Dielectrophoresis (DEP) approach was employed to achieve highly aligned multi-walled carbon nanotubes (MWCNTs) within the gelatin methacrylate (GelMA) hydrogels in a facile, rapid, inexpensive, and reproducible manner. This approach enabled us to make different CNTs alignments (e.g., vertical or horizontal alignments) within the GelMA hydrogel using different electrode designs or configurations. Anisotropically aligned GelMA-CNTs hydrogels showed considerably higher conductivity compared to randomly distributed CNTs dispersed in the GelMA hydrogel and the pristine and non-conductive GelMA hydrogel. Adding 0.3 mg/mL CNTs to the GelMA hydrogel led to a slight increase in the mechanical properties of the GelMA and made it to behave as a viscoelastic material. Therefore, it can be used as a suitable scaffold for soft tissues, such as skeletal muscle tissue. 3D microarrays of skeletal muscle myofibers were then fabricated based on the GelMA and GelMA-CNTs hydrogels and they were characterized in terms of gene expressions related to the muscle cell differentiation and contraction. Owing to high electrical conductivity of aligned GelMA-CNTs hydrogels, the engineered muscle tissues cultivated on these materials demonstrated superior maturation and functionality particularly after applying the electrical stimulation (voltage 8 V, frequency 1 Hz, and duration 10 ms for 2 days) compared to the corresponding tissues obtained on the pristine GelMA and randomly distributed CNTs within the GelMA hydrogel.

Single crystals of semiorganic nonlinear optical material Triglycine Sodium Halides(TGSH) have been grown from aqueous solution by slow evaporation technique at constant temperature. The powder X-ray diffraction of the grown crystals is recorded and indexed. Functional groups present in the samples are identified by FTIR spectral analysis. The optical absorption studies shows that the UV cut off wavelength is around 300nm and has a wide transparency window. The powder second harmonic generation efficiency of the crystals is measured by Kurtz and Perry powder technique using Nd:YAG laser and it is 1.5 times for Triglycine Sodium Chloride, 1.2 times for Triglycine Sodium Bromide and 1.4 times for Triglycine potassium Iodide crystals that of the standard KDP crystals. Triglycine Sodium halide crystals show very good stability under laser irradiation with no signs of decomposition. Laser damage threshold energy density of Triglycine Sodium Iodide is found to be 857 MW/cm2 and 540MW/cm2 for Triglycine Sodium Chloride crystals.

Recent discoveries have shown the presence of several shipwrecks and historical pieces submerged in the seacoast of the Yucatan Peninsula of Mexico. Within these remains, it is common to found objects manufactured in copper alloys that were part of the construction system of the vessel. For the present study, different surface analysis techniques were applied to tubular copper alloy objects collected in the wreck “El Tejas”. The metallographic study allowed us to know not only the microstructure but also features over its manufacturing technique, as an example of nineteenth-century handmade production. SEM, EDX and XRF techniques allowed us know the elemental composition and establish the mechanisms of degradation of the different copper alloys in the seabed and evaluated a preservation method that consist on removing chlorine compounds by cleaning with pressure steam of distilled water.

In the KBS-3 repository concept and safety analysis, the copper container with a cast iron insert plays a central role in assuring isolation of the waste from the surrounding during long periods of time. All processes that affect its stability are thoroughly analysed, including potential detrimental processes inside the canister. For this reason, an estimation of the helium produced during the long term decay of alpha emitters in the spent fuel is necessary to evaluate if the pressures generated inside can have consequences for the canister.

The spent nuclear fuel to be disposed of in Sweden is mainly LWR fuel. The maximum burn-up expected is 60 MWd/kg U for BWR and PWR. A small quantity of BWR MOX is expected to be stored with a maximum burn-up of 50 MWd/kg U.

This work has focused on carrying out calculations of the amounts of He generated during more than 1 million years in Swedish spent nuclear fuels with a benchmarking exercise by using both codes AMBER and Origen-ARP. The performance and agreement of the codes in the He generation from α-decay have been checked and validated against data reported in literature [1].

In the calculation of the maximal pressure inside the canister, the quantity of helium used to pre-pressurise the fuel rods has been accounted for. The pressure inside the canister due to He generation is at all times much lower than the hydrostatic pressure and/or the bentonite swelling pressure outside the canister.

The microwave-induced magnetoresistance oscillations are exhibited by the GaAs/AlGaAs two dimensional electron system (2DES) under microwave and terahertz photo-excitation at liquid helium temperatures. Such oscillations are presently understood in terms of various theories. In order to identify the relative physical contributions, we have concurrently examined magnetotransport and microwave reflection from the 2DES. For the reflection measurements, a sensitive microwave detector was assimilated into the standard experimental setup. Here, we correlate changes in reflection with the concurrent transport response of the photo-excited 2DES.

The understanding of the physical properties of hydrogels has been controversial because hydrogels inherently have a substantial amount of heterogeneities in their structures. In this study, we focused on one of the simplest heterogeneities, heterogeneous distribution of strand length, and investigated its influence on physical properties. We prepared Tetra-PEG gels with bimodal distribution in strand length (Tetra-PEG bimodal gels) by combining Tetra-PEG prepolymers with different molecular weights and measured the physical properties including elastic modulus and ultimate deformation ratio. The physical properties of Tetra-PEG bimodal gels were well described by the models for conventional Tetra-PEG gels with the average polymerization degrees between cross-links. We conclude that the mechanical properties of hydrogels that have heterogeneous distribution in strand length can be predicted from those of hydrogels with the average strand length in the range tested in this study.

As the conventional atomic force microscopy (AFM) uses a Cartesian coordinate system to scan sample and the probe has different characteristics in each direction, it is impossible to scan in arbitrary direction. Therefore, we present the AFM which is able to rotate its probe. The deflection of cantilever was measured using optical pickup head of DVD drive. For verifying the system feasibility, the multidirectional scanning of the standard sample was carried out. Also we presented the modified structure which includes aligner and mirror to enhance the performance.

Single-walled carbon nanotubes (SWCNTs) have attracted significant attention as building blocks for future nanoscale electronics due to their small size and unique electronic properties. However, current SWCNT production techniques generate a mixture of two types of nanotubes with divergent electrical behaviors due to structural variations. Some of the nanotubes act as metallic materials while others display semiconducting properties. This random mixture has prevented the realization of functional carbon nanotube-based nanoelectronics. Here, a method of purifying a continuous flow of semiconducting nanotubes from an initially random mixture of both metallic and semiconducting SWCNTs in suspension is presented. This purification uses A/C dielectrophoresis (DEP), and takes advantage of the large difference of the relative dielectric constants between metallic and semiconducting SWCNTs. Because of a difference in magnitude and opposite directions of a dielectrophoretic force imposed on the random SWCNT solution, metallic SWCNTs deposit onto an electrode while semiconducting SWCNTs remain in suspension [3]. A discussion of these techniques is presented, along with a dielectrophoretic force-utilized microfluidic lab-on-a-chip device that can accomplish purification of semiconducting nanoparticles at high processing rates. The effectiveness of the device is characterized using Raman spectroscopy analysis on separated samples.

Gold nanoparticles supported on ZnO nanostructures were prepared through a simple chemical-thermal method and characterized by SEM, TEM, XRD and photo luminescence (PL) spectroscopy. Effect of annealing temperature on catalytic activity of these Au/ZnO nanocatalysts were investigated by aerobic oxidation of benzyl alcohol. The results indicated that the catalyst with ZnO nanowire support annealed at 300 °C exhibited more activity than Au/ZnO catalyst supported on ZnO nanoparticles annealed at 600 °C. The Au/ZnO-nanowire achieved to increase the benzaldehyde selectivity and yield to 93.7 % and 85.6 %, respectively, at 60 °C whereas in Au/ZnO-nanoparticle the benzaldehyde selectivity and yield to 85.1 % and 69.9 %, respectively at 80 °C. The XRD and PL spectroscopy revealed that the supports have interstitial zinc (Zni), oxygen vacancy (Vo-2 ) defects definitely but there is no evidence for interstitial oxygen (Oi) and zinc vacancy (VZn) defects and single ionized charged oxygen vacancy (Vo- ).

The Flemish painter Simón Pereyns travelled to New Spain in 1566 as a member of the viceroyal court. In two important paintings La Virgen del Perdón (1568) and San Cristóbal (1588) we identified wide use of blue smalt pigment, a potassium glass with cobalt oxide. The color of this material depends on its manufacture process, from pale greyish blue to violet or dark blue. The more blue color the more expensive the pigment. On the 16th century market the commerce of smalt was divided into many categories based on the material quality. Historical archive documents testify smalt imports from Seville to New Spain in two different qualities: fine and smalt woody ashes. In Pereyns` paintings the smalt was used in specific parts of the composition as the dark sky in landscapes, shadows of draperies and under layers in order to create a color background for the figures. Nowadays, in these areas, the alteration of the paint layer is evident. The blue has been changed into brown color. Optical microscopy (MO), scanning and transmission electron microscopies were performed in order to characterize the particles of smalt. The degradation of potassium glass was verified, as a consequence of aging and degradation process due to environmental conditions. These phenomena are well known and study on European paintings. In this research our aim is to explore the intentional use of smalt on Pereyns’ compositions and how color change as a consequence of microscopic materials instability can influence the contemporary reception of the paintings. Many paintings from New Spain have a dull, dark and limited palette but the original was very different. The remarks about the color of New Spain's paintings should considered the normal aging of the paint components, studied by materials science and art history.

Nano-scale surface textures have been developed as photon management schemes for crystalline silicon (c-Si) solar cells with very thin absorber layers to compensate for light absorption losses. This paper investigates the optical properties of periodic “nano-muffin” and inverted nano-pyramid surface textures, simulated using the Rigorous Coupled Wave Analysis (RCWA) method. Obtained results are compared against those of a planar silicon film with equal thickness. The simulation results demonstrate that “nano-muffin” and inverted nano-pyramid surface textures with a small aspect ratio are able to achieve substantial absorption enhancement over a broadband wavelength range. Further investigation indicates that “nano-muffin” surface textures could trap light by concentrating light within a volume close to the texture (micro-lensing effect). With such nano-scale textures, light trapping similar to that of much larger scale textures can be achieved.

The influence of oxygenation in the magnetism, superconductivity and electronic states for the Mo0.3Cu0.7Sr2RECu2Oy (RE = Y, Er and Tm) compounds are discussed here. The magnetic measurements on the as-prepared (AP) samples suggest the existence of short-range magnetic correlations due to the presence of the paramagnetic MoV cations in the copper chain site. On the other hand, all the oxygenated samples are not magnetic but superconducting. The high pressure oxygenated sample shows the highest superconducting transition temperature of TC = 84 K. The influence of oxygenation in the electronic states for the Mo0.3Cu0.7Sr2YCu2Oy system associated with an oxidation reaction leading from a non-superconducting to a superconducting state has also been investigated by means of X-ray photoelectron spectroscopy (XPS). XPS measurements show the predominance of the MoV oxidation state over the MoVI one in the AP material; annealing under flowing oxygen enhances both the MoVI and CuII amounts. A detailed study of the electronic states for the Mo0.3Cu0.7Sr2YCu2Oy samples has been performed and is also discussed.

Collaborative student research takes place in educational settings where the teacher directs the laboratory (traditional class) or allows the students to research a topic (non-traditional class). This study examines the role of collaborative student research in two separate settings: in high school (grades 9-12) and in college undergraduate institutions. These experiences include college level Research Experiences for Undergraduates (REU) and high school level Authentic Science Research (ASR) programs. These programs promote collaboration among student peers, teachers, professors, graduate students, post-docs, community members, and industry experts. Benefits of these collaborative student research programs may include development of skills aligned with educational standards such as Common Core State Standards and the Next Generation Science Standards. This study examines the short and long-term outcome of student engagement in collaborative student research experiences, and offers new insight regarding the impact that these unique experiences have on 21st century skill development. Students in this study have participated in non-traditional, research-based experiences ranging from 8 weeks to 4 years. Pre-post and retrospective student survey data was examined qualitatively and quantitatively to better understand the role in which collaborative student research experiences play in the formation of 21st century skills. Results of the study support the notion that collaborative student research experiences offer students meaningful interdisciplinary benefits, and these experiences are more than just a means of recruiting students into science, technology, engineering and math (STEM) fields.

There is an increased need for highly sensitive imaging devices to develop high resolution and high speed image sensors. Incident light intensity per pixel of image sensors is getting lower because the pixel resolution and frame rate of image sensors are becoming higher. We investigated the feasibility of using a photoconductor with tin-doped gallium oxide (Ga2O3:Sn)/Cu(In,Ga)Se2 (CIGS) hetero-junction for visible light image sensors. CIGS chalcopyrite thin films have great potential for improving the sensitivity of image sensors and CIGS chalcopyrite semiconductors have both a high absorption coefficient and high quantum efficiency. Moreover, the band gap can be adjusted for visible light. We applied Ga2O3 as an n-type semiconductor layer and a hole-blocking layer to CIGS thin film to reduce the dark current. The experimental results revealed that dark current was drastically reduced due to the application of Ga2O3 thin film, and an avalanche multiplication phenomenon was observed at an applied voltage of over 6 V. However, non-doped Ga2O3/CIGS hetero-junction only had sensitivity in the ultraviolet light region because their depletion region was almost completely spread throughout the Ga2O3 layer due to the low carrier density of the Ga2O3 layer. Therefore, we used Ga2O3:Sn for the n-type layer to increase carrier density. As a result, the depletion region shifted to the CIGS film and the cells had sensitivity in all visible regions. These results indicate that Ga2O3:Sn/CIGS hetero-junction are feasible for visible light photoconductors.

Femtosecond near IR laser irradiation is explored as a general methodology to produce metal nanoparticles from metal precursor solutions. Initial studies of the formation and transformations of gold nanoparticles in aqueous solution are used as model processes to evaluate the effects of laser parameters, reaction medium and surfactants in controlling metal nanoparticle formation. The addition of polymer surfactants such as poly(ethylene glycol) (PEG) was found to significantly accelerate Au(III) reduction as compared to surfactant-free systems. Photo-reduction for aqueous solutions of Au(III) in the presence of PEG results in relatively small narrowly dispersed spherical gold nanoparticles compared to relatively large well-formed crystalline nanoparticles that are observed in the absence of surfactants. Varying the concentration of PEG is an effective approach to tune the diameter and size distribution from 3.9±0.7 nm to 11±2.4 nm for Au nanoparticles produced by laser processing.

Corrosion behavior is a key issue in the assessment of disposal performance for activated waste such as spent fuel assemblies (i.e., hulls and end-pieces) because corrosion is expected to initiate radionuclide (e.g., C-14) leaching from such waste. Because the anticipated corrosion rate is extremely low, understanding and modeling Zircaloy (Zry) corrosion behavior under geological disposal conditions is important in predicting very long-term corrosion. Corrosion models applicable in the higher temperature ranges of nuclear reactors have been proposed based on considerable testing in the 523−633 K temperature range.

In this study, corrosion tests were carried out to confirm the applicability of such existing models to the low temperature range of geological disposal, and to examine the influence of material, environmental, and other factors on corrosion rates under geological disposal conditions. A characterization analysis of the generated oxide film was also performed.

To confirm applicability, the corrosion rate of Zry-4 in pure water with a temperature change from 303 K to 433 K was obtained using a hydrogen measuring technique, giving a corrosion rate for 180 days of 8 × 10-3 μm/y at 303 K.

To investigate the influence of various factors, corrosion tests were carried out. The corrosion rates for Zry-2 and Zry-4 were almost same, and increased with a temperature increase from 303 K to 353 K. The influence of pH (12.5) compared with pure water was about 1.4 at 180 days at 303 K.

One of the critical issues for development of the nuclear fusion demonstration reactor (DEMO) is the high heat flux on heat-resistant equipments, especially the blanket and divertor. Materials of such equipments require relatively high thermal conductivities. In this study, we developed iron-based composite materials with carbon nanotube (CNT) and copper, which have high thermal diffusivities, by means of Hot Pressing (HP) and Spark Plasma Sintering (SPS).

The thermal diffusivity in the iron/CNT composites was not high enough compared with that of pure iron, while iron/copper composite showed a relatively high thermal diffusivity in the joining conditions. One of the reasons not to be improved thermal diffusivity could be non-mono-dispersion of CNT by the formation of carbides in the matrix.

The broad range of applications of copper, including areas such as electronics, fuel cells, and spent nuclear fuel disposal, require accurate description of the physical and chemical properties of copper compounds. Within some of these applications, cuprous hydroxide is a compound whose relevance has been recently discovered. Its existence in the solid-state form was recently reported. Experimental determination of its physical-chemical properties is challenging due to its instability and poop crystallinity. Within the framework of density functional theory calculations (DFT), we investigated the nature of bonding, electronic spectra, and optical properties of the cuprous oxide and cuprous hydroxide. It is found that the hybrid functional PBE0 can accurately describe the electronic structure and optical properties of these two copper(I) compounds. The calculated properties of cuprous oxide are in good agreement with the experimental data and other theoretical results. The structure of cuprous hydroxide can be deduced from that of cuprous oxide by substituting half Cu+ in Cu2O lattice with protons. Compared to Cu2O, the presence of hydrogen in CuOH has little effect on the ionic nature of Cu–O bonding, but lowers the energy levels of the occupied states. Thus, CuOH is calculated to have a wider indirect band gap of 2.73 eV compared with the Cu2O band gap of 2.17 eV.

Flexible surface acoustic wave (SAW) based temperature and humidity sensors were fabricated and characterized. ZnO piezoelectric films were deposited on polyimide substrates by DC magnetron sputtering. ZnO films possess (0002) crystal orientation with large grain sizes of 50∼70 nm. SAW devices showed two wave modes, namely the Rayleigh and Lamb modes, with the frequencies at f R ∼132MHz and fL ∼427MHz respectively for a wavelength of 12 μm device. The two resonant frequencies have a temperature coefficient of frequency (TCF) of −423ppm/K and −258ppm/K for the Rayleigh and Lamb waves, respectively. The SAW sensors exhibited a good repeatability in responding to cyclic change of humidity. The responses of the sensors increase with the increase in humidity, and the sensitivity increases with the decrease in wavelength. A high sensitivity of 34.7 kHz/10%RH has been obtained from a SAW device without any surface treatment, demonstrated that the flexible SAW humidity sensors are very promising for application in flexible sensors and microsystems.