30413815
Bioconjugated Ag nanoparticles and CdTe nanowires: metamaterials with field-enhanced light absorption.
The hybrid assembly of inorganic and metallic nanomaterials by means of chemical and biological bonding to yield manifold optical and electromagnetic properties has received widespread attention. Currently available highly monodispersed nanomaterials such as semiconductors and noble metals that can be conjugated by ligand–receptor, antigen– antibody reactions, polymer tethering, and DNA hybridization are used as building blocks for 2D or 3D superstructures in which new collective properties of these artificial assemblies have been obtained. They represent a large class of newmaterials (i.e., metamaterials) in which the properties are determined not only by classical atomic composition, but also by nanoscale organization of structural components. Recently, metamaterials based on metallic composites have received special attention as these are expected to display negative values for permittivity and refractive index. This property should lead to a multitude of unique optical effects. Many of these effects are related to surface plasmons on Au or Ag nanoparticles (NPs), which generate exceptionally high localized electromagnetic fields, and have been exploited in surface-enhanced Raman spectroscopy and some optoelectronic devices. 22] Metamaterials from semiconductors and their combinations with metals can also produce optical effects that are useful for development of advanced sensing and imaging technologies. Recently, we
11292781
Bioconjugated superstructures of CdTe nanowires and nanoparticles: multistep cascade Förster resonance energy transfer and energy channeling.
Nanoparticle/nanowire assemblies with a degree of radial organization were prepared around luminescent semiconducting CdTe nanowires using bioconjugation with streptavidin and D-biotin linkers. Red-emitting nanowires (6.62 +/- 1.55 nm diameter, 512 +/- 119 nm length) and green-emitting nanoparticles (3.2 +/- 0.7 nm diameter) were surface-modified with biotin, while orange-emitting nanoparticles (4.1 +/- 1.2 nm diameter) were decorated with streptavidin. CdTe nanocrystals produced two fuzzy layers around the nanowires in which the diameter of CdTe nanoparticles decreased with the distance from the nanowire axis. Förster resonance energy transfer (FRET) from the outside layer of nanoparticles to the central nanowire was observed for nanowires conjugated with 4.1 nm CdTe. Addition of 3.2 nm CdTe resulted in a red-orange-green optical progression with band gaps of CdTe decreasing toward the axis of the superstructure. In this case, 4-fold luminescence enhancement of the nanowire luminescence was observed and was attributed to multistep FRET. This observation indicated the accumulation of photogenerated excitons in the cascade terminal. A simple model of multiconjugated superstructure with cascade energy transfer is developed and used to describe and understand the experimental data. The experimental data and theoretical model suggest the possibility of utilization of the prepared superstructures with radial symmetry in several classes of optoelectronic devices including nanomaterials for energy collection. They can also be a convenient model object for the investigation of methods of energy funneling in nanoscale assemblies.
8439250
Nanoparticle assemblies with molecular springs: a nanoscale thermometer.
aretypicallystatic:Theyshowa limitedresponsetoenvironmentalparametersanddonotexhibitsmoothrever-sible transitions of their three-dimensional organization orgeometry in response to external stimuli. Dynamic NPsuperstructures with gradual structural adaptation tocommon physical parameters may reveal interesting analo-gies to biological entities of similar scale.
19885934
Identification and functional characterization of genes involved in the sexual reproduction of the ascomycete fungus Gibberella zeae.
We previously reported that G protein alpha subunit 1 (GPA1) is essential for sexual reproduction in the homothallic ascomycete fungus Gibberella zeae. In this study we performed microarray analyses on a GPA1 deletion mutant of G. zeae (Δgpa1) to identify genes involved in the sexual reproduction of this fungus. In the Δgpa1 strain, 645 genes were down-regulated and 550 genes were up-regulated during sexual reproduction when compared to the wild-type strain. One hundred of the down-regulated genes were selected for further investigation based on orthologous group clusters and differences in transcript levels. Quantitative real time-PCR was used to determine transcriptional profiles of these genes at various sexual and vegetative stages. We observed that transcript levels of 78 of these genes were dramatically increased in the wild-type strain during sexual reproduction compared to levels observed during vegetative growth, and were down-regulated in Δgpa1 compared to the wild-type strain. We deleted 57 of these genes and found that four of the deletion mutants lost self-fertility and five produced fewer perithecia compared to the wild-type strain. Two mutants produced wild-type numbers of perithecia, but maturation of perithecia and ascospores was delayed. In all we identified 11 genes that are involved in sexual reproduction of G. zeae and present evidence that some of these genes function at distinct stages during sexual reproduction in the fungus.
7545804
Oregon 'Pinot noir' grape anthocyanin enhancement by early leaf removal.
Complete cluster zone leaf removal of 'Pinot noir' was initiated at three separate pre-véraison growth stages (bloom, grain-pea size, and bunch closure) and maintained leaf free until harvest, for four growing seasons (2008-2011). Fruit anthocyanin composition was examined at harvest for the last two vintages (2010 and 2011) and compared to a control-no cluster zone leaf removal. Experiments were conducted at two commercially operating Oregon vineyards (site A=420 rootstock/'Pinot noir' 115 scion and site B=3309C rootstock/'Pinot noir' 777 scion). All clusters contained the five anthocyanins typically found in 'Pinot noir'. Leaf removal at bloom and maintained until harvest produced maximum anthocyanin accumulation in 'Pinot noir' grapes (site A=85.24 mg/100 g and site B=125.06 mg/100 g), compared to no leaf removal (control; site A=57.91 mg/100 g and site B=97.56 mg/100 g). Even leaf removal at bunch closure (last leaf removal initiation period) increased grape anthocyanin (site A=73.22 mg/100 g and site B=118.93 mg/100 g) compared to control, but total anthocyanins were lower than grapes from bloom leaf removal (first time period). Results differed slightly by vineyard site and rootstock/scion combination.
21814270
Electrical and thermal coupling to a single-wall carbon nanotube device using an electrothermal nanoprobe.
We utilize a multifunctional atomic force microscope (AFM) cantilever applying highly localized temperature and electric fields to interrogate transport in single-wall carbon nanotube field-effect transistors (CNTFETs). The probe can be operated either in contact with the CNT, in intermittent contact, or as a Kelvin probe, and can independently control the electric field, mechanical force, and temperature applied to the CNT. We modulate current flow in the CNT with tip-applied electric field, and find this field-effect depends upon both cantilever heating and CNT self-heating. CNT transport is also investigated with AFM tip temperature up to 1170 degrees C. Tip-CNT thermal resistance is estimated at 1.6 x 10(7) K/W and decreases with increasing temperature. Threshold force (<100 nN) for reliable contact mode imaging is extracted and used to determine set points for nanotube manipulation, such as displacement or cutting. The ability to measure thermal coupling to a single-molecule electronic device could offer new insights into nanoelectronic devices.
35716654
Elastomeric microwire-based optical gas flowmeter with stretching-enabled tunability in measurement range.
We report the utilization of transparent poly(dimethylsiloxane) (PDMS) microwires as the transducer for optical gas flowmetry. The elasticity of the PDMS microwire was exploited not only to miniaturize and simplify the flowmeter but also to widen and tune the measurement range through mechanical stretching. Using a 9 mm long microwire, we achieved 2.8~9.8 dB/SLM sensitivity. A 500 μm stretching of the microwire also shifted the measurement range from 1 to 4 SLM. The experimental results agreed well with predictions based on the fluid dynamic/optical model.
13464037
Evaluation of nano-technology-modified zirconia oral implants: a study in rabbits.
OBJECTIVE
The objective of this study was to screen candidate nano-technology-modified, micro-structured zirconia implant surfaces relative to local bone formation and osseointegration.


MATERIALS AND METHODS
Proprietary nano-technology surface-modified (calcium phosphate: CaP) micro-structured zirconia implants (A and C), control micro-structured zirconia implants (ZiUnite), and titanium porous oxide implants (TiUnite) were implanted into the femoral condyle in 40 adult male New Zealand White rabbits. Each animal received one implant in each hind leg; thus, 20 animals received A and C implants and 20 animals received ZiUnite and TiUnite implants in contralateral hind legs. Ten animals/group were euthanized at weeks 3 and 6 when biopsies of the implant sites were processed for histometric analysis using digital photomicrographs produced using backscatter scanning electron microscopy.


RESULTS
The TiUnite surface demonstrated significantly greater bone-implant contact (BIC) (77.6+/-2.6%) compared with the A (64.6+/-3.6%) and C (62.2+/-3.1%) surfaces at 3 weeks (p<0.05). Numerical differences between ZiUnite (70.5+/-3.1%) and A and C surfaces did not reach statistical significance (p>0.05). Similarly, there were non-significant differences between the TiUnite and the ZiUnite surfaces (p>0.05). At 6 weeks, there were no significant differences in BIC between the TiUnite (67.1+/-4.2%), ZiUnite (69.7+/-5.7%), A (68.6+/-1.9%), and C (64.5+/-4.1%) surfaces (p>0.05).


CONCLUSION
TiUnite and ZiUnite implant surfaces exhibit high levels of osseointegration that, in this model, confirm their advanced osteoconductive properties. Addition of CaP nano-technology to the ZiUnite surface does not enhance the already advanced osteoconductivity displayed by the TiUnite and ZiUnite implant surfaces.