A modified polyol synthesis has been utilized to study the different structures obtained in the bimetallic system of platinum (Pt) and palladium (Pd). Some results are shown in this work. Thermal methods under refluxing, carrying on the reaction up to 285 ºC, have been assayed to reduce metallic salts using ethylene glycol (EG) as reducer and polyvinylpyrrolidone (PVP) as protective reagent of the formed bimetallic nanoparticles. The special core-shell structure has been observed in these bimetallic nanoparticles, whose synthesis was assisted by Ag, showing polyhedral shapes. The average diameter size of the core has been estimated at 10 nm, and the diameter size of the shell in 13 nm, consequently the thickness of the shell is around 1.5 nm. Nanoparticles were structurally characterized with transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) equipped with detector to generate high angle annular dark field (HAADF) images. This kind of structures have been studied and utilized to increase successfully the catalytic properties of monometallic nanoparticles of Pt or Pd according to other works. Here, the synthesis procedure is described; as the main results, several images are presented showing the obtained bimetallic core-shell structures and their fast Fourier transform (FFT), and also the size and the elemental analysis of the nanoparticles are reported, concluding that this synthesis method is very efficient for preparing bimetallic core shell structures.

Structural materials in the new Generation IV reactors will operate in harsh radiation conditions coupled with high levels of hydrogen and helium production and will experience severe degradation of mechanical properties. Therefore, understanding of the physical mechanisms responsible for the microstructural evolution and corresponding mechanical property changes is critical. As the involved phenomena are very complex and span in several length scales, a multiscale approach is necessary in order to fully understand the degradation of materials in irradiated environments. In previous work, we used molecular dynamics simulations to develop critical rules for the mobility of dislocations in various iron alloys and their interaction with several types of defects that include, among others, helium bubbles and grain boundaries. In this work, Dislocation Dynamics simulations of iron alloys are used to study the mechanical behavior and the degradation under irradiation of large systems with high dislocation and defect densities.

Teflon amorphous fluoropolymer (TAF) multi-walled carbon nanotube (MWCNT) suspensions have the potential for creating conductive coatings on insulating films for numerous applications. However, there are few studies on polymer MWCNT suspension properties and even fewer that use Teflon. To define mechanical and electrical property relationships, bilayer films of TAF-MWCNT were created with differing concentrations of MWCNTs. Nanoindentation revealed that addition of 8 wt% MWCNTs to TAF increased the elastic modulus by about 25% and hardness by about 15%. Conducting indentation showed 8 wt% MWCNT films exhibit uniform stable conductance once indentation depth exceeds several hundred nanometers. Films with lower concentrations of CNTs were insulating. The two techniques provide a unique description of structure property relationships in this suspension film system.

In this work, we prepared graphite oxide (GO)/polyaniline nanocomposites by enzymatic polymerization of aniline in an aqueous dispersion of graphite oxide. Two GO dispersions with sheets having an average lateral size of 12.50 μm and 247 nm were used. The enzymatic polymerization was carried out in aqueous acidic medium using toluenesulfonic acid (TSA) as doping agent, horseradish peroxide (HRP) as catalyst, and hydrogen peroxide as oxidizer. The polymerization reaction was studied using 1.0, 2.5 and 5 wt % of GO and nGO dispersions. No changes were observed in the catalytic activity of the peroxidase during the enzymatic synthesis due to the additionof GO sheets. Scanning electron microscopy images show that PANI colloids were attached on GO sheets. The PANI-GO colloids were characterized by ultraviolet–visible spectroscopy and Fourier transformed infrared spectroscopy, whereas their colloidal stability was evaluated at different pHs. The UV-vis spectroscopy study revealed that GO affects the electronic conjugation of PANI modifying its absorption spectrum.

Understanding electromigration effects in monocrystalline metal becomes of increasing interest with decreasing width and thickness of interconnects. Using a three-dimensional, atomistic model based on the Kinetic Monte Carlo method, we investigate voids in monocrystalline silver. Subject to electromigration, voids begin to drift. We show that the drift velocity not only depends on the void size, but also on the electromigration force direction, with respect to the crystallographic orientation.

Layer transfer and simultaneous activation of phosphorus atoms in Si films induced by semiconductor diode laser (SDL) irradiation have been investigated. Phosphorus-doped a-Si films supported by columns on a starting substrate (quartz) and a counter substrate (glass) were closely contacted face-to-face, and an 812 nm light from a SDL was irradiated to the a-Si films from the backside of the starting substrate. After SDL irradiation, 20μm wide and 1000μm long Si films were transferred to the counter substrate and were crystallized simultaneously. From optical microscope images, it was confirmed that the original form was completely maintained after the film transfer. The electrical conductivity of transferred Si film was as high as 708 S/cm. Hall measurement of the films revealed very high electron concentration of 9.5×1020 cm-3, which indicated efficient doping is achieved by the laser transfer technique.

The low vapor pressure of many energetic materials presents a challenge for detection by non-contact methods. We address this limitation by illuminating energetic materials including TNT and RDX with infrared lasers tuned to strong molecular absorption bands to efficiently heat trace amounts present on substrates. This substantially increases their vapor signatures for direct detection, obviating the need to swab surfaces for solid particles or to collect headspace vapors for extended time periods. The instantaneously generated vapor produced by Laser Trace Vaporization (LTV) can be detected by any number of techniques which can accommodate vapor sampling or spectroscopic analysis. Currently the testbed for LTV incorporates a tunable quantum cascade laser (QCL) to illuminate the sample and an ion mobility spectrometer (IMS) to validate the signal enhancement. The LTV technique works well with all tested substrates, though the thermal and spectroscopic properties of the substrate can influence the efficiency of the vaporization. Computational results from laser heating along with experimental thermal kinetic measurements were used to optimize LTV laser irradiation parameters. In addition to a range of LTV results for different explosives and substrates, we explore the effects of wavelength-dependent heating on the sample and substrate.

In this paper, we present an example of a new generation of laser-crystallization approaches that can crystallize Si films for large active-matrix displays at drastically increased effective crystallization rates. The particular scheme presented in this paper is referred to as the advanced excimer-laser-annealing (AELA) method, and it can be readily configured for manufacturing large OLED TVs using various available and field-proven technical components. As in ELA, it is mostly a partial-/near-complete-melting-regime-based crystallization approach; AELA can, however, eventually achieve greater than one order of magnitude increase in the effective rate of crystallization over that of the conventional ELA technique utilizing the same laser source. We discuss in this paper how and why such a dramatic increase can be attained, and some strategical and technological benefits and options that can be entertained regarding, and as a result of the availability of, the AELA technique.

Although initially developed as an imaging tool, the helium ion microscope (HIM) is finding applications in nanofabrication as its focused ion beam is capable of highly-localized material modification. In this study, an external pattern generator is used to explore the capabilities of the HIM for localized milling of a ∼7 nm thick layer of silicon-on-insulator, with atomic force microscopy (AFM) used to characterize the resulting patterns. The dose and patterned area size are varied and milling to depths >7 nm is demonstrated. At high doses and large areas, protuberances form, primarily due to sub-surface swelling caused by the implanted helium. The results suggest this technique could enable the rapid prototyping of next-generation nanoelectronic devices in thin silicon.

Cancer is a major public health problem worldwide, especially in developed countries.Early detection of the cancer can greatly increase both survival rates and quality of life for patients. A magnto-acoustic based method had been previously proposed for early tumor detection, in a minimal invasive procedure, using magnetic nanoparticles (MNPs). However, in order to accompany tumor identification with immediate treatment, a complementary tumor localization algorithm was needed. Therefore, our objective was to measure the acoustic signals generated by the MNP conjugated tumor in an optimal multi sensor array and estimate the 3D location of the tumor in real time. A Time Difference of Arrival (TDOA) based localization algorithm was developed, and implemented in computerized simulations on the breast tissue geometry. Tumor localization feasibility and the hyperbolic positioning algorithm performance were evaluated. Overall performance yielded localization with a median Euclidean distance of 2.8mm. Such performance indicates that tumor localization was estimated with high accuracy, and suggests that the combination of magneto-acoustic detection along with a TDOA based localization algorithm can produce an efficient tumor diagnostic system. It enables the detection of tumor presence, as well as the triangulation of its location, and can be further developed into a powerful “image and treat” system.

Gold nanorods (AuNRs) show surface plasmon absorption bands in the near-infrared region. This characteristic property has stimulated utilization of gold nanorods as novel nanoprobes for noninvasive bioimaging, such as photoacoustic tomography. Herein, we discuss the synthesis of a series of gold nanorods coated with pH-responsive polymers to investigate the effect of the surface structure and zeta potential of nanoparticles on cellular uptake via a surface charge-mediated endocytic pathway. The surface of the gold nanorods was modified with polyethylene glycol (PEG@AuNR) and tertiary amine derivatives, specifically, diethylaminoethyl ester (1@AuNRs), its amide analog (2@AuNRs), and dimethylaminoethyl ester (3@AuNRs). It was found that the pH-sensitivity of 1@AuNRs was relatively high and the surface was positively charged at lower pH. In contrast, the tertiary amino group of 1@AuNRs was deprotonated to form an electrostatically neutral surface at higher pH. The pH-responsive gold nanorods were incubated with A549 cells (human lung cancer cells) to quantify the amount of cellular uptake using inductively coupled plasma mass spectrometry. The results indicate that 1@AuNRs can be taken up efficiently in the cells, and thereafter, slowly flow out of the cells. Interestingly, only small amounts of the amide analog (2@AuNRs) were taken into the cells, suggesting minor structural changes may affect the interaction between the cell surface and AuNRs. This study highlights a potential application of pH-sensitive nanorods as a probe for bioimaging the acidic environment of tumors.

We analyze thermoelastic dissipation in composite silicon MEMS resonators that exhibit multiple mechanical and thermal modes with complex dynamics. Silicon resonators that are coated with thin films of silicon dioxide can have near-zero temperature coefficients of frequency, making them attractive for use as precision time references. The quality factor of MEMS resonators can be dominated by thermoelastic dissipation (TED), which is triggered by the relaxation of mechanically induced temperature gradients. Recently, Chandorkar et al. (2009) have shown an expression of TED based on entropy generation as a weighted sum of the modal solutions of the three-dimensional heat transfer equation. This expression was obtained for weak coupling between mechanical and thermal dynamics. Applying this same technique to a fully coupled solution to the dynamics, we show that the TED contribution of the dominant thermal modes can be inhibited in the presence of a thin silicon dioxide film. Reduction of the contribution from the dominant thermal mode is shown with increasing oxide. We studied the effects of varying oxide film thickness and beam length. The quality factor was simulated for each unique case and compared to multimode energy dissipation. Our results suggest with some variability, thin film oxide coating affects the thermal relaxation of the composite resonator in the direction of lower TED and increased quality factor.

In the study of materials at extreme pressures and temperatures, there is an enduring need to extend the range of experiments to previously inaccessible regimes. To accomplish this, improvements in diagnostics for in situ material characterization at extremes must proceed in parallel with techniques used to generate extreme states. Simultaneously, there is a need to study material phenomena – e.g. phase transformations and chemical reactions triggered by the application of extreme conditions – on their natural timescales. Here we report on recent developments in the application of ultrafast laser spectroscopic techniques to high-pressure hightemperature experiments on materials confined in a diamond-anvil cell. Using a bright broadband source coupled to ultrafast detection to discriminate signal from high thermal and fluorescent backgrounds, we conducted broadband optical spectroscopy up to 60 GPa and 1560 K. By coupling the broadband source to a monochromatic pulse, nonlinear Coherent Anti- Stokes Raman Spectroscopy (CARS) with high signal brightness was achieved. Optical absorption data in hot compressed O2 and CARS data in N2 at extreme pressures are reported.

Graphite is used as a moderator and structural component in the United Kingdom’s fleet of Advanced Gas-Cooled Reactors (AGRs) and features in two Generation IV reactor concepts: the Very High Temperature Reactor (VHTR) and the Molten Salt Reactor (MSR). Under the temperature and neutron irradiation conditions of an AGR, nuclear-grade graphite demonstrates significant changes to it mechanical, thermal and electrical properties. These changes include considerable dimensional change with expansion in the c-direction and contraction in the a/b-directions. As the United Kingdom’s AGRs approach their scheduled decommissioning dates, it is essential that this behaviour be understood in order to determine under what reactor conditions their operating lifetimes can be safely extended.

Two models have been proposed for the dimensional change in graphite due to displacing radiation: the “Standard Model” and “Ruck and Tuck”. The Standard Model draws on a conventional model of Frenkel pair production, point defect migration and agglomeration but fails to explain several key experimental observations. The Ruck and Tuck model has been proposed by M.I. Heggie et al. and is based upon the movement of basal dislocation to create folds in the “graphene” sheets and seeks not only to account for the dimension change but also the other phenomena not explained by the Standard Model.

In order to test the validity of these models, work is underway to gather experimental evidence of the microstructural evolution of graphite under displacing radiation. One of the primary techniques for this is transmission electron microscopy with in situ ion irradiation. This paper presents the results of electron irradiation at a range of energies (performed in order to separate the effects of the electron and ion beams) and of combined electron and ion beam irradiation.

Basalt chemical weathering can be related to chemical composition of both atmospheric dust and rainfall, in published works authors have shown that weathered basalt exhibits a raise in anions like sulfate, nitrate, phosphate, chloride and carbonate, and doing a follow up of rainfall chemistry during 2009 at downtown Puebla, it was shown that rainfall has not an acid pH because there is a strong contribution from atmospheric dust.

In this paper it is reported obtained results for dust samples collected during the dry season, collection was done in 3 places exposed to different environment, analysis of solid samples clearly reflect anthropogenic activities since the highest oil and grease content corresponds to a site with high population, also mineral carbonate amounts 30% in weight. An analytical sample was prepared and the filtrate used to measure pH which ranges from 6.3 to 7.84, and conductivity from 11.91-13.87 mS-cm-1. Main soluble ions range are as follow: sulfate 3.4-5.9 mg g-1, nitrate 0.19-0.54 mg g-1, chloride 0.7-8.91 mg g-1, sulfide 4-7 mg g-1, carbonate 304-364 mg g-1, this last correspond to 10% of the mineral content. Also, metals were determined as total (applying an acid digestion) and water soluble, obtained results allow to affirm that there are highly soluble metals like Ca, Pb (up to 97%), moderately soluble ones such as Cu and Mn (60% and 20% respectively) and non soluble ones like Al, Fe and Zn.

It was confirmed that atmospheric dust has all properties, which could produce an alkalinization of rainwater. Also, its water soluble ionic content can be a source for those ions causing basalt weathering.

Magneto-sensitive shape-memory polymers (SMP) obtained by incorporating magnetic nanoparticles in a SMP matrix are an emerging class of multifunctional materials. The incorporation of the nanoparticles enhanced the mechanical properties and in addition enabled remote actuation by exposure to alternating magnetic fields. Here, we report on the thermallyinduced shape-memory properties of such magneto-sensitive nanocomposites based on poly(ω- pentadecalactone) (PPDL) switching segments and magnetic nanoparticles. A series of nanocomposites were prepared by crosslinking of poly(ω-pentadecalactone)dimethacrylate (M n = 2800 g·mol-1and 5100 g·mol-1) in the presence of silica encapsulated magnetic nanoparticles. The silica shell of the nanoparticles was selected to enhance the distribution and compatibility of the nanoparticles with the polymer matrix. Thermal and mechanical properties of the nanocomposites were explored as a function of PPDL chain length and nanoparticle weight content. All nanocomposites exhibited excellent shape-memory properties with shape fixity rates between 86% and 93% and shape recovery rates above 97%. Potential applications for such shape-memory nanocomposites include smart implants, medical instruments, which could be controlled on demand by thermal or indirect magnetic heating.

R. E. Smalley (1985 Nobel Laureate for discovery of C60) provided the humanity’s top ten important issues for next 50 years in 2005, which are energy, water, food, environment, poverty, terrorism & war, disease, education, democracy, and population[1]. In the past five years, the people has realized that with exhaustion of fossil fuel energy, global warming, population growth, and etc., the energy challenge & revolution is the most important issue. In order to solve this problem, many governments in the world have been developing the very important projects dealing with collecting, emitting, and manipulating energy. This paper reviewed the recent progress of these projects such as generation of renewable energies and save energies, especially focus on thin film solar cells, LEDs and smart power and grid, which including III-V materials on Si or ceramic substrates for high efficiency thin film solar cell and high power, high brightness and high efficiency LEDs, as well as smart control of mixture of electric, thermal and other energies. The Building Integrated Photovoltaics (BIPV) and City Integrated LEDs (CILED) will be most important manufacturing in this century.

Graphene oxide holds great promise for future applications in nano-technology. The chemistry of this material is not well understood. This understanding is crucial to enable future applications of graphene oxide. In this study, experiments and density functional theory calculations are combined to elucidate the chemical properties of multilayer graphene oxide obtained by oxidizing epitaxial graphene grown on silicon carbide via the Hummers method. This study shows that at room temperature as prepared graphene oxide films exhibit a uniform and homogeneous structure, include a minimal amount of edges and holes, and have an oxidation ratio of about 0.44. The comparison with density-functional calculations shows that graphene oxide includes a minimal amount of intercalated water molecules and well-defined fractions of epoxide and hydroxyl groups.

We demonstrate low operating voltage (<|1.5| V) chemical vapour deposited (CVD) graphene transistors using solution processable organic self-assembled monolayers (SAMs) as nanodielectrics. The transistors show weak extrinsic doping, hysteresis-free operation, low gate-leakage current and good operating stability with bias-stress free characteristics. Most importantly we demonstrate that the Dirac potential can be finely tuned by modifying the molecular end-group of the SAMs without compromising the electrical characteristics of the transistors.

In the frame of the Safety and Feasibility Case 1 development, the Belgian agency for radioactive waste (ONDRAF/NIRAS) has to demonstrate that the geological disposal of spent nuclear fuel in the Boom Clay host rock following the Supercontainer design provides sufficient radiological safety in the long term. This safety relies on the containment of the radionuclides by the overpack, the limitation of radionuclide release from the waste matrix, the diffusion controlled transport of the radionuclides, and their low solubility and sorption on the Boom Clay host rock. This paper presents an evaluation of the main processes considered for the limitation of radionuclide release by the Spent Fuel in Supercontainer conditions, characterized by the presence of a concrete buffer and hyperalkaline pore water. We present a description of the main expected processes with their potential impact on the fuel alteration mechanisms, and potential reference fuel matrix alteration rates and effective fuel surface areas for use in safety and performance assessment models.