4,319 research outputs found
Spin transport and accumulation in the persistent photoconductor AlGaAs
Electrical spin transport and accumulation have been measured in highly Si
doped Al0.3Ga0.7As utilizing a lateral spin transport device. Persistent
photoconductivity allows for the tuning of the effective carrier density of the
channel material in situ via photodoping. Hanle effect measurements are
completed at various carrier densities and the measurements yield spin
lifetimes on the order of nanoseconds, an order of magnitude smaller than in
bulk GaAs. These measurements illustrate that this methodology can be used to
obtain a detailed description of how spin lifetimes depend on carrier density
in semiconductors across the metal-insulator transition
Echocardiographic Features in Canine Myxomatous Mitral Valve Disease: An Animal Model for Human Mitral Valve Prolapse
Myxomatous mitral valve disease (MMVD) is the most common heart disease in dogs and has many similarities to human mitral valve prolapse (MVP). Transthoracic echocardiography is a non-invasive method for making a diagnosis and predicting the progression of heart failure (HF) in dogs and humans with mitral regurgitation (MR). It enables clinicians to detect the mitral valve (MV) lesions, to evaluate MR severity, and to assess its impact on cardiac remodeling, myocardial function, left ventricular (LV) filling pressures, as well as pulmonary arterial pressure. Furthermore, advanced ultrasound technologies such as tissue Doppler imaging (TDI), strain and strain rate imaging, and two-dimensional (2D) speckle tracking echocardiography (STE) provide a better assessment of global and regional myocardial function. Although the severity of MR and HF in dogs with MMVD is being evaluated as similar to human cardiology, the veterinary cardiologists are more focused on the severity of cardiac remodeling and cardiac dysfunction caused by MR, because surgical restoration of defected mitral apparatus is rarely done in dogs. The chapter will review conventional echocardiographic features of MMVD in dogs to provide a better understanding of the similarities and discrepancies between canine MMVD and human MVP to veterinary and human cardiologists and researchers
High-Performance Screen-Printed Thermoelectric Films on Fabrics.
Printing techniques could offer a scalable approach to fabricate thermoelectric (TE) devices on flexible substrates for power generation used in wearable devices and personalized thermo-regulation. However, typical printing processes need a large concentration of binder additives, which often render a detrimental effect on electrical transport of the printed TE layers. Here, we report scalable screen-printing of TE layers on flexible fiber glass fabrics, by rationally optimizing the printing inks consisting of TE particles (p-type Bi0.5Sb1.5Te3 or n-type Bi2Te2.7Se0.3), binders, and organic solvents. We identified a suitable binder additive, methyl cellulose, which offers suitable viscosity for printability at a very small concentration (0.45-0.60 wt.%), thus minimizing its negative impact on electrical transport. Following printing, the binders were subsequently burnt off via sintering and hot pressing. We found that the nanoscale defects left behind after the binder burnt off became effective phonon scattering centers, leading to low lattice thermal conductivity in the printed n-type material. With the high electrical conductivity and low thermal conductivity, the screen-printed TE layers showed high room-temperature ZT values of 0.65 and 0.81 for p-type and n-type, respectively
Basaloid Squamous Cell Carcinoma in Nasal Cavity
Basaloid squamous cell carcinoma (BSCC) is often founded in the head and neck region. However, BSCC in the sinonasal tract is rare. We report here on the case of a 58-yr-old woman who presented with nasal obstruction and epistaxis. Computed tomography and examination of the nasal cavity revealed a tumor mass that originated from the right inferior turbinate with erosion of the nasal floor. The tumor that was attached to the inferior turbinate, the lateral nasal wall and the eroded right side hard palate, and so all this was resected. Histopathologic examination of the excised tumor confirmed BSCC in the nasal cavity. We report here on a nasal cavity BSCC that was treated with partial maxillectomy only
Exploiting metallophilicity for the assembly of inorganic nanocrystals and conjugated organic molecules
The accurate engineering of interfaces between inorganic nanocrystals and semiconducting organic molecules is currently viewed as key for further developments in critical fields such as photovoltaics and photocatalysis. In this work, a new and unconventional source of interface interaction based on metal–metal bonds is presented. With this aim, an AuI organometallic gelator was exploited for the formation of hydrogel-like nanocomposites containing inorganic nanoparticles and conjugated organic molecules. Noteworthy, the establishment of metallophilic interactions at the interface between the two moieties greatly enhances interparticle coupling in the composites. Thus, we believe that this new hybrid system might represent a promising alternative in several fields, such as in the fabrication of improved light-harvesting devices.Peer ReviewedPostprint (author's final draft
Electromagnetic form factors of the bound nucleon
We calculate electromagnetic form factors of the proton bound in specified
orbits for several closed shell nuclei. The quark structure of the nucleon and
the shell structure of the finite nuclei are given by the QMC model. We find
that orbital electromagnetic form factors of the bound nucleon deviate
significantly from those of the free nucleon.Comment: 12 pages including 4 ps figure
Colloidal quantum dot hybrids: an emerging class of materials for ambient lighting
The rapid growth of the global economy and urbanization have resulted in major worldwide issues such as greenhouse gas emission, air pollution and the energy crisis. Artificial ambient light is one of the greatest inventions in human history, but it is also one of the primary energy consumption constituents and a focus of the global grand energy challenge. Therefore, low cost and low energy consumption lighting technology is in high demand. In this review, we will summarise and discuss one of the emerging lighting technologies – white electroluminescence light-emitting diodes enabled by hybrid colloidal quantum dots (WQLEDs), which have attracted intense attention because of promising potential in both flat-panel backlighting and solid-state lighting. WQLEDs have unique high luminescence efficiency, broad colour tunability and solution processability. Over the past few decades, the development of colloidal quantum dot synthesis, material engineering and device architecture has highlighted the tremendous improvements in WQLED formation. As WQLED efficiencies approach those of molecular organic LEDs, we identify the critical scientific and technological challenges and provide an outlook for ongoing strategies to overcome these challenges
Molecular environment and thermal X-ray spectroscopy of the semicircular young composite supernova remnant 3C 396
We have investigated the molecular environment of the semicircular composite
supernova remnant (SNR) 3C396 and performed a Chandra spatially resolved
thermal X-ray spectroscopic study of this young SNR. With our CO millimeter
observations, we find that the molecular clouds (MCs) at V(LSR)~84km/s can
better explain the multiwavelength properties of the remnant than the
V(LSR)=67-72km/s MCs that are suggested by Lee et al. (2009). At around 84km/s,
the western boundary of the SNR is perfectly confined by the western molecular
wall. The CO emission fades out from west to east, indicating that the eastern
region is of low gas density. In particular, an intruding finger/pillar-like
MC, which may be shocked at the tip, can well explain the X-ray and radio
enhancement in the southwest and some infrared filaments there. The SNR-MC
interaction is also favored by the relatively elevated 12CO J=2-1/J=1-0 line
ratios in the southwestern "pillar tip" and the molecular patch on the
northwestern boundary. The redshifted 12CO (J=1-0 and J=2-1) wings (86-90km/s)
of an eastern 81km/s molecular patch may be the kinematic evidence for shock-MC
interaction. We suggest that the 69km/s MCs are in the foreground based on HI
self-absorption while the 84km/s MCs at a distance of 6.2 kpc (the tangent
point) are in physical contact with SNR 3C396. The X-ray spectral analysis
suggests an SNR age of ~3kyr. The metal enrichment of the X-ray emitting gas in
the north and south implies a 13-15Msun B1-B2 progenitor star.Comment: 17 amulateapj pages, including 11 figures and 3 tables. Accepted to
ApJ. Version 2: minor correction
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