297 research outputs found
Boron Nitride Nanosheets Improve Sensitivity and Reusability of Surface Enhanced Raman Spectroscopy
Surface enhanced Raman spectroscopy (SERS) is a useful multidisciplinary
analytic technique. However, it is still a challenge to produce SERS substrates
that are highly sensitive, reproducible, stable, reusable, and scalable. Here,
we demonstrate that atomically thin boron nitride (BN) nanosheets have many
unique and desirable properties to help solve this challenge. The synergic
effect of the atomic thickness, high flexibility, stronger surface adsorption
capability, electrical insulation, impermeability, high thermal and chemical
stability of BN nanosheets can increase the Raman sensitivity by up to two
orders, and in the meantime attain long-term stability and extraordinary
reusability not achievable by other materials. These advances will greatly
facilitate the wider use of SERS in many fields
ISAC-Enabled Beam Alignment for Terahertz Networks: Scheme Design and Coverage Analysis
As a key pillar technology for the future 6G networks, terahertz (THz)
communication can provide high-capacity transmissions, but suffers from severe
propagation loss and line-of-sight (LoS) blockage that limits the network
coverage. Narrow beams are required to compensate for the loss, but they in
turn bring in beam misalignment challenge that degrades the THz network
performance. The high sensing accuracy of THz signals enables integrated
sensing and communication (ISAC) technology to assist the LoS blockage and user
mobility-induced beam misalignment, enhancing THz network coverage. In line
with the 5G beam management, we propose a joint synchronization signal block
(SSB) and reference signal (RS)-based sensing (JSRS) scheme to predict the need
for beam switches, and thus prevent beam misalignment. We further design an
optimal sensing signal pattern that minimizes beam misalignment with fixed
sensing resources, which reveals design insights into the time-to-frequency
allocation. We derive expressions for the coverage probability and spatial
throughput, which provide instructions on the ISAC-THz network deployment and
further enable evaluations for the sensing benefit in THz networks. Numerical
results show that the JSRS scheme is effective and highly compatible with the
5G air interface. Averaged in tested urban use cases, JSRS achieves near-ideal
performance and reduces around 80% of beam misalignment, and enhances the
coverage probability by about 75%, compared to the network with 5G-required
positioning ability
Effects of sitagliptin on blood glucose, lipids, pancreatic β cell secretory function and insulin resistance in patients with type 2 diabetes mellitus
Purpose: To study the influence of sitagliptin on blood glucose, lipid and pancreatic β cell function in type II diabetes mellitus (T2DM) patients.Methods: Two groups of T2DM patients (100/group) received either metformin only (control group), or metformin plus sitaglipin (study group) for 3 months. Blood lipid profiles, fasting blood glucose (FBG), indices of pancreatic function and insulin resistance were assayed using standard biochemical methods.Results: The metformin-sitaglipin combination resulted in significant decreases in FBG, 2-h PBG, HbAlc total cholesterol (TC), triacylglycerol, and low-density lipoprotein cholesterol (LDL-C), when compared with the metformin-only treatment (p < 0.05). Although there were significant decreases in pancreatic secretion of insulin, fasting insulin, and 2 h postprandial insulin in the two groups, these parameters were significantly lower in the metformin-only treated patients than in those with combination treatment (p < 0.05).Conclusion: Sitagliptin normalizes fasting blood glucose, lipid profiles and insulin secretion in type II diabetes mellitus (T2DM) patients.Keywords: Type 2 diabetes mellitus, Sitagliptin, Blood glucose, Pancreatic islet function, Insuli
Epithelial cell adhesion molecule aptamer functionalized PLGA-lecithin-curcumin-PEG nanoparticles for targeted drug delivery to human colorectal adenocarcinoma cells
To improve the efficacy of drug delivery, active targeted nanotechnology-based drug delivery systems are gaining considerable attention as they have the potential to reduce side effects, minimize toxicity, and improve efficacy of anticancer treatment. In this work CUR-NPs (curcumin-loaded lipid-polymer-lecithin hybrid nanoparticles) were synthesized and functionalized with ribonucleic acid (RNA) Aptamers (Apts) against epithelial cell adhesion molecule (EpCAM) for targeted delivery to colorectal adenocarcinoma cells. These CUR-encapsulated bioconjugates (Apt-CUR-NPs) were characterized for particle size, zeta potential, drug encapsulation, stability, and release. The in vitro specific cell binding, cellular uptake, and cytotoxicity of Apt-CUR-NPs were also studied. The Apt-CUR-NP bioconjugates exhibited increased binding to HT29 colon cancer cells and enhancement in cellular uptake when compared to CUR-NPs functionalized with a control Apt (P<0.01). Furthermore, a substantial improvement in cytotoxicity was achieved toward HT29 cells with Apt-CUR-NP bioconjugates. The encapsulation of CUR in Apt-CUR-NPs resulted in the increased bioavailability of delivered CUR over a period of 24 hours compared to that of free CUR in vivo. These results show that the EpCAM Apt-functionalized CUR-NPs enhance the targeting and drug delivery of CUR to colorectal cancer cells. Further development of CUR-encapsulated, nanosized carriers will lead to improved targeted delivery of novel chemotherapeutic agents to colorectal cancer cells
Stimulated Raman phase shift spectroscopy: a pathway to hyperfine fingerprint spectra
The principle and experimental realization of a novel Raman spectroscopic
technique entitled stimulated Raman phase shift (SRPS) spectroscopy was
demonstrated. This technique depends on the measurement of the stimulated Raman
scattering (SRS) induced phase shift of Stokes light field ( )
that is related to the real part of the third order nonlinear susceptibility of
SRS. In principle, the spectral lineshape of 1/| | is a delta
function waveform, which is insensitive to the fluctuation of Stokes light
intensity, the decoherence of phonon in materials, as well as the inhomogeneous
fluorescence background. In order to measure 1/| |, a SRPS
including a Mach-Zender interferometer and a signal processing device was
developed. Using the developed spectrometer, the SRPS and stimulated Raman gain
(SRG) spectra of neat dimethyl sulfoxide were detected simultaneously. Seven
Raman peaks corresponding to specific molecule vibrational and rotational modes
were observed in the SRPS spectra, while only two peaks could be identified in
the SRG spectra without a priori knowledge. The linewidth of the Raman peak
centered at 2913.283 cm indicating the v(CH)stretching mode of
the methyl groups was less than 0.00036 cm in the measured SRPS spectra,
which was almost four orders of magnitude narrower than that in the measured
SRG spectra. Meanwhile, the detection signal-to-noise ratio of the Raman peak
centered at 2913.283 cm was 25.3 dB, representing an increase of 14.3 dB
compared to the SRG spectra. The reliability of SRPS technique was verified by
10 independent measurements, and the standard deviation of the Raman peak
frequency was less than 0.338 cm . The SRPS technique paves the way
for characterizing the hyperfine fingerprint of materials
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