The
unique optical properties of surface plasmon resonances in
nanostructured materials have attracted considerable attention, broadly
impacting both fundamental research and applied technologies ranging
from sensing and optoelectronics to quantum computing. Electron energy-loss
spectroscopy (EELS) in the transmission electron microscope has revealed
valuable information about the full plasmonic spectrum of these materials
with nanoscale spatial resolution. Here we report a novel approach
for experimentally accessing the photon-stimulated electron energy-gain
and stimulated electron energy-loss responses of individual plasmonic
nanoparticles via the simultaneous irradiation of a continuous wave
laser and continuous current, monochromated electron probe. Stimulated
gain and loss probabilities are equivalent and increase linearly in
the low-irradiance range of 0.5 × 108 to 4 ×
108 W/m2, above which excessive heating reduces
the observed probabilities; importantly in our low-irradiance regime,
the photon energy must be tuned in resonance with the plasmon energy
for the stimulated gain and loss peaks to emerge. Theoretical modeling
based on Fermi’s golden rule elucidates how the plasmon resonantly
and coherently shuttles energy quanta between the electron probe and
the radiation field and vice versa in stimulated electron energy-loss
and -gain events. This study opens a fundamentally new approach to
explore the quantum physics of excited-state plasmon resonances that
does not rely on high-intensity laser pulses or any modification to
the EELS detector.
The ability to control and manipulate temperature at nanoscale dimensions has the potential to impact applications including heat-assisted magnetic recording, photothermal therapies, and temperature-driven reactivity. One challenge with controlling temperature at nanometer dimensions is the need to mitigate heat diffusion, such that the temperature only changes in well-defined nanoscopic regions of the sample. Here we demonstrate the ability to use far-field laser excitation to actively shape the thermal near-field in individual gold nanorod heterodimers by resonantly pumping either the in-phase or out-of-phase hybridized dipole plasmon modes. Using single-particle photothermal heterodyne imaging, we demonstrate localization bias in the photothermal intensity due to preferential heating of one of the nanorods within the pair. Theoretical modeling and numerical simulation make explicit how the resulting photothermal images encode wavelength-dependent temperature biases between each nanorod within a heterodimer, demonstrating the ability to actively manage the thermal near-field by simply tuning the color of incident light.
DNA from 100 unrelated patients, 97 of whom were Jewish and three half- Jewish, was analyzed for 22 mutations known to cause Gaucher disease. All but seven of the alleles were identified as having previously described mutations. Five of the unidentified mutations proved to be a previously undescribed nucleotide substitution in a splice junction (IVS2+1) that causes skipping of exon 2. Thus, only 2 of 197 alleles remained unidentified. Homozygotes for the most common mutation, that a nucleotide (nt) 1226, manifested, on average, the mildest disease and the latest age of onset. The mutation at nt 84 and the newly described IVS2+1 mutation, which do not produce any enzyme, were associated with earlier onset and more severe disease. Five of the mutations were considered to be “public,” in the sense that they were found in more than one unrelated individual. Screening for these five mutations permitted detection of 97.5% of all Gaucher alleles in this patient population. Because the mutation at nt 1226 is underrepresented in the patient population and because not all homozygotes come to medical attention, screening the Ashkenazi population using DNA analysis should detect approximately 99% of all heterozygotes.
Herein, we report studies leading to the discovery of the neoseptins and
a comprehensive examination of the structure–activity relationships of
this new class of small molecule mouse Toll-like receptor 4 (mTLR4) agonists.
The compound class, which emerged from screening a α-helix mimetic
library, stimulate the immune response, act by a well-defined mechanism (mouse
TLR4 agonist), are easy to produce and structurally manipulate, exhibit
exquisite structure–activity relationships, are non-toxic, and elicit
improved and qualitatively different responses than lipopolysaccharide (LPS)
even though they share the same receptor.
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