338 research outputs found
Spontaneous electric-polarization topology in confined ferroelectric nematics
Topological spin and polar textures have fascinated people in different areas
of physics and technologies. However, the observations are limited in magnetic
and solid-state ferroelectric systems. Ferroelectric nematic is the first
liquid-state ferroelectric that would carry many possibilities of spatially
distributed polarization fields. Contrary to traditional magnetic or
crystalline systems, anisotropic liquid crystal interactions can compete with
the polarization counterparts, thereby setting a challenge in understating
their interplays and the resultant topologies. Here, we discover chiral
polarization meron-like structures during the emergence and growth of quasi-2D
ferroelectric nematic domains, which are visualized by fluorescence confocal
polarizing microscopy and second harmonic generation microscopies. Such
micrometre-scale polarization textures are the modified electric variants of
the magnetic merons. Unlike the conventional liquid crystal textures driven
solely by the elasticity, the polarization field puts additional topological
constraints, e.g., head-to-tail asymmetry, to the systems and results in a
variety of previously unidentified polar topological patterns. The chirality
can emerge spontaneously in polar textures and can be additionally biased by
introducing chiral dopants. An extended mean-field modelling for the
ferroelectric nematics reveals that the polarization strength of systems plays
a dedicated role in determining polarization topology, providing a guide for
exploring diverse polar textures in strongly-polarized liquid crystals
Collective and non-collective molecular dynamics in a ferroelectric nematic liquid crystal studied by broadband dielectric spectroscopy
A great deal of effort has been recently devoted to the study of dielectric
relaxation processes in ferroelectric nematic liquid crystals, yet their
interpretation remains unclear. In this work, we present the results of
broadband dielectric spectroscopy experiments of a prototypical ferroelectric
nematogen in the frequency range 10 Hz-110 MHz at different electrode
separations and under the application of DC bias fields. The results evidence a
complex behavior in all phases due to the magnitude of polar correlations in
these systems. The observed modes have been assigned to different relaxation
mechanisms based on existing theoretical frameworks.Comment: The following article has been submitted to The Journal of Chemical
Physics. After it is published, it will be found at
https://pubs.aip.org/aip/jc
Toward Reproducing Network Research Results Using Large Language Models
Reproducing research results in the networking community is important for
both academia and industry. The current best practice typically resorts to
three approaches: (1) looking for publicly available prototypes; (2) contacting
the authors to get a private prototype; and (3) manually implementing a
prototype following the description of the publication. However, most published
network research does not have public prototypes and private prototypes are
hard to get. As such, most reproducing efforts are spent on manual
implementation based on the publications, which is both time and labor
consuming and error-prone. In this paper, we boldly propose reproducing network
research results using the emerging large language models (LLMs). In
particular, we first prove its feasibility with a small-scale experiment, in
which four students with essential networking knowledge each reproduces a
different networking system published in prominent conferences and journals by
prompt engineering ChatGPT. We report the experiment's observations and lessons
and discuss future open research questions of this proposal. This work raises
no ethical issue
Characterization of physicochemical properties of ivy nanoparticles for cosmetic application
Background
Naturally occurring nanoparticles isolated from English ivy (Hedera helix) have previously been proposed as an alternative to metallic nanoparticles as sunscreen fillers due to their effective UV extinction property, low toxicity and potential biodegradability. Methods
This study focused on analyzing the physicochemical properties of the ivy nanoparticles, specifically, those parameters which are crucial for use as sunscreen fillers, such as pH, temperature, and UV irradiation. The visual transparency and cytotoxicity of ivy nanoparticles were also investigated comparing them with other metal oxide nanoparticles. Results
Results from this study demonstrated that, after treatment at 100°C, there was a clear increase in the UV extinction spectra of the ivy nanoparticles caused by the partial decomposition. In addition, the UVA extinction spectra of the ivy nanoparticles gradually reduced slightly with the decrease of pH values in solvents. Prolonged UV irradiation indicated that the influence of UV light on the stability of the ivy nanoparticle was limited and time-independent. Compared to TiO2 and ZnO nanoparticles, ivy nanoparticles showed better visual transparency. Methylthiazol tetrazolium assay demonstrated that ivy nanoparticles exhibited lower cytotoxicity than the other two types of nanoparticles. Results also suggested that protein played an important role in modulating the three-dimensional structure of the ivy nanoparticles. Conclusions
Based on the results from this study it can be concluded that the ivy nanoparticles are able to maintain their UV protective capability at wide range of temperature and pH values, further demonstrating their potential as an alternative to replace currently available metal oxide nanoparticles in sunscreen applications.
doi:10.1186/1477-3155-11-
Noncontact Speckle Contrast Diffuse Correlation Tomography of Blood Flow Distributions in Tissues with Arbitrary Geometries
A noncontact electron multiplying charge-coupled-device (EMCCD)-based speckle contrast diffuse correlation tomography (scDCT) technology has been recently developed in our laboratory, allowing for noninvasive three-dimensional measurement of tissue blood flow distributions. One major remaining constraint in the scDCT is the assumption of a semi-infinite tissue volume with a flat surface, which affects the image reconstruction accuracy for tissues with irregular geometries. An advanced photometric stereo technique (PST) was integrated into the scDCT system to obtain the surface geometry in real time for image reconstruction. Computer simulations demonstrated that a priori knowledge of tissue surface geometry is crucial for precisely reconstructing the anomaly with blood flow contrast. Importantly, the innovative integration design with one single-EMCCD camera for both PST and scDCT data collection obviates the need for offline alignment of sources and detectors on the tissue boundary. The in vivo imaging capability of the updated scDCT is demonstrated by imaging dynamic changes in forearm blood flow distribution during a cuff-occlusion procedure. The feasibility and safety in clinical use are evidenced by intraoperative imaging of mastectomy skin flaps and comparison with fluorescence angiography
Characterization of physicochemical properties of ivy nanoparticles for cosmetic application
Background
Naturally occurring nanoparticles isolated from English ivy (Hedera helix) have previously been proposed as an alternative to metallic nanoparticles as sunscreen fillers due to their effective UV extinction property, low toxicity and potential biodegradability. Methods
This study focused on analyzing the physicochemical properties of the ivy nanoparticles, specifically, those parameters which are crucial for use as sunscreen fillers, such as pH, temperature, and UV irradiation. The visual transparency and cytotoxicity of ivy nanoparticles were also investigated comparing them with other metal oxide nanoparticles. Results
Results from this study demonstrated that, after treatment at 100°C, there was a clear increase in the UV extinction spectra of the ivy nanoparticles caused by the partial decomposition. In addition, the UVA extinction spectra of the ivy nanoparticles gradually reduced slightly with the decrease of pH values in solvents. Prolonged UV irradiation indicated that the influence of UV light on the stability of the ivy nanoparticle was limited and time-independent. Compared to TiO2 and ZnO nanoparticles, ivy nanoparticles showed better visual transparency. Methylthiazol tetrazolium assay demonstrated that ivy nanoparticles exhibited lower cytotoxicity than the other two types of nanoparticles. Results also suggested that protein played an important role in modulating the three-dimensional structure of the ivy nanoparticles. Conclusions
Based on the results from this study it can be concluded that the ivy nanoparticles are able to maintain their UV protective capability at wide range of temperature and pH values, further demonstrating their potential as an alternative to replace currently available metal oxide nanoparticles in sunscreen applications
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