19 research outputs found
Two stage superconducting quantum interference device amplifier in a high-Q gravitational wave transducer
We report on the total noise from an inductive motion transducer for a
gravitational-wave antenna. The transducer uses a two-stage SQUID amplifier and
has a noise temperature of 1.1 mK, of which 0.70 mK is due to back-action noise
from the SQUID chip. The total noise includes thermal noise from the transducer
mass, which has a measured Q of 2.60 X 10^6. The noise temperature exceeds the
expected value of 3.5 \mu K by a factor of 200, primarily due to voltage noise
at the input of the SQUID. Noise from flux trapped on the chip is found to be
the most likely cause.Comment: Accepted by Applied Physics Letters tentatively scheduled for March
13, 200
Iron Oxide@PEDOT-Based Recyclable Photothermal Nanoparticles with Poly(vinylpyrrolidone) Sulfobetaines for Rapid and Effective Antibacterial Activity
Growing microbial resistance that
renders antibiotic treatment
vulnerable has emerged, attracting a great deal of interest in the
need to develop alternative antimicrobial treatments. To contribute
to this effort, we report magnetic iron oxide (Fe<sub>3</sub>O<sub>4</sub>) nanoparticles (NPs) coated with catechol-conjugated poly(vinylpyrrolidone)
sulfobetaines (C-PVPS). This negatively charged Fe<sub>3</sub>O<sub>4</sub>@C-PVPS is subsequently encapsulated by poly(3,4-ethylenedioxythiophene)
(PEDOT) following a layer-by-layer (LBL) self-assembly method. The
obtained Fe<sub>3</sub>O<sub>4</sub>@C-PVPS:PEDOT nanoparticles appear
to be novel NIR-irradiated photothermal agents that can achieve effective
bacterial killing and are reusable after isolation of the used particles
using external magnetic fields. The recyclable Fe<sub>3</sub>O<sub>4</sub>@C-PVPS:PEDOT NPs exhibit a high efficiency in converting
photothermal heat for rapid antibacterial effects against <i>Staphylococcus aureus</i> and <i>Escherichia coli</i>. In this study, antibacterial tests for repeated uses maintained
almost 100% antibacterial efficiency during three cycles and provided
rapid and effective killing of 99% Gram-positive and -negative bacteria
within 5 min of near-infrared (NIR) light exposure. The core–shell
nanoparticles (Fe<sub>3</sub>O<sub>4</sub>@C-PVPS:PEDOT) exhibit the
required stability, and their paramagnetic nature means that they
rapidly convert photothermal heat sufficient for use as NIR-irradiated
antibacterial photothermal sterilizing agents
Pharmacological Properties of a Traditional Korean Formula Bojungchiseup-tang on 3T3-L1 Preadipocytes and High-Fat Diet-Induced Obesity Mouse Model
The global obesity epidemic has nearly doubled since 1980, and this increasing prevalence is threatening public health. It has been reported that natural products could contain potential functional ingredients that may assist in preventing obesity. Bojungchiseub-tang (BJT), mentioned in the Donguibogam as an herbal medication for the treatment of edema, a symptom of obesity, consists of eleven medicinal herbs. However, the pharmacological activity of BJT has not been investigated. The present study was designed to investigate the putative effect of BJT on the adipogenesis of 3T3-L1 cells and the weight gain of high-fat diet (HFD-) fed C57BL/6 mice. Oil Red O staining was conducted to examine the amount of lipids in 3T3-L1 adipocytes. Male C57BL/6 mice were divided into three groups: standard diet group (control, CON), 45% HFD group (HFD), and HFD supplemented with 10% of BJT (BJT). The expression levels of genes and proteins related to adipogenesis in cells, WAT, and liver were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot, respectively. We found that BJT treatment significantly decreased the protein and mRNA levels of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein α (C/EBPα), and sterol regulatory element-binding protein 1 (SREBP1) in a dose-dependent manner in differentiated 3T3-L1 cells. Similar to the results of the in vitro experiment, BJT suppressed HFD-induced weight gain in an obese mouse model. In addition, BJT effectively reduced the HFD-induced epididymal adipose tissue weight/body weight index. BJT also downregulated the mRNA levels of PPARγ, C/EBPα, and SREBP1 in the epididymal adipose and liver tissue of HFD-fed obese mice. These findings suggest that BJT induces weight loss by affecting adipogenic transcription factors
Light Controllable Surface Coating for Effective Photothermal Killing of Bacteria
Although the electronic properties
of conducting films have been widely explored in optoelectronic fields,
the optical absorption abilities of surface-coated films for photothermal
conversion have been relatively less explored in the production of
antibacterial coatings. Here, we present catechol-conjugated poly(vinylpyrrolidone)
sulfobetaine (PVPS) and polyaniline (PANI) tightly linked by ionic
interaction (PVPS:PANI) as a novel photothermal antibacterial agent
for surface coating, which can absorb broadband near-infrared (NIR)
light. Taking advantage of the NIR light absorption, this coating
film can release eminent photothermal heat for the rapid killing of
surface bacteria. The NIR light triggers a sharp rise in photothermal
heat, providing the rapid and effective killing of 99.9% of the Gram-positive
and -negative bacteria tested within 3 min of NIR light exposure when
used at the concentration of 1 mg/mL. Although considerable progress
has been made in the design of antibacterial coatings, the user control
of NIR-irradiated rapid photothermal destruction of surface bacteria
holds increasing attention beyond the traditional boundaries of typical
antibacterial surfaces
Highly Efficient Visible Blue-Emitting Black Phosphorus Quantum Dot: Mussel-Inspired Surface Functionalization for Bioapplications
The preparation of
blue-emitting black phosphorus quantum dots
(BPQDs) is based on the liquid-phase exfoliation of bulk BP. We report
the synthesis of soluble BPQDs showing a strong visible blue-light
emission. Highly fluorescent (photoluminescence quantum yield of ≈5%
with the maximum emission (λ<sub>max</sub>) at ≈437 nm)
and dispersible BPQDs in various organic solvents are first prepared
by simple ultrasonication of BP crystals in chloroform in the ambient
atmosphere. Furthermore, simple mussel-inspired surface functionalization
of BPQDs with catechol-grafted poly(ethylene glycol) in basic buffer
afforded water-soluble blue-emitting BPQDs showing long-term fluorescence
stability, very low cytotoxicity, and excellent fluorescence live
cell imaging capability