22 research outputs found
Parallel measurements of vibrational modes in a few-layer graphene nanomechanical resonator using software-defined radio dongles
Software-defined radio dongles are small and inexpensive receivers well known
to amateur radio enthusiasts. When connected to an antenna, they enable
monitoring of a wide range of the radio spectrum by conditioning the input
signal and transferring a downconverted version of it to a personal computer
for software processing. Here, we employ a composite of two such dongles,
interfaced with codes written in MATLAB and GNU Radio, as a measuring
instrument to study the flexural vibrations of a few-layer graphene
nanomechanical resonator. Instead of an antenna, we connect the dongles to the
split output of a photodetector used to detect vibrations optically. We first
perform a quantitative analysis of the dynamics of the first vibrational mode.
We then measure the response of the first two vibrational modes in parallel. To
illustrate our technique, we detect changes in the vibrational amplitude of
both modes induced by periodic strain modulation with a delay of ms
between measurements. Last, we show that our software-based instrument can be
employed to demodulate human voice encoded in the vibrations of our resonator.
For parallel measurements of several frequency channels, and provided that the
input signal is not too weak, our composite system may offer an alternative to
the use of multiple lock-in amplifiers or multiple spectrum analyzers, with the
distinct advantage of being cost-effective per frequency channel.Comment: 16 pages, 11 figure
Polydopamine-cladded montmorillonite micro-sheets as therapeutic platform repair the gut mucosal barrier of murine colitis through inhibiting oxidative stress
Montmorillonite (MMT), a layered aluminosilicate, has a mucosal nutrient effect and restores the gut barriers integrity. However, orally administrating MMT is not effective to combat the reactive oxygen species (ROS) and alleviate the acute inflammatory relapse for colitis patients. Herein, polydopamine-doped montmorillonite micro-sheets (PDA/MMT) have been developed as a therapeutic platform for colitis treatment. SEM and EDS analysis showed that dopamine monomer (DA) was easily polymerized in alkaline condition and polydopamine (PDA) was uniformly cladded on the surface of MMT micro-sheets. The depositing amount of PDA was reaching to 2.06 ± 0.08%. Moreover, in vitro fluorescence probes experiments showed that PDA/MMT presented the broad spectra of scavenging various ROS sources including •OH, •O2−, and H2O2. Meanwhile, the intracellular ROS of Rosup/H2O2 treated Caco-2 cell was also effectively scavenged by PDA/MMT, which resulted in the obvious improvement of the cell viability under oxidative stress. Moreover, most of orally administrated PDA/MMT was transited to the gut and form a protective film on the diseased colon. PDA/MMT exhibited the obvious therapeutic effect on DSS-induced ulcerative colitis mouse. Importantly, the gut mucosa of colitis mouse was well restored after PDA/MMT treatment. Moreover, the colonic inflammation was significantly alleviated and the goblet cells were obliviously recovered. The therapeutic mechanism of PDA/MMT was highly associated with inhibiting oxidative stress. Collectively, PDA/MMT micro-sheets as a therapeutic platform may provide a promising therapeutic strategy for UC treatment
Ohmic Contact of Pt/Au on Hydrogen-Terminated Single Crystal Diamond
In this study, contact properties of platinum/gold (Pt/Au) on the surface of hydrogen-terminated single crystal diamond (H-SCD) were studied with several treatment conditions. The electrodes of Pt (20 nm)/Au (100 nm) were deposited on H-SCD surface by electron beam evaporation technique. Then, the specific contact resistance (ρc) of the as-fabricated sample was measured by the circular transmission line model, which showed good ohmic properties with the value of 5.65 × 10−4 Ω·cm2. To identify the thermal stability of Pt/Au/H-SCD, the sample was annealed in hydrogen ambient from 200 to 700 °C for 20 min at each temperature. As the temperature increased, ρc demonstrated better thermal stability. In addition, the barrier height was evaluated to be −0.67 ± 0.12 eV by X-ray photoelectron spectroscopy (XPS) technique
Correction: Cerebral Glioma Grading Using Bayesian Network with Features Extracted from Multiple Modalities of Magnetic Resonance Imaging.
[This corrects the article DOI: 10.1371/journal.pone.0153369.]
Highly Ordered Hierarchical Pt and PtNi Nanowire Arrays for Enhanced Electrocatalytic Activity toward Methanol Oxidation
Highly ordered hierarchical
Pt and PtNi nanowire arrays were prepared using CdS hierarchical nanowire
arrays (HNWAs) as sacrificial templates and demonstrated high electrochemical
active surface areas. For the resulting Pt HNWAs sample, the peak
current for methanol oxidation at +0.74 V was almost 1 order of magnitude
higher than that of Pt solid nanowire arrays prepared in a similar
manner but without the use of CdS template, and the addition of a
Ni cocatalyst effectively enhanced the tolerance against CO poisoning.
The results demonstrated that highly ordered Pt and PtNi HNWAs may
be exploited as promising anode catalysts in the application of direct
methanol fuel cells