A coupled hydro-chemical-mechanical constitutive law for the Belgian Eurobitum bituminized waste is being developed by the International Centre for Numerical Methods and Engineering (Polytechnical University of Cataluña, Spain) to contribute to the study of the compatibility of Eurobitum with Boom Clay as a geological disposal environment. A large experimental programme is ongoing at SCK•CEN to support the development of a constitutive law for Eurobitum. Water uptake tests are being performed under different conditions to obtain insights in the parameters that influence the water uptake behaviour of Eurobitum. Furthermore, Environmental Scanning Electron Microscopy and microfocus X-ray Computer Tomography are used to characterize hydrated samples in order to improve the understanding of the water uptake processes.

The salt content, the distribution of the salt crystals, and the membrane efficiency in the Eurobitum samples affect the swelling and pressure increase rate. High membrane efficiencies and a large amount of hygroscopic salts inside the Eurobitum samples result in very high pressures when almost no swelling is allowed. The pressure in small inactive samples with 28 wt.% NaNO3has risen to ∼19 MPa after ∼3 years of hydration in nearly constant volume conditions. Slower pressure increase rates are being measured for samples with 6, 12, 18, and 33 wt.% NaNO3.

Hafnium(IV) oxide (HfO2) has replaced silicon oxide as a gate dielectric material in leading edge CMOS technology, providing significant improvement in gate performance for field effect transistors (FETs). We are currently exploring this high-k dielectric for its use in nucleic acid-based FET biosensors. Due to its intrinsic negative charge, label-free detection of DNA can be achieved in the gate region of high-sensitivity FET devices. Previous work has shown that phosphates and phosphonates coordinate specifically onto metal oxide substrates including aluminum and titanium oxides. This property can therefore be exploited for direct immobilization of biomolecules such as nucleic acids. Our work demonstrates that 5’ phosphate-terminated single stranded DNA (ssDNA) can be directly immobilized onto HfO2 surfaces, without the need for additional chemical modification or crosslinking. Non-phosphorylated ssDNA does not form stable surface interactions with HfO2, indicating that immobilization is dependent upon the 5’ terminal phosphate. Further work has shown that surface immobilized ssDNA can be hybridized to complementary target DNA and that sequence-based hybridization specificity is preserved. These results suggest that the direct DNA-HfO2 immobilization strategy can enable nucleic acid-based biosensing assays on HfO2 terminated surfaces. This work will further enable high sensitivity electrical detection of biological targets utilizing transistor-based technologies.

It has been reported that physico-chemical properties of diamond surfaces are closely related to the surface chemisorbed species on the surface. Hydrogen chemisorption on a chemical vapor deposition grown diamond surface is well-known to be important for stabilizing diamond surface structures with sp3 hybridization. It has been suggested that an H-chemisorbed structure is necessary to provide a negative electron affinity condition on the diamond surfaces. Negative electron affinity condition could change to a positive electron affinity by oxidation of the H-chemisorbed diamond surfaces. Oxidized diamond surfaces usually show characteristics completely different from those of the H-chemisorbed diamond surfaces. The unique electron affinity condition, or the surface potential, is strongly related to the chemisorbed species on diamond surfaces. The relationship between the surface chemisorption structure and the surface electrical properties, such as the surface potential of the diamond, has been modelled using DFT based calculations.

Skutterudite CoSb3 compounds are of increasing interest as materials with good thermoelectric performance over the temperature range of 600 to 800 K, but the thermal conductivity of the materials is relatively high. Nanostructured materials have been shown to enhance phonon scattering and lower the thermal conductivity of the thermoelectric materials. Partial substitution of Ni or Fe on the Co site of CoSb3 is a hopeful route for improving thermoelectric performance of the CoSb3 compounds. In the present work, synthesis of Ni-doped and Fe-doped CoSb3 nanoparticles through the modified polyol process was attempted and the optimum synthesizing condition was investigated. Co(OOCH3)2·4H2O, Ni(OOCH3)2·4H2O, FeCl3·6H2O and SbCl3, were prepared as precursors. The precursors were reduced by NaBH4 in tetraethyleneglycol at 513 K in an argon atmosphere, for different reaction times (holding times). The reaction products were characterized by the X-ray diffraction, the energy dispersive X-ray spectroscopy, and transmission electron microscopy. The nanoparticles with about 20 to 30 nm in size mainly existed in the reaction products regardless of the chemical composition and the reaction time. The skutterudite phase was identified as a main phase in the sample synthesized for long reaction time, but the other phases of Sb and MSb2 (M=Co, Ni, Fe) were also detected. The lattice parameter of the synthesized skutterudite phase linearly increased with increasing the doping agent concentration, following Vegard’s law.

Nanodiamonds (NDs) have desirable chemical, physical and biological properties that lend them to a wide range of applications. ND’s facile surface chemistry, for example, can be used to create a high affinity for adsorbing various biological molecules. However, NDs, which are commercially available from multiple vendors, show inconsistencies with surface groups, aggregate sizes and impurity contents that may limit adsorption. We explore adsorption mechanisms of molecules to NDs in efforts to expand ND applications to drug delivery agents, bio-labels and enterosorbents. In doing so, several types of NDs and modification methods are evaluated to increase adsorption capacity and selectivity of propidium iodide and aflatoxin B1. Capacities and binding strengths of target molecules are assessed by Langmuir isotherms and transform calculations. UV-Vis spectroscopy shows our modification treatments are successful in increasing ND adsorption capacities. Additionally, cyclic voltammetry measurements, used to monitor in-situ adsorption, show electrochemical detection even after binding.

The work function is one of the crucial quantities in understanding their field emission properties and applying carbon nanotubes to electronic devices. We perform the systematic study of work functions of 44 kinds of isolated single-walled carbon nanotubes in the framework of the density functional theory. It has been revealed that the first-principles study plays a very important role for predicting various properties of carbon nanotubes. In general, we have to perform the structural relaxation in order to know the accurate electronic properties of carbon nanotubes. Therefore we carry out the complete geometrical relaxations for 44 kinds of carbon nanotubes and evaluate their work functions. The diameters (D) of nanotubes studied satisfy 0.3 < D < 2.0 nm. Especially, we focus on the small diameter carbon nanotubes. We determine the values of work functions from the difference between the Fermi level and the vacuum level. In the semiconducting carbon nanotubes, the Fermi level is chosen at the midgap. As a result, it is found that the carbon nanotubes should be classified into three classes according to the diameter and chiral-angle dependences of work functions.

The paper addresses the �green innovation� in the non-fossil fuel energy industry. The objective of the study is to identify the changes in trends of non-fossil fuel energy industry demand, growth and opportunities. The study uses the databases such as patents, news events, income/financial statements to assess the company status and the track record of the industry. The research adopts the methodology of Innovation Radar (Sawhney, MIT Sloan Management Research, 2001) to assess the positioning of the dominant company and design in photovoltaic, geothermal and wind renewable energy industry. The study also summarizes the sustainable competitive advantages of some of the successful companies in the energy sector. This study correlates the gains in innovation tripartite (product, process, business) to the corporate competitive advantage. The companies selected in this study are based on the innovations brought to improve the product, process and business aspects and are evaluated in terms of market adaptability.

We present a theory of three-phonon interactions in nanophononic semiconductors at 300˜K. The intrinsic lifetime of phonon modes is estimated from the application of Fermi's Golden Rule, based on realistic phonon dispersion relations and a quasi-continuum model for the cubic anharmonicity. We show that the lifetime of phonon modes in the Si(0.543˜nm)/- Ge(0.543˜nm)[100] superlattice is shorter than the average of results for bulk Si and Ge. This is explained in terms of the availability of additional decay routes and an additional Dual Mass factor which arises due the different densities of Si and Ge.

In this work we have developed novel microfabrication processes using wet anisotropic etchants to perform advanced bulk micromachining in {100}Si wafers for the realization of microelectromechanical systems (MEMS) structures with new shapes. The etching is performed in two steps in pure and Triton-X-100 [C14H22O(C2H4O)n, n = 9-10] added 25 wt% tetramethyl ammonium hydroxide (TMAH) solutions. The local oxidation of silicon (LOCOS) is attempted after the first anisotropic etching step in order to protect the exposed silicon. Two types of structures (fixed and freestanding) are fabricated. The fixed structures contain perfectly sharp corners and edges. Thermally grown silicon dioxide (SiO2) is used for the fabrication of freestanding structures. Present research is an approach to fabricate advanced MEMS structures, extending the range of 3D structures fabricated by silicon wet anisotropic etching.

This paper reports on a molecular simulation study of the thermodynamics, structure and dynamics of water confined at ambient temperature in charged silica nanopores of a width H = 10 and 20 Å. The adsorption isotherms for water resemble those observed for experimental samples; the adsorbed amount increases continuously in the multilayer adsorption regime until a jump occurs due to capillary condensation of the fluid within the pore. Strong layering of water in the vicinity of the silica surfaces is observed as marked density oscillations are seen up to 8 Å from the surface in the density profiles for confined water. Our results also indicate that the Ca2+ counterions remain in a space close to the silica surface whatever the pore width and the adsorbed amount of water. For all pore sizes and adsorbed amounts, the self-diffusivity of confined water is lower than the bulk due to the strong hydrophilic nature of the pore surface. Our results also suggest that the self-diffusivity of confined water is sensitive to the adsorbed amount of water molecules.

Two common problems with implantation after cancerous tumor resection are cancer recurrence and bacteria infection at the implant site. Tumor resection surgery sometimes can not remove all the cancerous cells, thus, cancer can return after implantation. In addition, bacteria infection is one of the leading causes of implant failure. Therefore, it is desirable to have anti-cancer and anti-bacterial molecules which both rapidly (for anti-infection purposes) and continuously (for anti-cancer purposes) are available at the implant site following implantation. Therefore, the objective of the present in vitro study was to create a multi-functional coating for anti-cancer and anti-bacterial orthopedic implant applications. Elemental selenium was chosen as the biologically active agent in this effort because of its known chemopreventive and anti-bacterial properties. To achieve that objective, titanium (Ti), a conventional orthopedic implant material was coated with selenium (Se) nanoclusters. Different coating densities were achieved by varying Se concentration in the reaction mixture. Titanium substrates coated with Se nanoclusters were shown to enhance healthy osteoblast (bone-forming cell) and inhibit cancerous osteoblast proliferation in co-culture experiments. Functions of S. epidermidis (one of the leading bacteria that infect implants) were inhibited on Ti coated with Se-nanoclusters compared to uncoated materials. Thus, this study provided for the first time a coating material (selenium nanoclusters) to the biomaterials’ community to promote healthy bone cells’ functions, inhibit cancer growth and prevent bacteria infection.

Nanophase semiconductor composites are widely researched for the development of third-generation photovoltaic (PV) devices. Through quantum-size effects and phase assembly manipulation the optical absorption and carrier transport properties of nanocomposite films can be influenced. We investigate the potential for improved PV-relevant material performance by examining the photo-sensitization of indium-tin-oxide (ITO) with nanophase germanium (Ge). Nanocomposite films are produced by a sequential, RF-magnetron sputter deposition technique. Deposition control and post-deposition annealing are used to demonstrate the manipulation of the extended-assembly of the nanocrystalline Ge phase. Optical absorption characteristics were correlated to variations in the composite film structure as confirmed by transmission electron microscopy. In addition to structure-dependent variation in spectral absorption, spectrally resolved photoconductivity measurements demonstrate enhanced photoconductivity of composite films associated with the incorporation of the Ge phase into the ITO host. These results support the further evaluation of such nanocomposite TCO materials in optoelectronic devices, including PV systems.

We synthesized BiFe1-xMnxO3 (BFMO) for various compositions by sol gel process and thin films were deposited by spin coating on platinum Pt/Ti/SiO2/Si substrates. X-ray diffraction shows all the diffraction planes corresponding to rhombohedrally distorted perovskite BiFeO3 structure. The absence of any impurity phase in the films suggests the incorporation Mn ion preferentially to Fe site in the structure for low concentration. Magnetic measurements reveal the formation of ferromagnetic phase at room temperature with increased Mn substitution. On the other hand, ferroelectric polarization decreases with increasing Mn ion concentration. Raman studies suggest the dopant induced structural distortion.

The morphology, phase and stability of titania-coated SiOX NWs are investigated for two coating methods: solution-based deposition of Ti-alkoxides and Atomic Layer Deposition (ALD). Analysis of as-deposited and annealed films shows that it is possible to produce stable coatings of the anatase phase of TiO2. The limitations of these two approaches are also discussed.

Synchrotron x-ray tomography was performed on titanium foams with aligned, elongated pores, initially created by sintering directionally freeze-cast preforms using two different powder sizes. Three-dimensional reconstructions of the pore structures were analyzed morphologically using interface shape and interface normal distributions. A smaller powder size leads to more completely sintered titanium walls separating the dendritic pores, which in turn created a more compact distribution of pore shapes as well as stronger pore directionality parallel to the ice growth direction. The distribution of pore shapes is comparable to trabecular bone reported in the literature, indicating the foam's potential as a bone replacement material.

Since the initiation and propagation of a micro-crack in a silicon wafer introduces local variations in stress, it is critical to the understanding of wafer breakage that accurate profiling of stress be performed in the vicinity of the micro-crack. In this study, nanoindentation has been used to investigate the stress-relaxation during crack initiation and propagation in material of particular interest to the photovoltaic (PV) industry. The low load (<1 mN) capability of a Hysitron Triboindenter® was used to accurately profile the extent of plastic deformation and resulting amorphization. Measurements were made on Si samples extracted from top, middle and bottom of a (100) oriented single crystal ingot to evaluate the impact of different carbon, oxygen and metallic impurity concentrations. A gradual but significant drop in hardness from 10.2 to 6.9 GPa occurred as indents were made closer to the micro-crack and was attributed to local amorphization. Electron back scattered diffraction (EBSD) and Raman spectroscopy confirmed the amorphization, respectively, at nano- and micro-scale.

Luminescent nanoparticles such as quantum dots (QDs) are beginning to appear in SSL devices and other commercial products. The allure of QDs in SSL these applications is the potential to provide enhanced device performance (e.g., improved energy efficiency, better color rendering properties, etc.) than is possible with conventional technologies. When used in SSL and other applications, QDs are typically incorporated into or coated onto a solid organic or inorganic matrix and then are excited using external stimuli (e.g., blue light with a maximum wavelength of 450 nm). This structure is vastly different from the colloidal environment in which QDs are typically synthesized and characterized. Bridging the gap between the measurements typically acquired by QD providers and those needed by potential end-users is currently difficult due to the absence of agreed upon standard test methods. Measurements taken in colloidal QD suspensions often do not translate to solid-phase material characterizations due to a variety of factors including sample preparation methods (e.g., temperature, solvents, etc), QD concentrations, and effects arising from the presence of the solid matrix. Additionally, solid samples are more likely to exhibit diffuse reflectance and/or diffuse transmittance necessitating the use of an integrating sphere and a computer-controlled spectrometer to acquire accurate readings. This paper discusses the development of a standard test method to measure the quantum efficiency of QDs contained in solid organic and inorganic matrices. This standard is being developed under the auspices of the International Electrotechnical Commission, Technical Committee 113 on Nano-electrotechnologies.

With the increasing demand for the development of nuclear power comes the responsibility to address the issue of waste, including the technical challenges of immobilizing high-level nuclear wastes in stable solid forms for interim storage or disposition in geologic repositories. The immobilization of high-level nuclear wastes has been an active area of research and development for over 50 years. Borosilicate glasses and complex ceramic composites have been developed to meet many technical challenges and current needs, although regulatory issues, which vary widely from country to country, have yet to be resolved. Cooperative international programs to develop advanced proliferation-resistant nuclear technologies to close the nuclear fuel cycle and increase the efficiency of nuclear energy production might create new separation waste streams that could demand new concepts and materials for nuclear waste immobilization. This article reviews the current state-of-the-art understanding regarding the materials science of glasses and ceramics for the immobilization of highlevel nuclear waste and excess nuclear materials and discusses approaches to address new waste streams.

A sol-gel derived organosilica material that energetically swells when exposed to organic molecules was tested as a means to extract dissolved organic species from water. Swellable organically modified silica (SOMS) was demonstrated to be effective at removing butanol, methyl t-butyl ether (MTBE), tetrachloroethylene, trichloroethylene, ethanol, and toluene from lab grade water, salt water, and natural waters. Partition coefficients for the absorption of organic species from water by SOMS ranged from 2.8�105 – 1.0�102, and vary depending on polarity of the contaminant, concentration, and the total mass of contaminant absorbed. Absorption of organic species to SOMS appears to be enhanced by matrix expansion of nanometer sized pores leading to non-selective capture of organics beyond what could be attributed to physisorption.

In this work, scattered electric and magnetic fields of all-dielectric metamaterials were derived using a commercial RF finite-element partial differential equations solver. We present the implementation of rod-type composites consisting of a mixture of two components: the first one, which is called guest, is made of Ba1-xSrxTiO3 (0 ≤ x ≤ 1) and the second one, the host, made of SiO2. Analysis includes both the scattering effect, well described by the MIE theory, and dielectric inhomogeneous structure properties, determined using the MAXWELL-GARNETT approximation.