106 research outputs found
Monolithic Metamaterial-Integrated Graphene Terahertz Photodetector with Wavelength and Polarization Selectivity
The
frequency spectra and polarization states of terahertz waves
can convey significant information about physical interactions and
material properties. Compact and miniaturized on-chip platforms for
effective capturing of these quantities are being extensively investigated
because of their promising potential for paramount applications of
terahertz technology such as in situ sensing and characterization.
Here, we present a metamaterial–graphene hybrid device that
integrates the functions of photodetection, wavelength, and polarization
selectivity into a monolithic architecture. Leveraging the ultrahigh
design freedom of metamaterial optical properties and the electronically
controllable hot-carrier-assisted photothermoelectric effect in graphene,
our detector shows resonantly enhanced photoresponse at two specific
target wavelengths with orthogonal polarizations. We demonstrate its
versatile capabilities for spectrally selective and polarization resolved
imaging on a single-chip platform that is free from advanced optical
components. Our strategy is beneficial to the future development of
multifunctional, compact, and low-cost terahertz sensors
Extraperitoneal versus transperitoneal cesarean section: a retrospective study
To evaluate extraperitoneal cesarean section as a routine elective surgery. In this retrospective study, 461 primiparas were divided into the extraperitoneal and transperitoneal cesarean section groups according to the operation type in a random, but non-blinded, manner. The outcome measures were intraoperative blood loss, operation duration, postoperative gas passage time, postoperative pain, postoperative complications, and neonatal indicators The operation duration of the extraperitoneal cesarean section group was significantly lower than that of the transperitoneal cesarean section group (PÂ While extraperitoneal cesarean section can be safely performed as a routine procedure in the surgical delivery of primiparas, it must be performed by well-trained surgeons. In view of its advantages, it is worth being promoted in senior general hospitals as a routine choice. Abbreviations: CS: Cesarean section; ECS: Extraperitoneal; TCS: Transperitoneal; VAS: Visual analogue scale.</p
Templateless Infrared Heating Process for Fabricating Carbon Nitride Nanorods with Efficient Photocatalytic H<sub>2</sub> Evolution
The
bottom-up fabrication of carbon nitride nanorods is realized through
the direct infrared heating of dicyandiamide. The approach requires
no templates or extra organics. The controlled infrared heating has
a major influence on the morphology of the obtained carbon nitrides.
The precursors assemble into carbon nitride nanorods at low power
levels, and they grow into nanoplates at high power levels. The formation
mechanism of the carbon nitride nanorods is proposed to be a kinetically
driven process, and the photocatalytic activity of the carbon nitride
nanorods prepared at 50% power for hydrogen evolution is about 2.9
times that of carbon nitride nanoplates at 100% power. Structural,
optical, and electronic analysis demonstrates that the enhancement
is primarily attributed to the elimination of structural defects and
the improved charge-carrier separation in highly condensed and oriented
carbon nitride nanorods
sj-docx-1-heb-10.1177_10901981231158412 – Supplemental material for Persuasive Narratives About Osteoporosis: Effects of Protagonist Competence, Narrator Point of View, and Subjective Risk
Supplemental material, sj-docx-1-heb-10.1177_10901981231158412 for Persuasive Narratives About Osteoporosis: Effects of Protagonist Competence, Narrator Point of View, and Subjective Risk by Meng Chen, Laramie D. Taylor and Robert A. Bell in Health Education & Behavior</p
Pd(II)-Mediated Triad Multilayers with Zinc Tetrapyridylporphyrin and Pyridine-Functionalized Nano-TiO<sub>2</sub> as Linkers: Assembly, Characterization, and Photocatalytic Properties
Triad hybrid multilayers containing the light sensitizers
of zinc tetrapyridylporphyrin (ZnTPyP) and pyridine-functionalized
TiO<sub>2</sub> (TiO<sub>2</sub>-Py) nanoparticles were constructed
on substrate surfaces with the use of PdÂ(II) ions as the connectors
using the layer-by-layer (LBL) method. The assembly process was monitored
using ultraviolet–visible (UV–vis) absorption and X-ray
photoelectron spectra as well as scanning electron microscopy and
atomic force microscopy. The content of the pyridine substituents
in the TiO<sub>2</sub>-Py nanocomposites was about 2% (w/w). The Soret
absorption band of ZnTPyP was 24 nm red-shifted in the hybrid multilayers
due to a strong intermolecular electronic coupling interaction among
porphyrin macrocycles or porphyrin macrocycle/TiO<sub>2</sub>-Py nanoparticles.
The average surface density of each ZnTPyP layer was about 1.4 ×
10<sup>–10</sup> mol/cm<sup>2</sup>. Aggregation of the small
TiO<sub>2</sub>-Py nanoparticles to larger domains with sizes up to
hundreds of nanometers occurred in the hybrid multilayers; however,
such an aggregation behavior was weaker than that in the solutions.
The quartz substrate modified with the as-prepared Pd/ZnTPyP/Pd/TiO<sub>2</sub>-Py triad hybrid multilayers was used as a heterogeneous photocatalyst
for the degradation of methyl orange (MO) under irradiation (λ
> 420 nm) at room temperature with a catalytic efficiency of about
1.3 × 10<sup>–3</sup> MO/ZnTPyP·s. Without the use
of the filter, the catalytic efficiency increased because both ZnTPyP
and TiO<sub>2</sub>-Py nanocomposites acted as the light sensitizers.
It is suggested that the present heterogeneous catalyst has the advantages
of facile separation, high stability, structural controllability on
the molecular and nanoscale level, and good recyclability
A Simple and Fast Extraction Method for the Determination of Multiclass Antibiotics in Eggs Using LC-MS/MS
The
purpose of this study was to develop and validate a simple, fast,
and specific extraction method for the analysis of 64 antibiotics
from nine classes (including sulfonamides, quinolones, tetracyclines,
macrolides, lincosamide, nitrofurans, β-lactams, nitromidazoles,
and cloramphenicols) in chicken eggs. Briefly, egg samples were simply
extracted with a mixture of acetonitrile–water (90:10, v/v)
and 0.1 mol·L<sup>–1</sup> Na<sub>2</sub>EDTA solution
assisted with ultrasonic. The extract was centrifuged, condensed,
and directly analyzed on a liquid chromatography coupled to tandem
mass spectrometry. Compared with conventional cleanup methods (passing
through solid phase extract cartridges), the established method demonstrated
comparable efficiencies in eliminating matrix effects and higher or
equivalent recoveries for most of the target compounds. Typical validation
parameters including specificity, linearity, matrix effect, limits
of detection (LODs) and quantification (LOQs), the decision limit,
detection capability, trueness, and precision were evaluated. The
recoveries of target compounds ranged from 70.8% to 116.1% at three
spiking levels (5, 20, and 50 μg·kg<sup>–1</sup>), with relative standard deviations less than 14%. LODs and LOQs
were in the ranges of 0.005–2.00 μg·kg<sup>–1</sup> and 0.015–6.00 μg·kg<sup>–1</sup> for all
of the antibiotics, respectively. A total of five antibiotics were
successfully detected in 22 commercial eggs from local markets. This
work suggests that the method is suitable for the analysis of multiclass
antibiotics in eggs
Forest plot showing adverse effects of antidepressants versus placebo.
<p>Antidepressants significantly increase adverse events compared with placebo.</p
Noise Attenuation in the ON and OFF States of Biological Switches
Biological switches
must sense changes in signal concentration
and at the same time buffer against signal noise. While many studies
have focused on the response of switching systems to noise in the
ON state, how systems buffer noise at both ON and OFF states is poorly
understood. Through analytical and computational approaches, we find
that switching systems require different dynamics at the OFF state
than at the ON state in order to have good noise buffering capability.
Specifically, we introduce a quantity called the input-associated
Signed Activation Time (iSAT) that concisely captures an intrinsic
temporal property at either the ON or OFF state. We discover a trade-off
between achieving good noise buffering in the ON versus the OFF states:
a large iSAT corresponds to noise amplification in the OFF state in
contrast to noise buffering in the ON state. To search for biological
circuits that can buffer noise in both ON and OFF states, we systematically
analyze all three-node circuits and identify mutual activation as
a central motif. We also study connections among signal sensitivity,
iSAT, and noise amplification. We find that a large iSAT at the ON
state maintains signaling sensitivity while minimizing noise propagation.
Taken together, the analysis of iSATs helps reveal the noise properties
of biological networks and should aid in the design of robust switches
that can both repress noise at the OFF state and maintain a reliable
ON state
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