898 research outputs found
The Development of Polymer-coated Electrodes for Chemical Detection
This research focuses on the development of simple and cost effective approaches for making electrochemical sensors with a great sensitivity and selectivity. As an economic and abundant starting material, organic substrates were investigated to making conductive polymers that showed promising electrocatalytic activities. Firstly, a poly(4-bromoaniline) film was successfully synthesized on a gold electrode and the porous film which was made up of nano-ribbons on the Au electrode was used for the recognition of amino acids enantiomers. Secondly, different halogen ions were introduced to manifest the properties of the synthesized polymers. The results show that bromide ions have significantly inhibited the transition of leucoemeraldine to emeraldine, letting the PANI polymer to be in Pernigraniline form, which exhibited much improved performance in pH sensing. In addition, a simple way to controllably deposit copper nanoparticles inside poly-2,5-dimethoxyaniline matrix, which can be employed as a glucose sensor, was developed
SimPLE: Similar Pseudo Label Exploitation for Semi-Supervised Classification
A common classification task situation is where one has a large amount of
data available for training, but only a small portion is annotated with class
labels. The goal of semi-supervised training, in this context, is to improve
classification accuracy by leverage information not only from labeled data but
also from a large amount of unlabeled data. Recent works have developed
significant improvements by exploring the consistency constrain between
differently augmented labeled and unlabeled data. Following this path, we
propose a novel unsupervised objective that focuses on the less studied
relationship between the high confidence unlabeled data that are similar to
each other. The new proposed Pair Loss minimizes the statistical distance
between high confidence pseudo labels with similarity above a certain
threshold. Combining the Pair Loss with the techniques developed by the
MixMatch family, our proposed SimPLE algorithm shows significant performance
gains over previous algorithms on CIFAR-100 and Mini-ImageNet, and is on par
with the state-of-the-art methods on CIFAR-10 and SVHN. Furthermore, SimPLE
also outperforms the state-of-the-art methods in the transfer learning setting,
where models are initialized by the weights pre-trained on ImageNet or
DomainNet-Real. The code is available at github.com/zijian-hu/SimPLE.Comment: Accepted to CVPR 2021. First two authors contributed equall
In vitro study of surface functionalization of titanium substrates for potential enhancement of osseointegration and reduction of bacterial infection
Ph.DDOCTOR OF PHILOSOPH
Correlated flat bands in the paramagnetic phase of triangular antiferromagnets NaBaX(PO) (X = Mn, Co, Ni)
Flat band systems in condensed matter physics are intriguing because they can
exhibit exotic phases and unconventional properties. In this work, we studied
three correlated magnetic systems, NaBaX(PO) (X = Mn, Co, Ni), and
revealed their unusual electronic structure and magnetic properties. Despite
their different effective angular momentum, our first-principles calculations
showed a similar electronic structure among them. However, their different
valence configurations led to different responses to electronic correlations in
the high-temperature paramagnetic phase. Using the dynamical mean-field method,
we found that all systems can be understood as a multi-band Hubbard model with
Hund'ss coupling. Our calculations of spin susceptibility and the {\it
ab-initio} estimation of magnetic exchange coupling indicated strong
intra-plane antiferromagnetic coupling and weak inter-plane coupling in all
systems. The ground states of these systems are largely degenerate. It is
likely that none of these magnetic states would dominate over the others,
leading to the possibility of quantum spin liquid states in these systems. Our
work unifies the understanding of these three structurally similar systems and
opens new avenues for exploring correlated flat bands with distinct electronic
and magnetic responses.Comment: 11 pages and 4 figure
Construction of multi-mineral digital rocks for upscaling the numerical simulation of tight rock physical properties
Tight sandstone reservoirs are characterized by multi-scale pore space and high clay content, resulting in intricate rock physical responses. In this work, multi-scale imaging techniques, including computed tomography and stitched scanning electron microscopy, are applied to identify the large intergranular pores and micropores within major minerals. The pore structure of tight sandstones is quantitatively investigated using multi-scale images. Besides, multi-mineral digital rocks are constructed by performing registration and segmentation processing on the images obtained from microcomputed tomography and energy-dispersive scanning electron microscopy. These digital rocks are treated as composite materials consisting of different mineral types and micro-porosities, which enables the upscaling of the numerical simulation of rock physics properties. The results reveal that residual intergranular pores are interconnected through micropores within clay minerals, which significantly influences the electrical conductivities and permeabilities of tight sandstones. The proposed upscaling method can effectively couple the contribution of formation brine in multi-scale pores and clay minerals to bulk rock physics properties. This approach is suitable for the numerical simulation of diverse rock physical properties and can be applied to various tight reservoirs.Document Type: PerspectiveCited as: Hu, J., Xiao, Z., Ni, H., Liu, X. Construction of multi-mineral digital rocks for upscaling the numerical simulation of tight rock physical properties. Advances in Geo-Energy Research, 2023, 9(1): 68-70. https://doi.org/10.46690/ager.2023.07.0
Prospects of Searching for Type Ia Supernovae with 2.5-m Wide Field Survey Telescope
Type Ia Supernovae (SNe Ia) are the thermonuclear explosion of a
carbon-oxygen white dwarf (WD) and are well-known as a distance indicator.
However, it is still unclear how WDs increase their mass near the Chandrasekhar
limit and how the thermonuclear runaway happens. The observational clues
associated with these open questions, such as the photometric data within hours
to days since the explosion, are scarce. Thus, an essential way is to discover
SNe Ia at specific epochs with optimal surveys. The 2.5-m Wide Field Survey
Telescope (WFST) is an upcoming survey facility deployed in western China. In
this paper, we assess the detecability of SNe Ia with mock observations of
WFST. Followed by the volumetric rate, we generate a spectral series of SNe Ia
based on a data-based model and introduce the line-of-sight extinction to
calculate the brightness from the observer. By comparing with the detection
limit of WFST, which is affected by the observing conditions, we can count the
number of SNe Ia discovered by mock WFST observations. We expect that WFST can
find more than pre-maximum SNe Ia within one-year running. In
particular, WFST could discover about 45 bright SNe Ia, 99 early-phase SNe Ia,
or well-observed SNe Ia with the hypothesized Wide, Deep, or
Medium mode, respectively, suggesting WFST will be an influential facility in
time-domain astronomy.Comment: Accepted by Univers
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