Molecular conduction channels between two ferromagnetic electrodes can produce strong exchange coupling and dramatic effect on the spin transport, thus enabling the realization of novel logic and memory devices. To realize such device, we produced Multilayer Edge Molecular Spintronics Devices (MEMSDs) by bridging the organometallic molecular clusters (OMCs) across a ∼2 nm thick insulator of a magnetic tunnel junction (MTJ), along its exposed side edges. These MEMSDs exhibited unprecedented increase in exchange coupling between ferromagnetic films and dramatic changes in the spin transport. This paper focuses on the dramatic current suppression phenomenon exhibited by MEMSDs at room temperature. In the event of current suppression, the effective MEMESDs’ current reduced by as much as six orders in magnitude as compared to the leakage current level of a MTJ test bed. Current suppression phenomenon was found to be associated with the equally dramatic changes in the MTJ test beds due to OMCs. Role of OMC in changing MTJ test bed properties was determined by the three different types of magnetic characterizations: SQUID Magnetometer, Ferromagnetic Resonance, and Magnetic Force Microscopy. Observation of current suppression by independent research groups and supporting studies on similar systems will be crucially important to unequivocally establish the utility of MEMSD approach.

Nitrogen-vacancy (NV) center in diamond is an emerging system for quantum-logic device and sensor applications. The key feature of the NV center is the ability of spin manipulation at room temperature. We apply a wide range of electron irradiation to generate the NV centers in nitrogen-rich diamond for creating best sensitivity. The NV0 and NV─ concentrations in electron irradiated diamond are determined from optical spectra. Additionally, electron spin resonance (ESR) has also proven to be an effective method for probing the electron spin transition between |ms=±1> and |ms=0> states of the NV centers. A study of ESR frequency shift and signal broadening and magnetometer sensitivity as a function of electron irradiation dose has been conducted. The research presented herein is a demonstration of minimum detectable magnetic field tailoring required for future-generation high-sensitivity diamond magnetometry.

Immobilization of fluorescent nanoparticles on graphene is an important step in the assembly of certain graphene-based photonic devices as well as in optical visualization of graphene and its defects. Hereby we report a viable approach to deposit diamond nanoparticles on a wide-area graphene substrate. It is demonstrated that a suitable plasma treatment leads to a selective immobilization of deposited nanodiamond on graphene with practically no agglomeration. Absence of photoemission from the individual adsorbed diamond nanoparticles suggests an energy transfer from the excited N-V centers to graphene.

The present work focuses on the development of a reproducible and cost-effective size-controlled synthesis route for nanoscale MgO and the preliminary assessment of its bactericide capacity as a function of crystal size. Nanoscale MgO was produced through the thermal decomposition of Mg-carbonate hydrate precursor (hydromagnesite) synthesized in aqueous phase. The exclusive formation of the MgO phase, with an average crystallite size between 7 and 13 ± 1 nm, was evidenced by X-Ray Diffraction and HRTEM analyses. Fourier Transform – Infrared spectroscopy confirmed the evolution of the precursor into the desired MgO structure. The bactericidal tests were conducted by measuring the optical density at 600 nm of E. coli in presence of MgO nanoparticles of specific sizes. MgO nanocrystals with average crystallite sizes of 13nm inhibited bacterial growth up to 35% at 500 mg MgO/L. The mechanism of inhibition could be attributed to the formation of superoxide species on the MgO surface.

In this paper we demonstrate an add/drop filter based on SiC technology. Tailoring of the channel bandwidth and wavelength is experimentally demonstrated. The concept is extended to implement a 1 by 4 wavelength division multiplexer in the visible range.The add/drop filter consists of a p-i'(a-SiC:H)-n/p-i(a-Si:H)-n photodetector with two front and back optical gates. Tailoring the filter wavelength is achieved by applying a 400 nm background and changing front and back biased optical gates. Results show that, front background enhances the light-to-dark sensitivity of the long and medium wavelength channels and quench strongly the others. Back violet background has the opposite behavior; it enhances channel magnitude in short wavelength range and reduces it in the long ones. This nonlinearity provides the possibility for selective removal or addition of wavelengths. An optoeletronic model gives insight on the system physics and explains the light filtering properties of the add/drop filter.

The feasibility of using a photoconductor with a Ga2O3/CuGaSe2 heterojunction for visible light sensors was investigated. CIGS chalcopyrite semiconductors have both a high absorption coefficient and high quantum efficiency. However, their dark current is too high for image sensors. In this study, we applied gallium oxide (Ga2O3) as a hole-blocking layer for CIGS thin film to reduce the dark current. Experimental results showed that the dark current was drastically reduced, and an avalanche multiplication phenomenon was observed at an applied voltage of over 6 V. However, this structure had sensitivity only in the ultraviolet light region because its depletion region was almost completely spread in the Ga2O3 layer since the carrier density of the Ga2O3 layer was much lower than that of the CIGS layer. These results indicate that the Ga2O3/CuGaSe2 heterojunction has potential for use in visible light sensors but that we also need to increase the carrier density of the Ga2O3 layer to shift the depletion region to the CIGS film.

In this study we analyze the electrical behavior of a junction formed by an ultraheavily Ti implanted Si layer processed by a Pulsed Laser Melting (PLM) and the non implanted Si substrate. This electrical behavior exhibits an electrical decoupling effect in this bilayer that we have associated to an Intermediate Band (IB) formation in the Ti supersaturated Si layer. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) measurements show a Ti depth profile with concentrations well above the theoretical limit required to the IB formation. Sheet resistance and Hall mobility measurements in the van der Pauw configuration of these bilayers exhibit a clear dependence with the different measurement currents introduced (1µA-1mA). We find that the electrical transport properties measured present an electrical decoupling effect in the bilayer as function of the temperature. The dependence of this effect with the injected current could be explained in terms of an additional current flow in the junction from the substrate to the IB layer and in terms of the voltage dependence in the junction with the measurement current.

We introduce a new approach for fabricating hollow microneedles using vertically-aligned carbon nanotubes (VA-CNTs) for rapid transdermal drug delivery. Here, we discuss the fabrication of the microneedles emphasizing the overall simplicity and flexibility of the method to allow for potential industrial application. By capitalizing on the nanoporosity of the CNT bundles, uncured polymer can be wicked into the needles ultimately creating a high strength composite of aligned nanotubes and polymer. Flow through the microneedles as well as in vitro penetration of the microneedles into swine skin is demonstrated. Furthermore, we present a trade study comparing the difficulty and complexity of the fabrication process of our CNT-polymer microneedles with other standard microneedle fabrication approaches.

The one pot-synthesis and use of monolithic biohybrid foams in a continuous flow device reported inhere presents the advantages of covalent stabilization of the enzymes, together with a low steric hindrance between proteins and substrates, an optimized mass transport due to the interconnected macroporous network and a rather simplicity in regard of the column in-situ synthetic path. Those features, concerning transesterification (biodiesel production) enzyme- based catalyzed reaction, provide high enzymatic activity addressed with bio-hybrid catalysts bearing unprecedented endurance of continuous catalysis for a two months period of time.

Mixed phase thin films consisting of hydrogenated amorphous silicon (a-Si:H) in which germanium nanocrystals (nc-Ge) are embedded have been synthesized using a dual-chamber co-deposition system. Raman spectroscopy and x-ray diffraction measurements confirm the presence of 4 - 4.5 nm diameter nc-Ge homogenously embedded within the a-Si:H matrix. The conductivity and thermopower are studied as the germanium crystal fraction X Ge is systematically increased. For X Ge < 10%, the thermopower is n-type (as in undoped a-Si:H) while for X Ge > 25% p-type transport is observed. For films with 10 < X Ge < 25% the thermopower shifts from p-type to n-type as the temperature is increased. This transition is faster than expected from a standard two-channel model for charge transport.

Colloidal β-In2S3 quantum dots stabilized in water by a number of polymers or sodium polyphosphate and mercaptoacetate were synthesized. An increase in the stabilizer content was found to result in a decrease in the average dot size from 20–30 to 5–10 nm and formation of a narrow absorption band centered at 290 nm. The position and spectral width of the band were found to be independent on stabilizer concentration, synthesis temperature and molar In:S ratio. The band was assumed to belong to a molecular cluster smaller than 1 nm which is a precursor for formation of larger regular indium sulfide quantum dots.

A hydrothermal reactor has been used for surface doping of anatase TiO2 nanoparticles (∼ 13 nm across) with Eu3+ ions in aqueous fluids to 370 °C and ∼20 MPa. XRD and Raman measurements made both before and after hydrothermal treatment with Eu show that the anatase structure of the TiO2 nanoparticles (NPs) is preserved. SEM imaging, combined with XRD indicates that the size and overall morphology of the TiO2 nanoparticles is preserved subsequent to hydrothermal treatment in the presence of Eu. The photoluminescence occurring in the 400 to ∼700 nm range of the (as prepared) Eu surface-doped TiO2 NPs are red-shifted by ∼ 50 nm and reduced in intensity relative to the photoluminescence of TiO2 NPs.

In the presented study, a new application for distyrylbenzene oligoelectrolyte, named DSBN+, as a marker for bioimaging is presented. DSBN+ is a water-soluble, conjugated oligoelectrolyte (COE) with novel photophysical and solvatochromatic properties. Previous studies have shown that this compound spontaneously inserts into bilayer membranes in both synthetic and microbial living systems and can facilitate visualization of cell membranes through fluorescence imaging. In the presented research, we seek to further study and exploit the multifunctional nature of DSBN+ in terms of membrane interactions and photophysical properties for visualization of membranous structures of more complex mammalian cells, namely a human cervical carcinoma (HeLa) cell line. Obtained results confirm the possibility of applying DSBN+ as a fluorescent dye for bioimaging of membranes in human cell cultures systems, both in live-cell imaging and in the studies required formaldehyde fixation. Due to the defined structure of this conjugated oligoelectrolyte we suspect that it will display organelle membrane selectivity, but this has to be further investigated.

In order to understand the fundamental charge transport in a-B4-5C:H/Si heterostructure devices, we have utilized x-ray photoelectron spectroscopy to determine the valence band offset at interfaces formed by Plasma Enhanced Chemical Vapor Deposition of a-B4-5C:H on (100) Si. For such interfaces, we observed relatively small valence band offset values of ± 0.25 eV.

Inverse-photoemission spectroscopy (IPES) in the near-ultraviolet range is a new tool for investigating the LUMO levels of organic materials. Previous IPES methods have had two serious weaknesses, i.e. low energy resolution and sample damage to organic materials. In the present method, on the other hand, the irradiation damage to the organic sample is significantly reduced by decreasing the kinetic energy of electrons below the damage threshold. The energy resolution of the instrument is improved by a factor of two to 0.3 eV by using multilayer band pass filters. Acceptor materials widely used in organic photovoltaic cells, C60 and phenyl-C61-butyric acid methyl ester (PC61BM), are measured with this new technique to determine the electron affinities.

The body and elytra of the diamond weevil, Entimus imperialis, is studded with numerous brightly colored scales. The scales exhibit brilliant reflections because they contain unusually large diamond-type photonic crystals. The scales are concentrated in pits on the otherwise black elytra. This framing enhances the color contrast when the weevil is observed from nearby. From a distance the diamond weevil looks green, alike green foliage. Another weevil, Eupholus cuvieri, has also scales with green reflective photonic crystals, but here the scales are arranged closely apposed on the planar elytra. Both weevils use photonic crystals for camouflage, but the display methods are different.

Recently we postulated that polystyrene Petri dishes become soft when in contact with an aqueous milieu. Specifically, we assumed that the effect is restricted to a superficial nanolayer, a condition presumably favoring the establishment of a stable nanolayer of reactive oxygen species (ROS) at the liquid/solid-interface. Cells are known to be hypersensitive to ROS. Previously we used P19 mouse embryonal carcinoma cells and systematically analyzed their capability to climb different substrates placed vertically into a Petri dish. The worst and best performance was found on polystyrene (Petri dish material) and nanocrystalline diamond, respectively. Polystyrene Petri dishes are today standard in laboratories conducting in vitro fertilization (IVF). Here we proceed and extend the investigation to human spermatozoa and show that their performance (vitality) on polystyrene Petri dishes is low compared to that on diamond Petri dishes. This work may propel further research and inspire the development of a new generation of cell-friendly Petri dishes.

The National Institute of Standards and Technology (NIST) has developed a dynamic and on-going educational outreach program designed to support middle school science teachers and increase their understanding of the science they teach with applications to the real world and connections to the latest NIST research. In the NIST Summer Institute for Middle School Science Teachers, science topics are taken from NIST research pertinent to the middle school curriculum, and the research is translated for use in the classroom. During the two-week summer program teachers from around the country are given the opportunity to focus on NIST research as it relates to the middle school classroom by participating in a combination of hands-on activities, lectures, tours, and visits with scientists and engineers in their laboratories. The NIST Summer Institute is designed to increase teacher understanding of the subjects they teach, provide inquiry activities for the classroom, rekindle teachers’ enthusiasm for science, provide increased understanding of how scientific research is performed, create a learning community of teachers and scientists, and provide role models for the teachers. Teachers finish the NIST Summer Institute with a wealth of knowledge about core topics in introductory biology, chemistry, physics, and materials to integrate these topics into their existing curriculum.

The NIST Summer Institute has spawned additional related outreach activities, including “Science Afternoons at NIST,” in which teachers are invited back to NIST during the school year for events in which the focus is on a single topic such as designing buildings to resist earthquakes, infrared energy, and nanomagnetism. Based on continued requests from participants in the NIST Summer Institute, an additional program, the NIST Research Experience for Teachers program, was begun in 2011 with teachers performing research at NIST under the guidance of NIST scientists and engineers, and designing ways to take their research experience back into the classroom to share with their students. This proceeding will give examples of topics covered and activities developed in past Summer Institutes, as well as ways similar Institutes are being implemented at other locations. While not a teaching institution but a research institute focused on meeting the measurement science needs of the nation, NIST has a wealth of resources for the education community. The NIST Summer Institute for Middle School Science Teachers is one way of sharing these resources and building partnerships between middle school science teachers and their students and NIST scientists and engineers.

Dielectric materials with GDR (e.g. CaCu3Ti4O12 – CCTO and isostructural systems, co-doped NiO etc) attract major research interest due to their bright prospective in energy storage and memory devices. However, after years of intensive experimental and theoretical studies of GDR materials, physical nature of their extremely high complex dielectric permittivity (specifically, real part ∼ 104 - 106) is still not established convincingly. Another serious problem is excessively high imaginary part of the permittivity (which usually exceeds real one). Better understanding on physical mechanisms and limitations of GDR behavior in aforementioned dielectrics could be achieved based on polaronic phase transition criteria, proposed S. Fratini and P. Quémerais [Eur. Phys. Journ. B14, 99 (2000)]. In particular, ‘melting’ of Polaronic Wigner Crystal (PWC) either to ‘polaronic liquid’ or ‘electron liquid’ manifests two different scenarios of PWC phase transition at increment of concentrations of appropriate dopants. The former scenario is certainly preferable for ionic dielectrics with GDR behavior, while the latter one would yield in metal-like dielectric response with very high real permittivity, but unacceptable loss. Described approach provides physically transparent guidelines for selection of prospective host dielectrics with GDR behavior and quantitative estimations on critical dopant/polaron concentrations, corresponding to both aforementioned types of the phase transitions as well as temperature ranges suitable for GDR.

Capillary-driven microfluidics, utilizes the capillary force generated by fibrous hydrophilic materials (e.g., paper and cotton) to drive biological reagents, has been extended to various biological and chemical analyses recently. However, the restricted capillary-driving mechanism persists to be a major challenge for continuous and facilitated biofluidic transport. In this abstract, we have first introduced a new interfacial microfluidic transport principle to automatically and continuously drive three-dimensional liquid flows on a micropatterned superhydrophobic textile (MST). Specifically, the MST platform utilizes the surface tension-induced Laplace pressure to facilitate the liquid motion along the fibers, in addition to the capillary force existing in the fibrous structure. The surface tension-induced pressure can be highly controllable by the sizes of the stitching patterns of hydrophilic yarns and the confined liquid volume. Moreover, the fluidic resistances of various configurations of connecting fibers are quantitatively investigated. Furthermore, a demonstration of the liquid collection ability of MST has been demonstrated on an artificial skin model. The MST can be potentially applied to large volume and continuous biofluidic collection and removal.