arXiv subjects

Di Wu

Publications and source records attributed to Di Wu.

709 records · Page 40Linked to original sources

arXiv2012

In Vivo Renal Clearance, Biodistribution, Toxicity of Gold nanoclusters

Gold nanoparticles have shown great prospective in cancer diagnosis and therapy, but they can not be metabolized and prefer to accumulate in liver and spleen due to their large size. The gold nanoclusters with small size can penetrate kidney tissue and have promise to decrease in vivo toxicity by renal clearance. In this work, we explore the in vivo renal clearance, biodistribution, and toxicity responses of the BSA- and GSH-protected gold nanoclusters for 24 hours and 28 days. The BSA-protected gold nanoclusters have low-efficient renal clearance and only 1% of gold can be cleared, but the GSH-protected gold nanoclusters have high-efficient renal clearance and 36 % of gold can be cleared after 24 hours. The biodistribution further reveals that 94% of gold can be metabolized for the GSH-protected nanoclusters, but only less than 5% of gold can be metabolized for the BSA-protected nanoclusters after 28 days. Both of the GSH- and BSA-protected gold nanoclusters cause acute infection, inflammation, and kidney function damage after 24 hours, but these toxicity responses for the GSH-protected gold nanoclusters can be eliminated after 28 days. Immune system can also be affected by the two kinds of gold nanoclusters, but the immune response for the GSH-protected gold nanoclusters can also be recovered after 28 days. These findings show that the GSH-protected gold nanoclusters have small size and can be metabolized by renal clearance and thus the toxicity can be significantly decreased. The BSA- protected gold nanoclusters, however, can form large compounds and further accumulate in liver and spleen which can cause irreparable toxicity response. Therefore, the GSH-protected gold nanoclusters have great potential for in vivo imaging and therapy, and the BSA-protected gold nanoclusters can be used as the agent of liver cancer therapy.

physics.med-ph↗

arXiv2012

Magnetic ordering and structural phase transitions in strained ultrathin SrRuO$_{3}$/SrTiO$_{3}$ superlattice

Ruthenium-based perovskite systems are attractive because their Structural, electronic and magnetic properties can be systematically engineered. SrRuO$_3$/SrTiO$_3$ superlattice, with its period consisting of one unit cell each, is very sensitive to strain change. Our first-principles simulations reveal that in the high tensile strain region, it transits from a ferromagnetic (FM) metal to an antiferromagnetic (AFM) insulator with clear tilted octahedra, while in the low strain region, it is a ferromagnetic metal without octahedra tilting. Detailed analyses of three spin-down Ru-t$_{2g}$ orbitals just below the Fermi level reveal that the splitting of these orbitals underlies these dramatic phase transitions, with the rotational force constant of RuO$_6$ octahedron high up to 16 meV/Deg$^2$, 4 times larger than that of TiO$_6$. Differently from nearly all the previous studies, these transitions can be probed optically through the diagonal and off-diagonal dielectric tensor elements. For one percent change in strain, our experimental spin moment change is -0.14$\pm$0.06 $μ_B$, quantitatively consistent with our theoretical value of -0.1 $μ_B$.

cond-mat.str-el↗

arXiv2012

Colossal electroresistance in metal/ferroelectric/semiconductor tunnel diodes for resistive switching memories

We propose a tunneling heterostructure by replacing one of the metal electrodes in a metal/ferroelectric/metal ferroelectric tunnel junction with a heavily doped semiconductor. In this metal/ferroelectric/semiconductor tunnel diode, both the height and the width of the tunneling barrier can be electrically modulated due to the ferroelectric field effect, leading to a colossal tunneling electroresistance. This idea is implemented in Pt/BaTiO3/Nb:SrTiO3 heterostructures, in which an ON/OFF conductance ratio above 10$^4$ can be readily achieved at room temperature. The colossal tunneling electroresistance, reliable switching reproducibility and long data retention observed in these ferroelectric tunnel diodes suggest their great potential in non-destructive readout nonvolatile memories.

cond-mat.mtrl-sci↗

arXiv2012

Detecting Priming News Events

We study a problem of detecting priming events based on a time series index and an evolving document stream. We define a priming event as an event which triggers abnormal movements of the time series index, i.e., the Iraq war with respect to the president approval index of President Bush. Existing solutions either focus on organizing coherent keywords from a document stream into events or identifying correlated movements between keyword frequency trajectories and the time series index. In this paper, we tackle the problem in two major steps. (1) We identify the elements that form a priming event. The element identified is called influential topic which consists of a set of coherent keywords. And we extract them by looking at the correlation between keyword trajectories and the interested time series index at a global level. (2) We extract priming events by detecting and organizing the bursty influential topics at a micro level. We evaluate our algorithms on a real-world dataset and the result confirms that our method is able to discover the priming events effectively.

cs.DB↗

arXiv2008

Comparison of Binary Classification Based on Signed Distance Functions with Support Vector Machines

We investigate the performance of a simple signed distance function (SDF) based method by direct comparison with standard SVM packages, as well as K-nearest neighbor and RBFN methods. We present experimental results comparing the SDF approach with other classifiers on both synthetic geometric problems and five benchmark clinical microarray data sets. On both geometric problems and microarray data sets, the non-optimized SDF based classifiers perform just as well or slightly better than well-developed, standard SVM methods. These results demonstrate the potential accuracy of SDF-based methods on some types of problems.

cs.LG↗

arXiv2008

Electron Tunneling in Monolayer and Bilayer Graphene

Electron's tunneling through potential barrier in monolayer and bilayer graphene lattices is investigated by using full tight-binding model. Emphasis is placed on the resonance tunneling feature and inter-valley scattering probability. It is shown that normal incidence transmission probabilities for monolayer and bilayer graphene exhibit different properties. Our calculation indicates that valleytronics in graphene systems may be detected, generated and controlled by changing the structure parameters of the external electric potential.

cond-mat.mes-hall↗

arXiv2006

Complementary Set Matrices Satisfying a Column Correlation Constraint

Motivated by the problem of reducing the peak to average power ratio (PAPR) of transmitted signals, we consider a design of complementary set matrices whose column sequences satisfy a correlation constraint. The design algorithm recursively builds a collection of $2^{t+1}$ mutually orthogonal (MO) complementary set matrices starting from a companion pair of sequences. We relate correlation properties of column sequences to that of the companion pair and illustrate how to select an appropriate companion pair to ensure that a given column correlation constraint is satisfied. For $t=0$, companion pair properties directly determine matrix column correlation properties. For $t\geq 1$, reducing correlation merits of the companion pair may lead to improved column correlation properties. However, further decrease of the maximum out-off-phase aperiodic autocorrelation of column sequences is not possible once the companion pair correlation merit is less than a threshold determined by $t$. We also reveal a design of the companion pair which leads to complementary set matrices with Golay column sequences. Exhaustive search for companion pairs satisfying a column correlation constraint is infeasible for medium and long sequences. We instead search for two shorter length sequences by minimizing a cost function in terms of their autocorrelation and crosscorrelation merits. Furthermore, an improved cost function which helps in reducing the maximum out-off-phase column correlation is derived based on the properties of the companion pair. By exploiting the well-known Welch bound, sufficient conditions for the existence of companion pairs which satisfy a set of column correlation constraints are also given.

cs.IT↗