume, whereas the hydrogen release for bulk LiBH4 is negligible at the same temperature. In addition to some irreversible reactions with carbon surface groups the explanation for such modification could lie in the LiBH4 destabilization through confinement to the nanoscale range and associated amorphization.

Any world’s metropolis requires urban public water networks composed by thousands of kilometres of pipelines and various other installations. Such infrastructure ensemble is expected to be in service for rather long periods of time, as it involved decades of costly investments. Anyway, and independently of careful operation and maintenance of such assets, eventually and unavoidable they will decay and will need replacement. This will occur sooner when soil conditions, or operation and maintenance is unfavourable. The paper explores typical and general problems for renewing infrastructure, with examples from specific studies for some Mexican cities and from other countries found in literature. Also mentions usual materials and elements and their life spans under different conditions, along with replacement techniques and probable costs.

The topics, elements and focuses of attention around water infrastructure renewal are broad and varied and must cover the WHY, HOW, WHEN, WHERE, and WITH WHAT money. They range from technical, constructive and diagnosis tasks, to institutional organization, financial and public awareness. As it is impossible to cover everything in a single paper, the present one is a modest intent to give a brief panorama of the state of the art on several of those issues and focuses. The paper underlines and gives recommendations regarding gaps and needs requiring research, as well as the production of more technical papers and discussion forums particularly in Mexico and the Latin America Regions.

Hitachi High Technologies is On the Frontlines of Science Education Outreach Programs. Hitachi High-Technologies Corporation (Hitachi High-Tech), a global leader in the electron microscope industry, is working to inspire a new generation of achievement in science education. In loaning out its tabletop microscopes Hitachi High-Tech is tackling the problem of waning interest in science education, which is becoming a global issue throughout all industrialized nations. Hitachi High-Tech aims to become the global leader in providing high-tech solutions, and its support for science extends beyond Japan to North America, South America, and Europe.

In recent years, there has been much interest in modelling graphene nanoribbons as they have great potential for use in molecular electronics. We have employed the NEGF formalism to determine the conductivity of graphene nanoribbons in various configurations. The electronic structure calculations were performed within the framework of the Extended Huckel Approximation. Both zigzag and armchair nanoribbons have been considered. In addition, we have also computed the transmission and conductance using the non-equilibrium Greens function formalism for these structures. We also investigated the effect of defects by considering a zigzag nanoribbon with six carbon atoms removed. Finally, the effect of embedding boron nitride aromatic molecules in the nanoribbon has been considered. The results of our calculations are compared with that obtained from recent work carried out using tight-binding model Hamiltonians.

We describe a hybrid organic-inorganic fuel cell membrane material based on silica colloidal crystal and using EEMA/SPM co-polymers. We demonstrate that there is an S-shaped dependence of proton conductivity on the amount of sulfonyl groups in the copolymer for the copolymer-modified membranes and that there is no significant increase in proton conductivity with increasing amount of sulfonated monomer content above 60%. The studies of fuel cell potential dependence on the degree of sulfonation show that the presence of non-ionic moieties improves the performance of fuel cell, likely due to the reduction of methanol cross-over through the membrane. The fuel cells using the polymer-modified silica colloidal membranes perform better than Nafion 117.

A necessary prerequisite for a successful theory-guided up-scale design of materials with application-driven elastic properties is the availability of reliable homogenization techniques. We report on a new software tool that enables us to probe and analyze scale-bridging structure-property relations in the elasticity of materials. The newly developed application, referred to as SC-EMA (Self-consistent Calculations of Elasticity of Multi-phase Aggregates) computes integral elastic response of randomly textured polycrystals. The application employs a Python modular library that uses single-crystalline elastic constants C ij as input parameters and calculates macroscopic elastic moduli (bulk, shear, and Young's) and Poisson ratio of both single-phase and multi-phase aggregates. Crystallites forming the aggregate can be of cubic, tetragonal, hexagonal, orthorhombic, or trigonal symmetry. For cubic polycrystals the method matches the Hershey homogenization scheme. In case of multi-phase polycrystalline composites, the shear moduli are computed as a function of volumetric fractions of phases present in aggregates. Elastic moduli calculated using the analytical self-consistent method are computed together with their bounds as determined by Reuss, Voigt and Hashin-Shtrikman homogenization schemes. The library can be used as (i) a toolkit for a forward prediction of macroscopic elastic properties based on known single-crystalline elastic characteristics, (ii) a sensitivity analysis of macro-scale output parameters as function of input parameters, and, in principle, also for (iii) an inverse materials-design search for unknown phases and/or their volumetric ratios.

This work focuses on the patterning of SiC substrates prior to carbon nanotube (CNT) formation using the surface decomposition growth method for the purpose of improving the field emission capabilities of the resultant CNT film. The thermal decomposition of silicon carbide (SiC) substrates is an established approach to create highly dense arrays of vertically aligned CNTs. The attractiveness of this growth approach is that the CNTs form without the aid of a catalyst metal, yielding potentially defect free CNTs ideal for various applications. Due to the high temperature anneals (1400-1700oC) and moderate vacuum conditions (10−2 – 10−5 Torr) necessary for the thermal decomposition process to initiate on the SiC substrate, patterning CNT outcroppings ideal for enhancing the surface’s field emission properties is more difficult when compared to metal catalyst based chemical vapor deposition growth processes on silicon substrates. The intent of the SiC patterning is to reduce field screening effects between neighboring emission sites during field emission while maintaining a high emission site density. Specifically, the SiC substrate is etched to form μm scale pillars on the SiC surface. Experimental findings show that SiC substrates patterned with μm scale pillars can be decomposed to form CNT topped field emission sites, yielding a field emission substrate that outperforms a non-patterned SiC/CNT film. A turn-on electric field of 4.0 V/μm was measured.

The shape memory effect is closely related to the reversible martensitic phase transformation, which is diffusionless and involves shear deformation. The recoverable transformation between the two phases with different crystalline symmetry results in reversible changes in physical properties such as electrical conductivity, magnetization, and elasticity. Accompanying the transformation is a change of entropy. Fascinating applications are developed based on these changes. In this paper, the history, fundamentals and technical challenges of both thermoelastic and ferromagnetic shape memory alloys are briefly reviewed; applications related to energy conversion such as power generation and refrigeration as well as recent developments will be discussed.

Cu2ZnSnSe4 p-type semiconductors currently investigated for use in thin film solar cells can be synthesized by firstly depositing a metallic precursor and secondly annealing the precursor in selenium vapor. Differently stacked Cu-Sn-Zn metallic precursors were characterized after a soft annealing at 350°C under nitrogen atmosphere. For the stack where the Sn and Zn were in direct contact with sufficient Cu to form a stable alloy, a bi-layered structure consisting of Cu-Sn on the bottom and Cu-Zn on the top was formed. Contrarily, when Zn was not in direct contact with Cu, the metals diffused to form a stable alloy and the system segregates horizontally, forming a mixed columnar structure. These two types of precursors were selenized under exactly the same conditions to form kesterite absorbers for solar cell devices. Using this approach the improvement from 0.44% power conversion efficiency for the bi-layered precursor to 4.5% for the mixed precursor was achieved.

In the past 20 years, one of the best catalytic materials for hydrodesulphurization reactions of crude oil has been the transition sulfides, MoS2, known also as the “workhorse” of the refinery industry. It has been proven by this and other research groups that the MoS2 laminar structure can increase its catalytic activity when promoted with cobalt or nickel. The location of active sites seem to be at rim and edge sites on that particular laminar structure, as demonstrated using Mössbauer spectroscopy and x-ray techniques. However, due to maximum capability of this promoted systems, Co(Ni)/MoS2 to remove heterogeneous atoms (S, N, O) - a search for new catalytic materials has currently been an ongoing activity in the HDS community. Here, we will present the new family of ternary phase catalyst with special emphasis on their structural aspects, as revealed by aberration corrected (Cs) high-resolution transmission electron microscopy techniques, in an attempt to describe the nature of active sites on this porous nano-rod like catalytic materials.

This study demonstrates that thin metallic oxide layers, such as OsOx and ZnO, function as a strong adhesion layer between Cu film and glass substrate. The adhesion strength was studied with a micro-scratch tester and the films and interfaces were characterized by energydispersive X-ray spectrometry. The presence of an extremely thin intermixing layer was confirmed at the metal/glass interfaces. The formation of such an interfacial layer increased the adhesion strength significantly.

Our objective is to design nanostructured hybrid inorganic-biological materials using the selfassembly of functionalized nanotubes and lipid molecules. In this presentation, we summarize the multiple control parameters which direct the equilibrium morphology of a specific class of nanostructured biomaterials. Individual lipid molecules are composed of a hydrophilic head group and two hydrophobic tails. A bare nanotube encompasses an ABA architecture, with a hydrophobic shaft (B) and two hydrophilic ends (A). We introduce hydrophilic hairs at one end of the tube to enable selective transport through the channel. The dimensions of the nanotube are set to minimize its hydrophobic mismatch with the lipid bilayer. We use a Molecular Dynamicsbased mesoscopic simulation technique called Dissipative Particle Dynamics which simultaneously resolves the structure and dynamics of the nanoscopic building blocks and the hybrid aggregate. The amphiphilic lipids and functionalized nanotubes self-assemble into a stable hybrid vesicle or a bicelle in the presence of a hydrophilic solvent. We demonstrate that the morphology of the hybrid structures is directed by factors such as the temperature, the molecular rigidity of the lipid molecules, and the concentration of the nanotubes. We present material characterization of the equilibrium morphology of the various hybrid nanostructures. A combination of the material characterization and the morphologies of the hybrid aggregates can be used to predict the structure and properties of other hybrid materials.

Cadmium sulfide (CdS) films were deposited onto glass substrates by chemical bath deposition (CBD) from a bath containing cadmium acetate, ammonium acetate, thiourea, and ammonium hydroxide. The CdS thin films were annealed in argon (neutral atmosphere) or hydrogen (reducing atmosphere) for 1 h at various temperatures (300, 350, 400, 450 and 500 °C). The changes in optical and electrical properties of annealed treated CdS thin films were analyzed. The results showed that, the band-gap and resistivity depend on the post-deposition annealing atmosphere and temperatures. Thus, it was found that these properties of the films, were found to be affected by various processes with opposite effects, some beneficial and others unfavorable. The energy gap and resistivity for different annealing atmospheres was seen to oscillate by thermal annealing. Recrystallization, oxidation, surface passivation, sublimation and materials evaporation were found the main factors of the heat-treatment process responsible for this oscillating behavior. Annealing over 400 °C was seen to degrade the optical and electrical properties of the film.

Nanoporous gold is a material with many possible applications e.g. in catalysts, sensors and electrode materials. We studied the functionalization of the nanoporous gold with TiO2 particles. Aiming at the low temperature oxidation of CO, the nanoporous gold can be coated with TiO2 in order to enhance catalytic activity. Structure and distribution of the TiO2 on the gold surface are important structural features, which were investigated by transmission electron microscopy. The preparation of the porous gold was tested with focused ion beam - preparation, conventional Ar+ ion beam preparation of nanoporous gold embedded in epoxy and ultramicrotome preparation of nanoporous gold embedded in epoxy. Considering the beam damage on the structure and the contamination of the surface, ultramicrotome preparation turned out to be the best solution. It was shown, that the gold ligaments are abundantly covered by approximately 5 nm TiO2 particles. The determination of the largest lattice fringe distance in high resolution mode revealed that the crystalline nanoparticles consist of the anatase phase. The spatial Ti distribution was measured with energy filtered transmission electron microscopy. Scanning transmission electron microscopy tomography was applied to reconstruct the three-dimensional structure of the gold coated with TiO2 particles.

We contribute a fast numerical approach to simulating the roller-imprinting of complex patterns. The technique predicts the extent to which imprinted patterns are fully formed, as well as variation of the imprinted material’s residual layer thickness (RLT). The approach can be used for roll-to-roll and roll-to-plate configurations, and for rollers with or without elastomeric coatings. If patterns vary in pitch, shape or areal density across the roller, RLT and the completeness of pattern transfer can vary with position as well as with processing parameters, and our technique is able to model these effects. The technique has been successfully validated against published experimental data from two different roller-NIL processes: one involving an ultraviolet-curing resist film on a glass plate, and another involving a flexible thermoplastic web softened at its surface.