The mid-infrared wavelength region offers a plethora of possible applications ranging from sensing, medical diagnostics and free space communications, to thermal imaging and IR countermeasures. Hence group IV mid-infrared photonics is attracting more research interest lately. Sensing is an especially attractive area as fundamental vibrations of many important gases are found in the 3 to 14 μm spectral region. To realise group IV photonic mid-infrared sensors several serious challenges need to be overcome. The first challenge is to find suitable material platforms for the mid-infrared. In this paper we present experimental results for passive mid-infrared photonic devices realised in silicon-on-insulator (SOI), silicon-on-sapphire (SOS), and silicon on porous silicon (SiPSi). Although silicon dioxide is lossy in most parts of the mid-infrared, we have shown that it has potential to be used in the 3-4 μm region. We have characterized SOI waveguides with < 1 dB/cm propagation loss. We have also designed and fabricated SOI passive devices such as MMIs and ring resonators. For longer wavelengths SOS or SiPSi structures could be used. An important active device for long wavelength group IV photonics will be an optical modulator. We present relationships for the free-carrier induced electro-refraction and electro-absorption in silicon in the mid-infrared wavelength range. Electro-absorption modulation is calculated from impurity-doping spectra taken from the literature, and a Kramers-Kronig analysis of these spectra is used to predict electro-refraction modulation. We have examined the wavelength dependence of electro-refraction and electro-absorption, and found that the predictions suggest longer-wave modulator designs will in many cases be different than those used in the telecom range.

Two fundamental processes associated with shock compression of energetic materials (EM) are initiation and ignition. Initiation occurs just behind a shock front and ignition occurs anywhere from a few nanoseconds to hundreds of nanoseconds later. Experiments are described that probe the fundamental mechanisms of these processes on relevant length and time scales: picosecond vibrational spectroscopy of nanometer thick layers of energetic materials (EM) with laser-driven shock waves, and nanosecond emission spectroscopy of micrometer thick layers of EM using laser-driven flyer plates.

In many countries, regulations for the management of nuclear waste require a performance (safety/risk) assessment to demonstrate the safety asserted to be provided by the sites/facilities proposed for handling, storing, and disposing of the wastes. However performance assessment can play a bigger role than solely demonstration of compliance with applicable safety standards in support of a regulatory decision (i.e., licensing of a waste management facility). Performance assessment can be an effective management tool during all phases of a waste management program: from development of national nuclear waste management policies; to programmatic environmental impact assessments associated with design and siting evaluations, site selection, and site characterization; to licensing and operation of facilities.

International experience has demonstrated that nuclear waste management programs are long-term efforts, lasting at least two to three decades from initial policy development to licensing and commencement of waste management and disposal operations. This experience has also demonstrated that consistent attention to, and integration of, initial component studies are necessary to provide a comprehensive total system analysis for programmatic environmental impact assessments and for licensing.

For nearly 40 years, Sandia National Laboratories has developed and applied a performance assessment methodology in numerous national and international nuclear waste management programs. These applications range from development and feasibility testing of environmental health standards to preliminary evaluation of waste disposal sites; to establishing the basis for demonstration of compliance; to informing licensing (compliance demonstration) decisions. In many of these applications the performance assessment methodology has also served as a management tool for confirming the added value of research and development investments.

This paper presents examples to illustrate how performance assessment has been used as an effective management tool through multiple phases of a nuclear waste management program.

We develop a plasma processing technique for modifying the surface properties of micro- and nanostructured materials for biomedical applications. We also investigate the physical and chemical roles of the plasma in modifying the surfaces of micro- and nanostructured materials such as magnetic nanoparticles (MNPs), carbon nanotubes (CNTs), nanophosphors, and biomolecules for various biomedical applications. We introduced amino groups onto the surfaces of graphite-encapsulated iron compound nanoparticles using a low-pressure Ar plasma pre-treatment and ammonia plasma post-treatment followed by immobilization of biomolecules, such as dextran and N-acetyllactosamine (LacNAc). The present technique was also used to introduce amino groups onto CNT dot arrays grown on Si substrates for use in biochip sensors.

The analyses of work traces in the shell objects found in the offerings of the Great Temple of Tenochtitlan, by scanning electron microscopy (SEM), has allowed to find an important group of objects made locally in Tenochtitlan. These shell pieces have been found in the constructive stages IVb to VII (1469-1520). Recently, another groups of objects have been found that present different work traces and that seems to be foreign productions. In this paper this new data will be presented and it will be discuss the possible origin of the objects.

Catastrophic degradation of high power laser diodes is due to the generation of extended defects during the laser operation. The stress necessary for is induced by temperature gradients generated by local enhancement of the temperature due to non radiative recombination and subsequent laser self absorption. The thermal stresses induced by such temperature gradient are calculated using finite element methods, showing that the yield strength can be surpassed. The thermal conductivity of the laser structure is shown to play a relevant role in the process.

This paper describes a semi-automated conductive ink process used for packaging MEMS devices. The method is applied to packaging of MEMS sensors for wind tunnel testing. The primary advantage of the method is a reduction in surface topology between the package and the integrated MEMS sensors. In this paper we explore the relationship between trace dimensions, resistivity, and deposition parameters such as feed rate, tip-substrate separation and tip diameter. Using this procedure it is possible to generate interconnects between a PC board and MEMS sensor chip with a topology of less than 25 micrometers.

The Ba(Ti,Zr)O3 powders was synthesized for many methods because its properties as a piezoelectric, dielectric and ferroelectric material that insert it as an functional material, but there is little information in the studied of its optical properties. In this work Ba(Ti,Zr)O3films were produced by ultrasonic spray pyrolysis method for optical applications. The precursors used were an barium acetyl-acetonate, titanium acetyl-acetonate, and zirconium acetyl-acetonate powders dissolved in a N-N, dimethylformamide solution. Optical and morphological properties of the films shown a non crystalline structure and its emission spectra shown a broad and intense luminescence at 468nm which correspond to visible emission in the green region.

CVD polycrystalline diamond surfaces were etched using reactive ion etching system with either a conventional stainless steel electrode or MgO sintered ceramic containing electrode. The micro-needle array of high aspect on diamond substrate surfaces obtained with MgO electrode was fabricated by using back-sputtering from MgO electrode. The RMS roughness of diamond substrate surfaces obtained with MgO electrode is higher than those obtained with stainless steel electrode.

In four offerings of the Great Temple of Tenochtitlan five groupings of Pinctada Mazatlanica shell pendants were found. Due to the burial conditions, damages on the surfaces can be observed in almost all the objects. In order to assess the deterioration degree, we used a visible light spectrometer. This is an inexpensive method to determine qualitatively the reflectance of the light at the surface that is directly related to the amount of organic material remains in these objects. This data may be used as a conservation marker for monitoring the collection and it can provide outstanding information to preserve the fragile shell pendants using a non-destructive method.

Xavier Guerrero (1896-1974) had an important role in the so-called Mexican Mural Renaissance, as a technical leader in the murals painted by Roberto Montenegro and Diego Rivera in the early 1920’s. Jean Charlot, Diego Rivera and David Alfaro Siqueiros considered him as a sophisticated fresco craftsman, whose knowledge came from a popular mural painters guild.

In 1941 the Mexican Government donated a School to Chillan, a Chilean town almost destroyed by a strong earthquake. David Alfaro Siqueiros and Xavier Guerrero were commissioned to paint murals on the Mexico School. Between 1941-1942 Guerrero decorated several walls and the staircase ceiling, the mural program is called De México a Chile (From Mexico to Chile). In 2010 another earthquake destroyed part of the ceiling. This study is part of the diagnosis project of De México a Chile, and consists in the characterization of the mortar and painting layers with optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermal analysis (TGA), while textural properties of the mortars were studied with nitrogen adsorption-desorption techniques.

Analytical results show a stratigraphic sequence composed of several layers of Portland and lime combinations, and also an interesting painting technique that possibly involves the Portland cement setting process, with the development of specular gypsum.

Catalytic synthesis of graphene occurs when methane reacts with cubic SiC nanopowder at 1000-1200K. The composite, created under relatively mild experimental conditions, consists primarily of 30-40 nm diameter cylinders with aspect ratios near unity whose walls are composed of 10-20 layers of graphene surrounding nano-SiC particles. Sputtering by electron irradiation sequentially removes the graphene shells thus exposing the SiC cores. Electron as well as X-ray diffraction studies reveal the highly crystalline nature of the graphene shells which constitute 90 mol% of the composites. Raman data support a model involving growth of graphene on carbon rather than on silicon terminated SiC.

Thin‑film silicon solar cells based on hydrogenated amorphous silicon (a‑Si:H) and hydrogenated microcrystalline silicon (μc‑Si:H) absorber layers are typically deposited using static plasma-enhanced chemical vapor deposition (PECVD) processes. It has been found that the use of very‑high frequencies (VHF) is beneficial for the material quality at high deposition rates when compared to radio-frequency (RF) processes. In the present work a dynamic VHF‑PECVD technique using linear plasma sources is developed. The linear plasma sources facilitate the use of very-high excitation frequencies on large electrode areas without compromising on the homogeneity of the deposition process. It is shown that state-of-the-art a‑Si:H and μc‑Si:H single-junction solar cells can be deposited incorporating intrinsic layers grown dynamically by VHF-PECVD at 0.35 nm/s and 0.95 nm/s, respectively.

In this work we present preliminary results from multi-million fully atomistic classical molecular dynamics simulations carried out to test different existing mechanisms that have been proposed in the literature to explain the drawing of yarns from carbon nanotube forests. Despite the fact that it has been almost ten years since yarns were first drawn, there are still controversies on the mechanisms and necessary conditions that can produce yarns and sheets drawn from carbon nanotube forests. Moreover, few works have tried to understand at atomistic level the details of yarn drawing mechanisms, and no fully atomistic simulations have been carried out so far on this particular subject. Our preliminary results suggest that only direct van der Waals interactions among large bundles seem not to be enough to explain the yarn drawing process. Bundle interconnectors (such as small bundles connecting large bundles) were observed to play a critical role in our simulations. Depending on the topology of these interconnectors it was possible to observe from the simulations fibers/yarn formation from proposed structural models. These models were built based on structural information inferred from scanning electron microscopy data.

We have carried out in-situ measurements of cluster volume fraction in silicon films during deposition by using quartz crystal microbalances (QCM’s) together with a cluster-eliminating filter. The cluster volume fraction in films is deduced from in-situ measurements of film deposition rates with and without silicon clusters using QCM’s. The results show that the higher deposition rate leads to the higher volume fraction of clusters.

The polycrystalline n+/intrinsic silicon thin film stacks with various original intrinsic amorphous silicon layer thicknesses were formed using the multiple pulsed rapid thermal annealing process with the Ni-induced crystallization mechanism. The thick polycrystalline silicon stack was prepared by repeated steps of 1) amorphous silicon thin film deposition, 2) solution oxidation, 3) dehydrogenation, 4) pulsed rapid thermal annealing, and 5) oxide stripping. The poly-Si film properties, such as the grain size, orientation, and volume fraction of the crystalline phase, were related to the original intrinsic silicon film thickness and the total thermal budget. This process is effective in preparing the high volume fraction polycrystalline silicon thin film, which is important for low-cost thin-film solar cells, electronic and optoelectronic devices.

Plutonium oxide heat sources are used to power space missions. The heat produced by alpha decay of the 238 isotope of Pu is converted to electricity in a thermopile, providing electricity during a substantial fraction of the 88 year half-life of the isotope. Decay of the Pu produces helium and uranium, and a fraction of the evolved helium is captured in the oxide matrix. All of the helium produced in decay can in principle be contained in the oxide lattice, where it occupies the tetrahedral sites. Some helium diffuses out at a rate that is somewhat dependent on the form and morphology of the fuel. Rates have previously been measured for oxide aged about 1 year. Current measurements on sealed heat sources as old as 34 years indicate that the rate of diffusion has changed only slightly over time. Possible mechanisms for helium release include bubble diffusion, point defect migration, agglomeration and movement of He at grain boundaries, and volume diffusion through the lattice sites. We observe primarily diffusion from site to site within the lattice, with an activation energy of 18.7 kcal/mole, independent of point defect movement, despite the rising concentration of helium in the lattice over time and the accumulation of radiation damage within the lattice. Because of the slow diffusion of helium from the fuel to the headspace, heat sources are anticipated to be stable over a long lifetime.

A roast experiment was carried out by using vanadium stone coal from Hubei Province as object, in the condition of compound additive dosage is 6%, the effects of roasting temperature, roasting time and material size on vanadium lixiviate efficiency were investigated. Experimental results indicate that, for the vanadium stone coal from Hubei Province, at the condition of additive dosage is 6%, the ideal target of vanadium lixiviate efficiency 82.3% can be acquired in the optimum condition of roasting temperature at 850 oC, roasting time is 120 minutes, material size is minus 0.5mm.

Level set methods have been used for Solid phase epitaxial regrowth, etching and deposition.This study is to model the growth of nickel silicide accurately using the level set method. NiSi growth has been observed to follow a linear-parabolic law which takes into account both diffusion and interfacial reaction. This linear-parabolic system is very similar to the Deal and Grove model of SiO2 growth. This model uses similar diffusion transport and reaction rate equations. This simulation models the growth of silicide coupling diffusion solutions to level-set techniques. Dual level sets have been used for top and bottom interface propagation of silicide; velocities were estimated based on nickel concentrations at both interfaces as well as diffusivity and reaction rate of nickel. This is important to predict precise shape of silicide that will allow current crowding and field focusing effects to be modeled in transport out of the intrinsic device into the contacting layers. These simulation models can be used for latest technology nodes at 45, 32, 22nm and special devices such as FinFET’s etc. The level set method is successfully implemented and verified in Florida Object Oriented Process Simulator and growth shapes matches well with the literature Transmission Electron Microscopy data.

We have investigated some diamondoids encapsulation into single walled carbon nanotubes (with diameters ranging from1.0 up to 2.2 nm) using fully atomistic molecular dynamics simulations. Diamondoids are the smallest hydrogen-terminated nanosized diamond-like molecules. Diamondois have been investigated for a large class of applications, ranging from oil industry to pharmaceuticals. Molecular ordered phases were observed for the encapsulation of adamantane, diamantane, and dihydroxy diamantanes. Chiral ordered phases, such as; double, triple, 4- and 5-stranded helices were also observed for those diamondoids. Our results also indicate that the modification of diamondoids through chemical functionalization with hydroxyl groups can lead to an enhancement of the molecular packing inside the carbon nanotubes in comparison to non-functionalized molecules. For larger diamondoids (such as, adamantane tetramers), we have not observed long-range ordering, but only a tendency of incomplete helical structural formation.