156 research outputs found
Tumor-Infiltrating γδ T Cells Suppress T and Dendritic Cell Function via Mechanisms Controlled by a Unique Toll-like Receptor Signaling Pathway
Summaryγδ T cells are important contributors to innate immunity against cancer, but their regulatory role in controlling immune responses remains largely unknown. Here we report that a dominant γδ1 T cell population among lymphocytes infiltrating breast tumors possessed a potent ability to suppress naive and effector T cell responses and to block the maturation and function of dendritic cells. Adoptive cotransfer experiments demonstrated their in vivo suppressive activity. However, their immunosuppressive activity could be reversed by human Toll-like receptor (TLR) 8 ligands both in vitro and in vivo. siRNA-mediated knockdown experiments revealed that MyD88, TRAF6, IKKι IKKβ, and p38ι molecules in γδ1 cells were required for these cells to respond to TLR8 ligands, whereas TAK1, JNK, and ERK molecules did not appear to be involved in functional regulation. These results provide new insights into the regulatory mechanisms of tumor-specific γδ T cells and identify a unique TLR8 signaling pathway linking to their functional regulation
A modulated model predictive control scheme for the brushless doubly-fed induction machine
This paper proposes a modulated model predictive control (MMPC) algorithm for a brushless double-fed induction machine. The Brushless Doubly-Fed Induction Machine has some important advantages over alternative solutions for brushless machine applications. The proposed modulation technique achieves a fixed switching frequency, which gives good system performance. The paper examines the design and implementation of the modulation technique and simulation results verify the operation of the proposed modulation technique
Arrayed van der Waals Vertical Heterostructures based on 2D GaSe Grown by Molecular Beam Epitaxy
Vertically stacking two dimensional (2D) materials can enable the design of
novel electronic and optoelectronic devices and realize complex functionality.
However, the fabrication of such artificial heterostructures in wafer scale
with an atomically-sharp interface poses an unprecedented challenge. Here, we
demonstrate a convenient and controllable approach for the production of
wafer-scale 2D GaSe thin films by molecular beam epitaxy. In-situ reflection
high-energy electron diffraction oscillations and Raman spectroscopy reveal a
layer-by-layer van der Waals epitaxial growth mode. Highly-efficient
photodetector arrays were fabricated based on few-layer GaSe on Si. These
photodiodes show steady rectifying characteristics and a relatively high
external quantum efficiency of 23.6%. The resultant photoresponse is super-fast
and robust with a response time of 60 us. Importantly, the device shows no sign
of degradation after 1 million cycles of operation. Our study establishes a new
approach to produce controllable, robust and large-area 2D heterostructures and
presents a crucial step for further practical applications
Magnetotransport properties of Cd3As2 nanostructures
Three-dimensional (3D) topological Dirac semimetal is a new kind of material
that has a linear energy dispersion in 3D momentum space and can be viewed as
an analog of graphene. Extensive efforts have been devoted to the understanding
of bulk materials, but yet it remains a challenge to explore the intriguing
physics in low-dimensional Dirac semimetals. Here, we report on the synthesis
of Cd3As2 nanowires and nanobelts and a systematic investigation of their
magnetotransport properties. Temperature-dependent ambipolar behavior is
evidently demonstrated, suggesting the presence of finite-size of bandgap in
nanowires. Cd3As2 nanobelts, however, exhibit metallic characteristics with a
high carrier mobility exceeding 32,000 cm2V-1s-1 and pronounced anomalous
double-period Shubnikov-de Haas (SdH) oscillations. Unlike the bulk
counterpart, the Cd3As2 nanobelts reveal the possibility of unusual change of
the Fermi sphere owing to the suppression of the dimensionality. More
importantly, their SdH oscillations can be effectively tuned by the gate
voltage. The successful synthesis of Cd3As2 nanostructures and their rich
physics open up exciting nanoelectronic applications of 3D Dirac semimetals.Comment: 18 pages, 5 figure
The band-gap structures and recovery rules of generalized n-component Fibonacci piezoelectric superlattices
The spectral evolution from periodic structure to random structure has always
been an interesting topic in solid state physics, the generalized n-component
Fibonacci sequences (n- CF) provide a convenient tool to investigate such
process since its randomness can be controlled via the parameter n. In this
letter, the band-gap structures of n-CF piezoelectric superlattices have been
calculated using the transfer-matrix-method, the self-similarity behavior and
recovery rule have been systematically analyzed. Consistent with the rigorous
mathematical proof by Hu et al.[A. Hu et al. Phys. Rev. B. 48, 829 (1993)], we
find that the n-CF sequences with 2 \leq n \leq 4 are identified as
quasiperiodic. The imaginary wave numbers are characterized by the self-similar
spectrum, their major peaks can all be properly indexed. In addition, we find
that the n = 5 sequence belongs to a critical case which lies at the border
between quasiperiodic to aperiodic structures. The frequency range of
self-similarity pattern approaches to zero and a unique indexing of imaginary
wave numbers becomes impossible. Our study offers the information on the
critical 5-CF superlattice which was not available before. The classification
of band-gap structures and the scaling laws around fixed points are also given
Wafer-scale arrayed p-n junctions based on few-layer epitaxial GaTe
Two-dimensional (2D) materials have attracted substantial attention in
electronic and optoelectronic applications with superior advantages of being
flexible, transparent and highly tunable. Gapless graphene exhibits
ultra-broadband and fast photoresponse while the 2D semiconducting MoS2 and
GaTe unveil high sensitivity and tunable responsivity to visible light.
However, the device yield and the repeatability call for a further improvement
of the 2D materials to render large-scale uniformity. Here we report a
layer-by-layer growth of wafer-scale GaTe with a hole mobility of 28.4 cm2/Vs
by molecular beam epitaxy. The arrayed p-n junctions were developed by growing
few-layer GaTe directly on three-inch Si wafers. The resultant diodes reveal
good rectifying characteristics, photoresponse with a maximum photoresponsivity
of 2.74 A/W and a high photovoltaic external quantum efficiency up to 62%. The
photocurrent reaches saturation fast enough to capture a time constant of 22
{\mu}s and shows no sign of device degradation after 1.37 million cycles of
operation. Most strikingly, such high performance has been achieved across the
entire wafer, making the volume production of devices accessible. Finally,
several photo-images were acquired by the GaTe/Si photodiodes with a reasonable
contrast and spatial resolution, demonstrating for the first time the potential
of integrating the 2D materials with the silicon technology for novel
optoelectronic devices
Biophysical Phenotyping and Modulation of ALDH+ Inflammatory Breast Cancer StemâLike Cells
Cancer stemâlike cells (CSCs) have been shown to initiate tumorigenesis and cancer metastasis in many cancer types. Although identification of CSCs through specific marker expression helps define the CSC compartment, it does not directly provide information on how or why this cancer cell subpopulation is more metastatic or tumorigenic. In this study, the functional and biophysical characteristics of aggressive and lethal inflammatory breast cancer (IBC) CSCs at the singleâcell level are comprehensively profiled using multiple microengineered tools. Distinct functional (cell migration, growth, adhesion, invasion and selfârenewal) and biophysical (cell deformability, adhesion strength and contractility) properties of ALDH+ SUM149 IBC CSCs are found as compared to their ALDHâ nonâCSC counterpart, providing biophysical insights into why CSCs has an enhanced propensity to metastasize. It is further shown that the cellular biophysical phenotype can predict and determine IBC cellsâ tumorigenic ability. SUM149 and SUM159 IBC cells selected and modulated through biophysical attributesâadhesion and stiffnessâshow characteristics of CSCs in vitro and enhance tumorigenicity in in vivo murine models of primary tumor growth. Overall, the multiparametric cellular biophysical phenotyping and modulation of IBC CSCs yields a new understanding of IBCâs metastatic properties and how they might develop and be targeted for therapeutic interventions.This study comprehensively profiles the biophysical characteristics of inflammatory breast cancer stemâlike cells to delineate the soâcalled âbiophysical phenotypeâ of the model of the most metastatic breast cancer subtype. Evidence indicates that the cellular biophysical phenotype can predict and determine cancer cellsâ tumorigenic ability.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147780/1/smll201802891_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147780/2/smll201802891.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147780/3/smll201802891-sup-0001-S1.pd
A Modulated Model Predictive Control Scheme for the Brushless Doubly Fed Induction Machine
Š 2013 IEEE. Brushless doubly fed induction machines (BDFIMs) feature some important advantages, such as high reliability and low maintenance cost, over alternative solutions for brushless machine applications. This paper proposes a modulated model predictive control (MPC) algorithm for BDFIMs, which achieves a fixed switching frequency and superior system performance. An improvement of power quality is shown in this paper when compared to the conventional finite-control set-MPC. This paper examines the design and implementation of the modulation technique as well as presenting the simulation and experimental results to verify the technique's operation
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