Alumina-silicone hybrid nanolaminate films were synthesized by plasma enhanced chemical vapor deposition (PECVD) process. PECVD allows digital control over nanolaminate construction, and may be performed at low temperature for compatibility with flexible substrates. These materials are being considered as dielectrics for application such as capacitors in thin film transistors and memory devices. Temperature dependent electrical and dielectric properties of the nanolaminate dielectric films in metal-insulator-metal structures are taken in the range of 200- 340 K to better asses their potential applications for different devices. It is observed that the frequency dependent dielectric constant (εr) and ac conductivity (σac) increase with the temperature. Both quadratic (α) and linear (β) voltage coefficient of capacitance (VCC) increases as the temperature increases. The temperature co-efficient of capacitance (TCC) decreases from 894 to 374 ppm/K as the Al2O3 composition increases in the alumina/silicone nanolaminates. Activation energy (E a ) for hopping conduction mechanism varies from 0.011 eV to 0.008 eV as the alumina composition increases from 50 to 83.3%.

Spent nuclear fuel from TVO's (Teollisuuden Voima Oy) and Fortum's nuclear power plants will be deposited deep in the crystalline bedrock in Olkiluoto, Western Finland. The bedrock needs to be well characterized to assess the risks inherent to the waste disposal at the site. If radionuclides (RN) are transported, it happens via water conducting fractures. Retardation may occur either by diffusion into stagnant pore water or by immobilization on mineral surfaces of the rock matrix.

RN’s retardation from flowing water is linked to parameters defining porosity and microscopic rock pore structure, such as pore size distribution, connectivity, tortuosity and constrictivity, and by the mineralogy and chemical nature of the minerals and charge of the pore surfaces.

In this work, centimeter scale rock cores from Olkiluoto were investigated. The work is part of the in situ project REPRO (Experiments to investigate Rock Matrix Retention Properties) where the diffusion and sorption of RN are studied experimentally. Porosity and pore structures were characterized with the PMMA autoradiography method and polarized microscopy, which was used also to ascertain the mineralogy of the samples.

The results show that the rock from the REPRO site has low porosity with a mean value of 0.5% and a range of 0.1-1.5%. Rock heterogeneity explains the variation of porosity values. Correlation between the porosity and the mineralogy was found. Areas of high porosity correspond to areas of altered minerals, such as cordierite, biotite and plagioclase, which cover spatially between 10 and 20% of the rock volume

Modern polypropylene film power capacitors are state of the art for power factor correction and many DC link applications, but their long-term commercial use is limited to temperatures of less than 85°C. The temperature limit is given by the dielectric polypropylene which has a melting point in the range of 140 to 170°C, while glass is much higher. Thus, the temperature limit could potentially be overcome by use of thin, alkali-free glass as dielectric. “Glass capacitors” employing ultra-thin and high purity glass layers are promising devices for high temperature applications in oil, gas, aerospace, hybrid electric vehicles, DC transmission, and pulsed power systems. This includes emerging power electronic systems using silicon carbide switches and diodes.

This work analyzes and compares various glasses with a thickness of less than 50 µm by dielectric spectroscopy and elemental analysis. It is demonstrated that glass is attractive as dielectric for a wide frequency range up to 200°C. It argues that the dielectric losses are currently too great for thin glass to be used within a commercial power capacitor.

While high temperature prototypes already exist, we demonstrate through our analysis that further developments are required to integrate this promising device into commercial systems. It is seen that even trace amounts of alkali materials can have an impact on losses. These losses must be further reduced through fundamental research into polarization/conduction mechanisms of various glass components.

Peptides have become attractive molecules for fabricating biomaterials. Studies of peptide structure, assembly properties, and dynamic behavior in response to external parameters have led to rational novel design of peptide biomaterials. One model sequence selected was a β-spiral motif of spider flagelliform silk protein, [GPGGX]n (X = any amino acid). Modifying the X residue can change the quantity of secondary structure and the stability of this spider silk motif. Glycine provides flexible properties, and proline influences the secondary structure and mechanical properties. Another model sequence was GXGXDXUX (U = hydrophobic residue), a Ca2+ binding domain of lipase Lip A from Serratia marcescens, in which aspartate residue is required for ion binding. Combining with [GPGGX]n, we rationally designed peptide as GPGGDGPGGD (eD2). The Ca2+ binding sequence was hidden in the first eight residues of eD2. As expected, this peptide can assemble into nanofibrils triggered by Ca2+ ions. Using the segment FLIVIGSII (h9) from the third trans-membrane segment of subunit IV in the dihydropyridine sensitive human muscle L-type calcium channel as the hydrophobic motif, we obtained FLIVIGSIIGPGGDGPGGD (h9e) peptide. The h9e self-assembled into nanofibrils and further formed shear-thinning and rapid recovery hydrogel in neutral pH range from 6.0 to 8.0 with a large working range of temperature. NMR study showed that amphiphilic structure of h9e peptide tended to adopt a more helical structure during hydrogel formation. The h9e peptide has great potential for biomedical applications. MCF-7 cells were successfully grown as colony-like clusters (reminiscent of real tumors) in h9e hydrogel system. The drug response test of cisplatin further demonstrated the capability of h9e system for drug screen. Moreover, h9e hydrogel showed a promising adjuvanticity by enhancing the vaccine efficacy for killed H1N1 swine influenza virus and PRRS modified live virus.

The sensor team at the Los Alamos National Laboratory is an integrated multidisciplinary group that develops both core technologies as well as accessory tools for efficient biodetection. We have developed a waveguide-based optical biosensor for the efficient and ultra-sensitive, rapid detection of biological agents. We have previously demonstrated the use of this technology for the detection of biomarkers associated with many diseases. Herein, we present the preliminary data demonstrating the extension of this technology to the discovery and detection of Traumatic Brain Injury (TBI). TBI afflicts a significant percentage of US troops deployed in Iraq and Afghanistan, but is difficult to diagnose efficiently. Currently, only neuropsychological questionnaires are being used for the diagnosis of this condition, which can range from mild concussion to severe brain damage. The ultimate goal of this project is to develop a rapid biomarker-based diagnostic for TBI in blood. However, this cannot be accomplished until a comprehensive repertoire of biomarkers secreted during brain injury is established. This requires an integrated biomarker discovery and detection approach that is sampled directly from human serum and cerebrospinal fluid.

The results reported here are preliminary steps in that direction wherein we aim to develop two different methods for the discovery of novel biomarkers of TBI in blood and cerebrospinal fluid, as well as develop assays for two biomarkers on an ultra-sensitive waveguide-based platform that was developed at LANL. We were able to evaluate two different methods for biomarker discovery: Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and two dimensional gel electrophoresis (2-DE) in serum samples. In addition to development of depletion protocols to remove abundant proteins in serum, we were also able to detect spiked TBI biomarkers using both methods. However, the results clearly show that for protein biomarkers, MALDI MS is much more sensitive than 2-DE. We also developed a sandwich immunoassay on a waveguide-based platform for a TBI biomarker, procalcitonin, using commercially available antibodies. We show with our methods that we were able to directly detect procalcitonin from human serum. While our discovery and detection methods show promising results, these methods need to be further optimized before we can apply it to clinically relevant samples.

We have investigated the photon-energy dependence of nonlinear optical absorption in graphene in the near infrared (NIR) and visible range (1.13 – 3.1 eV). Two nonlinear processes, namely one-photon interband absorption saturation and two-photon absorption (2PA), have been unambiguously determined in high-quality, CVD-grown, multilayer graphene films with using femtosecond Z-scan technique. The absorption saturation is found to have a square dependence on the photon energy. The 2PA spectrum is measured to be close to the theoretical prediction of ω -4 dependence at NIR wavelengths. In the visible range, however, the photon-energy dependence of 2PA is dominated by the excitonic Fano resonance.

Silver thin films are used as a functional layer in many applications such as low-emissivity and solar control coatings on glass for insulating windows, as well as transparent conducting electrodes for OLEDs and PV. For these applications, the conductivity of the film is critical; it is linked to the crystallinity and the grain size of silver layers which thickness ranges from 5 to 15nm. Such coatings often undergo thermal treatments up to 700°C aimed at toughening the glass substrate or improving the coating itself by promoting grain growth and curing point defects. This treatment can however dramatically damage the silver layer by inducing the formation of defects in the layer, such as holes or silver domes, decreasing both conductivity and light transmission of the coatings. Because of the extreme thinness of the films (less than 15 nm), the investigation of these phenomena requires in situ imaging at the nanoscale. In this study, grain growth and defects formation were observed in 15 nm-thick Ag films encapsulated with zinc oxide and silicon nitride using Transmission Electron Microscopy with in-situ heating from ambient temperature to 600°C. Significant grain growth was found to occur only from 400°C, and from 500°C holes in the silver layer started to form and grow, as well as thick silver domes formed by dewetting. Irradiation by the electron beam was also found to cause grain growth.

Electrical and Optical measurements were carried out on permalloy oxide (PyO) thin films made by reactive dual ion beam sputtering at room temperature. VSM measurements at room temperature and 15 Kelvin did not reveal any magnetic moment in 120 nm thick films. The optical refraction and extinction spectra from 200-1000 nm were determined from ellipsometry measurements using a Cody-Lorentz model and provided in a reproducible method to determine the film thickness of PyO films on different substrate materials. PyO is transparent above 700 nm and is strongly absorbing below 500 nm. The resistivity values of PyO samples sputtered at room temperature depend on the oxygen flow rate and is approximately 4E3 Ohm cm for films prepared at 10 sccm. The resistivity of PyO decreases as a function of temperature. The dielectric constant is strongly frequency dependent, decreasing from 500 at 500 Hz to 10 at 1 MHz.

Recent experimental evidence on nano-particle and nano-wire silicon anodes showed an initial rapid velocity of reaction front at the initial stage of lithiation, followed by an apparent slowing or even halting of the reaction front propagation. This intriguing phenomenon is attributed to the lithiation-induced mechanical stresses across the reaction front which is believed to play an important role in the kinetics of reaction at the front. Here, through theoretical formulation, we presented a comprehensive study on lithiation-induced stress field and its contribution to the driving force of lithiation in hollow spherical anodes with different boundary conditions at the inner surface of the particle. Our results reveal that hollow spherical silicon anodes can be lithiated more easily than solid spherical silicon particles and thus may serve as an optimal design of high performance anodes of lithium-ion battery.

We present preliminary results on a processing protocol by chemical activation that transforms organic waste product such as coconut husk into high surface area activated carbon. Dried raw materials of the coconut husk were carbonized anaerobically into char. The char was impregnated with KOH of different ratios and were activated at 800°C and 900°C. The transmission electron microscope was used to acquire structural and morphological information of the activated carbon, and the surface area and porosity analysis were performed using Micromeritics ASAP 2020 analyzer. The activated carbons show both micropores and mesopores with specific surface area as high as 2900m2/g.

The migration behavior of plutonium is expected to be affected by the corrosion products of carbon steel in compacted bentonite at high-level waste repositories. Electrochemical experiments were carried out to simulate the reducing environment created by ferrous iron ions in equilibrium with anoxic corrosion products of iron. The concentration profiles of plutonium could be described by the convection -dispersion equation to obtain two migration parameters: apparent migration velocity V a and apparent dispersion coefficient D a . The apparent migration velocity was evaluated within 1 nm/s and was found to be independent of the experiment duration and the dry density of bentonite in the interval 0.8-1.4 Mg/m3. The apparent dispersion coefficient increased with the experiment duration at a dry density of 1.4 Mg/m3. The results for other dry densities also showed the same trend. These findings indicate that plutonium migration likely starts after ferrous ions reach the plutonium, in other words, the reducing environment due to ferrous ions could change the chemical form of plutonium and/or the characteristics of compacted bentonite. The apparent diffusion coefficient was estimated to be around 0.5 to 2.2 µm2/s and increased with decreasing the dry density of bentonite.

We have investigated on a relation between C-related deep-level defects and turn-on recovery characteristics in bulk regions of AlGaN/GaN hetero-structures containing various C concentrations, employing their Schottky barrier diodes. With decreasing the growth temperature of the GaN buffer layer, three specific deep-level defects located at ∼2.07, ∼2.75, and ∼3.23 eV below the conduction band were significantly enhanced probably due to the C impurity incorporation into the GaN buffer layer. Among them, the ∼2.75 and ∼3.23 eV levels are considered to be strongly responsible for the two-dimensional electron gas (2DEG) carrier trapping in the bulk regions of the hetero-structures, from their turn-on current recovery characteristics under various optical illuminations.

InP membranes have been bonded both oxide free and oxide mediated onto a Si substrate. The mechanical responses of the obtained thin (0.4 µm) membranes could be tested by nanoindentation and compared. Delamination of the membrane was observed to occur when the indenting load reached 55 mN for an oxide mediated bonded structure and 80 mN for an oxide free bonded one. Weibull analysis of these events yielded a modulus m of magnitude 6 to 10, indicating that delamination fracture is relatively predictable with a stronger interface obtained in oxide free approach. Delamination of the membrane is the result of constraint of plastic flow by the InP/Si interface. Membrane rotation is induced and increases with the indentation load, until it is sufficient to induce and propagate an interfacial crack.

Chemical Vapor Deposition of graphene on metallic substrates is one of the most attracting techniques for large area graphene production. The technique widely employed for transferring graphene to other substrates involves deposition of a polymer support with subsequent etching of the metal substrate. Here we report a safer transfer process, which requires a two-step PMMA deposition and bonding under pressure. Sheets of graphene before and after transfer have been both characterized by Raman spectroscopy, and show comparable quality, indicating that the proposed technique does not introduce additional defects in graphene.

As a promising transition metal dichalcogenide (TMDC), molybdenum disulfide (MoS2) has recently attracted a lot of attention due to its graphene-liked two dimensional layer structure, which leads to potential applications in electronic and optoelectronic devices. However, the fabrication of mono- or few-layer MoS2 is limited to ether liquid exfoliation or CVD, and the chemical solution deposition is limited to ammonium thiomolybdate-based precursor. In this paper, hydrazine-based dimensional reduction technique is applied in the chemical solution deposition of MoS2 thin-film, and a larger area uniform thin-film is obtained from bulk powder MoS2. This solution-based process could be applied with a variety coating techniques and lead to wafer level MoS2 thin film production.

The effect of Y dopant incorporated into ZTO with different Y ratios in Y-ZTO system on the performances of ZTO-based TFTs is investigated by using sol-gel process. The proper Y doped ZTO present both high film crystallization temperature and superior electrical properties as an active channel layer of TFTs. The fabricated YZTO-based TFTs with 11% Y show the excellent devices performance such as the channel field effect mobility of 1.756 cm2/Vs, SS of 2.13 V/dec, threshold voltage of 0.8V and on/off ratio of 3.12×106.

Monolayers of arrays of periodic polystyrene (PS) spheres are designed to couple onto the surface of cerium-doped lutetium-yttrium oxyorthosilicate scintillator to improve the light extraction efficiency. The enhancement of extraction efficiency up to 38% relative to the reference case without polystyrene spheres is achieved. Combining with the simulation for the transmission as well as its dispersion relation, detailed analysis of the effect of whispering gallery modes and diffraction on the extraction mechanism are given. As a result, the optimal diameter of 414 nm is obtained based on a trade-off between the transmission loss and the diffraction enhancement.

Thready stripe-patterned thermo-responsive surfaces were prepared and their surface properties were characterized. Prepared 3 μm wide stripe-patterned surfaces were evaluated by observing the adhesions and detachments of three types of cells: HeLa cells (HeLas), human umbilical vein endothelial cells (HUVECs), and NIH-3T3 cells (3T3s). Although cell adhesion and detachment in response to temperature were observed on all cells on a conventional thermo-responsive surface without patterns, the thermo-responsive surface with a 3 μm striped-pattern exhibited various cell adhesion properties. HeLas hardly adhered to the patterned surface even at 37 °C. On the other hand, although HUVECs adhered on the patterned surface at 12 h after incubation at 37 °C, the adhered HUVECs detached themselves after another 12 h incubation at 37 °C. 3T3s adhered to the patterned surface at 37 °C and detached themselves after reducing temperature to 20 °C. A mixture of HeLa, HUVEC and 3T3 was separated using their different specific cell-adhesion properties, and the composition of cells was analyzed by a flow-cytometry. As a result, the conventional thermo-responsive surface with a stripe-pattern was found to function as a cell-separating interface by using specific cell adhesion properties.