Nanotechnology is currently undergoing unprecedented development in various fields. There has been a widespread interest in the application of nanomaterials in medicine with its promise of improving imaging, diagnostics, and therapy. The recent advances in engineering and technology have led to the development of new nanoscale platforms such as quantum dots, gold nanocrystals, superparamagnetic nanocrystals, and other semiconductor nanoparticles. Literature on the applications of quantum dots in life sciences has recently increased in number. This may have led to predictions that nanotechnology in life sciences research will contribute $3.4 billion by 2010 while institutions have predicted that the market for nanotechnology and corresponding products will reach $1 trillion in 2012 (1).

Ocean NanoTech is at the height of developmental stages of nanoparticle production for biological applications. Ocean’s high quantum-yield quantum dots (QDs) is currently being tested and used for cell imaging, as wells as for the detection of proteins, DNA, whole cells, and whole organisms. Imaging of cells involves conjugation of QDs to highly sensitive and specific antibody to form QD˜Ab conjugates that attach to specific protein target on the cell surface. Attachment of the QD˜Ab on the cell surface allows imaging of the cell under a fluorescence microscope. QD based imaging can be used in a multiplex immunoassay detection of several types of cells (or microorganisms) in a single sample when several size tunable quantum dots are used as reporter probes.

We report the QD imaging of breast cancer cells. Using the breast cancer cell line SK-BR3, which expresses high levels of her2 antigens on the cell surface, anti-her2 were conjugated to Ocean’s quantum dots, QSH620. To eliminate non-specific binding of the QD˜20Ab Ocean’s super blocking buffer BBB and BBG were used. Preliminary results of in vitro studies indicated that QD based systems can be used to image cells. We anticipate that this system can be transferred to in vivo detection.

Ge monoxide [GeO(II)] and dioxide [GeO2(IV)], which are selectively formed on Ge substrate by controlling pH and redox potential in pretreatment solution, are confirmed by XPS. ΔEC in GeO(II)/Ge and GeO2(IV)/Ge are almost the same, whereas ΔEV in GeO(II)/Ge is smaller than that in GeO2(IV)/Ge, resulting in smaller Eg of GeO(II). GeO(g) desorption is suppressed in LaAlO3/Ge gate stack, whereas GeO(g) desorbs through LaAlO3 layer when there is an intentional interfacial GeO(II) layer, leading to a large increase in Jg. GeO(g) desorption temperature in Ge oxide/Ge gate stacks decreases with the increase in the ratio of GeO(II) in Ge oxide and is independent of the oxidation techniques. Since GeO(g) desorption is accompanied by H2O(g) desorption, a new model to explain the GeO(g) desorption phenomena is proposed, in which Ge(OH)2 decomposes into GeO(g) and H2O(g). Highly effective etching methods of Ge oxide, using HCl solution and HCl vapor at higher temperature than boiling point of Ge (hydro-)chloride are demonstrated.

To augment or replace defective, diseased, or impaired human digits, the design and development of tissue-engineered phalanges are important and include a middle phalanx model. This construct consists in part of two square-shaped biodegradable polyglycolic acid (PGA) scaffolds (1 x 1 x 0.2 cm in length, width and thickness, respectively) seeded with cartilage cells (chondrocytes) obtained from young calves. One such seeded scaffold is sutured to each end of a rectangular-shaped scaffold (˜2 x 0.7 x 0.5 cm in length, width and thickness) serving as the midshaft of the model. To examine the biological regenerative capacity of these biomimetic composites, midshafts were left uncovered or wrapped with periosteum, a tissue from calves giving rise to cartilage and bone. Midshafts were composed of poly(L-lactide-ε-caprolactone) [P(LA-CL)] or one of two ceramics, hydroxyapatite (HA) or β-tricalcium phosphate (β-TCP), admixed with P(LA-CL). When engineered middle phalanx models were implanted and grown for up to 20 weeks under dorsal skin flaps of athymic (nude) mice, resulting constructs varied in their midshaft bone and end plate cartilage composition and structure. Harvested from mice at 20 weeks, all constructs (n = 3 for each type) without periosteum developed viable end plate cartilage as determined by Safranin-O staining for chondrocyte-secreted proteoglycans but cells were not organized as in normal growth plate cartilage of human digits. Midshafts remained devoid of cells and mineral. Implanted for the same time 20 week period, constructs of P(LA-CL) (n = 3), HA-P(LA-CL) (n = 3), or β-TCP-P(LA-CL) (n = 3) and enclosed by periosteum each developed viable end plate cartilage whose chondrocytes were organized into columns resembling normal growth plate cartilage of digits. Midshafts mineralized through the normal process of endochondral ossification. While these features were common to all periosteum-wrapped composites, specific differences occurred between them, apparently depending on midshaft copolymer composition. In particular after 10 or 20 weeks of implantation, gene expression of end plate chondrocytes varied in their levels of type II collagen, aggrecan (proteoglycan), or bone sialoprotein, all markers for development of normal cartilage extracellular matrix and mineralization. These results indicate that the composition of midshaft scaffolds comprising middle phalanx models of human digits affects the composition and structure of both midshaft bone and end plate cartilage of constructs. Continuing studies are defining more completely the relationships between structure and composition of bone and cartilage tissues developed and properties of their underlying copolymer scaffolds in these biomineralized models.

This paper presents a thermochemical method, based on a mixture of molten alkaline halides to produce a Ti coating on AISI 316L stainless steel. The thickness of the coatings is a function of temperature and time. It is observed that the physical form of the Ti source employed affects both coating thickness and morphology. The formation of several inter-diffusion layers is detected, each having a characteristic chemical composition, morphology and location at the substrate/coating interface. It is proposed that some of the produced Ti coatings can be employed to improve osseointegration of stainless steel for potential prosthetic devices.

We investigated the possibility of doping poly (sodium poly[2-(3-thienyl)-ethoxy-4-butylsulfonate) (PTEBS) with perylene tetracarboxylicdiimide (PTCDI) nanobelts through ultraviolet photoelectron spectroscopy (UPS) measurements. For our experiment, PTEBS was tuned to absorb maximum light in the range of 450 nm to 550 nm which corresponds to the maximum solar irradiance of the Earth’s atmosphere. Nanobelts of PTCDI were synthesized by gas phase self assembly process. Doping PTEBS with PTCDI nanobelts causes a shift in the Fermi level of the composite material with respect to the vacuum level as observed in the photoemission spectrum. With increased PTCDI doping, PTCDI does not act much like an electron donor, but more like an electron acceptor. The peaks corresponding to the sigma bonds shift towards the vacuum level with higher concentrations of the dopant. Using angled resolved photoemission spectra from a 3m toroidal grating monochromator, PTEBS displays change in the highest occupied molecular orbital in respect to its Fermi level when the side groups were substituted by H+ or OH- groups. The results confirm that the binding energy decreases with increase in activity of the dissolved hydrogen ions. It is evident that there is an increase in the density of states near the Fermi level and shifts to lower binding energies of the occupied molecular orbitals with pH level decrease, which is in agreement with the published optical absorption characteristics of PTEBS. Since UPS data confirm that PTCDI nanobelts dope PTEBS, along with its tunable absorption characteristics, this composite might be a promising material for optoelectronic application.

Some compositions of Ni-Mn-X (X = Ga, In, Sn) ferromagnetic shape memory alloys exhibit a first order magnetostructural phase transition. Magnetic entropy change ΔSm in the vicinity of this transition has been studied by magnetization and heat capacity measurements. Comparison of these results point to a large difference in magnitudes of ΔSm obtained from magnetization and heat capacity data. It is suggested that this discrepancy originates from overestimation of \Delta S_m determined from the magnetization measurements and underestimation of ΔSm obtained from the heat capacity measurements.

In this work, SiC nanowires (NWs) were grown by chemical vapor deposition (CVD) on commercial 4H-SiC substrates. The growth was conducted in an inductively heated hot wall CVD reactor traditionally used for homoepitaxy of 4H-SiC, operating at 150 Torr with H2 as the carrier gas. The growth experiments utilized the precursor chemistry that previously enabled the so-called low-temperature homoepitaxial growth of SiC – SiCl4 as the silicon precursor and CH3Cl as the carbon precursor. Vapor-liquid-solid (VLS) growth mode was employed. Two metal catalysts Au and Ni were used for NW growth in a wide range of growth temperatures from below 10500C to above 13000C. It was established that high precursor flow rates favor the regular epitaxial growth (though disturbed by the presence of the islands of the metal catalyst) at temperatures above 12000C. Reduction of the precursor flow rates and the growth temperature caused formation of micro-needles and eventually NWs. NW diameters in the range from below 10 to 100 nm were observed using scanning electron microscopy. Only SiC phase with no presence of Si, even for the growth temperatures down to 10500C, was confirmed by X-ray diffraction.

Quantifying the effects of thin metallic coatings on the damping factors of micro- and nanomechanical resonators is important for the design of high-performance devices for sensing and communications. This study presents experimental results for the increase in damping caused by aluminum films coated on cantilevered single-crystal silicon beams. The monolithic silicon beams (100 to 125 microns thick) can operate at the ultimate limits of dissipation established by thermoelastic damping with quality factors ranging from 104 to 105. However, coating these beams with 60 to 100 nm of aluminum can increase the damping by factors of three to five. These results provide guidelines for designing composite micromechanical resonators, and establish the foundation of a new approach for accurate measurement of internal friction in substrate-bonded thin films.

We report on metal organic chemical vapor deposition growth of GaMnN/p-GaN/n-GaN multilayer structures and manipulation of room temperature (RT) ferromagnetism (FM) in a GaMnN layer. The GaMnN layer was grown on top of a n-GaN substrate and found to be almost always paramagnetic. However, when grown on a p-type GaN layer, a strong saturation magnetization (Ms) was observed. Ms was almost doubled after annealing demonstrating that the FM observed in GaMnN film is carrier-mediated. To control the hole concentration of the p-GaN layer by depletion, GaMnN/p-GaN/n-GaN multilayer structures of different p-GaN thickness (Xp) were grown on sapphire substrates. We have demonstrated that the FM depends on the Xp and the applied bias to the GaN p-n junction. The FM of these multilayer is independent on the top GaMnN layer thickness (tGaMnN) for tGaMnN >200 nm and decreases for tGaMnN < 200 nm. Thus the room temperature FM of GaMnN i-p-n structure can also be controlled by changing Xp and tGaMnN in the GaMnN i-p-n structures.

We have synthesized a series of ion exchange functionalized fibers (IXF) from polystyrene (PS) and polyacrylonitrile (PAN). To obtain strong-acid cation exchange fibers, polystyrene was sulfonated using specific sulfonation protocols. Micron sized fibers (average diameter of 100m) were then produced from the functionalized polystyrene using a single-screw extruder equipped with a 30 hole spinneret with orifice diameter of 0.5 mm with a precise screw speed of 5 rpm, pump speed of 15 rpm, and with a feed rate of 2.4 cc/min. The extruder zone temperature was kept at 250 – 270 °C. Fiber was drawn at 120 degree with a draw ratio of 2. Electrospinning of functionalized polystyrene was also carried out to produce ultrafine functionalized fibers of 100 nm in average diameter. We have also electrospun polystyrene and polyisoprene blended nanofibers to increase the strength of the resulting blend nanofibers compared to pure PS nanofibers. To synthesize weak-acid cation exchange fibers polyacrylonitrile (PAN) was electrospun and the nanofibers obtained were alkaline hydrolyzed with 2 N NaOH for 20 minutes at room temperature to convert nitrile bonds to carboxylate. Cation exchange capacity (CEC) of the microfibers and nanofibers was determined. Sulfonated PS microfibers show high CEC of 4.0 meq/gm compared to that of nanofibers with 2.5 meq/gm. CEC of blended nanofibers of PS and polyisoprene was 2.0 meq/gm. In case of PAN fibers, nanosized electrospun fibers were found to show a CEC of 1.5 meq/gm. Weak-base anion exchange fiber synthesis was undertaken using appropriate protocol and its CEC was measured. For all IXF synthesized, fiber diameter was measured using SEM, degree of functionalization was qualitatively determined using FTIR and ion exchange capacity was computed after mass balance on a binary exchange system after equilibrium.

Hydrogen storage in metallic nanoparticles was investigated by classical molecular dynamics and parameter physics. We observed phenomenological variation due to the differences in potential parameters of metal-hydrogen pair and crystal lattices. Three patterns of hydrogen distribution in both b.c.c. and f.c.c. nanoparticles were observed: non-absorbing, homogeneously-absorbing and heterogeneously-absorbing.In the last case, hydrogen atoms distribute just beneath the particle surface to form a hydrogen-rich layer. This layer prevents the diffusive motions of hydrogen atoms into the nanoparticle. We also carried out long simulation runs up to 1 nm to observed the structural variation of nanoparticles due to hydrogenation.Generation of grain boundaries was observed in b.c.c nanoparticles with the condition of strong metal–hydrogen interaction. Most of the grain boundaries were symmetric-tilt type and migrated inside the particle to reduce the interface energies. Formation of grain boundary was not observed in f.c.c. nanoparticles.

We have achieved what we believe to be the first atomic resolution STM images for a uranium compound taken at room temperature. The a, b, and c lattice parameters in the images confirm that the USb2 crystals cleave on the (001) basal plane as expected. The a and b dimensions were equal, with the atoms arranged in a cubic pattern. Our calculations indicate a symmetric cut between Sb planes to be the most favorable cleavage plane and U atoms to be responsible for most of the DOS measured by STM. Some strange features observed in the STM will be discussed in conjunction with ab initio calculations.

Powder processing of thermoplastic polymer composites offers multiple advantages for both micro- and nano-scale systems. A high degree of component homogenization is achieved prior to melt forming of the composite, thus minimizing degradation associated with extended thermal processing at high shear. Polymer blends can be prepared that would otherwise not be possible due to thermodynamic incompatibility. Initial evaluation of this concept was conducted by processing PMMA and HDPE micron size powder prepared by emulsion polymerization. Spherical silica particles of comparable size (mean size = 5 μm) were added to a 30/60 PMMA/HDPE blend at the 10 volume percent concentration and mixed in an aqueous medium prior to drying and extrusion. Analysis of optical and electron microscope images of the raw mixture shows good homogeneity and distribution of the small inorganic particles around the larger matrix phase particles by the process of interstitial filling. The melt-processed composite was observed by SEM and consisted of a three-phase system of dispersed silica and PMMA particles in a HDPE matrix.

An experimental study of the mechanical properties of a Cu-Al-Be shape memory alloy is presented. The samples are tested in a cantilever arrangement. They consist of polycrystalline thin plates of shape memory material with a MS near 0 °C and a monocrystalline sample with MS near −90 °C. The measurements are made with strain gauges attached to the top side of the samples. In these conditions, strain Vs load curves are obtained. A polycrystalline sample is instrumented and tested and then it is cut into three samples for further testing. The results show a relationship between the transformation stress and the sample grain size which differs from the typical Hall-Petch relationship. The analysis of transformation plane stress diagrams shows the development of a stress component perpendicular to those induced by the applied load.

Shape-memory polymer foams based on poly(ω-pentadecalactone) (PPDL) and poly(ε-caprolactone) (PCL) multiblock copolymer with 60 wt% PCL content were prepared by environmentally-friendly high pressure supercritical carbon dioxide scCO2 foaming technique. A foam with a density of approximately 0.11 ± 0.02 g/cm3 and an average pore size of 150-200 μm with excellent compressibility and shape-memory properties was created at 25 bar/s depressurization rate in the temperature range between 78 and 84 °C. The shape-memory behavior of this foam was investigated using different programming modules, such as, under stress-free condition and under constant strain condition. The thermally-induced shape-memory effect (SME) was found to be strongly dependent on the programming conditions. Excellent shape fixity has been observed for all foams indicating the high efficiency of the switching domains to fix the temporary shape by crystallization. The stress recovery of this foam could be controlled by changing compression percentage (εc%) at a constant compression temperature. The production of these foams with unprecedented properties by commercially available processing equipment raises much hope with the potential to provide new materials with a unique combination of shape-memory properties and porous structure as well as desired properties for many industrial and biomedical applications

ZnO crystals were irradiated with high energy electrons (1MeV). The main defects created were analyzed by cathodoluminescence (CL) spectroscopy. The main effects of irradiation on the CL spectrum were the partial quenching of the emission, the shift of the visible luminescence to the yellow, and the observation of an additional band and its phonon replicas at ∼3.32 eV. Zinc vacancy related defects are postulated as responsible for the changes induced in the spectrum.

Poly(3,4-ethylenedioxythiophene) (PEDOT) nanofibers were obtained by the combination of electrospinning and vapour-phase polymerization. The fibers had diameters around 350 ± 60 nm, and were soldered at every intersection, ensuring superior dimensional stability of the mats. The nanofiber mats demonstrated very high conductivity (60 ± 10 S/cm, the highest value reported so far for polymer nanofibers) as well as very interesting electrochemical properties, due to the porous and nanostructured nature of the electrospun mats. The mats were incorporated into all-solid flexible supercapacitors that showed interesting performances for applications where flexible and lightweight energy storage devices are required.

Recent experiments provide evidence of intrinsic localized modes (ILMs) in the lattice dynamics of conventional 3D materials. Here evidence that ILMs in uranium metal enhance the thermal conductivity is presented along with speculation on how thermal transport by ILMs might be used to improve a reported design for a solid-state thermal rectifier.

A high quantity of tungsten oxide nanosheets were synthesized by oxidizing tungsten plates with potassium hydrate as the catalyst and tungsten plate as the substrate. The structural and geometrical properties were characterized by various techniques. It was found that the crystalline nanosheets have a WO3 structure with thicknesses of 30–50 nm and widths up to tens of micrometers. There exist two characteristic acute angles of about 37° or 51° on the nanosheet plane. The formation of these angles and the growth mechanism were discussed.

The effect of the amount of Na present during the 3-stage growth of CIGS at very low temperature T2 on polyimide (PI) foils is studied. While at higher growth temperatures Na seems to impede In-Ga interdifussion, at very low temperatures it appears to further the process. An increase in Voc for a higher Na concentration can be explained by a higher net carrier concentration as measured by drive level capacitance profiling. Admittance spectroscopy measurements show shallow defects when the Na concentration increases. These results suggest that the main role of Na could be the passivation of InCu donor deep defect, in agreement with Wei's theory. Efficiencies of up to 15.1 % (0.5 cm2 active area with antireflection coating) and 13.6%, 14.1% (1 cm2 total and active area respectively without antireflection coating) for nominal T2=420° C were achieved on PI substrates so far.