123 research outputs found
Opportunities and challenges for deep learning in cell dynamics research
With the growth of artificial intelligence (AI), there has been an increase
in the adoption of computer vision and deep learning (DL) techniques for the
evaluation of microscopy images and movies. This adoption has not only
addressed hurdles in quantitative analysis of dynamic cell biological
processes, but it has also started supporting advances in drug development,
precision medicine and genome-phenome mapping. Here we survey existing AI-based
techniques and tools, and open-source datasets, with a specific focus on the
computational tasks of segmentation, classification, and tracking of cellular
and subcellular structures and dynamics. We summarise long-standing challenges
in microscopy video analysis from the computational perspective and review
emerging research frontiers and innovative applications for deep
learning-guided automation for cell dynamics research
Enhanced Thermoelectric Properties in Bulk Nanowire Heterostructure-Based Nanocomposites through Minority Carrier Blocking
To design superior thermoelectric materials the minority carrier blocking effect in which the unwanted bipolar transport is prevented by the interfacial energy barriers in the heterogeneous nanostructures has been theoretically proposed recently. The theory predicts an enhanced power factor and a reduced bipolar thermal conductivity for materials with a relatively low doping level, which could lead to an improvement in the thermoelectric figure of merit (ZT). Here we show the first experimental demonstration of the minority carrier blocking in lead telluride–silver telluride (PbTe–Ag_2Te) nanowire heterostructure-based nanocomposites. The nanocomposites are made by sintering PbTe–Ag_2Te nanowire heterostructures produced in a highly scalable solution-phase synthesis. Compared with Ag_2Te nanowire-based nanocomposite produced in similar method, the PbTe–Ag_2Te nanocomposite containing ∼5 atomic % PbTe exhibits enhanced Seebeck coefficient, reduced thermal conductivity, and ∼40% improved ZT, which can be well explained by the theoretical modeling based on the Boltzmann transport equations when energy barriers for both electrons and holes at the heterostructure interfaces are considered in the calculations. For this p-type PbTe–Ag_2Te nanocomposite, the barriers for electrons, that is, minority carriers, are primarily responsible for the ZT enhancement. By extending this approach to other nanostructured systems, it represents a key step toward low-cost solution-processable nanomaterials without heavy doping level for high-performance thermoelectric energy harvesting
Topological insulator Bi2Te3 films synthesized by metal organic chemical vapor deposition
Topological insulator (TI) materials such as Bi2Te3 and Bi2Se3 have attracted
strong recent interests. Large scale, high quality TI thin films are important
for developing TI-based device applications. In this work, structural and
electronic properties of Bi2Te3 thin films deposited by metal organic chemical
vapor deposition (MOCVD) on GaAs (001) substrates were characterized via X-ray
diffraction (XRD), Raman spectroscopy, angle-resolved photoemission
spectroscopy (ARPES), and electronic transport measurements. The characteristic
topological surface states (SS) with a single Dirac cone have been clearly
revealed in the electronic band structure measured by ARPES, confirming the TI
nature of the MOCVD Bi2Te3 films. Resistivity and Hall effect measurements have
demonstrated relatively high bulk carrier mobility of ~350 cm^2/Vs at 300K and
~7,400 cm^2/Vs at 15 K. We have also measured the Seebeck coefficient of the
films. Our demonstration of high quality topological insulator films grown by a
simple and scalable method is of interests for both fundamental research and
practical applications of thermoelectric and TI materials.Comment: 14 pages, 4 figure
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