1,978 research outputs found
High current carbon nanotube cathode for miniature high power THz source application
No full textThis RG 100/05 (SEP) is a supplement fund to support the A*STAR SERG grant 042
101 0080 entitled “High Current Carbon Nanotube (CNT) Cathode for Miniature High
Power THz sources” (Jan 2005 –Jan 2008), where the PI is Asst Professor Ang Lay Kee,
Ricky.
For coherent radiation at THz frequency using Smith-Purcell based free electron laser
(SP-FEL), a high current electron beam is required
High current carbon nanotube cathode for miniature high power THz source application
No full textThis RG 100/05 (SEP) is a supplement fund to support the A*STAR SERG grant 042
101 0080 entitled “High Current Carbon Nanotube (CNT) Cathode for Miniature High
Power THz sources” (Jan 2005 –Jan 2008), where the PI is Asst Professor Ang Lay Kee,
Ricky.
For coherent radiation at THz frequency using Smith-Purcell based free electron laser
(SP-FEL), a high current electron beam is required
A modified Schottky model for graphene-semiconductor (3D/2D) contact: A combined theoretical and experimental study
No full textIn this paper we carry out a theoretical and
experimental study of the nature of graphene/semiconductor
Schottky contact. We present a simple and parameter-free
carrier transport model of graphene/semiconductor Schottky
contact derived from quantum statistical theory, which is
validated by the quantum Landauer theory and first-principle
calculations. The proposed model can well explain
experimental results for samples of different types of
graphene/semiconductor Schottky contact.
INTRODUCTIO
A new perspective on the nature of graphene- semiconductor (3D/2D) Schottky contact: A combined theoretical and experimental approach
No full textIn this paper we carry out a theoretical and experimental study of the nature of graphene/ (3D/2D)-semiconductor Schottky contact. We use quantum statistical theory to derive a simple and parameter-free carrier transport model of graphene/ (3D/2D)-semiconductor Schottky contact, which is validated by the quantum Landauer theory and First-principle calculations. The proposed model can well explain experimental results for large samples of different types of graphene/ (3D/2D)-semiconductor Schottky contact
A Roadmap of human liver differentiation from pluripotent stem cells
No full textLiver cells stained for protein expression by immunostaining in Figure 1G, 2H, 5B and 6D
Angiotensin II induces soluble fms-Like tyrosine kinase-1 release via calcineurin signaling pathway in pregnancy
No full textMaternal endothelial dysfunction in preeclampsia is associated with increased soluble fms-like tyrosine kinase-1 (sFlt-1), a circulating antagonist of vascular endothelial growth factor and placental growth factor. Angiotensin II (Ang II) is a potent vasoconstrictor that increases concomitant with sFlt-1 during pregnancy. Therefore, we speculated that Ang II may promote the expression of sFlt-1 in pregnancy. Here we report that infusion of Ang II significantly increases circulating levels of sFlt-1 in pregnant mice, thereby demonstrating that Ang II is a regulator of sFlt-1 secretion in vivo. Furthermore, Ang II stimulated sFlt-1 production in a dose- and time-dependent manner from human villous explants and cultured trophoblasts but not from endothelial cells, suggesting that trophoblasts are the primary source of sFlt-1 during pregnancy. As expected, Ang II-induced sFlt-1 secretion resulted in the inhibition of endothelial cell migration and in vitro tube formation. In vitro and in vivo studies with losartan, small interfering RNA specific for calcineurin and FK506 demonstrated that Ang II-mediated sFlt-1 release was via Ang II type 1 receptor activation and calcineurin signaling, respectively. These findings reveal a previously unrecognized regulatory role for Ang II on sFlt-1 expression in murine and human pregnancy and suggest that elevated sFlt-1 levels in preeclampsia may be caused by a dysregulation of the local renin/angiotensin system
Optimum Energy Absorption of a Short-Pulse Laser in a Doped Dielectric Slab
No full textA model is used to calculate energy absorption efficiency when a short-pulse laser impinges on a dielectric slab doped with an impurity for which the electrons have a resonant line at the laser wavelength. The amount of the energy resonant absorption is due to the overlapping between laser spectrum and resonance spectrum. The energy absorption efficiency can be maximized for a certain degree of doping concentration (at a given pulselength) and also for a certain pulselength (at a given doping concentration). For a modest amount of impurity, the resonant absorption may increase the fraction of energy absorption up to tens of percent of laser energy at 100s optical cycles when the laser wavelength is tuned within 1% of the resonant line. Dimensionless parameters are constructed so that the scaling to various parameters: laser wavelength, laser pulselength, dielectric constant, slab thickness, impurity concentration, resonant linewidth, and separation between the laser wavelength and the line resonance, could easily be obtained
Asymmetric Schottky Contacts in Bilayer MoS2 Field Effect Transistors
No full textThe high-bias electrical characteristics of back-gated field-effect transistors
with chemical vapor deposition synthesized bilayer MoS2 channel and
Ti Schottky contacts are discussed. It is found that oxidized Ti contacts on
MoS2 form rectifying junctions with ≈0.3 to 0.5 eV Schottky barrier height.
To explain the rectifying output characteristics of the transistors, a model
is proposed based on two slightly asymmetric back-to-back Schottky barriers,
where the highest current arises from image force barrier lowering at
the electrically forced junction, while the reverse current is due to Schottkybarrier-
limited injection at the grounded junction. The device achieves a
photoresponsivity greater than 2.5 A W−1 under 5 mW cm−2 white-LED light.
By comparing two- and four-probe measurements, it is demonstrated that the
hysteresis and persistent photoconductivity exhibited by the transistor are
peculiarities of the MoS2 channel rather than effects of the Ti/MoS2 interface
Modeling of field emission from a sharp tip
No full textThe interaction of the charged particles in a vacuum gap has essentially remained an area that is worth exploring in domains of accelerator physics, sheath physics, high current diodes, microwaves sources, and vacuum microelectronics including nano-electronics. Most of the theoretical developments focused on one dimensional (1D) classical models and they have extended to simple geometries or shapes.
Recently, two dimensional (2D) models are developed and build upon, and had extended to multi-dimensional models, but they are simple of geometries instead of complex geometries.
In this Final Year Project (FYP) report presents the existing knowledge and understanding the behavior of the field emission in the transition from field emission to space charge limited (SCL) regime using a sharp tip model. In the transition region, the electron particles are emitted due to the field emission and both the trajectories of the emitted electrons are tracked using the classical Newtonian physics.Bachelor of Engineerin
Multi-dimensional theory of space-charge-limited current : quantum, short-pulse and transition
No full textThe interaction of the intense charged particles in a vacuum gap has remained an area of considerable interest to accelerator physics, sheath physics, high current diodes, high power microwave sources, vacuum micro- and nano-electronics. Previously, most of the developments of space-charge-limited (SCL) flows are focused on one-dimensional (1D) classical models and the multi-dimensional SCL flows (especially for 3D features) are relatively undeveloped. The classical Child-Langmuir law, which predicts the maximum space-charge-limiting current that can be transported across a 1D planar gap under steady-state condition, is one of the most important considerations used in various types of high current diodes, triodes and multi-stage acceleration gaps. This thesis presents recent advances in the theories of multi-dimensional SCL flows in various operating regimes such as quantum, short pulse and transition from field emission.DOCTOR OF PHILOSOPHY (EEE
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